GASOMETRY; 
 
 COMPRISING THE LEADING 
 
 PHYSICAL AND CHEMICAL PROPERTIES 
 OF GASES. 
 
 
 vv 
 
GA SOME TRY 
 
 COMPRISING THE LEADING 
 
 PHYSICAL AND CHEMICAL PROPERTIES 
 
 OF GASES. 
 
 ROBERT B.UNSEN 
 
 PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF HEIDELBERG. 
 
 TRANSLATED BY 
 
 HENRY E. ROSCOE, B.A., PH.D. 
 
 WITH SIXTY ILLUSTRATIONS. 
 
 LONDON 
 PRINTED FOR WALTON AND MABERLY 
 
 UPPER GOWER STREET, AND IVY LANE, PATERNOSTER ROW. 
 1857. 
 
BRUNSWICK : 
 PRINTED BY FREDERICK VIEWEG AND SON. 
 
PREFACE. 
 
 It was the author's original intention merely to 
 arrange in a more connected and suitable form, 
 those methods of gasometric analysis which he 
 has from time to time published in his various 
 researches. In following out this idea it was soon 
 found, that in order to make the processes more 
 universally available, it was necessary to generalise 
 many methods which were previously only applicable 
 to special cases. This involved the execution of 
 a series of laborious experimental investigations, 
 a detailed account of which must be given, in 
 order that the processes described may rest on a 
 scientific foundation. The materials of gaseous 
 analysis, otherwise so limited, have thus received 
 no unimportant additions. 
 
 The three equations which the author has 
 employed for the calculation of the unknown re- 
 
VI PREFACE. 
 
 lation existing between the components of a mixture 
 of three combustible gases of known composition, 
 and from which the formula afterwards used by 
 Reiset and Regnault in their celebrated researches 
 on respiration are deduced, have been increased 
 by the addition of a fourth equation, obtained 
 from the volume of aqueous vapour formed by 
 the combustion of the hydrogen. Hence we are 
 able to determine by a single combustion -analysis 
 not only the unknown composition and conden- 
 sation of a combustible gaseous mixture of four 
 components, but also the unknown quantitative 
 relation of four known gases. By this means, as 
 well as by employing the absorption- together with 
 the combustion-analysis (as seen on page 182), 
 the composition of a gas can easily be found 
 which contains ten constituents, and of these 
 seven combustible gases. 
 
 In the chapter on absorption of gases in 
 liquids, the author has shown that the original 
 hypothesis of Henry, not borne out by any of 
 the previous experiments, is based upon an actual 
 law; which is found to apply with the greatest 
 precision when it is remembered, that the tem- 
 perature has often more influence on the values 
 of the coefficients of absorption than the nature 
 of the gas itself. 
 
PREFACE. VII 
 
 The absorptiometric methods, based upon this 
 law, serving as a means of detecting the con- 
 stituents of a mixed gas, will gradually become 
 of greater importance in proportion as the coef- 
 ficients of absorption of gases in -various liquids 
 are accurately determined. In as much as a large 
 field lies open for work in this direction, it is to 
 be hoped that a detailed account of the methods 
 employed may not be found uninteresting. 
 
 ROBERT BUNSEN. 
 Heidelberg. March 1857. 
 
 From the fact that the book now offered to the 
 English scientific public is the first and only work 
 on gaseous chemistry, and as the original German 
 and the English edition appear simultaneously, the 
 translator's has been a simple task. He has endea- 
 voured to render the translation as literal and 
 exact as possible, and the only additions which 
 be has thought it necessary to make are the 
 tables IX, X and XI in the appendix, for the 
 reduction of the constants now almost universally 
 employed in scientific research to those still par- 
 tially adopted in England. 
 
VIII PREFACE. 
 
 The eudiometers, and other glass apparatus 
 described in the work may be obtained from 
 Messrs. Negretti and Zambra meteorological in- 
 strument makers Hatton Garden. 
 
 H. E. R. 
 
 London. April 1857. 
 
CONTENTS. 
 
 Page 
 
 COLLECTION AND MEASUREMENT OF GASES 1 
 
 Collection of gases from geysirs or springs 5 
 
 Collection of gases issuing with aqueous vapour 7 
 
 Collection of atmospheric gases 10 
 
 Transference of gases 12 
 
 Collection of gases absorbed by liquids 15 
 
 Gases from furnaces 17 
 
 Quantitative transference of gases 20 
 
 Arrangement of a gas laboratory 21 
 
 Description of eudiometers employed 23 
 
 Method of graduating the tubes 25 
 
 Process of etching 27 
 
 Method of obtaining the cubic capacities of the tubes ... 30 
 
 Description of mercurial trough 33 
 
 Processes in gas analysis 35 
 
 Primary observations 36 
 
 Fundamental calculation 38 
 
 Example of the mode of calculation 39 
 
 GASOMETRIC ANALYSIS 42 
 
 Derivation of formulae 44 
 
 Precautions during explosion 46 
 
 Determination of aqueous vapour 47 
 
 Example of a combustion -analysis 50 
 
 Manipulation in the absorption of gases 53 
 
 Development of a general formula 54 
 
 Special determinations. 1. Nitrogen 58 
 
 2. Oxygen 66 
 
X CONTENTS. 
 
 Page 
 
 Analyses of atmospheric air 71 
 
 Special determinations. 3. Carbonic acid 80 
 
 4. Sulphuretted -hydrogen .... 83 
 
 5. Sulphurous acid 88 
 
 G. Hydrochloric acid 89 
 
 7. Hydrogen 91 
 
 8. Carbonic oxide 94 
 
 9. Marsh gas 99 
 
 10. defiant gas 103 
 
 11. Ditetryl gas 107 
 
 Analysis of Manchester coal gas 107 
 
 Special determinations. 12. 2Ethyl gas 114 
 
 SPECIFIC GRAVITY OF GASES 116 
 
 Methods of determining the specific gravity of gases . . . 118 
 
 Effusion method 122 
 
 Examples of the latter method 125 
 
 ABSORPTION OF GASES IN LIQUIDS 128 
 
 Derivation of general formulae 130 
 
 Determination of the coefficients of absorption 137 
 
 Example of the mode of calculation 140 
 
 Water freed from air 143 
 
 Determination of the coefficients of absorption 144 
 
 No. 1. For nitrogen in water 144 
 
 2. nitrogen in alcohol 144 
 
 3. hydrogen in water 145 
 
 4. hydrogen in alcohol 145 
 
 5. sethyl gas in water 146 
 
 G. carbonic oxide in water 147 
 
 ,, 7. carbonic oxide in alcohol 147 
 
 8. marsh gas in water 147 
 
 9. marsh gas in alcohol 149 
 
 10. methyl gas in water 150 
 
 11. olefiant gas in water 150 
 
 12. olefiant gas in alcohol 152 
 
 13. carbonic acid in water 152 
 
 14. carbonic acid in alcohol 153 
 
 15. oxygen in water 153 
 
 1C. oxygen in alcohol 158 
 
CONTENTS. XI 
 
 Page 
 
 No. 17. For nitrous oxide in water 158 
 
 18. nitrous oxide in alcohol 159 
 
 19. nitric oxide in alcohol 159 
 
 20. sulphuretted -hydrogen in alcohol .... 160 
 
 21. sulphuretted -hydrogen in water 103 
 
 22. sulphurous acid in alcohol 1G4 
 
 23. sulphurous acid in water 168 
 
 24. ammonia in water 169 
 
 25. atmospheric air in water 174 
 
 Practical applications of the law of absorption 175 
 
 Absorptiometric analysis of a mixture of two gases . . . 178 
 
 Absorptiometric analysis a new reagent in gasometry . . 182 
 
 Absorptiometric determination of two unknown gases . . 186 
 
 Gases absorbed in mineral springs 193 
 
 DIFFUSION OF GASES 198 
 
 Description of diffusioineter 200 
 
 Experimental determination of the laws of diffusion ... 201 
 
 Theoretical explanation of the laws of diffusion 219 
 
 Experimental verification of the theory 225 
 
 Conclusions 230 
 
 Diffusion an aid to gasometric analysis 231 
 
 Example of the diffusion of marsh gas 233 
 
 PHENOMENA OF THE COMBUSTION OF GASES 235 
 
 The heat of combustion 235 
 
 The temperature of combustion 238 
 
 The explosive force of gases 243 
 
 Peculiar action of diluents 253 
 
 Explanation of catalytic actions 254 
 
 Simple relation between the products of combustion . . . 256 
 
 APPENDIX. 
 
 TABLES FOR THE CALCULATION OF ANALYSES. 
 
 I. Table of the tension of aqueous vapour from 2 to 
 
 -f 35 C. (Regnault) 265 
 
 II. Table for the calculation of the value of (1 -f 0.00366 268 
 III. Table of the tension of the vapour of absolute alcohol 
 
 (Regnault) 274 
 
XII CONTENTS. 
 
 Page 
 IV. Table for the reduction of barometric observations 
 
 made upon a glass scale to C 276 
 
 V. Table of the specific gravities and composition by vol- 
 ume of gases 283 
 
 Table for the reduction of the pressure of a column of 
 
 water to a column of mercury 285 
 
 VI. Table of the coefficients of absorption of various gases 
 
 in water and alcohol 287 
 
 VII. Table for the calculation of the proportion of oxygen 
 
 and nitrogen contained in the air 290 
 
 VIII. Table for ascertaining the weights of given volumes of 
 
 gases 290 
 
 IX. Table for the reduction of temperatures from Fahren- 
 heit's to the centigrade scale 294 
 
 X. Table for the reduction of the barometric pressure from 
 
 millimetres into English inches 295 
 
 XI. Table for the reduction of French measures and weights 
 
 to English measures and weights 296 
 
COLLECTION, 
 
 PRESERVATION, AND MEASUREMENT 
 OF GASES. 
 
 A he preservation and collection of gases is the first, 
 and one of the most important operations in gasometry; 
 and, being accompanied by many experimental difficulties, 
 special precautionary measures must in every case be 
 adopted. 
 
 For the purpose of collecting gases, it is customary 
 to make use of small glass vessels, the contents of which, 
 consisting of either water, mercury, or air. are displaced 
 by the gas to be collected. Of these three fluids, water 
 is the one which is capable of the least general appli- 
 cation. This liquid gives rise to phenomena of absorp- 
 tion and diffusion, which cause the gas collected over 
 water to become mixed with varying amounts of atmo- 
 spheric nitrogen, oxygen, and carbonic acid. The gas 
 itself, also, dissolves in the water in quantities deter- 
 mined by the varying solubility, composition, and pres- 
 sure of its components: thereby causing an alteration not 
 
 i 
 
Fig. 1. 
 
 2 COLLECTION OF GASES. 
 
 only of the total mass , but also of the relative volumes 
 of its constituent parts. 
 
 The larger the volume, and the absorbing surface of 
 the water is, in proportion to the inclosed mass of gas, 
 the more considerable will be the impurity thus intro- 
 duced. In those cases only, in which gases of constant 
 composition pass continuously through a mass of water, 
 is this source of error avoided. This condition, however, 
 is often found in many springs in which the free and 
 absorbed gases already exist in a state of equilibrium. 
 
 In order to collect the gases from such a spring, to 
 which the experimenter can immediately approach, the 
 instrument represented by Fig. 1 is employed. The ap- 
 paratus consists of a small test 
 tube c having a capacity of about 
 40 to 60 cbc. This tube is drawn 
 out at a before the blowpipe, to 
 the thickness of a straw; and 
 is fixed by means of a cork, or 
 a vulcanized caoutchouc tube, 
 to the funnel b. Instead of the 
 test tube, a small longnecked 
 flask may be used, the neck of 
 which has been similarly drawn 
 out before the blowpipe. 
 
 The first operation is to fill 
 the apparatus with the spring- 
 water; this, however, cannot be 
 done without bringing the water 
 
 in contact with the air, whereby the composition of the 
 gas absorbed in the water would be altered. It is there- 
 fore necessary to immerse the tube with the mouth of 
 the funnel upwards, and to suck the water which has 
 
COLLECTION OF GASES. 3 
 
 been in contact with the air out of the apparatus, by 
 means of a small tube reaching to the lowest part, until 
 the whole has been displaced by other water from the 
 spring. The gases of the spring may now be allowed to 
 pass through the funnel into the tube, without any danger 
 of their being rendered impure. If the bubbles, in rising, 
 should be stopped in the neck of the funnel, or in the 
 narrow part of the tube , it is easy to make them ascend, 
 by tapping the edge of the funnel against any hard sub- 
 stance. 
 
 After the apparatus has been removed from the 
 spring by means of a small basin, the tube is melted off 
 at ; this is easily accomplished with the blowpipe, the 
 moisture on the part of the tube about to be melted 
 being previously expelled by the flame. 
 
 The column of water which rises in the funnel above 
 the level of the water in the basin, renders the pressure 
 on the gas less than that of the atmosphere ; hence no 
 bulging of the glass at the point of fusion can take place. 
 In order to have both hands free during the fusion, the 
 mouth blowpipe represented in Fig. 2 is employed. The 
 Fig 2 . small vessel a which ser- 
 
 ves as a lamp, contains 
 only about 3 grammes of 
 oil, and is connected with 
 the blowpipe by means 
 of a wire which can be 
 easily bent, and a small 
 ring fitting on to the 
 nozzle of the blowpipe. 
 By slightly bending this 
 wire, it is easy to give 
 the flame the requisite form, and length. The cork c 
 
 l* 
 
4 COLLECTION OF GASES. 
 
 serves as a mouth -piece, so that the whole apparatus 
 can be held and regulated with the teeth alone. By this 
 arrangement the flame can he placed at any instant in a 
 horizontal, vertical, or transverse direction; for the po- 
 sition of the point of the blowpipe to the lamp, remains 
 always the same, whichever way the little instrument 
 may be held. 
 
 If the small vessel drawn out before the blowpipe be 
 not at hand, a common bottle, or flask filled in the man- 
 ner just described, may be made use of. After the bottle 
 has been filled, the funnel is removed under the surface 
 of the water, and in its stead is placed a moistened cork 
 exactly fitting the neck of the bottle, and covered with 
 a thin and moistened plate of caoutchouc. In closing the 
 bottle under water, care must be taken that no liquid re- 
 mains above the cork. If the cork be now cut off close 
 to the neck, and covered with a layer of the finest sea- 
 lingwax, all possibility of the access of impurities from 
 the air is avoided, unless the sealingwax be cracked by 
 shaking, or by changes of temperature. 
 
 Gases evolved from volcanic lakes, geisers, or boil- 
 ing springs, can, in general, be collected in the manner 
 described. It is, however, often necessary to fasten the 
 apparatus upon a long stick in order not to be inconve- 
 nienced by the periodical discharge of vapours which 
 almost always accompany these springs. Should it 
 happen that the gas from such a hot spring be retained 
 in the narrow part of the tube, so that it collects in the 
 funnel, it may easily be driven into the tube by alter- 
 nately raising the apparatus into the cold air, and de- 
 pressing it into the hot water. The air expanded, during 
 the depression, by the heat of the spring, drives a small 
 quantity of water 'through the narrow opening, and by 
 
GEISERS AND SPRINGS. 5 
 
 cooling in the air a similar volume of gas is drawn into 
 the tube. 
 
 In volcanic districts especially, springs are often 
 found, either in such a state of ebullition and eruption, 
 or so peculiarly situated, that it is impossible to approach 
 near to them. In such cases the apparatus represented 
 in Fig. 3 may be used. This arrangement is also well 
 
 Fig- 3. 
 
 adapted for collecting the gases from the mud deposited 
 by any ordinary water. It consists of a funnel c weighted 
 with lead, attached by a vulcanized caoutchouc to a 
 long tin tube furnished with a stop -cock, at the end of 
 which are placed the small collecting tubes ccc. When 
 the apparatus has been immersed in the spring, and the 
 water drawn by suction up to the stop -cock 6, the gas 
 is allowed to collect in the funnel until it possesses a 
 pressure greater than that of the atmosphere. The stop- 
 cock b is then opened, and the gas is allowed to pass 
 through the collecting tubes ccc until all the atmospheric 
 air has been displaced. These tubes have a capacity 
 from 40 to 60 cbc., and the narrow ends are again drawn 
 out, and thickened, at the points at which they are melt- 
 ed off. Three or four such tubes connected together by 
 airtight vulcanized caoutchouc joinings, may be advan- 
 
G VOLCANIC GASES. 
 
 tageously employed for each operation. After slightly 
 heating, the system of tubes is closed simply by pressing 
 the first and last caoutchouc joinings with the fingers; 
 and as soon as the temperature has again diminished, so 
 that the atmospheric pressure slightly exceeds that of 
 the gas in the tubes, they are one by one hermetically 
 sealed. 
 
 Gases liberated from openings in rocks, from the 
 clefts of glaciers, from furnaces &c. &c. may be thus col- 
 lected, even when their tension only exceeds the atmo- 
 spheric pressure by O.l mm of mercury ; and in order to obtain 
 the gaseous products in a state of purity, it is only ne- 
 cessary to sink a tube to the depth from which it is desir- 
 ed to obtain them. When the openings at the end of the 
 collecting tubes have a diameter not larger than that of 
 a common pin, the gases pass through rapidly and easily, 
 under a very small pressure. This occurs with still greater 
 facility in the case of gases which issue mixed with steam 
 of considerable tension, as is found in the clefts, as well as 
 in the fumarole and solfatara plains of active volcanoes. 
 
 Under certain circumstances the collection of gases 
 is accompanied with great inconvenience. In volcanic 
 districts, for example, where large volumes of steam, and 
 boiling water are alternately discharged from the ope- 
 nings; and where the surrounding boiling mud is only 
 covered by a thin crust of hardened clay, it is adviseable 
 to test the stability of the ground with a rod in order 
 to secure a safe retreat in case of a sudden eruption of 
 hot vapour. The adoption of this precaution is particu- 
 larly necessary in the dangerous solfatara plains of Ice- 
 land. If these gases , as is usually the case , contain sul- 
 phuretted hydrogen, hydrochloric acid, or sulphurous 
 acid, which are decomposed by tin or lead, it is neces- 
 
ARTIFICIAL JET OF VAPOUR, 7 
 
 >ary to make use of a glass delivery tube, instead of a 
 metallic one, which, otherwise, is most convenient. 
 
 Should no natural source of vapour be found suitable 
 for experiment, an artificial one may be sometimes pro- 
 duced. For this purpose it is sufficient to bore a hole 
 in the hot softened fumarole clay, from which a jet of. 
 vapour generally issues. If a tube be sunk in this hole, 
 and the surrounding clay tightly stamped down, the gases 
 may be collected in the following manner. The jet of 
 vapour passing from the ground through the tube a, 
 Fig. 4, is led into the divided glass cylinder I half filled 
 Fig 4 with water, and of 
 
 known capacity. The 
 vapour is thus com- 
 pletely condensed 
 by the water, which 
 is kept as cold as 
 possible ; whilst the 
 gas, as soon as the 
 water is saturated, 
 passes through un- 
 altered, and expels 
 the air from the 
 cylinder &, and the 
 collecting tubes cec, 
 the end d of which 
 dips under water. 
 It often happens 
 
 that the volume of the permanent gases is very small 
 compared with that of the aqueous vapour; and that the 
 whole of the water in the cylinder, is raised to- the boil- 
 ing point before the air in the apparatus can be com- 
 pletely expelled by the small amount of permanent gas. 
 
8 GASES WITH AQUEOUS VAPOUR. 
 
 Under these circumstances it is necessary to fill the 
 whole apparatus with water which has been previously 
 saturated with the gas, by leading a stream of the vapour 
 through it. In this way the collecting tubes placed in 
 an inclined position, may be completely filled with gas, 
 before the water in the cylinder reaches the boiling point; 
 it is in this case scarcely necessary to allow the gas to 
 pass through the tubes for any length of time before 
 melting off with the blowpipe. 
 
 It is of great interest, in order to explain certain 
 important points concerning the theory of volcanoes, 
 
 to know approximately 
 the relation between 
 the volumes of volca- 
 nic gases, and the 
 aqueous vapour is- 
 suing simultaneously. 
 
 The apparatus re- 
 presented by Fig. 5 
 serves for this deter- 
 mination. The cylin- 
 der is filled up to a 
 certain height with 
 water, and the gas 
 delivery tube b dips a 
 few millimetres under 
 the surface of the 
 liquid. In place of the 
 small collecting tubes 
 a strong collodion bal- 
 loon , of known capa- 
 city, is fastened tightly 
 on to the exit tube e. 
 
DECOMPOSITION UNDER PRESSURE. 9 
 
 As soon as the delivery tube has been connected with 
 the tube immersed in the jet of vapour, the length of 
 time is observed which is required for tilling the balloon ; 
 and the volume of the condensed water is read off from 
 the divisions on the cylinder. In order to determine this 
 volume with accuracy, the delivery tube must be raised 
 in proportion as the volume of water increases, so that 
 at the end of the operation, the tube dips only a few 
 millimetres below the surface of the water in the cylin- 
 der b. The relation between the volume of the condensed 
 water, and the gas contained in the balloon, is thus ob- 
 Fig 6. tained with sufficient accuracy. The tension of 
 the escaping gases and aqueous vapour, may be 
 easily determined by simply sinking the delivery 
 tube communicating freely with the jet of vapour, 
 into the hot water contained in the cylinder, until 
 the bubbles of gas cease to rise through the liquid. 
 The depth of immersion observed, gives the amount 
 of pressure, above that of the atmosphere, under 
 which the gas, or aqueous vapour issues. 
 
 Many liquids are decomposed at a tempera- 
 ture above their boiling points, yielding gaseous 
 products. When it is required to collect these 
 gases for examination, the decomposition may 
 be effected in a glass tube, Fig. 6, 'of somewhat 
 greater diameter than a quill, and from 1 to 2 mm in 
 thickness. The tube, having been filled with the 
 liquid, is drawn out at a to a thickened capillary 
 which is hermetically closed as soon as all the air 
 has been expelled. The tube is then heated in a 
 bath of air, water, or oil, and when the decom- 
 position is complete, it is opened under a bell-jar 
 filled with water, or mercury. The gas issues 
 
1(1 
 
 COLLECTION OF GASES. 
 
 from the capillary tube in a fine stream, the evolution 
 continuing for some time. The success of this operation 
 depends essentially on the length and diameter of the 
 capillary tube. If it be so wide that the compressed gas 
 can escape very quickly, the tube is liable to be broken 
 by the suddenly expanding gas. When water is employed 
 to collect the gas, the atmospheric impurities intro- 
 duced must be accounted for in the analysis. The oxygen 
 thus introduced as an impurity, is very troublesome when 
 elayl, methyl, ethyl, or similar bodies are contained in 
 the gas. In this case, pure water may be replaced by a 
 solution of pyrogallate of potash, or sulphide of potassium, 
 and thus access of oxygen prevented. The nitrogen which 
 is then the sole impurity can easily be determined in the 
 analysis. 
 
 When free gases have to be collected in situations 
 easy of access, as for instance is the case in researches 
 on the composition of the atmosphere, or of the gaseous 
 mixtures contained in mines and caves, a common 
 flask of a capacity from 2 to 16 
 ounces,' may be advantageously 
 employed. The neck of this bottle 
 is somewhat thickened before the 
 blowpipe, at a distance of three- 
 quarters of an inch from the mouth, 
 and then drawn out to a tube hav- 
 ing a diameter of 2 min , as represen- 
 ted at a, Fig. 7. In order to effect 
 this contraction, the flask must first 
 be heated at the point at which the 
 bottle rounds off to the neck. If 
 the latter be brought directly to 
 the flame it is almost certain to 
 
VESSELS HERMETICALLY CLOSED. 11 
 
 crack off. The neck becomes so strongly heated that it 
 is impossible to hold it with the hand, and for this 
 purpose iron tongs (Fig. 8) into which the neek fits, may 
 Fifr 8 be used. In order to fill the bottle with gas, the 
 air is sucked out by means of a narrow glass 
 tube reaching to the bottom, until it is certain 
 that the previously contained air is replaced by 
 gas from without. Five or six deep inspirations 
 are sufficient for this purpose ; and the air drawn 
 from the bottle, must be removed from the space 
 .from which the gas is to be collected. The 
 glass closed by a cork, is then slightly heated 
 over a spirit lamp; and the heated gas inside 
 the bottle, is brought into equilibrium with the 
 outer air by carefully opening the cork for an 
 instant. The diminished pressure in the vessel 
 after cooling, prevents the bulging of the glass 
 during the fusion of the narrow neck. 
 
 When gases have to be collected on high mountains, 
 or other exposed places, great inconvenience is expe- 
 rienced in melting off the glass, owing to the impossibility 
 of producing a blowpipe flame even when the atmosphere 
 is tolerably still. In such cases, in the absence of a tent, 
 a large plaid is found to be sufficient. This simple co- 
 vering, which at once serves as a protection against cold, 
 wind, and rain, is strongly recommended to all those who 
 are occupied with researches on gases in uninhabited, and 
 mountainous districts. Under such a plaid, spread out 
 like a tent, the ends of which are held down by stones 
 to prevent currents of air, all the operations in which a 
 flame is necessary may be carried out in exposed situa- 
 tions, even during storms. 
 
 In this way, alone, I was able to collect the volcanic 
 
12 
 
 TRANSFERENCE OF GASES. 
 
 gases issuing from the fissures in the crater of Heel a 
 after the great eruption of 1845. 
 
 It is unnecessary to close the vessels containing 
 the gas, before the blowpipe, if it can be analysed 
 immediately after collecting. A common bottle may 
 then be used, closed by a soft, airtight cork, over which 
 a piece of sheet caoutchouc should be drawn. It is not 
 adviseable to collect the gas in vessels having a greater 
 capacity than from 40 to 100 cbc., on account of the 
 difficulty of transferring the gas from larger vessels over 
 the mercurial trough. But should the gas be received in 
 vessels which, owing to their size, cannot be brought 
 below the surface of the mercury in the trough, the neck 
 of the bottle must be placed under mercury, and the 
 cork withdrawn, and replaced by another the arrange- 
 
 Fig. 9. 
 
 ment of which is seen in Fig. V). 
 The glass tube b, passing through 
 the cork a, is connected airtight, 
 with the tube c by means of a 
 caoutchouc joining dd shewn in 
 section in the figure. The space in 
 the caoutchouc between the ends of 
 the two tubes, is filled by a solid 
 glass rod fitting loosely into it, so 
 that free communication between 
 the tubes b and c can at any time 
 be established or cut off, by IQOS- 
 ening or tightening a ligature round 
 the caoutchouc tube. This arrange- 
 ment which serves instead of a stop- 
 cock , but is much more secure, and 
 may be renewed in a few moments, 
 or easily placed at any part of the 
 
I'SE OF AIR-PUMP. 13 
 
 apparatus , is universally adopted in all investigations on 
 gases. When the cork has been placed airtight, in the 
 neck of the bottle under mercury, with the caoutchouc 
 valves closed, and the tubes I, b^ filled with mercury, 
 the bottle is set upright. It is then easy to transfer the 
 gas to the vessels in which it can be measured, by fixing, 
 by means of caoutchouc joinings, a funnel filled with 
 mercury on to the tube c x . and a capillary gas delivery 
 tube, also filled with mercury, on to the tube c. A current 
 of gas through the exit tubes may be thus continued, 
 or stopped, at pleasure, by opening or shutting the 
 ligatures. 
 
 Gases issuing with a certain tension from inaccessible 
 situations, must be withdrawn by means of an aspirator 
 or hand air-pump. A small air-pump Fig. 10 (see p. 14) 
 such as is commonly used for desiccation in organic 
 analysis, answers the purpose completely. The instru- 
 ment is screwed fast on to the middle of a small board 
 mi, upon which the experimenter stands during the ope- 
 ration. The gas is then pumped through the system of 
 collecting tubes b l> until all the air has been withdrawn. 
 
 Many solid substances, soluble in water contain gas 
 inclosed in their pores, as, for example, the decrepitating 
 >alt from Wieliczka. The gas thus contained, may be 
 collected in the following manner. Fifteen to twenty 
 litres of water is completely freed from air by continuous 
 boiling, in an open vessel, and kept at such a tempera- 
 ture that a slight ebullition takes place at that part of 
 the liquid most exposed to the action of the fire. The 
 glass tube represented by Fig. 1 together with the funnel, 
 is then filled with the boiling water, and the mouth of 
 the funnel placed on the bottom of the vessel. The de- 
 crepitating salt is now thrown into the boiling water, and 
 
14 GASES ABSORBED BY LJQUIDS. 
 
 the mouth of the funnel placed over it. The salt dis- 
 solves, and the gas is set free, and collects in the vessel c. 
 When the water under the funnel has become saturated 
 with the salt, it is easily renewed by rapidly moving the 
 
 Fig. 10. 
 
 funnel up and down in the boiler. As soon as the col- 
 lecting tube is filled with gas, it is hermetically sealed 
 at the drawn out extremity (a. Fig. 1). 
 
 In many investigations it is required to determine 
 the volume, and composition, of gases absorbed by liquids. 
 The nature of the atmosphere diffused through springs, 
 rivers, pools, and seas; the alterations which this atmo- 
 sphere undergoes at various depths; and the relations 
 which exist between this atmosphere and the living or- 
 
GASES ABSORBED BY LIQUIDS. 15 
 
 ganisms contained in it, are all questions which can only 
 be solved by these determinations. In order to collect 
 the water for such investigations from different depths, 
 a flask filled with water (Fig. 11) is sunk by means of a 
 
 rod or a string weighted with 
 lead, to the required depth, 
 
 V lr and a long gutta-percha tube 
 
 '?\ , reaching to the bottom of 
 
 * the flask, serves to suck out 
 
 the contained water, until the 
 whole has been replaced by 
 water from the particular layer 
 required. In order to prevent 
 a reflux of water from the 
 tube a, a stop -cock b or a 
 valve of caoutchouc, is attached 
 to the end of the tube. The 
 flask is closed by a plate of 
 caoutchouc bound over its 
 mouth, through a small slit in 
 which the tube a passes. The 
 elasticity of the caoutchouc 
 plate causes this opening to 
 
 shut completely as soon as the tube has been withdrawn; 
 the flask is therefore closed, and after being filled at the 
 requisite depth can be drawn up to the level of the 
 observer. When this has been effected, the caoutchouc 
 valve , Fig. 12 (see p. 16) previously filled with boiled 
 water, is quickly connected with the flask, and the ligci- 
 tures made fast. The tube b containing some water, is 
 next fastened to the caoutchouc a and this, again, is 
 connected with a second divided tube c, also furnished 
 with a caoutchouc valve d. The apparatus is then inclin- 
 
K; 
 
 COLLECTION OF ABSORBED GASES. 
 
 ed so that some water flows into the bulb b\ this is 
 boiled for some time, whilst the valve a is shut and the 
 Fi<>-. 12. valve d open, until the whole of the air 
 is displaced, and the tubes filled with 
 vapour of water: the caoutchouc tube c 
 is then completely closed by a ligature 
 or a screw-clamp. Immediately on open- 
 ing the valve a the water in the flask 
 begins to boil, and the absorbed gases 
 enter the vacuous space. If the flask be 
 heated for about an hour and half, not 
 beyond the temperature of 90 C., the 
 water continues to boil rapidly, and the 
 whole of the gas coming in contact with 
 the boiling water is excelled, and col- 
 lected in the tube c. By carefully heating 
 and inclining the body of the flask, the 
 vapour may be expanded, so as to drive 
 the boiling water up to the ligature d. 
 At the instant this takes place the valve 
 d is closed, the tube c removed from the 
 bulb 6, and opened under mercury by 
 carefully loosening the ligature e, and the 
 volume of the expelled gas is read oft 7 on 
 the divisions. 
 
 The nature of the gaseous educts 
 often varies with the progressive phases 
 of a decomposition, as, for instance, in 
 process of coking ; or in the phenomena 
 of combustion and decomposition occur- 
 ring in the strata of a furnace. It is 
 therefore, in these cases, necessary to 
 collect a series of specimens of gas during the progress of 
 
GASES FROM FURNACES. 17 
 
 the decomposition. To effect this at various depths in 
 the shaft of a furnace, the arrangement already described 
 at Fig. 3 may be used. The delivery tube must however, 
 be replaced by a long tube of wrought iron several inches 
 in diameter. The tube is fixed by means of a stand in 
 the centre of the shaft, on to the highest layer of coal, 
 so that the tube sinks gradually, with the addition of 
 the fresh layers. A tin tube, of the thickness of a fin- 
 ger, is soldered on to the upper end of the iron tube, 
 and carried to the place where the apparatus for collect- 
 ing the gas has been set up. By melting off, from time 
 to time, the collecting tubes, and replacing them by new 
 ones, the gas from any desired depth may be procured. 
 The condensed volatile products are collected in a gra- 
 duated cylinder placed before the tubes, which can be 
 occasionally changed. If a glass tube dipping vertically 
 under water, be joined to the end of the last collecting 
 tube, the pressure under which the gas issues at that 
 spot of the furnace where the tube ends, may be deter- 
 mined by noting the depth to which the glass tube must 
 be immersed in order that the current of gas should cease. 
 If gases of varying composition are liberated from 
 a closed vessel, they are best collected by the following 
 
 Fig. 13. 
 
 arrangement .(Fig. 13). The gaseous products evolved 
 from the retort a pass at first through both the tubes c 
 
 2 
 
18 COLLECTION OF GASES. 
 
 and b. The tube c is then dipped into a vessel containing 
 mercury d, so that the gas passes only through the tube b 
 and the following collecting tubes ee. If it is required 
 
 Fig. 14. 
 
 to fuse off a tube during the continuation of the process, 
 the open. caoutchouc tube is closed by pressure, and the 
 tube c raised out of the mercury, in order that a dimi- 
 nished pressure may prevent the bulging of the tube on 
 fusion. 
 
 In many investigations on mixed gases , it is neces- 
 sary to take several samples from the original volume of 
 gas. The apparatus Fig. 15 serves to collect large vol- 
 umes of a gaseous product, small portions of which can 
 be successively withdrawn for examination. It consists 
 of a cylinder a a filled with mercury, in which the bell- 
 jar bb can be moved up and down by means of the hold- 
 er c. The delivery and exit tubes e^e each furnished 
 with a caoutchouc valve dd^ stand inside this bell -jar. 
 When the bell -jar is to be filled, it must be sunk as far 
 as possible in the cylinder a a, care being taken that the 
 tubes ee, do not dip under the mercury. As soon as the 
 air has been completely displaced by the current of gas, 
 the valve d is closed, the bell -jar drawn out of the mer- 
 cury in proportion as it fills, and when this is accom- 
 plished, the valve d l is also closed. In order to take a 
 sample of the gas thus collected, a capillary gas delivery 
 
TRANSFERENCE OF GASES. 19 
 
 tube / filled with mercury, is fixed airtight into the closed 
 caoutchouc valve J, and the end of the delivery tube, 
 being placed under the vessel in which the gas is to be 
 
 Fig. 15. 
 
 collected, in the mercurial trough, the valve c^ is slowly 
 opened. 
 
 If the nature of the investigation require the trans- 
 ference of a given volume of gas without loss , it is ad- 
 viseable to employ the small mercury gasometer Fig. 16 
 (see p. 20) which possesses the great advantage of re- 
 quiring much less mercury than the arrangement just 
 described. The glass vessel a furnished with a tubulus, 
 
 2* 
 
20 TRANSFERENCE OF GASES. 
 
 bent upwards, and situated close to the foot of th'e glass, 
 is connected by a caoutchouc valve with the capillary 
 delivery tube c. The gasometer placed in a horizontal 
 
 Fig. 10. 
 
 position, is filled with mercury, whilst the caoutchouc 
 valve is closed; and on again placing the gasometer up- 
 right, the gas is collected through the tubulus b which, 
 if possible, should dip under mercury. When it is re- 
 quired to transfer the gas wholly, or partially, without 
 loss, the delivery tube is dipped into mercury under the 
 vessel in which the gas is to be collected, and a tube e 
 is fixed so deep in the tubulus Z>, by means of a well- 
 fitting cork, that the level of the mercury in the tube rises 
 to about the point /, whilst the surface in the gaso- 
 
MEASUREMENT OF GASES. 21 
 
 meter stands at a lower level; as, for instance, at </. The 
 valve d can now be opened, and it is only necessary to 
 pour mercury into the tube e, in order to transfer the 
 whole, or any required portion of the gas into another 
 vessel. Should the caoutchouc tubing of the valve J, as 
 is usually the case, remain completely closed even after 
 the removal of the ligature, the sides must be slightly 
 pressed together to establish the communication, and by 
 a greater or less pressure of the fingers the current of 
 gas may be most exactly regulated. 
 
 The volume of gas in the capillary tube is so extreme- 
 ly small in comparison with that in the gasometer, 
 that the error incurred by its remaining behind in the 
 tube may in most cases be considered inappreciable. But 
 to be free from all error it is only necessary to determine 
 the volume of the capillary by filling it with mercury, and, 
 then to allow for this volume in the calculation. 
 
 Having thus become acquainted with the most im- 
 portant operations of collecting and preserving gases, we 
 can now proceed to describe the methods employed for 
 their measurement. 
 
 All eudiometrical investigations must be conducted 
 in a situation which is as much as possible protected 
 from changes of atmospheric temperature; and, at the 
 same time, light enough to admit of exact measurement 
 with a telescope. For this purpose, it is desireable to 
 employ a room, having thick walls, not adjoining heated 
 chambers, and with one or two large windows having a 
 north aspect. The temperature of such a gas laboratory 
 does not alter more than 1 C. in a day, even when 
 sudden variations of 8 to 12 C. occur in the open air. 
 The experiments are conducted upon a large table (Fig. 17, 
 see p. 22) furnished with a rim, and a tube a to carry off 
 
22 
 
 GAS LABORATORY. 
 
 Fig. 17. 
 
Fig. IS. Fig. -20. 
 
 DESCRIPTION OF EUDIOMETERS. 
 
 the mercury which is spilled during the operations. Two 
 upright supports bb, about 1.5 m to 2 U1 high, are firmly 
 fixed at each end of the table; these supports are fur- 
 nished with moveable arms cc, which can be placed in any 
 direction on the table, and serve as holders for the baro- 
 meter 7s, and the eudiometer //*. 
 The cathetometer used for read- 
 ing off the height of the volumes 
 of mercury in both of these in- 
 struments is represented in the 
 figure at pp. 
 
 The measurement of the vol- 
 ume of a gas is effected in eu- 
 diometers, and absorption tubes, 
 on which millimetre divisions 
 have been finely etched; the cor- 
 responding volumes being after- 
 wards accurately determined. The 
 absorption tube Fig. 18 is about 
 250 mm long, 20 mm in diameter, 
 and of about 60 cbc. capacity. 
 The open end, as is seen in the 
 figure, is furnished with a small 
 lip, by means of which the mea- 
 sured volume of gas can be trans- 
 ferred over mercury, without loss. 
 The tube Fig. 19 differs from the 
 first by terminating in a small 
 retort used for receiving the ab- 
 sorbing substances. The eudio- 
 meter Fig. 20 is about 20 mm in 
 diameter, and from 500 to 600 111111 
 long, and has a capacity of about 
 
 Fig. U. 
 
24 DESCRIPTION OF EUDIOMETERS. 
 
 1 60 cbc. Besides this instrument, the glass of which need 
 only be about 2 mm in thickness, two others of similar 
 construction, but of larger dimensions are required. One 
 of these eudiometers having the same diameter and thick- 
 ness of glass as the first, is from 700 to 800 mm long, the 
 other contains from 500 to 600 cbc., and is 22 mm in inter- 
 nal diameter. Platinum wires for passing the electric 
 spark through the gases, are fused into these tubes, the 
 wires are bent into the curve of the tube, so that the 
 ends remain about 1 to 2 mm apart. It is not advise able 
 to have the wires placed straight across the head of the 
 eudiometer, as in this case they are very liable to be 
 bent, in cleaning, or in filling the instrument with 
 mercury. 
 
 Great care must be taken in fusing the wires into 
 the glass, to prevent the slightest opening between the 
 glass and the wire, which, although too small to allow 
 even strongly compressed air to pass through, may still 
 effect a diffusion of the inclosed gases. These interstices 
 are best avoided by choosing a glass whose coefficient of 
 expansion is as nearly as possible equal to that of pla- 
 tinum. The wires are melted into the glass in the fol- 
 lowing manner; the eudiometer heated before the glass 
 blowpipe, is touched at the required point with a white- 
 hot platinum wire, and as the wire adheres firmly to the 
 hot tube, a fine thread of glass may be drawn out, which, 
 when cut off, forms a small opening into which the wire 
 can be melted. To avoid the contact - action of the pla- 
 tinum, it is well to amalgamate the wires. This is best 
 done by bringing them in contact with zinc -amalgam and 
 hydrochloric acid, as the negative electrode in the circuit 
 of a galvanic battery. This precaution, however, is scar- 
 cely necessary, as the surface of the platinum is very 
 
MEASUREMENT OF GASES. 25 
 
 soon covered with foreign bodies. Before the tube is 
 furnished with a scale of divisions, it must be carefully 
 examined to see if the fusion of the wires has been com- 
 plete. For this purpose the eudiometer is completely 
 tilled with mercury, and the open end, dipping under 
 mercury, is knocked against the bottom of the trough 
 as forcibly as the brittleness of the glass will permit. 
 The column of mercury thus receives a sudden downward 
 motion, and a momentary vacuum is formed at the upper 
 end of the tube ; if the wires are not properly fused into 
 the glass, a small bubble of air will be seen to ascend 
 each time into the vacuous space. The eudiometer, hav- 
 ing successfully stood this examination, may next be gra- 
 duated. I employ for this operation a copying machine 
 of very simple construction. 
 
 In the groove a a, Fig. 21 (see p. 26), lies the model- 
 tube of hard glass 66, with millimetre divisions etched 
 upon it, from which the eudiometers are graduated. This 
 tube is fixed firmly down with a straight slip of thin 
 brass, which is pressed against it by screws ccc, so that 
 the curvature of the glass rises a little above the edge 
 of the brass slip. The tube to be graduated dd, covered 
 with a thin coating of wax, is fastened in a similar man- 
 ner with two pieces of brass, the edges of which are 
 separated a few millimetres at the part of the tube on 
 which the divisions are to be made. The deeply etched 
 divisions on the normal tube can easily then be transfer- 
 red on to the waxed surface of the tube dd by means of 
 the rod, represented in the figure, which has a knife 
 edge at one end, and a sharp point at the other. This 
 can be done with great accuracy and rapidity by allow- 
 ing the sharp point of the rod, guided by the thumb and 
 fore -finger of the left hand, to pass lightly from one 
 
26 
 
 GRADUATION OF TUBES. 
 
 division to another on 
 the normal tube, the 
 sense of touch, and the 
 ear, alone regulating the 
 movement. By a little 
 practice it is, in this way, 
 easy accurately to trans- 
 fer from 50 to 60 divi- 
 sions per minute, without 
 once looking at the gra- 
 duation. The length of 
 the divisions transferred 
 to the waxed tube de- 
 pends upon the distance 
 between the slips of brass 
 ee. The longer divisions 
 for the whole-, and half- 
 centimetres, are formed 
 by the knife edge pass- 
 ing into grooves in the 
 brass slip, which have 
 been previously made to 
 coincide with the divi- 
 sions by slightly moving 
 the normal tube. To pre- 
 vent the thin wax co- 
 vering on the tube from 
 being removed by the 
 pressure of the brass 
 slips, and the glass thus 
 laid bare, two small 
 square rods of brass are 
 soldered along the edge 
 
PROCESS OF ETCHING. 27 
 
 of each slip, pressing on the glass at such a distance that 
 it matters little if some of the wax be there rubbed off. 
 
 In order to etch on to the glass the divisions thus 
 graven on the wax, some finely powdered fluor spar is 
 strewed at the bottom of a leaden gutter, Fig. 22 a , and 
 
 Fig. 22. 
 
 covered with a large quantity of strong sulphuric acid. 
 The leaden gutter is then heated in several places with 
 the spirit-lamps bbb until a rapid evolution of hydro- 
 fluoric acid begins, the lamps are then removed, and the 
 tube covered with a sheet of paper , is placed above the 
 mixture , and allowed to remain exposed to the acid va- 
 pour for from 3 to 15 minutes, according to the hardness 
 of the glass. The etching is sharp and clear only when 
 the hydrofluoric acid is anhydrous ; but this can be easily 
 effected by the presence of an excess of sulphuric acid. 
 In order to see whether the operation is complete, the 
 depth of the etching on one of the lower divisions, which 
 may be destroyed without any detriment to the instru- 
 ment, is examined with the fingernail. The divisions are 
 still better etched if the mixture of fluor spar and sul- 
 phuric acid is not heated at all, and if the tube remains 
 for several hours exposed to the action of the vapour. 
 
 If it be required to divide any given length into a 
 certain number of equal parts, the arrangement repre- 
 sented in Fig. 23 (see p. 28) may be used. On a plate 
 
28 GRADUATION OF TUBES. 
 
 of hard glass, a system of lines is etched all starting 
 from a point, and extending to the line al. The use of 
 this arrangement is best explained by an example. For 
 instance, in order to divide a length of eleven millimetres 
 
 Fig. 23. 
 
 into thirteen equal parts, it is necessary to find the point 
 at which the first line is eleven millimetres distant from 
 the thirteenth; the brass slip is then placed at this point 
 parallel to the line a&, and the thirteen divisions trans- 
 ferred to the waxed tube according to the method just 
 described. 
 
 The etched graduation on the tube cannot be used 
 as representing the cubic capacity of the instrument ; for 
 in the first place the calibre of such tubes is not constant 
 for any moderate length; and, in the second place, the 
 volume of gas at the closed end of the eudiometer cannot 
 correspond to the number etched on the divisions.- It is 
 therefore necessary, in order to determine these cubic 
 irregularities, to pour the same portion of mercury into 
 various parts of the tube , and to read off in each case 
 the height to which the mercury rises on the divided 
 scale. The error introduced by the supposition that 
 the tube is cylindrical within the length occupied by 
 each small column of mercury , is inappreciable. 
 
PROCESS OF CALIBRATION. 
 
 29 
 
 This operation is conducted in the following manner. 
 The eudiometer with its closed end downwards, is firmly 
 fixed in a vertical position, and a measured quantity of 
 mercury, enough to cover about twenty divisions, is 
 poured in from a tube. The height of this volume of 
 mercury is then accurately read off on the graduation, 
 and in order to avoid heating the mass, as well as to 
 eliminate the errors arising from parallax, this is best 
 Fig 24 accomplished by 
 
 C? means of a tele- 
 
 scope sliding 
 upon a vertical 
 support (see Fig. 
 17 pp). A short 
 test tube of thick 
 glass furnished 
 with a wooden 
 handle a, Fig. 24, 
 serves to. contain 
 the measured 
 quantity of mer- 
 cury, and the ex- 
 cess of the mer- 
 cury is expelled 
 from the tube by 
 means of aground 
 glass plate, which 
 ispressedagainst 
 the ground edge 
 of the tube in 
 the manner seen 
 in the figure. The 
 measure is filled 
 
30 
 
 PROCESS OF CALIBRATION. 
 
 with mercury from the vessel b furnished with a glass 
 tube, and stop -cock; and in order to prevent the forma- 
 tion of bubbles on the sides of the measuring tube, the 
 point c is placed at the bottom of the measure. The 
 mercury is then poured into the eudiometer through a 
 Fig. 25. long funnel. Any bubbles of air which 
 remain between the sides of the eudio- 
 meter and the mercury must be carefully 
 removed by means of a slip of wood , or 
 of whalebone. If an iron wire be used 
 instead of these, the glass is apt to be 
 slightly scratched, and these almost in- 
 visible scratches become in time larger, 
 and give rise to cracks which render the 
 instrument entirely useless. 
 
 110 
 
 too 
 
 70 
 
 .644 
 
 ....23.3 
 
 Iff 
 
 Supposing that 
 
 the first reading off was at b 23.3 (Fig. 25) 
 second c 44.0 
 third d 64.4 
 fourth e 84.4 
 
 the volume of mercury used for the mea- 
 surement occupied 
 
 between /> and c the volume 20.7 
 c d 20.4 
 d e 20.0 
 
 If the volume of the measuring mer- 
 cury be supposed to be 20.7 (the largest 
 amount read off on the instrument) ; the 
 volume contained up to each of the ob- 
 served divisions is, 
 
CALCULATION OF VOLUME. 
 
 23.3 volume 1 X 20.7 = 20.7 
 44.0 2 X 20.7 = 41.4 
 
 64.4 3 X 20.7 = 62.1 
 84.4 4 X 20.7 = 82.8. 
 
 These 20.7 volumes are however equal to 20.0 vo- 
 lumes read off between e and d\ therefore one division 
 between these two points of the scale corresponds to a 
 20.7 
 
 rolume 
 
 20.0 
 
 = 1.035, and one tenth of a division = 0.1035. 
 
 In a similar manner the corresponding volumes are found 
 for the interval on the scale 
 
 from dc - = 1-0147 and 0.10147 
 
 bc " = L000 and aiooo and so 
 
 By means of these calculations it is easy to find the 
 volume corresponding to each graduation on the tube. The 
 results are arranged in a table similar to that given below. 
 
 I. 
 
 II. 
 
 I. 
 
 II. 
 
 I. 
 
 II. 
 
 I. 
 
 II. 
 
 I. 
 
 II. 
 
 
 
 
 17 
 
 
 34 
 
 31.40 
 
 51 
 
 48.50 
 
 68 
 
 65.84 
 
 1 
 
 
 18 
 
 
 35 
 
 3240 
 
 52 
 
 49.52 
 
 69 
 
 66.88 
 
 2 
 
 
 19 
 
 
 36 
 
 33.40 
 
 53 
 
 50.53 
 
 70 
 
 67.91 
 
 3 
 
 
 20 
 
 
 37 
 
 34.40 
 
 54 
 
 51.55 
 
 11 
 
 68.95 
 
 4 
 
 
 21 
 
 
 38 
 
 35.40 
 
 55 
 
 52.56 
 
 72 
 
 69.98 
 
 5 
 
 
 22 
 
 
 39 
 
 36.40 
 
 56 
 
 53.58 
 
 73 
 
 71.02 
 
 G 
 
 
 23 
 
 20.40 
 
 40 
 
 37.40 
 
 57 
 
 54.59 
 
 74 
 
 72.05 
 
 7 
 
 
 24 
 
 21.40 
 
 41 
 
 38.40 
 
 58 
 
 55.60 
 
 75 
 
 73.09 
 
 8 
 
 
 25 
 
 22.40 
 
 42 
 
 39.40 
 
 59 
 
 56.62 
 
 76 
 
 74.12 
 
 9 
 
 
 2G 
 
 23.40 
 
 43 
 
 40.40 
 
 60 
 
 57.63 
 
 77 
 
 75.16 
 
 10 
 
 
 27 
 
 24.40 
 
 44 
 
 41.40 
 
 61 
 
 58.65 
 
 78 
 
 76.19 
 
 11 
 
 
 28 
 
 25.40 
 
 45 
 
 42.41 
 
 62 
 
 59.66 
 
 79 
 
 77.22 
 
 12 
 
 
 29 
 
 20.40 
 
 46 
 
 43.43 
 
 63 
 
 60.68 
 
 80 
 
 78.26 
 
 13 
 
 
 30 
 
 27!40 
 
 47 
 
 44.44 
 
 64 
 
 61.70 
 
 81 
 
 7930 
 
 14 
 
 
 31 
 
 28.40 
 
 48 
 
 45.46 
 
 65 
 
 62.74 
 
 82 
 
 80.33 
 
 15 
 
 
 32 
 
 29.40 
 
 49 
 
 46.47 
 
 66 
 
 63.77 
 
 83 
 
 81.37 
 
 10 
 
 
 33 
 
 30.40 
 
 50 
 
 47.49 
 
 67 
 
 64.81 
 
 84 
 
 8240 
 
 
 
 
 
 
 
 
 
 &c. 
 
 &c. 
 
32 ERROR OF THE MENISCUS. 
 
 The linear divisions are given in column I, whilst 
 column II gives the corresponding capacity of the tube 
 according to an arbitrary, but comparable standard. The 
 immediate readings off represented in the first column, 
 must then be exchanged for the corresponding corrected 
 volume in the second column. The volume taken from 
 the table corresponding to the division read off on the 
 eudiometer, still requires a slight correction. When the 
 volume of the eudiometer is determined with the open 
 end of the tube upwards, the height of the mercury must 
 always be read off at the highest point of the meniscus, 
 at a a, Fig. 26; the volume thus read off is not, however, 
 equal to the total capacity of the tube up to 
 the division a, that is the volume aab, but 
 to the volume ccb\ the volume read off is 
 therefore less than the required volume by the 
 space a ace. If the instrument be now placed, 
 as when in use, with the open end downwards, 
 a volume of gas read off exactly at a will cor- 
 respond still less to the volume of mercury 
 cob employed in the graduation, for it is easy 
 to see that the gas now occupies a space larger 
 by twice caac than the volume of the gra- 
 duating mercury. Twice the spaae caac must, 
 therefore, be added to the volume of the gas 
 as contained in the table. This volume, ex- 
 pressed in divisions of the tube , can be deter- 
 "& mined once for all. This is done by pouring 
 some mercury into the tube placed with its 
 closed end downwards , and reading off the height of the 
 meniscus. A few drops of sublimate solution are now 
 poured into the tube , and the surface of the mercury im- 
 mediately becomes perfectly horizontal. Twice the space 
 
PROCESSES IN GAS ANALYSIS. 33 
 
 between the first curved surface of the mercury, and the 
 same surface, rendered horizontal, gives the constant 
 volume which must be added to each reading off, and 
 may be called the error of the meniscus. 
 
 It is not often required to reduce these determina- 
 tions of relative volume to absolute measure. Should 
 this be the case, it is only necessary to know the weight 
 g and temperature t of a mass of mercury which occu- 
 pies the volume V used in the graduation. The coef- 
 ficient of expansion of mercury is 0.0001815 and its spe- 
 cific gravity at C. 13.596, hence the volume of a redu- 
 ced division expressed in cubiccentimetres c is found 
 from the formula 
 
 _ g x (1 + 0.0001815 t) 
 13.596 V 
 
 The measurements necessary in gas analysis are best 
 performed in a small mercurial trough (Fig. 27) about 
 
 Fig. 27. 
 
 O m 350 long, and O m 080 broad. This trough has two 
 transparent sides of plate glass, and the bottom and 
 
 . 3 
 
34 PROCESSES IN GAS ANALYSIS. 
 
 other sides of the trough is made of dense pear wood, 
 which is well rubbed with sublimate solution and mercury 
 before use, to ensure adhesion of the metal. The trough 
 stands on a board c into which is fixed one, or better, 
 two standards </, for supporting the groove ee lined with 
 felt, in which the eudiometer lies. 
 
 If gas has to be transferred from large vessels, a 
 similar but larger mercurial trough must be employed. 
 F . 2g F; 29 Particular precautions must be 
 
 taken in filling the eudiometers with 
 mercury, and in transferring the 
 gases. The instrument having been 
 washed out with water, must be 
 cleaned and dried with filtering 
 paper. This is best done by a 
 wooden rod (Fig. 28), which is fur- 
 nished at the upper end with a num- 
 ber of points of wire projecting half 
 a millimetre from the surface of the 
 wood, and serve to hold the roll of 
 paper firm. In cleansing the eudio- 
 meter care must be take to remove 
 all fine threads of paper so that no 
 error from their combustion should 
 ensue on the explosion of the gas. 
 When practicable, a drop of water 
 is brought into the head of the tube 
 thus cleaned, by means of a glass 
 rod, so that the collected gas is perfectly sa- 
 turated with aqueous vapour. In order to fill 
 the eudiometer with mercury, the funnel Fig. 29 
 containing the metal is placed in the opening 
 of the reversed instrument. This funnel is 
 
PROCESSES IN GAS ANALYSIS. 35 
 
 fastened on to a long fine tube, the end of which reaches 
 to the bottom of the eudiometer; the mercury issues in 
 a fine stream, and gradually rises in the tube, forming 
 a mirror -like surface on the sides of the instrument, to 
 which one bubble of air now adheres around the pla- 
 tinum wires. In order to expel this bubble from the 
 platinum wires the eudiometer is placed with its open 
 end under the surface of the mercurial trough, and by 
 knocking the end against the bottom of the trough, the 
 bubble is detached from the wire, and is seen between 
 the surface of mercury and the glass. As soon as this 
 occurs, it is easy to let the bubble rise in the tube, which 
 is held reversed and closed by the thumb. The mercury 
 is apt to be thrown about in filling the long eudiometers ; 
 this is best avoided by sinking the tube to be filled, by 
 means of strings, into the tube a in the table Fig. 17, 
 through which the excess of mercury is carried into the 
 vessel /. 
 
 When it is required to transfer the gas from the 
 collecting tubes into the eudiometer, the closed end of 
 the tube is broken under mercury, by pressure against 
 the bottom of the trough ; and the aperture thus made 
 is brought under the open end of the eudiometer; the 
 gas is then easily displaced by giving the inclined tube 
 an oscillating motion, when the gas rises into the eudio- 
 meter even if the broken aperture is not large. 
 
 It often happens that in this operation small bubbles 
 of air remain hanging between the inside of the tube, 
 and the mercury. These bubbles must be carefully re- 
 moved into the gas contained in the upper part of the in- 
 strument, by setting the column of mercury in oscillation, 
 so that the upward motion is more rapid than the down- 
 ward. This is best effected by placing the eudiometer in 
 
 3* 
 
36 PRIMARY OBSERVATIONS. 
 
 the groove ee, Fig. 27, and giving it a quick downward, 
 and still quicker upward motion, so that the movement 
 of the tube is synchronous with the oscillations of the 
 column of mercury. 
 
 If mercury has to he added to that already contained 
 in the trough, care must be taken to pour, in the metal 
 at a considerable distance from the eudiometer and ab- 
 sorption tubes, as bubbles of air may thus be carried 
 under the mercury into the instruments, even when their 
 lower ends dip several inches below the surface. 
 
 Every determination of the volume of gases requires 
 the following four primary observations: 
 
 1. The level of the mercury in the eudiometer. 
 
 2. The level of the mercury in the trough, measured on 
 the etched divisions on the eudiometer. 
 
 3. The atmospheric temperature. 
 
 4. The barometric pressure. 
 
 All these observations are made by help of the tele- 
 scope g, Fig. 17, which can be moved up and down upon 
 a vertical wooden rod. If such a telescope be placed at 
 a distance of from 6 to 11 feet from the object observed, 
 the small displacement from the horizontal position, which 
 is unavoidable with a wooden stand, does not produce 
 any perceptible amount of parallax, particularly whe-n 
 the observation is made in the middle of the field of 
 view. In the first place the highest level of the mercury 
 meniscus in the eudiometer is read off on the etched di- 
 visions; and in the second place the level of mercury in 
 the trough is also read off on the same divided scale. 
 The first observation gives the volume of gas to be found 
 in the table, of capacity of the instrument; and the second 
 observation minus the number read off in the first obser- 
 vation, gives the height of the column of mercury, which 
 
PRECAUTIONS IN READING OFF. 37 
 
 acts in opposition to the barometric pressure, and must, 
 therefore, be subtracted from that quantity. For the 
 measurement of the atmospheric pressure the syphon ba- 
 rometer A, Fig. 17, is employed, placed in a vertical po- 
 sition in the neighbourhood of the eudiometre. The 
 height of the mercury is read off on a millimetre scale 
 which is etched on the two limbs, lying in one vertical 
 line. The thermometer is also furnished with a scale 
 etched on the glass ; and rests in the shorter limb of the 
 barometer supported by a small spring of whalebone. By 
 means of this arrangement all the observations can be 
 made from distant positions with very slight alterations 
 of the telescope. 
 
 Before the apparatus has been left to assume a con- 
 stant temperature it is adviseable to direct the telescope 
 upon the divisions, which should be cleaned with filter- 
 paper and rubbed with a little vermilion to render them 
 more plain. For the purpose of throwing a better light 
 on the lower divisions, a small paper screen , Fig. 30, 
 
 is placed between the mercury 
 and the glass side of the trough, 
 and the surface of the mercury 
 and the divisions of the scale 
 are seen through a slit m in 
 the screen. The barometer is 
 always read off last ; as it then 
 is necessary to approach the 
 tubes in order to give the mer- 
 cury in the barometer a slight 
 motion, to destroy any adhe- 
 sion between it and the glass. 
 This motion can be best ef- 
 fected by dipping the bulb of 
 
 Fig. 30. 
 
38 FUNDAMENTAL CALCULATION. 
 
 the thermometer i into the metal in the lower limb of 
 the barometer. 
 
 In order that the alterations of temperature of the 
 mercury, should coincide as much as possible with those 
 of the surrounding air, it is well to employ as little of 
 the metal as possible ; and to allow from half an hour to 
 two hours to elapse between each observation. The vo- 
 lumes of gas are always read off with the eudiometer 
 placed in a vertical position. For this purpose vertical 
 lines may be drawn on the wall of the room, and by 
 comparison with these the tube may be placed in the 
 required position. * 
 
 The observed volumes of gas are reduced by calcu- 
 lation ,to the volumes occupied in the dry state at 
 centigrade and under a pressure of 1 metre of mercury. 
 This volume v 1 of dry gas reduced to C. and l m is 
 found from the equation, 
 
 (v + m) (b - b, - b,} 
 
 (1 4- 0.00366 *) 
 
 in which b represents the height of the barometer, 6 L the 
 height of the column of mercury rising from the level of 
 the trough into the eudiometer, t the observed tempe- 
 rature, b 2 the tension of aqueous vapour* for the tem- 
 perature t , m the error of the meniscus , and lastly v the 
 volume of gas found in the table of capacity. 
 
 This reduced value v 1 is one which is employed in all 
 the calculations. 
 
 The following measurement of the same volume of 
 
 These tensions are found in table I calculated by Rcgnault 
 from his own experiments- Table II contains the values of 
 1 -]~ 0.003GG t for a range of temperature from 2 to 40 C. 
 Table III contains the tension of the vapour of absolute alco- 
 hol calculated from Kegnault's experiments. 
 
EXAMPLE OF CALCULATION. 39 
 
 air first saturated with aqueous vapour, and afterwards 
 dry, may serve as an example of the calculation. 
 
 1. Air saturated with moisture. 
 
 Observation at the lower level of mercury . = 565.9 min 
 Observation at the upper level in eudiometer = 317.3 
 Height of column Z^ to be subtracted from 
 
 barometer = 248.6 
 
 The division 317.3 corresponds to a volume 
 
 in the table of capacity v =292.7 
 
 Correction for the meniscus m = 0.4 
 
 Temperature of the air t = 20.2 C. 
 
 Height of the barometer b = O m 7469 
 
 Tension of aqueous vapour for 202 C. . b. 2 = O m 0176 
 
 log. (v +') = log. 293.1=2.46702 
 4- log. (I l>i b y ) = log. 0.4807 = 0.681871 
 +compl. log. (1+0.00366 t)=compl. log. 1.0739 = 0.969031 
 
 log. 01 = 2.11792 
 t;i = 131.20 
 
 2. The same volume of air dried over chloride of calcium. 
 Observation at the lower level of mercury . = 565.9 
 Observation at the upper level in eudiometer- = 310.7 
 Height of column b v to be subtracted from 
 
 the barometer = 255.2 
 
 The division 310.7 corresponds to a volume 
 
 in the table of capacity v = 286.0 
 
 Correction for the meniscus m = 0.4 
 
 Temperature of the air * = 20.2 C. 
 
 Height of the barometer b = 0.7474 
 
 log. (v + m) = log. 286.4 = 2.45697 
 _|_ log. (b bj) = log. 0.4922 = 0.692141 
 +compllog. (1 + 0.00366 t)=compLlog.W739 = 0.969031 
 
 log. v 1 = 2.11814 
 
40 CORRECTIONS FOR TEMPERATURE. 
 
 If the temperature of the gas laboratory, as is usually 
 the case, only varies one or two degrees during the ope- 
 rations of a gas analysis, the error arising from the va- 
 riation in density which the mercury undergoes is so 
 small that unless the determination is a normal one, it 
 may be overlooked. When the variations in temperature 
 exceed these limits, or when it is required to determine 
 not only the relative, but also the absolute volume of a 
 gas, the column of mercury (b 6J must be reduced 
 from the atmospheric temperature to C. by substituting 
 for (b bi) the expression 
 
 in which a represents the coefficient of lineal expansion 
 of glass = 0.0000092, and /3 the coefficient of cubic ex- 
 pansion of mercury = 0.0001815. The columns of mer- 
 cury O m 4922 and O m 4807 in the former example when re- 
 duced to according to the formula, become O m 49049 
 and O m 47903. In order to avoid this troublesome calcu- 
 lation, the table IV in the appendix is employed, in which 
 the expansion of the glass as well as the mercury is 
 allowed for. The first vertical division contains the lengths 
 of the observed columns of mercury for every 5 milli- 
 metres, and the following divisions contain the amounts 
 of expansion of these columns for each degree of the 
 centesimal scale from to 9. 
 
 The use of the table is best explained by an example. 
 Required to reduce the column of mercury 0.7105 observ- 
 ed at 234 C. to C. The nearest pressure in the table 
 is found to be 0.7100. The intervals in the table are 
 so chosen, that the difference between any observed pres- 
 sure, and the nearest number found in the table is so 
 
EXPANSION OF MERCURY. 41 
 
 small, that any alteration of density on this small length, 
 arising from variation of temperature, is inappreciable. 
 Hence the numher which must be subtracted from the 
 pressure 0.7100 to give its length at C. may also be 
 subtracted from the observed pressure 0.7105 without 
 exceeding the limit of the observational errors. The 
 column 0.7105 has then in cooling from 234 to 
 
 subtracted 
 
 for 20^0 2.4296 mm 
 
 30 0.3644 
 
 QQ4 0.0186 
 
 for 2304 2.8126""" 
 
 These 2.8126 mm subtracted from O m 7105 give the length 
 at Oo to be 0.70769 m . 
 
GASOMETRIC ANALYSIS. 
 
 One of the most important problems in gasometry 
 consists in the determination of the nature , volume , and 
 condensation of the elementary constituents of a single 
 combustible gas of unknown composition. 
 
 To begin with the most complicated case, we may 
 suppose the gas contains x volumes of carbon vapour, 
 y volumes of hydrogon, z volumes of oxygen, and n vo- 
 lumes of nitrogen; we require therefore four equations 
 for the determination of the four unknown quantities #, 
 y, z and n. In order to obtain these four equations it is 
 necessary to explode a volume V of the gas , and to de- 
 termine, 1) the contraction C which occurs in the com- 
 bustion, 2) the aqueous vapour Y formed, 3) the carbonic 
 acid X produced, and 4) the residual nitrogen N. 
 
 The volume of carbon vapour x contained in the unit 
 volume of gas gives 2# volumes of carbonic acid, V vo- 
 lumes of gas give therefore 2 x V. Hence we have 
 
 X== 2xV 
 
DERIVATION OF FORMULA. 43 
 
 The volume of hydrogen y contained in the unit vo- 
 lume of gas gives y volumes of aqueous vapour. Hence 
 
 Y = y V .or y = -pr. 
 
 As also n volumes of nitrogen are contained in the 
 unit volume, of gas, and V volumes contain Vn volumes 
 of nitrogen, we have 
 
 N 
 N = Vn or n = -=-. 
 
 The volume of the gases before the explosion, is 
 composed of the volume 1 of gas to be examined, together 
 with the volume of oxygen 6>, which has to be added. 
 The volume of gas remaining after the explosion, is equal 
 to the volume of oxygen 0, originally taken, minus the 
 oxygen 2 x necessary for the formation of carbonic acid, 
 minus the oxygen */ 2 y required for the combustion of the 
 hydrogen, plus the carbonic acid 2# produced, plus the 
 oxygen z contained in the gas, plus the nitrogen n libe- 
 rated by the combustion of the gas. The volume V of 
 gas employed, when the values of x and y are substituted, 
 is found to be: 
 
 volume before the combustion V -\- 0, 
 
 y 
 
 volume after the combustion Vz-\-0-\-XX -\-N. 
 
 2 
 
 If the first volume be subtracted from the second we 
 get for the volume of gas which has disappeared the 
 expression 
 
 C=V-V,+ 1. -N or *=i + ^_-_ *. 
 
 In order to determine F, X, Y, N and C experi- 
 mentally, V volumes of gas are brought into the com- 
 bustion-eudiometer, the amount of oxygen required for 
 
44 DERIVATION OF FORMULAE. 
 
 combustion added and the mixture exploded. The vo- 
 lume of gas which has disappeared after the combustion 
 is equal to C. The eudiometer is next exposed to a tem- 
 perature of 100 C. in an apparatus about to be described. 
 The difference between the reduced volumes before and 
 after heating is Y, The carbonic acid X is then deter- 
 mined by means of a potash ball. - - The residual gas 
 consists of nitrogen mixed with an unknown quantity of 
 superfluous oxygen. This volume of oxygen, determined 
 by explosion with hydrogen, subtracted from the residual 
 gas gives the amount of nitrogen N. 
 
 If experiment has shown that oxygen is not contained 
 in the gas, that is if z = 0, we have, 
 
 o-i + JL A * 
 
 ~ 2V V V 
 and if the value y V be substituted for Y, we have, 
 
 ._, + {__,_,(.+*_,) 
 
 By means of this equation the volume of hydrogen 
 contained in the unit volume of a gas free from oxygen 
 can be calculated from the contraction, without it being 
 necessary directly to determine the amount of aqueous 
 vapour Y formed. This method is applicable to hydrogen, 
 oxygen, nitrogen, and to all gases of the following com- 
 position : 
 
 n vol. C -\- HI vol. N = 1 vol. 
 
 n C + n t = 1 
 
 n ,; C -J- H! H= I 
 
 n H -(- nj 0=1 
 
 n // + Hi N =1 
 
 n NnO=I 
 
PRECAUTIONS DURING EXPLOSION. 45 
 
 n vol. C -)- ??i vol. PI -(- w 2 vol. = 1 vol. 
 
 n (7 -(- M! ,, H -\- n 2 JV = 1 
 n ., //+! +'"2 #=1 
 
 ??, c -f- ft! 0- -f- w. 2 jv = i 
 
 ??, C -\- rii ,. // -f 71-2 -|- % vol. ^ = 1 vol. 
 
 It is seen that cases occur in which the mixture does 
 not contain any gases combustible with oxygen, as for 
 instance and n vol. A 7 -)- ^ vol. 0=1. Such a gas 
 must be exploded with hydrogen instead of oxygen. 
 If the original volume is F, that disappeared after ex- 
 plosion C, and the residual nitrogen A", we obtain the 
 following equations by similar reasoning. 
 
 V (1 + 2 z n) = C 
 
 
 C+NV N 
 
 ^V~ ~V' 
 
 All the combustions of gases required in the analysis 
 must be conducted in closed eudiometers. The tubes are 
 best closed for the explosion by means of a plate of cork, 
 Fig. 31, covered with thick vulcanized caoutchouc, and so 
 Fig. si. cu ^ that it lies firm on the bottom of 
 the mercurial trough. The open end of 
 the eudiometer is pressed against this 
 cushion, and held tightly down by the 
 wooden arm of a holder, at the under 
 surface of which there is a slight hollow lined with cork. 
 The layer of air, which adheres on to the surface of the 
 caoutchouc plate under the mercury, may cause the most 
 serious errors, for on opening the eudiometer after ex- 
 plosion, the small bubbles of air would be drawn into the 
 instrument, and mix with the measured contents of the 
 
46 ELECTRICAL APPARATUS. 
 
 tube. This source of error can be easily avoided, by 
 moistening the surface of the caoutchouc with a solution 
 of corrosive sublimate. A thin film of subchloride of 
 mercury is produced, which causes a complete ad- 
 hesion of the metal, and thus prevents the presence of 
 air bubbles. 
 
 The firing of the gaseous mixture is always effected 
 by the electric spark. A small cylinder about 3 inches 
 high and 1 broad serves as a Leyden jar. This cylinder 
 is lined inside with tin foil, but in order to avoid amal- 
 
 Fig. 32. 
 
 gamation the outer metallic coating consists of platinum 
 foil. Electrophori or common electrical machines are 
 very apt to become useless, by remaining in the damp 
 and cold rooms which are most suitable for gas labora- 
 tories. The jar is therefore best charged by means of 
 the simple and effectual arrangement represented in 
 Fig. 32. 
 
 It consists merely of a large porcelain tube, which 
 when held before the iron wire of the cylinder, and rubbed 
 with the silk and amalgam*, evolves so much electricity 
 that the jar is charged in a few seconds. 
 
 K The amalgam by aid of which a porcelain tube 3 feet long 
 and iy 2 inches thick may be made to supply the place of a 
 tolerably powerful electrical machine, is made as follows. Two 
 
DETERMINATION OF AQUEOUS VAPOUR. 
 
 47 
 
 The following apparatus serves to measure the amount 
 of aqueous vapour formed by the combustion. The iron 
 
 Fig. 33. 
 
 boiler .4, Fig. 33, half fil- 
 led with water, carries a 
 long glass cylinder cc, 
 from the iron lid d of 
 which hangs the support 
 ff for the eudiometer e. 
 The volume of the vapour 
 of water formed by the 
 combustion, is measured 
 by placing the eudio- 
 meter in the vessel { half 
 filled with mercury, and 
 bringing it, by means of. 
 the supports//, into the 
 glass cylinder cc, through 
 which a rapid current of 
 steam is passed from the 
 boiler A. The tempera- 
 ture of lOOo c. thus at- 
 tained, is amply sufficient 
 to vaporize the water in 
 the eudiometer, owing to 
 it boiling point being 
 
 parts of mercury are heated in a common test tube and 1 part 
 of thin zinc foil, and one part of zinc added whilst the metal is 
 well stirred. In order to make the amalgam more plastic, it is 
 melted and stirred several times, and then placed on a pieco 
 of the thickest and best silk which serves as a rubber. In 
 rubbing the tube, the silk is so arranged that only half the sur- 
 face in contact with the porcelain is covered with amalgam, the 
 remainder being left free. The powerful action of the amal- 
 gam begins generally after it has been some time in use, and 
 it preserves its activity often for months. 
 
48 
 
 DETERMINATION OF AQUEOUS VAPOUR. 
 
 much lowered by the diminution of pressure caused by 
 the column of mercury in the tube acting in opposition 
 to the barometric pressure. 
 
 I give as an example of such a determination, an 
 analysis of the gas evolved by the action of four parts of 
 sulphuric acid upon one part of methylic alcohol, which 
 was made in my laboratory by M. Quincke. The gas was 
 washed with water and caustic potash before collection, 
 and in order to free it from the last traces of sulphurous 
 acid and carbonic acid gases, it was left for a long time 
 in contact with solid caustic potash. 
 
 For the sake of greater accuracy two portions of 
 this gas were analysed, but in the first, the amount of 
 aqueous vapour, and in the second, the amount of nitro- 
 gen was determined. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Te ,np. 
 
 0C. and 
 l m press. 
 
 1) Original volume of gas . . . 
 
 79.G 
 
 0.3140 
 
 4.0 
 
 24.63 
 
 2) After addition of oxygen . . 
 
 327.2 
 
 0.5615 
 
 5.0 
 
 180.42 
 
 3) After the explosion .... 
 
 2G8.7 
 
 0.4915 
 
 4.9 
 
 129.74 
 
 4) After heating to 100 C. . . 
 
 418.1 
 
 0.6752 
 
 99.5 
 
 206.95 
 
 5) Observation 3) repeated . . 
 
 2G8.2 
 
 0.4914 
 
 3.7 
 
 129.47 
 
 G) After absorption of carbonic acid 
 
 193.3 
 
 0.4188 
 
 0.7 
 
 80.75 
 
 From these observations we have: 
 
 Original volume of gas . . . . V= 24.63 or 1.0000 
 
 Contraction after explosion . . C = 50.68 or 2.0576 
 
 Aqueous vapour formed . . . Y = 77.35 or 3.1405 
 
 Carbonic acid produced . . . X = 48.72 or 1.9781 
 
 The volume of gas originally taken in this experi- 
 ment, as well as the oxygen employed for explosion, were 
 
DETERMINATION OF AQUEOUS VAPOUR. 49 
 
 both measured in the dry state by filling into a dessi- 
 cated eudiometer over dried and warm mercury. All the 
 columns of mercury are reduced to C. 
 
 Observation 4) is obtained from the following expe- 
 rimental data: 
 
 Barometric pressure at 51 C 745.9 
 
 Column of mercury in the eudiometer .... 73.0 
 Column of water above the mercury in vessel i . 22.4 
 Temperature of the aqueous vapour . . . . . 99.5 
 Observed volume corrected from the table of capacity 417.0 
 
 The column of water 22.4 represents a pressure of 
 
 22 4 
 mercury equal to ' . = 1.7 min . 
 
 The column of mercury measured in the eudiometer 
 73.0 1.7 = 71.3 mm is when reduced to C. equal to 
 70.1 mm . This quantity subtracted from the barometric 
 pressure reduced from 51 C. to 0C. 745.3 mm gives G75.2 mm . 
 
 The coefficient of cubic expansion of glass between 
 Oo and 100 C. is according to Dulong and Petit 0.00002583. 
 The interior of the eudiometer filled with gas 417.0, was 
 therefore expanded, by heating from C. to i)95 C., 
 (1 _|_ 0.0000258 X 99.5) 417.0 = 418.1. 
 
 The same analysis repeated for the nitrogen deter- 
 mination gave: 
 
 
 
 
 
 Vnl at 
 
 
 Vol. 
 
 Pres- 
 
 sure. 
 
 Temp. 
 C. 
 
 V Ol. Uli 
 
 C. and 
 
 
 
 
 
 l m press. 
 
 1) Original volume of gas . . . 
 
 50.6 
 
 0.1419 
 
 1.4 
 
 7.14 
 
 2) After addition of oxygen . . 
 
 199.8 
 
 0.3112 
 
 2.6 
 
 61.59 
 
 3) After the explosion .... 
 
 172.4 
 
 0.2738 
 
 3.7 
 
 46.57 
 
 4) After absorption of the carb. acid 
 
 132.8 
 
 0.2409 
 
 3.9 
 
 31.54 
 
 5) After addition of hydrogen 
 
 547.3 
 
 O.G955 
 
 2.6 
 
 377.06 
 
 G) After the explosion .... 
 
 4GG.G 
 
 O.G12G 
 
 1.5 
 
 284.28 
 
 4 
 
50 DETERMINATION OF NITROGEN. 
 
 Hence : 
 
 Original volume of gas ... V = 7.14 or 1.0000 
 
 Contraction after explosion . . C = 15.02 or 2.1036 
 
 Carbonic acid formed . . . . X = 15.03 or 2.1050 
 
 Nitrogen^. , JV = 0.61 or 0.0854 
 
 The amount of nitrogen found, is so small that it 
 must arise either from the unavoidable errors of obser- 
 vation, or else from the presence of a slight trace of 
 atmospheric air. 
 
 These two analyses give the following mean values : 
 V = 1.000 
 = 2.081 
 Y = 3.141 
 X = 2.042 
 N = 0.000 
 
 1 volume of gas therefore contains, 
 
 if 
 Carbon vapour . x = -^ =1.021 
 
 Hydrogen ...?/ = ... .*"'. m . '';' :/ = 3.141 
 
 Oxygen . . . z = ~ (V i/ 2 V N C) = 0.490 
 
 Nitrogen . . . n _= N = 0.000 
 
 Hence 1 volume of the gas consists of 
 
 Found. Calculated. 
 
 Carbon vapour . . 1.02 1.03 
 Hydrogen .... 3.14 3.10 
 Oxygen ..... 0.49 0.52 
 
 As an example of a gas which only contains oxygen 
 and nitrogen 1 have chosen nitric oxide. This gas was 
 evolved from nitric acid and copper and was led into a 
 concentrated solution of protosulphatc of iron. On sub- 
 
ANALYSIS OF NITRIC OXIDE. 51 
 
 sequently heating the saturated solution, the gas was 
 obtained in a state of purity, care being taken not to col- 
 lect the portions evolved at the end of the operation. As 
 nitric oxide, contrary to the statements of most of the 
 handbooks, cannot be exploded with hydrogen, it was ne- 
 cessary to mix the gas with a known volume of nitrous 
 oxide. The following numbers were obtained from an 
 analysis made in this manner. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 1 press. 
 
 Nitric oxide 
 
 101 3 
 
 02105 
 
 44 
 
 20.99 
 
 Nitrous oxide added 
 Hydrogen added 
 
 2G4.1 
 423 5 
 
 0.3944 
 05G30 
 
 4.6 
 5 3 
 
 102.44 
 233 90 
 
 Alter explosion 
 
 2945 
 
 04261 
 
 5 3 
 
 123 10 
 
 Oxygen added 
 After explosion . 
 
 351.3 
 292 5 
 
 0.4864 
 04247 
 
 5.3 
 
 4.8 
 
 1G7.G2 
 12208 
 
 
 
 
 
 
 The volume of nitric oxide employed was V= 20.99. 
 81.45 volumes of nitrous oxide were added; these 
 81.45 volumes on combustion produce a contraction of 
 81.45 volumes. The total contraction is however 110.80, 
 hence that caused by the combustion of the nitric oxide 
 is C = 110.8 81.45 = 29.35. The gas remaining after 
 the first explosion 123.10 can only contain nitrogen and 
 excess of hydrogen. A second explosion with oxygen 
 gave a contraction of 45.54 ; two thirds of this gives the 
 volume of hydrogen, 2 3 45.54 = 30.36. The amount of 
 nitrogen liberated from the nitrogenised gases was there- 
 fore 123.10 30.36 = 92.74. Of this 81.45 volumes 
 came from the nitrous oxide, the remainder in the quan- 
 tity contained in the nitric oxide; N is therefore equal 
 
52 MANIPULATION IN 
 
 to 11.29. The following composition is calculated from 
 F, C, and N by means of the equations 
 
 N - 
 
 n = and z = 
 
 
 2F 
 
 Found. 
 
 Calculated. 
 
 n = 0.52 
 
 0.5 
 
 z = 0.47 
 
 0.5 
 
 0.99 
 
 1.0 
 
 A second class of eudiometric determinations relates 
 to the separation of a mixture of known gases. Although 
 the methods employed vary considerably with the nature 
 of the gas to' be determined., still the general order of 
 the processes adopted in gas analysis may here be 
 detailed. 
 
 The analysis is commenced by the absorption of 
 those gases which are easily decomposed or enter easily 
 into combination. The analysis of the residual unabsorbed 
 gas, which usually contains inflamable constituents to- 
 gether with nitrogen, forms the second part of the in- 
 vestigation. The first absorption is effected in the small 
 graduated tube Fig. 18. For the purpose of absorbing 
 the gases only those substances can be used, the tension 
 of whose vapour is either exactly determined, or is an 
 inappreciable quantity. In order to bring these sub- 
 stances in contact with the gas without admission of air, 
 they are made into the form of small balls fastened on 
 to the end of platinum wires, by means of which they can 
 be pushed up under the mercury into the absorption tube. 
 
 These balls when composed of fusible substances 
 can be most conveniently cast in common iron bullet 
 moulds in which the canal for pouring in the metal has 
 been filed off. A platinum wire bent at one end is placed 
 
THE ABSORPTION OF GASES. 53 
 
 into the mould and the melted substance poured in, care 
 being taken to prevent the formation of a hollow at the 
 aperture from the contraction of the substance on cooling, 
 by pouring over it some freshly melted substance. It 
 often happens that on opening the mould the ball splits 
 into two pieces; this is best avoided by heating the out- 
 side of the mould for a few moments in the flame of a 
 spirit lamp before opening. Infusible bodies must be 
 made into a paste with water and the mass pressed into 
 the mould containing the platinum wire; on drying they 
 are generally hard enough for use. The balls thus pre- 
 pared, however, often possess the property of absorbing 
 a considerable quantity of gas in their pores; when this 
 is the case, these bodies can only be used after having 
 been saturated with some liquid which does not absorb 
 gases, such as syrupy phosphoric acid &c. If it is re- 
 quired to act upon a gas with a liquid, a ball of coke 
 fastened upon a platinum wire is employed, and the coke 
 ball saturated with the absorbent. These balls are made 
 from a mixture of one part of bituminous coal, as free 
 as possible from iron pyrites, and two parts of coke. This 
 dry powder is placed in the mould round a platinum wire 
 and the whole slowly heated over a charcoal fire until the 
 mould is red-hot. If the mass is found to be too porous 
 after heating, it is easy to give it the requisite solidity 
 by dipping the ball, heated above 100 C., into syrup of 
 sugar or coal tar, and then strongly heating it in a gas 
 blowpipe. Before such balls can be used, they must be 
 well boiled in hydrochloric and nitric acids to remove 
 the metals and metallic sulphides which are present. In- 
 stead of a coke ball it is often convenient to employ 
 one of papier-mache made by pressing wet filtering paper 
 into the mould and drying at 100 C. 
 
54 DEVELOPMENT OF A GENERAL FORMULA. 
 
 Although the volume of such balls generally does 
 not exceed one 'division of the absorption tube, still the 
 layer of atmospheric air adhering to the surface may 
 cause an error of from 0.05 to 0.1 division: In order to 
 dimmish this almost imperceptible error, it is only neces- 
 sary to hold the moistened ball under mercury between 
 the thumb, fore- and second-finger and to rub the surface 
 of the ball so as to allow the adhering air to escape up 
 the surface of the wire, which is then pushed on with 
 the fingers, until the ball appears above the surface of 
 the mercury in the absorption tube. If merely a small 
 point of the ball is seen at the side of the tube, it may 
 be directly pushed up into the gas, if, however, a bubble 
 of air surrounds the ball , it must be instantly withdrawn 
 and the operation repeated. When the ball is to be 
 removed from the gas, it must be rapidly drawn down 
 below the mercury and may then remain, until the volume 
 of gas has been read off. When these precautionary 
 measures are carried out, a ball may be taken in and 
 out 6 or 8 times without diminishing the volume of 
 the gas. 
 
 In almost all cases it is impossible to make use of 
 liquid absorbents, as the gases are then dissolved in 
 quantities depending upon their coefficients of absorption 
 and their relative volumes. 
 
 Having thus described the order of the processes 
 adopted, I proceed to develope a general formula for the 
 calculation of the relative volumes of the constituents of 
 a mixture of known gases. 
 
 Supposing that V Q volumes of the original gas was 
 employed for analysis, and that V l volumes remained 
 after the first absorption, V 2 volumes after the second 
 absorption, and V n volumes after the third absorption, 
 
DEVELOPMENT OF A GENERAL FORMULA. 55 
 
 the gas must have consisted of V - - V l volumes of the 
 first constituent, V l V 2 of the second, and K, V n 
 of the third, whilst the residual volume V n was composed 
 of non-absorbable combustible gases. If this volume V, 
 contained four combustible constituents, they may in most 
 cases be determined by transferring a portion P of the 
 total volume into the combustion -eudiometer, exploding 
 with oxygen, and determining, according to the method 
 just described, the volumes of carbonic acid and watery 
 vapour formed , and the quantity of oxygen used. 
 
 Let the component volumes of the gas P, be #, y, z, 
 and 10, the volumes of carbonic acid which the units of 
 these components form on combustion j, 6], Ci, ?i, and 
 let the volumes of oxygen required for the combustion of 
 the units of the same components, or the contraction 
 which ensues on the combustion, be ._,. l>.,. c. 2 . d?, and the 
 volume of aqueous vapour which is formed from the units 
 of each component t/ 3 , 6 3 , f 3 , <4- And let. also, the total 
 amount of carbonic acid produced by explosion of the 
 volume of gas PbeP^ and the volume of oxygen required 
 for this combustion P 2 , and, lastly, let the amount of 
 aqueous vapour formed by explosion from P volumes of 
 gas be P 3 , the values of x , y , z , and w are then found 
 from the following equations in which the values of a, b. 
 c. d are to be made equal to 1. 
 
56 GENERAL FORMULA. 
 
 p = a X+b Y+cZ+d W 
 P l = a,X + ^ Y J r c l Z-}-d l W 
 P 2 = a 2 X-\-b 2 Y+e 2 Z+dv W 
 
 P 3 = 8 x 4- 6 3 y 4- c 3 z 4- 4 w 
 
 X =(PA + PiA, + P 2 A 2 + P 3 A 3 ) 
 Y = (PB + P.B, + P 2 B 2 + P 3 B 3 ) 
 Z = (PC+ P& + P 2 C 2 + P 3 C 3 ) 
 
 W = (PD + P 1 A + P-2 A + A A) 
 
 A = 
 
 A l = b 2 (c 3 d c c? 3 ) -f- 6 3 (c c7 2 
 
 ^4 2 = b B (c d 1 c l d)-\-b (ci^ 3 
 
 A B = b fadt ctdj + b! (c 2 d c d 2 ) +b. 2 (c di 
 
 B = c'! (d 2 3 4 a 2 ) -f- 
 
 j&! = c 2 (d 3 a d 
 
 # 2 = c 3 (cZ c/! d l a)- J r c (d 1 a s 4i) + c i (4 d a- 3 ) 
 
 B 3 = c (d 1 a 2 d 2 ai) -f- GI (d 2 a d a 2 ) -\- c 2 (d ^ d l a ) 
 
 C = d l ( 2 b 3 a 3 b 2 ) + 4j (a ^i i &s) + ^3 (i ^2 2 ^i ) 
 
 Ci == d 2 (3 b a b 3 ) -)- d 3 (a b 2 a 2 b)-\-d (a 2 b 3 3 b 2 ) 
 
 C 2 = d 3 (a b l a l b)-}-d (a l b 3 a 3 b 1 )-^-d 1 (a 3 b a b 3 ) 
 
 C 3 = d (ci}b 2 a 2 bi)-{-d l (a 2 b a b 2 )-\-d 2 (a b a^b ) 
 
 D = ! (b 2 c 3 b 3 c 2 ) -\- a 2 (b 3 c l b^ c 3 ) -)- a 3 (^ c 2 b 2 c l ) 
 D l = a 2 (b 3 c b c 3 )-f-3(^ C 2 b 2 c)-\-a (b 2 c 3 b 3 G 2 ) 
 D 2 = a 3 (b c l 61 c ) -f- a (^ c 3 b 3 c t ) -|- i (^3 G b c 3 ) 
 D = a 6 c b C -- ^2 ^ <? 2 ^ C 6 c 
 
 -f- a 2 ^4 2 - 
 bB + ^ B, + b, B 2 + b 3 B 3 
 cC -f c x Q 4- c 2 C 2 4- 
 
 + ^ A + d 2 A 4- 
 
GENERAL FORMULA. 57 
 
 or when only three gases are to be determined: 
 
 P = a X+b Y+c Z 
 P l = a 1 X+b 1 Y 
 
 X = - (PA 
 Y (PB 
 
 Z = 
 
 A = V-2 
 
 AI = b. 2 c - - b c 2 
 
 A 2 = b <?! biC 
 
 B = c l a 2 6*2^! 
 BI = c^a c a^ 
 
 B 2 = C j - Cj 
 
 C = aib 2 a 2 bi 
 Ci = a 2 b - - a b 2 
 C% = a bi j6 
 
 z/ = a A -f- j A l -\- 2 A 2 
 = bJ3 + &i-#i +b. 2 & 2 
 
 = C C -f- 0'! 6\ -)- C 2 C" 2 
 
 or, lastly, for a mixture of two gases: 
 
 p =a X+b Y 
 P l = 
 
 X =-j(Pb l --P 1 b) 
 Y =(P l a --Pa,) 
 
58 SPECIAL DETERMINATIONS. 
 
 When the volume of gas P contains a fifth consistent 
 non - combustible and non - absorbable gas, as for instance 
 nitrogen, it is easy to determine its amount by deducting 
 the volume of the superfluous oxygen from the residual 
 gas after determination of the other constituents. This 
 is best done by exploding the residual gas with a known 
 volume of hydrogen large enough to burn all the oxygen. 
 
 If the sample P of the gas volume V n was thus found 
 to contain x y z w n volumes of the five gases, the follow- 
 ing simple proportion gives the volumes contained in V n \ 
 
 V ^ y__H 7 _ Vn U,'_Zs. N^' 
 
 which, together with the constituents determined by ab- 
 sorption F - - F! , Fj - - F 2 , F! - - V n , compose the ori- 
 ginal volume F . 
 
 After these general considerations we proceed to the 
 special determination of each gas. 
 
 1. NITROGEN. 
 
 Nitrogen can easily be made to combine with oxy- 
 gen to form nitric acid by exploding both gases with 
 double their volume of a mixture of two volumes of 
 hydrogen, and one of oxygen. If this detonating gas 
 amounts to from three to five times the volume of the 
 original gases, the quantity of nitric acid produced is so 
 considerable that the mercury which is in contact with 
 the gas, is dissolved with evolution of nitric oxide, and 
 on drying the gas , crystals of subnitrate of mercury are 
 found to be deposited on the sides of the eudiometer. 
 It is, however, not possible to obtain exact results with 
 such a combustion, as the decomposition is never com- 
 
NITROGEN. 
 
 59 
 
 plete, and the tension of the vapour of nitric acid as 
 well as the quantity of nitric oxide formed from the de- 
 composition of the nitric acid, prevent the attainment of 
 any accurate measurements. The following experiments 
 made with mixtures of the electrolytic detonating gas and 
 atmospheric air, show the limits within which the nitro- 
 gen combines with the oxygen to form nitric acid. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 
 c. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Air employed 
 
 275.2 
 
 0.4779 
 
 17.5 
 
 123.62 
 
 -{- detonating gas 
 No explosion ... ... 
 
 298.3 
 298.3 
 
 0.5006 
 
 0500G 
 
 17.7 
 17.7 
 
 140.24 
 140 24 
 
 
 319.0 
 
 0.5210 
 
 17.7 
 
 156.09 
 
 \iter explosion .... . 
 
 274.7 
 
 0.4784 
 
 17.2 
 
 123 64 
 
 -4 detonating gas . 
 
 331.1 
 
 0.5344 
 
 17 2 
 
 166.47 
 
 Alter explosion 
 
 272.1 
 
 0.4821 
 
 16.3 
 
 12380 
 
 -{- detonating gas ... 
 
 341.G 
 
 0.5521 
 
 16.3 
 
 177.67 
 
 Alter explosion . . . 
 
 272.1 
 
 0.4824 
 
 16.7 
 
 123.70 
 
 Air employed 
 
 278.6 
 
 0.4895 
 
 16.7 
 
 128.52 
 
 + detonating gas 
 
 3G1.0 
 
 0.5711 
 
 16.9 
 
 194.22 
 
 Alter explosion . . . . 
 
 278.6 
 
 0.4896 
 
 16.9 
 
 128.50 
 
 + detonating gas 
 
 379.8 
 
 0.5912 
 
 173 
 
 211.17 
 
 \iter explosion 
 
 278.0 
 
 0.4899 
 
 16.6 
 
 128.40 
 
 Air employed 
 -\- detonating gas 
 
 285.9 
 409.7 
 
 0.4985 
 0.6225 
 
 16.4 
 16.7 
 
 134.45 
 240.35 
 
 Alter explosion . 
 
 285.2 
 
 0.4976 
 
 16.8 
 
 133 70 
 
 -{- detonating gas 
 Alter explosion 
 
 435.2 
 281.0 
 
 0.6488 
 0.4921 
 
 16.8 
 16.7 
 
 266.00 
 130.32 
 
 \ir employed 
 
 169.1 
 
 0.4407 
 
 6.3 
 
 72.84 
 
 -{- detonating gas 
 After exolosion . 
 
 378.5 
 153.4 
 
 0.6483 
 0.4342 
 
 6.7 
 6.5 
 
 239.51 
 65.06 
 
GO SPECIAL DETERMINATIONS. 
 
 Hence 100 volumes of air with 
 13.45 volumes of detonating gas did not explode. 
 
 100 volumes of air with 
 
 26.26 detonating gas when exploded left 100.02 residual air 
 34.66 100.15 &- 
 
 43.72 100.07 
 
 51.12 . 99.98 
 
 64.31 99.90 
 
 78.76 99.43 
 
 97.84 96.92 
 
 226.04 88.56 
 
 The irregularities and inaccuracies which occur in 
 almost all the older eudiometric results, arise chiefly 
 from the fact that in the explosions this formation of 
 nitric acid was not guarded against. The error is easily 
 avoided, as is seen from the above experiment, by never 
 adding more than from 26 to 64 volumes of combustible 
 gas for every 100 volumes of non- combustible gases. 
 
 In order to see if a gas consists of pure nitrogen or 
 whether in addition it also contains oxygen, or a com- 
 bustible gas, the following process is employed. First 
 of .all we determine whether the gas is combustible, by 
 passing an electric spark through a measured volume of 
 the gas itself. If no ignition takes place, we may conclude 
 that no large quantity of combustible gas is mixed with 
 oxygen and nitrogen. About 40 volumes of electrolytic 
 detonating gas is next added to every 100 volumes of the 
 original gas, and the mixture exploded. If the original 
 volume is not altered after this explosion, we may be 
 certain that oxygen and combustible gases are not present 
 together in the mixture. In order to determine whether 
 oxygen, and not a combustible gas, is present, so much 
 hydrogen and detonating gas is added that the volume 
 
NITROGEN. Gl 
 
 of the original gas plus hydrogen is to the detonating 
 gas again in the ratio of 100 to 40. If after the explosion 
 the volume is found to be equal to the original gas plus 
 the hydrogen added, oxygen cannot be present, and we 
 only have now to determine whether or not a trace of a 
 combustible gas is contained in the original gaseous 
 mixture. This is done by exploding with excess of at- 
 mospheric air, added in such a quantity that the volume 
 of the detonating gas, formed by the hydrogen added, 
 and the oxygen of the air, amounts to from 26 to 64 
 per cent of the residual incombustible gases. If 2 / 3 of 
 the volume of gas, which has disappeared by the explosion, 
 is exactly equal to the volume of hydrogen added, we 
 may be sure that the gas under examination consisted 
 of pure nitrogen. 
 
 As the volumes of gas in the eudiometer are almost 
 always read off under various pressures, and as the 
 relation between the volumes of combustible and non- 
 combustible gases is determined for equal pressures, a 
 long calculation would each time be necessary in order to 
 find the required volume of detonating gas. This trouble- 
 some operation is avoided by once for all determining 
 the various depths to which the mercury is depressed by 
 admission of equal volumes of air into the eudiometer. 
 These observations are thrown together into a table, in 
 which the barometric pressure, and the small variation 
 in the level of the mercury in the trough is not con- 
 sidered. By the successive addition of equal volumes of 
 air for instance the following results were obtained. 
 
G2 SPECIAL DETERMINATIONS. 
 
 Difference 
 
 The 1st measure agreed with division 100 
 1. 2nd 123 
 
 ., 
 
 145 21 
 
 11 4th 166 2() 
 
 11 5th 186 lg 
 6th 204 
 
 7fli 991 
 
 I? ' tu it 11 11 11 ""*- -I p 
 
 
 
 8th 237 
 
 9th 253 
 
 " 1 A 
 
 11 10th 267 
 
 By help of such a table, the required volume of de- 
 tonating gas can be easily found. Suppose, for instance, 
 that we had to add so much to a volume of gas reaching 
 to division 190, that the original and added volumes 
 should be in the proportion of 100 to 30. The nearest 
 number to 190 which we find in the foregoing table, is 
 186 representing 5 volumes; 18 divisions are equal to 
 one volume in this part of the tube and hence the 4 di- 
 visions required to make up 190. are equal to 0.22 vol. 
 The volume 190, therefore, represents a volume of gas 
 5 -f- 0.22 = 5.22 reduced to the atmospheric pressure, 
 and as 100 : 30 : 5.22 : 1.57 we have to add 1.57 volumes 
 of detonating gas in order to have the required amount. 
 The total volume after addition of the detonating gas 
 must be 5.22 -f- 1.57 = 6.79. Hence the division, which 
 corresponds to this 6.79 measures, is 217.4 and the 
 detonating gas is to be added until the level of the 
 mercury sinks to this division. 
 
 The detonating gas as used for gasometric purposes 
 is prepared by electrolysis, and plays a most important 
 and essential part in the processes of gas analysis. The 
 
NITROGEN. . G3 
 
 small apparatus Fig. 34 is employed for the preparation 
 of this gas. 
 
 The small platinum plates aa which dip into a 
 liquid composed of one volume of pure monohydrated 
 
 Fig. 34. 
 
 sulphuric acid to 10 of water , are welded on to the pla- 
 tinum wires bb. These wires are placed in connection 
 with the poles of four common sized zinc -carbon ele- 
 ments, and thus a regular current of gas is evolved 
 which may he instantly stopped hy breaking contact. It 
 is adviseable to surround the decomposing cell by a glass 
 cylinder containing some non-conducting liquid which 
 does not easily freeze, by means of the arrangement 
 
G4 
 
 SPECIAL DETERMINATIONS. 
 
 represented in the wood-cut. The wires and acid are kept 
 cool by the surrounding liquid and the requisite height 
 given to the delivery tube e which is ground into the 
 neck of the decomposing cell and the joint rendered air- 
 tight by a layer of water. The volume of this tube, and 
 of the bulbs containing a little strong sulphuric acid , is 
 only a few cubic centimetres, so that by allowing the 
 evolution to continue for 5 minutes the whole of the 
 atmospheric air is completely removed. Irregularities in 
 the composition of the detonating gas from the pro- 
 duction of the higher oxides of hydrogen cannot occur 
 with this instrument, since the formation of peroxide of 
 hydrogen takes place only 1 at the beginning of the evo- 
 lution and ceases as soon as the electrolyte has dissolved 
 a certain amount of this substance. When exploded with 
 other non - combustible gases, the electrolytic detonating 
 gas disappears completely without leaving any residue 
 of either oxygen or hydrogen, as may be seen from the 
 following experiments conducted under extremely varying 
 circumstances. 
 
 .'- 
 
 Vol. 
 
 Pres- 
 sure.* 
 
 Temp. 
 C. 
 
 Vol. at 
 
 0C. and 
 
 
 
 
 
 l m press. 
 
 Original air in which the detonating 
 gas had been once exploded . 
 
 225.8 
 
 0.5107 
 
 G.4 
 
 112.G8 
 
 After addition of detonating gas 
 
 295.9 
 
 0.5806 
 
 G.4 
 
 1G7.87 
 
 After explosion 
 
 225 5 
 
 05110 
 
 6 2 
 
 112 67 
 
 
 
 
 
 
 The same 24 hours later ; . . 
 
 224.8 
 
 0.5112 
 
 5.7 
 
 112.61 
 
 After a second addition of de- 
 
 
 
 
 
 
 314.0 
 
 0.5977 
 
 5.7 
 
 183.84 
 
 After exDlosion . 
 
 224.4 
 
 0.5125 
 
 5.7 
 
 112.65 
 
 * In these and all the following data for pressure the correction 
 for the tension of aqueous vapour and for the difference of 
 
NITROGEN. 
 
 65 
 
 Original volume of air 112.68 
 
 After first combustion with 55.19 detonating gas 112.68 
 
 Measured again after 24 hours 112.57 
 
 After a second combustion with 71.23 detonating gas 112.66 
 
 As an example of a nitrogen determination made 
 with electrolytic detonating gas I cite the analysis of the 
 gas from a spring in the small group of geysirs near 
 Maelifell in the north of Iceland, which is free from car- 
 bonic acid and contains only traces of hydrogen. 
 
 
 Vol. 
 
 Pres- 
 sure, 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 
 l m press. 
 
 Original firas ... ... 
 
 185.0 
 
 03948 
 
 16.0 
 
 69.00 
 
 
 229 8 
 
 4380 
 
 16 1 
 
 95 05 
 
 After the explosion 
 
 186.4 
 
 0.3934 
 
 16.4 
 
 69.18 
 
 I hydrogen 
 
 277 3 
 
 4838 
 
 16 3 
 
 126 61 
 
 -j- detonating eras .... 
 
 360.3 
 
 0^5617 
 
 16.4 
 
 190.92 
 
 After the explosion 
 
 277.2 
 
 0.4837 
 
 16.4 
 
 126.47 
 
 + air 
 
 525.7 
 
 0.7301 
 
 15.8 
 
 362.84 
 
 After the explosion .... 
 
 447. G 
 
 0.6529 
 
 16.2 
 
 275.88 
 
 
 
 
 
 
 Gas before the combustion 
 
 Gas after the combustion with detonating gas 
 Gas and hydrogen before the combustion . . 
 Gas and hydrogen after the combustion with de- 
 tonating gas . , 
 
 Hydrogen added , 
 
 Hydrogen found by combustion with air . . . 
 
 69.00 
 
 69.18 
 
 126.61 
 
 126.50 
 57.61 
 57.97 
 
 height between the mercury in the eudiometer and in the 
 trough is already made. The numbers in the first column 
 likewise represent the volumes, corrected for the error of the 
 meniscus , as taken from the capacity table of the eudiometer. 
 
 5 
 
GG SPECIAL DETERMINATIONS. 
 
 The gas under examination consists therefore of 
 nitrogen with a trace of hydrogen ; viz 
 
 Nitrogen . . . 99.48 
 
 Hydrogen . . . 0.52 
 
 100.00 
 
 2. OXYGEN. 
 
 Oxygen when present alone or when mixed with 
 nitrogen, is best determined by explosion with excess of 
 hydrogen. .As~*/ 3 of the volume of gas undergoing com- 
 bustion consists of hydrogen and l / z - of oxygen, the re- 
 quired volume of oxygen is found by dividing the de- 
 crease of volume ensuing from the explosion by 3. The 
 hydrogen required for the combustion is evolved in a 
 small flask from pure zinc and dilute sulphuric acid, and 
 it is freed from all traces of carbonic acid , sulphuretted 
 hydrogen, and sulphuric acid mechanically carried over, 
 by passing through a small delivery tube containing 
 pieces of hydrate of potash. When the evolution has 
 proceeded for 5 or 10 minutes, we may assume that all 
 the air has been displaced from the liquids and the small 
 spaces in the apparatus. When the greatest amount of 
 accuracy is required, it is preferable to evolve the hy- 
 drogen by electrolysis. For this purpose the small ap- 
 paratus Fig. 35 may be used. The decomposing cell 
 contains pure sulphuric acid diluted with 10 times its 
 weight of water, and the positive pole consists of a pla- 
 tinum wire a melted through the glass placed in contact 
 with mercury amalgamated with zinc 6, whilst the ne- 
 gative pole c is composed of a platinum plate. If the 
 current from two or three carbon -zinc elements is led 
 through the apparatus in the direction indicated by the 
 
OXYGEN. G7 
 
 arrows, pure inodourous hydrogen is evolved in a con- 
 stant stream, and after being washed by the small 
 quantity of sulphuric acid contained in the bulbs <7, the 
 
 Fig. 35. 
 
 gas may be collected for analytical purposes. As the 
 surface of the zinc -amalgam very soon becomes covered 
 with a layer of saturated solution of sulphate of zinc, the 
 liquid must often be removed, generally after each ope- 
 ration. This is accomplished by removing the glass 
 stopper fitting into the tube A, and also the delivery 
 tube ground in at i, and pouring the new solution into 
 the vessel through the small reservoir n which serves 
 during the evolution as a water joint; the saturated 
 solution thus flows out from the tube A, and is replaced 
 by fresh acid. This arrangement is best contained in a 
 
G8 SPECIAL DETERMINATIONS. 
 
 glass cylinder filled with alcohol to prevent the heating 
 of the platinum wires during the passage of the current. 
 
 If the gas under examination is known to consist 
 almost entirely of pure oxygen , or if this has been as- 
 certained by preliminary experiment, from three to ten 
 times its volume of hydrogen can be added for explosion. 
 When a greater amount of hydrogen is added, the in- 
 flamability of the mixture is destroyed, or, what is more 
 to be feared, considerably diminished. If, on the other 
 hand, the gas contains only a small amount of oxygen, 
 it is mixed with double its volume of hydrogen, and if 
 the mixture is not inflamable, so much detonating gas is 
 added that a perfect explosion takes place. In every 
 case care must be taken to mix the gases completely, 
 before ignition, in the manner described. 
 
 In order to be satisfied that the combustion has not 
 occured near the limits of the inflamability of the mixture, 
 the experiment must be repeated with addition of rather 
 a larger quantity of detonating gas. If the two expe- 
 riments do not agree, it is to be supposed that the last 
 result with the greater amount of explosive gas is the 
 more accurate. With a little practice, however, it is easy 
 to tell from the force of the explosion, whether the re- 
 lation between the combustible and non-combustible gases 
 was such that a complete combination could occur. 
 
 The amount of oxygen contained in the atmosphere 
 may be determined according to this method with the 
 greatest accuracy, when a very carefully calibrated eudio- 
 meter is employed, l m long and about 0.025 wide, and 
 the observations are conducted in a space within which 
 the changes of temperature are small and as gradual as 
 possible. 
 
OXYGEN. G9 
 
 The air for these determinations is collected in 
 small flasks of about 14 ounces capacity whose necks 
 have been previously elongated before the blowpipe. 
 Inside the flask a small piece of fused chloride of cal- 
 cium is placed for the purpose of absorbing the ammonia, 
 and a similar piece of fused potash to absorb the car- 
 bonic acid is also introduced, and both substances are 
 allowed to crystallize on the sides of the glass by ad- 
 dition of a drop of water. It is quite requisite to remove 
 the carbonic acid of the air previous to analysis , for if 
 the quantity of this gas present amounts only to 0.05 
 per cent of the total volume still this quantity would 
 produce an appreciable error in the oxygen determination, 
 as carbonic acid when exploded with excess of hydrogen 
 in presence of the detonating gas is decomposed into an 
 equal volume of carbonic oxide, an equal volume of 
 hydrogen disappearing, so that the volume of combined 
 gas would be 0.05 per cent too large. 
 
 The eudiometers used for analysis of air are so 
 long that when placed in a vertical position a vacuum is 
 formed at their upper end; hence on admission of air, 
 the mercury is apt to be carried with great violence 
 against the head of the tube which is thus often broken. 
 On admitting air , the end of the eudiometer must there- 
 fore be so lowered that no vacuous space is formed above 
 the mercury. In order to fill a large tube with mercury, 
 it is most convenient to lay the tube in a groove, a a, 
 Fig. 36 (see p. 70), slanting at about an angle of 30, 
 and to allow the mercury to flow from the funnel J, 
 furnished with a stop -cock, through a long tube into the 
 lowest part of the eudiometer. All increase of tempe- 
 rature of the mercury by handling must as much as 
 possible be avoided. The air is always measured saturated 
 
70 
 
 SPECIAL DETERMINATIONS. 
 
 with the maximum amount of aqueous vapour. For this 
 purpose a drop of water , whose volume is inappreciable 
 compared to the total capacity of the tube, is brought 
 
 Fig. 36. 
 
 into the head of the eudiometer before filling -in the 
 mercury, so that on admission of air, the drop moistens 
 the whole length of the tube containing gas. If the 
 moisture remains at one spot only of the eudiometer, the 
 aqueous vapour would not adjust itself quickly enough 
 throughout the mass of the gas to correspond to the 
 alterations of temperature, and hence a slight error 
 would be introduced. 
 
 It is, lastly, necessary to subtract the volume of the 
 water formed by the combustion from the volume of gas 
 which has disappeared. This correction is made by mul- 
 tiplying the volume of gas which has disappeared, reduced 
 to l m pressure and C., by 0.0007, and subtracting the 
 product thus obtained from the observed contraction. 
 
 In order to show the great accuracy of this method, 
 I cite the following series of analyses of atmospheric air 
 from the court of the Marburg laboratory , which I made 
 in January and February 1846, more for the sake of 
 testing the exactitude of the method, than for determining 
 the composition of the air. 
 
ANALYSES OF AIR. 
 
 71 
 
 ANALYSES OF AIR 
 
 in January and beginning of February 1846. 
 
 l. SERIES. 
 
 9th January. Temperature of the air Max. 14 C. Min. 025 C. 
 Barometer 0.7648. 
 
 
 Vol. 
 
 Pres- 
 sure 
 at 0. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Air e 
 Alter 
 Alter 
 
 tnployed . . . . f . . 
 
 841.8 
 1051.7 
 878.8 
 
 parts 
 
 0.5101 
 0.7137 
 0.5469 
 
 0.3 
 0.3 
 0.3 
 
 428.93 
 749.77 
 480.09 
 
 addition of hydrogen . . 
 the explosion 
 
 Air in 100 
 
 
 Nitrogen . . . 79.030 
 
 
 Oxygen . . . 20.970 
 
 100.000 
 
 Air employed .... 
 Alter addition of hydrogen 
 After the explosion . . 
 
 859.3 
 
 1051.9 
 
 870.3 
 
 0.5225 
 0.7079 
 0.5317 
 
 0.6 
 0.6 
 0.6 
 
 448.00 
 743.01 
 461.72 
 
 Air in 100 parts 
 Nitrogen . . . 79.037 
 Oxygen . . . 20.963 
 
 100.000 
 
 llth January. Max. temp, of air 088 C. Min. 26 C. Bar. 0.7562. 
 
 Air employed .... 
 After addition of hydrogen 
 After the explosion . . 
 
 885.4 
 
 1052.7 
 
 858.3 
 
 0.5388 
 0.7031 
 0.5136 
 
 0.5 
 0.5 
 *0.5 
 
 476.20 
 738.82 
 440.03 
 
 Air in 100 parts 
 Nitrogen ... 79.073 
 Oxygen . . . 20.927 
 100.000 
 
72 SPECIAL DETERMINATIONS. 
 
 13th January. Max. temp, of air 15 C. Min. 25 G. Bar. 0.7423. 
 
 
 Vol. 
 
 Pres- 
 sure 
 
 Temp. 
 p 
 
 Vol. at 
 0C. and 
 
 
 
 at 0. 
 
 
 l m press. 
 
 Air employed ' >' 
 
 882.2 
 
 527G 
 
 9 
 
 464 94 
 
 
 
 
 
 
 After addition of hydrogen . . 
 
 1053.8 
 
 O.G929 
 
 0.8 
 
 729.38 
 
 After the explosion 
 
 8G1.8 
 
 0.5084 
 
 0.7 
 
 437.83 
 
 Air in 100 parts 
 Nitrogen . . . 79.086 
 Oxygen . . . 20.914 
 
 14th January. 
 Air employed 
 After addition 
 After the explosion 
 
 Air in 100 parts 
 
 Nitrogen . . . 79.050 
 
 Oxygen . . . 20.950 
 
 100.000 
 
 SERIES 2., 
 A different eudiometer used in these determinations. 
 
 18th January. Max. temp, of air 14 C. Min. C. Bar. 0.7397. 
 
 100.000 
 
 Max. temp, of air 24 C. Min. 49 C. Bar. 0.7477. 
 
 
 870.3 
 
 0.5213 
 
 0.3 
 
 453.20 
 
 of hydrogen 
 
 1045.0 
 
 0.6914 
 
 0.3 
 
 721.71 
 
 osion '. . .- .. u - 
 
 858.0 
 
 0.5099 
 
 0.2 
 
 437.01 
 
 Air employed . . . . , 
 After addition of hydrogen 
 After the explosion . . 
 
 831.6 
 994.7 
 
 808.0 
 Air in 100 parts 
 
 0.5272 
 0.6836 
 0.5015 
 
 0.9 
 0.9 
 0.9 
 
 436.97 
 677.74 
 403.88 
 
 Nitrogen 
 Oxygen . 
 
 79.094 
 
 20.906 
 
 100.000 
 
 845.3 
 
 1004.6 
 
 809.4 
 
 Air employed 
 
 After addition --of hydrogen 
 
 After the explosion .... 
 
 Air in 100 parts 
 Nitrogen . . . 79.072 
 Oxygen . . . 20.928 
 
 100.000 
 
 0.5380 
 0.6917 
 0.5057 
 
 1.2 
 
 1.4 
 1.4 
 
 452.78 
 691.36 
 407.24 
 
ANALYSES OF AIR. 73 
 
 20th January. Max. temp, of air 6 C. Min. 25 C. Bar. 0.7402. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Air employ 6<i . 
 
 809.G 
 
 0.5001 
 
 1.7 
 
 402.39 
 
 
 After addition of hydrogen . . 
 
 991.0 
 
 0.6751 
 
 1.8 
 
 664.64 
 
 After the explosion 
 
 823.9 
 
 0.5041 
 
 2.1 
 
 412.16 
 
 
 Air in 100 parts 
 
 Nitrogen . . . 79.073 
 
 Oxygen .... 20.927 
 
 100.000 
 
 Air employed ... 
 
 833.5 
 
 0.5170 
 
 2.7 
 
 426.74 
 
 Alter addition of hydrogen . . 
 
 997.1 
 
 0.6744 
 
 3.0 
 
 665.19 
 
 
 811.8 
 
 0.4949 
 
 3.0 
 
 397.42 
 
 Air in 100 
 
 parts 
 
 
 
 
 Nitrogen . . . 79.073 
 
 Oxygen . . . 20.927 
 
 100.000 
 
 22nd January. Max. temp, of air 109 C. Min. 56 C. Bar. 0.7339. 
 
 Air employed 
 
 839.0 
 
 0.5236 
 
 3.4 
 
 433.92 
 
 Alter addition of hydrogen . . 
 
 991.3 
 
 0.6707 
 
 3.6 
 
 656.20 
 
 After the explosion 
 
 801. G 
 
 0.4854 
 
 3.6 
 
 384.03 
 
 Air in 100 parts 
 
 Nitrogen . . . 79.081 
 
 Oxygen . . . 20.919 
 
 100.000 
 
 \ir employed 
 
 851.4 
 
 0.5374 
 
 4.0 
 
 450.96 
 
 
 After addition of hydrogen . . 
 
 992.1 
 
 0.6725 
 
 4.2 
 
 657.06 
 
 Alter the exolosion 
 
 793.2 
 
 0.4797 
 
 4.2 
 
 374.73 
 
 Air in 100 parts 
 Nitrogen ... 79.120 
 Oxygen .... 20.880 
 100.000 
 
74 SPECIAL DETERMINATIONS. 
 
 24th January. Max. temp, of air 10 C. Min. 5 C. Bar. 0.7384. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 Air employed ; ./ - 
 
 855.2 
 
 0.5448 
 
 3.4 
 
 460.21 
 
 After addition of hydrogen . . 
 
 1004.7 
 
 0.6850 
 
 3.4 
 
 679.52 
 
 After the explosion 
 
 80G.O 
 
 0.4913 
 
 3.6 
 
 390.83 
 
 Air in 100 parts 
 Nitrogen . . . 79.079 
 Oxygen . . . 20.921 
 
 Air employed 
 After additior 
 After the explosion 
 
 100.000 
 
 
 860.0 
 
 0.5382 
 
 5.2 
 
 454.22 
 
 f hydrogen . . 
 
 1004.6 
 
 0.6769 
 
 5.4 
 
 665.34 
 
 ion . . -. :< '1 ; f . - 
 
 805.0 
 
 0.4833 
 
 5.3 
 
 381.65 
 
 Air iii 100 parts 
 Nitrogen . . . 79.057 
 Oxygen . . . 20.943 
 
 100.000 
 
 26th January. Max. temp, of air 9 C 
 
 OC. M 
 
 842.2 
 1002.5 
 811.2 
 
 in. 85 C 
 
 0.5274 
 0.6825 
 0.4994 
 
 /. Bar. 
 
 5.6 
 5.7 
 5.5 
 
 0.7334. 
 
 435.35 
 670.26 
 397.13 
 
 After addition of hydrogen ... 
 After the explosion 
 
 Air in 100 parts 
 Nitrogen .'- . . . fi 79.073 
 Oxygen . . . 20.927 
 
 Air employed 
 After additior 
 Alter the explosion 
 
 
 100. 
 
 868.5 
 1007.8 
 799.7 
 
 000 
 
 0.5613 
 0.6930 
 0.4909 
 
 5.1 
 5.1 
 5.2 
 
 478.59 
 685.65 
 385.25 
 
 ' hydrogen . . 
 ion 
 
 Air in 100 parts 
 Nitrogen . . ." 79.066 
 Oxygen . .. . .- 20.934 
 100.000 
 
ANALYSES OF AIR. 75 
 
 jsth January. Max. temp, of air 50 C. Min. 18 C. Bar. 0.7402. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 0C. and 
 l m press. 
 
 Air employed 
 
 841.1 
 
 0.5317 
 
 5.4 
 
 438.58 
 
 Alter addition of hydrogen . . 
 After the explosion 
 
 992.7 
 800.G 
 
 0.6771 
 
 0.4889 
 
 5.4 
 5.3 
 
 G59.17 
 383.97 
 
 Air employed 
 After addition 
 After the expl 
 
 30th January 
 
 Air employed 
 Alter addition 
 After the expl 
 
 Air employed 
 
 Alter addition 
 After the expl 
 
 Air in 100 
 Nitrogen . . 
 Oxygen .- .- 
 
 parts 
 79.072 
 . 20.928 
 
 .4 458.61 
 .5 679.55 
 .5 392.00 
 
 Jar. 0.7457. 
 
 .0 455.41 
 .0 689.77 
 .0 403.73 
 
 .4 458.05 
 .4 685.75 
 .2 398.82 
 
 100.000 
 
 854.3 0.5474 5 
 1003.2 0.6911 5 
 802.8 0.4981 5 
 parts 
 . 79.089 
 . 20.911 
 
 of hydrogen . . 
 
 Air in 100 
 Nitrogen . . 
 Oxygen . . 
 
 Max. temp, of air 7 
 
 100.000 
 8 C. Min. 38 C. 1 
 
 851.2 0.5468 6 
 1010.1 0.6979 G 
 81G.9 0.5051 6 
 parts 
 . 79.111 
 20.889 
 
 of hydrogen . . 
 osion ..... 
 
 Air in 100 
 Nitrogen . . 
 Oxygen . . 
 
 100.000 
 
 856.2 0.5475 6 
 1010.5 0.6945 G 
 811.2 0.5028 G 
 parts 
 . 79.108 
 20.892 
 
 of hydrogen . . 
 
 Air in IOC 
 Nitrogen . . 
 Oxygen . . 
 
 100.000 
 
76 SPECIAL DETERMINATIONS. 
 
 1st February. Max. temp, of air 98 C. Min. 51 C. Bar. 0.7382. 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 0C. and 
 l m press. 
 
 Air employed .'* 862.1 0.5512 6.3 464.51 
 
 After addition of hydrogen . . 1005.1 0.6866 6.3 674.59 
 
 After the explosion 801.2 0.4906 6.2 384.34 
 
 Air in 100 parts 
 Nitrogen ... 79.160 
 Oxygen . . . 20.840 
 100.000 
 
 Air employed t: V^} -':.U'V. ".', ' 854.9 0.5520 5.9 461.97 
 After addition of hydrogen . . 1003.9 0.6940 6.0 681.78 
 After the explosion . . >> v .. . 805.5 0.4980 5.9 392.69 
 
 Air in 100 parts 
 
 Nitrogen . . . 79.141 
 
 Oxygen .- . . . 20.859 
 
 100.000 
 
 3rd February. Max. temp, of air 65 C. Min. 12 C. Bar. 0.7458. 
 
 Air employed U^:.>v.!V . . 850.7 0.5467 6.2 454.75 
 After addition of hydrogen . . 1010.8 0.7001 6.2 691.95 
 After the explosion . ... .r '. ' . 812.7 0.5115 6.1 406.63 
 
 Air in 100 parts 
 Nitrogen . . . 79.075 
 Oxygen . . . 20.925 
 100.000 
 
 Air employed . |p <.;,*, i.-.. ; 863.7 0.5576 5.5 472.11 
 After addition of hydrogen . . 1006.7 0.6911 5.5 682.02 
 
 After the explosion 800.7 0.4914 5.6 385.60 
 
 Air in 100 parts 
 Nitrogen . . . 79.060 
 Oxygen . ., . 20.940 
 100.000 
 
ANALYSES OF AIR. 77 
 
 5th February. Max. temp, of air 38 C. Min. 012 C. Bar. 0.7428. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Air employed 
 
 848.5 
 
 0.5425 
 
 5.5 
 
 451.24 
 
 After addition of hydrogen , . 
 After the explosion 
 
 1003.4 
 80G.2 
 
 O.G919 
 0.5025 
 
 5.5 
 
 5.4 
 
 680.57 
 397.29 
 
 
 
 
 Air in 100 parts 
 
 
 
 
 Nitrogen . . . 79.063 
 
 
 
 
 Oxygen .... 20.937 
 
 
 
 
 100.000 
 
 Air employed 
 
 
 
 858.0 
 
 0.5500 
 
 5.4 
 
 462.78 
 
 
 
 After 
 
 addition 
 
 of hydrogen . . 
 
 1002.7 
 
 0.6867 
 
 5.6 
 
 674.72 
 
 After 
 
 the explosion 
 
 798.G 
 
 0.4893 
 
 5.6 
 
 383.99 
 
 
 
 Air in 1QO parts 
 
 
 
 
 Nitrogen . . . 79.048 
 
 
 
 
 Oxygen . . . 20.952 
 
 
 
 
 100.000 
 
 8th 
 
 February. 
 
 Max 
 
 . temp, of air 61 C. Min. 15 C. Bar. 0.7441. 
 
 Air employed 
 
 849.8 
 
 0.5460 
 
 5.1 
 
 455.52 
 
 9IU|TWJ ^v- 
 
 After addition 
 
 of hy< 
 
 Irogen . . 
 
 1006.0 
 
 0.6958 
 
 5.0 
 
 687.33 
 
 After 
 
 the explosion 
 
 807.5 
 
 0.5053 
 
 4.7 
 
 401.13 
 
 Air in 100 parts 
 Nitrogen . . . 79.047 
 Oxygen .... 20.953 
 
 100.000 
 
 In normal determinations of the composition of the 
 air a still greater degree of precision may be attained, 
 by repeating the observation of the height of the mercury 
 several times at regular intervals. From the agreement 
 between the reduced volumes read off, the point in the 
 series of observations is found, at which the temperature 
 
78 
 
 SPECIAL DETERMINATIONS. 
 
 has been most constant. As an example of such a de- 
 termination, I may give an analysis of air, also collected 
 from the court of the Marburg laboratory, for the ana- 
 lysis of which a somewhat smaller eudiometer was 
 employed. 
 
 - 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at C. 
 and l m pres- 
 sure. 
 
 
 GhO' 
 
 754.9 
 
 0.5045 
 
 15.4 
 
 3G0.52 
 
 
 Air employed . . . 
 
 7hO' 
 
 755.0 
 
 0.504G 
 
 15.4 
 
 3GO.G3 
 
 360.62 
 
 
 8hO' 
 
 755.2 
 
 0.5047 
 
 15.5 
 
 360.70 
 
 
 jllhO' 
 
 After addition of /I9h0' 
 hydrogen . j 
 ( IhO' 
 
 904.0 
 904.G 
 904.9 
 
 0.6520 
 O.G521 
 O.G518 
 
 15.8 
 1G.O 
 1G.O 
 
 557.20 
 557.24 
 557.17 
 
 > 557.20 
 
 
 3hO' 
 
 732.3 
 
 0.4781 
 
 1G.1 
 
 330.G4 
 
 
 After the explosion 
 
 4h()' 
 
 732.5 
 
 0.4777 
 
 1G.1 
 
 330.45 
 
 330.54 
 
 
 5M>' 
 
 732.7 
 
 0.4777 
 
 10. 1 
 
 330.54 
 
 [; 
 
 Nitrogen 
 Oxygen . 
 
 79.036 
 
 20.964 
 
 100.0UO 
 
 Should an alteration of temperature take place 
 during the observations, a reduction of the mercury in 
 the eudiometer and barometer to the same density by 
 means of table IV must not be omitted. 
 
 When oxygen occurs mixed with combustible gases 
 it is most convenient to determine it by absorption. A 
 ball of phosphorus cast under warm water may be used 
 for this purpose. The absorption only occurs at tem- 
 peratures above 10 or 12, indeed sometimes not until 
 the temperature has risen to 15 or 20. If oxygen is 
 
OXYGEN. 79 
 
 present in large quantities, or if the gas contains sethyl, 
 methyl, elayl, or other similar hydrocarbons, the phos- 
 phorus may often be heated almost up to it melting 
 point without the slow combustion beginning. It is, 
 therefore, necessary to observe at the commencement of 
 the experiment, whether the ball is surrounded by a 
 white cloud of phosphorous acid. If this be the case, 
 the absorption of the oxygen takes place completely, but 
 from the absence of such a cloud we cannot infer that 
 oxygen is not contained in the gas. 
 
 The tension of the vapour of the phosphorous acid 
 which coats the walls of the absorption tube, is con- 
 siderable, and would introduce a large error into the 
 analysis, were the gas not most carefully dried with a 
 ball of potash, before the volume is read off. This is, 
 however, attended with some difficulty, as the phosphorous 
 acid is very hygroscopic. It is, on the whole, far better 
 to adop.t Liebig's suggestion for the determination of 
 oxygen, and to employ, instead of the phosphorus, a 
 ball of papiermache saturated with a concentrated so- 
 lution of pyrogallate of potash. The absorption occurs 
 generally slowly, but in the end completely, particularly 
 if the ball be once renewed. After this absorption the 
 gas must also be dried by a ball of potash containing as 
 little water as possible. If other gases are present which 
 are absorbed by potash, their amount must be deter- 
 mined before the ball of pyrogallate of potash is intro- 
 duced. The syrupy solution of the potash salt used for 
 the absorption does not require to be chemically pure. 
 The rough product obtained from the destructive de- 
 stillation of Chinese galls when concentrated in the water- 
 bath, and saturated with potash, answers this purpose 
 extremely well. 
 
80 SPECIAL DETERMINATIONS. 
 
 An analysis of atmospheric air made with pyrogallate 
 of potash gave the following results. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 l m press. 
 
 
 3G8.9 
 
 0.5759 
 
 3.1 
 
 210.08 
 
 After absorption of the oxygen . 
 
 313.8 
 
 0.5358 
 
 3.1 
 
 1GG.25 
 
 Nitrogen 
 Oxygen . 
 
 Found. Actual composition. 
 79.14 7-9.04 
 
 20.8G 20.9G 
 
 100.00 
 
 100.00 
 
 3. CARBONIC ACID. 
 
 When pure carbonic acid is required in gasometric 
 research, it can in no case be prepared by the action of 
 nitric or hydrochloric acids on a carbonate, as traces of 
 these volatile acids might pass over with the carbonic 
 acid, and render the gas under examination impure. A 
 perfectly chemically pure product is obtained by pouring 
 concentrated sulphuric acid over chalk, and adding a few 
 drops of water. The gas is in this way evolved in a re- 
 gular stream lasting for a long time, owing to the 
 gradual decrepitation of the chalk under the liquid, 
 whilst the gypsum formed effects no irregularity in the 
 production of the carbonic acid, as is the case, when dilute 
 sulphuric acid is employed. Carbonic acid is determined 
 by absorption with a potash -ball attached to a platinum 
 wire. The ball of caustic alkali must contain so much 
 water that it is soft enough to receive an impression from 
 
CARBONIC ACID. 81 
 
 the nail, and must be moistened externally with water 
 before admission to the gas. 
 
 If very large quantities of carbonic acid have to be 
 absorbed, the ball must after some time be withdrawn 
 from the gas, and again introduced, after the hard crust 
 of carbonate has been completely washed off. When 
 particularly accurate results are required, it is best to 
 bring a second potash ball containing as little water as 
 possible into the gas, in order to ensure perfect absence 
 of aqueous vapour ; this precaution should always be 
 attended to when the sides of the eudiometer have been 
 moistened more than was necessary. Even in this case, 
 however, the error incurred is not very considerable. 
 
 The following is an analysis of the carbonic acid 
 evolved from the large well of the mineral springs at 
 Nauheim, near Frankfort am Maine. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 0C. and 
 l m press. 
 
 Air in absorption tube .... 
 
 20.1 
 
 0.524 
 
 10.1 
 
 10.16 
 
 After admission of carbonic acid 
 
 530.0 
 
 0.745 
 
 10.2 
 
 165.19 
 
 After absorption with potash . . 
 
 20.4 
 
 0.5164 
 
 10.2 
 
 10.16 
 
 It is thus seen that the carbonic acid from the 
 springs at Nauheim is perfectly pure. 
 
 If an analysis has to be made of a gas containing 
 oxygen and nitrogen, as well as carbonic acid, the amount 
 of this latter gas is first determined in an absorption 
 tube, and the residual mixture of gases then transferred 
 into the combustion -eudiometer, in order to explode the 
 gases with hydrogen in a tube- whose sides are free from 
 
 6 
 
82 
 
 SPECIAL DETERMINATIONS. 
 
 potash, which alters the amount of the tension of aqueous 
 vapour allowed for, when the gas is measured moist. 
 
 If the analysis can only be made in one and the 
 same eudiometer, the oxygen may be absorbed by pyro- 
 galate of potash after the determination of the carbonic 
 acid; in this case it is, however, necessary to dry the gas 
 completely before observing the residual volume of 
 nitrogen. 
 
 I select as an example of this last process an ana- 
 lysis of choke-damp from the mines of lignite at Ha- 
 bichtswald near Cassel. Under the term .choke-damp, 
 are classed all those non-explosive gases, poor in oxygen 
 and containing carbonic acid, which often collect in the 
 adits and workings driven through the coal-beds and 
 render the working of the mines extremely dangerous 
 if air-shafts or other means of ventilation are not 
 employed. 
 
 The gas used for analysis was collected by the di- 
 rector of the mine, from a side level in a situation in 
 which it would have been dangerous to remain for any 
 length of time. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Original o-as .... . . 
 
 171.2 
 
 0.6240 
 
 13 5 
 
 101.66 
 
 After absorption of carbonic acid 
 
 1G7.3 
 
 O.G196 
 
 13.5 
 
 98.78 
 
 After absorption of oxygen . . 
 
 147.0 
 
 0.6058 
 
 13.9 
 
 84.75 
 
 Nitrogen . . 
 Oxygen . . . 
 Carbonic acid . 
 
 83.37 
 
 13.80 
 
 2.83 
 
 100.00 
 
SULPHURETTED - HYDROGEN. 
 
 83 
 
 As the volume of free oxygen in the gas, together 
 with that contained in the carbonic acid, stands in a less 
 proportion to the nitrogen, than the atmospheric oxygen 
 to the atmospheric nitrogen, it may be concluded, that 
 in the formation of such gaseous mixtures only a part of 
 the oxygen is converted into carbonic acid, a part re- 
 maining combined in the products of decomposition of 
 the coal. A quantity of moist lignite was left for se- 
 veral weeks at a common temperature in contact with 
 a large volume of air, which gave the following com- 
 position very similar to that just examined. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Original gas 
 
 124.0 
 
 0.5043 
 
 16.5 
 
 58.97 
 
 After absorption of carbonic acid 
 
 114.3 
 
 0.5052 
 
 1G.5 
 
 54.58 
 
 Alter absorption of oxygen . . 
 
 106.5 
 
 0.4838 
 
 17.5 
 
 48.56 
 
 Nitrogen . . . 
 Oxygen . . . 
 Carbonic acid . 
 
 82.35 
 
 10.21 
 
 7.44 
 
 100.00 
 
 4. SULPHURETTED-HYDROGEN. 
 
 The means usually employed for the separation of 
 sulphuretted -hydrogen from other gases are inapplicable 
 to exact gasometric researches. A ball of coke coated 
 with a solution of sulphate of copper, lactate of silver, 
 tartar -emetic or other metallic salt decomposeable by 
 sulphuretted -hydrogen, is soon covered with a layer of 
 sulphide, which renders further action on the gas im- 
 
84 SPECIAL DETERMINATIONS. 
 
 possible. The result is not more satisfactory when a 
 moistened crystal, or a piece of the solid salt is used. 
 Chromate of mercury, or sulphate of copper, when used 
 in the form of moderately sized balls , do not absorb 
 more than about 9 divisions in 12 hours. Dry binoxide of 
 manganese, or peroxide of lead, decompose sulphuretted- 
 hydrogen quickly and completely, but these substances 
 evince, on account of their porosity, so great a power 
 of absorbing gases, that the diminution of volume is 
 always found to be more than that corresponding to the 
 amount of sulphuretted -hydrogen present. This error 
 may, however, be completely avoided in the following 
 manner. Pure binoxide of manganese brought into a 
 state of very fine division, is moistened with distilled 
 water to a thin paste, and then placed in a well oiled 
 bullet -mould, in which the end of a platinum wire is coiled. 
 By drying this paste in a moderately hot sandbath, a 
 compact mass of binoxide of manganese is formed, without 
 any kind of cement, and the ball can be easily removed 
 from the mould. The ball is the moistnened several 
 times over with a syrupy solution of phosphoric acid, 
 but not allowed to lose its compactness, so that it can 
 still be pushed under the mercury into the eudiometer. 
 If the moisture on the sides of the tube has disappeared 
 during the absorption of the sulphuretted -hydrogen, the 
 gas must be thoroughly dried by a ball of phosphoric 
 acid. These balls of phosphoric acid are easily made 
 by dipping the coiled end of a platinum wire into cooling 
 red -hot -liquid phosphoric acid, and covering the drop 
 of phosphoric acid hanging on the wire with the viscous 
 melted mass, until it has attained a spherical form of 
 the size of large pea. By observing all these precau- 
 tions, sulphuretted -hydrogen can be separated with great 
 
SULPHURETTED - HYDROGEN. 
 
 85 
 
 accuracy from hydrogen, nitrogen, carbonic acid, hydro- 
 carbons &c., as may be seen from the following analyses 
 of a mixture of hydrogen, carbonic acid and sulphuretted- 
 
 liydrogen. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Carbonic acid employed 
 
 71.2 
 
 G551 
 
 8.6 
 
 45 ^2 
 
 Alter addition of hydrogen .... 
 
 98.G 
 
 0.6817 
 
 8.8 
 
 65.12 
 
 After addition of sulphuretted - hy- 
 
 
 
 
 
 dro fen 
 
 139.0 
 
 720G 
 
 88 
 
 97 04 
 
 
 
 
 
 
 Alter absorption of sulphuretted-hy- 
 
 
 
 
 
 drogen 
 
 98.8 
 
 06813 
 
 9 3 
 
 65 10 
 
 
 
 
 
 
 Giving : 
 
 Carbonic acid . . . . 
 
 Hydrogen . 
 
 Sulphuretted hydrogen 
 
 Carbonic acid employed 
 
 After addition of sulphuretted -hy- 
 drogen 
 
 After absorption of sulphuretted- 
 hydrogen by binoxide of man- 
 ganese and phosphoric acid . . 
 
 The same operation repeated . . . 
 
 Employed. 
 46.60 
 20.51 
 32.89 
 
 100.00 
 
 Found. 
 4G.59 
 20.50 
 32.91 
 
 102.5 
 121.8 
 
 0.6990 
 
 0.7176 
 
 100.00 
 
 10.3 
 
 10.3 
 
 Carbonic acid .... 
 Sulphuretted - hydrogen 
 
 103.2 
 103.3 
 
 Found. 
 82.49 
 17.51 
 
 100.00 
 
 0.7005 10.3 
 
 0.6974! 10.7 
 
 I 
 
 Employed. 
 82.16 
 17.84 
 
 100.00 
 
 69.04 
 
 84.03 
 
 69.66 
 69.32 
 
86 SPECIAL DETERMINATIONS. 
 
 The sulphuretted-hydrogen used in these experiments 
 was evolved from sulphide of iron. This gas can, there- 
 fore, be thus prepared in a chemically pure state, and un- 
 dergoes in contact with mercury so slow a decomposition, 
 that the result of the analysis is not sensibly altered. 
 
 In cases in which only traces of sulphuretted -hydro- 
 gen are present, another method is most conveniently em- 
 ployed, although the results are not so accurate as those 
 arrived at by the process just described. In this case the 
 carbonic acid and the sulphuretted-hydrogen are absorbed 
 together, by a ball of pure caustic potash. This ball must 
 contain a large quantity of water and must be introduced 
 into the gas, without being moistened externally, so that 
 on withdrawal none of the potash remains in contact with 
 the mercury. Distilled water acidulated with acetic acid 
 is then boiled in two flasks, until all the dissolved air has 
 been removed, and the water in one flask poured, whilst 
 boiling, into the other up to the top of the neck. The 
 flask is then well closed by a cork covered with a plate 
 of caoutchouc, so that no bubble of air is left between the 
 liquid and the caoutchouc plate. As the liquid cools, the 
 cork is pushed further into the neck, in order to prevent 
 the formation of a vacuous space, and the possible en- 
 trance of air. The ball of potash , cut off from its pla- 
 tinum wire immediately on withdrawal from the gas, is 
 allowed to dissolve in this liquid, when cool, and a few 
 drops of clear solution of starch are added. In this way 
 all the sulphuretted-hydrogen in the gas is dissolved in 
 the acidified water free from air and containing starch. 
 By means of an accurately graduated pipette a solution 
 of iodine of known strength (containing about 0.01 milli- 
 gramme of iodine in each division of the pipette), is added 
 to the acidified solution of the potash-ball, and the iodine 
 
SULPHURETTED - HYDROGEN. 87 
 
 slowly dropped into the liquid, kept constantly stirred, 
 until the blue colouring of the starch has been observed, 
 marking the exact point at which the decomposition of 
 the sulphuretted -hydrogen is complete. The volume of 
 the sulphuretted -hydrogen is found from the amount of 
 iodine consumed, every milligramme of this substance 
 representing 0.087771 cbc. sulphuretted - hydrogen at 
 and O m 76. 
 
 In order to free the determination from any error 
 which might arise from impurities in the potash, the ex- 
 periment is repeated exactly in the same way with a ball 
 of the same potash , but containing no sulphide of pot- 
 assium, and the amount of iodine which has to be added 
 until the blue colouring occurs, subtracted from the 
 amount found in the previous experiment. In these ex- 
 periments it is adviseable, in order to obtain accurate 
 results, always to employ equal quantities of acetic acid 
 and starch, and not to take too large an amount of either 
 substance; it is also necessary, to have the solution con- 
 taining the sulphuretted-hydrogen so dilute, that less than 
 5 parts of this gas is contained in 1000 parts of the li- 
 quid. These precautionary measures were adopted in the 
 following experiment. 
 
 
 Vol. 
 
 Temp. 
 
 Pres- 
 
 Vol. at 
 C. and 
 
 
 
 C. 
 
 sure. 
 
 
 
 
 
 
 1 press. 
 
 Hydrogen 
 
 40.2 
 
 5.8 
 
 0.6497 
 
 9.409 
 
 
 
 
 
 
 After addition of sulphuretted-hy- 
 
 
 . 
 
 
 
 drogen . 
 
 64.3 
 
 5.6 
 
 0.6730 
 
 15.573 
 
 
 
 
 
 
 After absorption of the sulphuretted- 
 
 
 
 
 
 hydrogen by hydrate of potash . 
 
 40.4 
 
 5.4 
 
 0.6516 
 
 9.468 
 
SULPHUROUS ACID. 
 
 Iodine required for decomposition 
 
 of the sulphuretted-hydrogen . . O0688 
 
 Iodine required in the control ex- 
 periment . . , . , . . O0009 
 
 Sulphuretted-hydrogen determined 
 
 as Iodine OO679 = 5.96 cbc. 
 
 Sulphuretted hydrogen found hy 
 
 absorption 6.10 
 
 If sulphuretted-hydrogen occurs merely with nitrogen, 
 hydrogen or other gases not absorbed by potash, it can 
 be determined by simple absorption with a potash -ball 
 like carbonic acid. 
 
 5. SULPHUROUS ACID. 
 
 Sulphurous acid occurs with carbonic acid as a very 
 largely diffused constituent of volcanic gases, and may be 
 determined in exactly the same manner as sulphuretted- 
 hydrogen. The following analyses of a mixture of carbo- 
 nic acid and sulphurous acid shows the great degree of 
 accuracy, which may thus be attained. 
 
 
 Vol. 
 
 Pres- 
 
 Temp 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 1 press. 
 
 Carbonic acid employed . . 
 
 116.5 
 
 0.6720 
 
 19.8 
 
 73.00 
 
 
 
 
 
 
 Alter addition of sulphurous acid . 
 
 152.2 
 
 0.7071 
 
 19.8 
 
 100.35 
 
 After absorption with binoxide of 
 
 
 
 
 
 manganese and phosphoric acid 
 
 115.6 
 
 0.6901 
 
 19.6 
 
 72.94 
 
 Carbonic acid 
 Sulphurous acid 
 
 Found. 
 72.69 
 27.31 
 
 Employed. 
 72.75 
 27.25 
 
 100.00 
 
 100.00 
 
HYDROCHLORIC ACID. 
 
 89 
 
 As a second example of this method, follows an ana- 
 lysis of gases mixed with air, which I collected from one 
 of the fissures in the large crater of Hecla, a few months 
 after the last great eruption of this volcano. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 l m press. 
 
 vTclS CIfl.t)lovCQ 
 
 114.9 
 
 0.6944 
 
 20.4 
 
 74.24 
 
 
 
 
 
 
 Alter absorption with MnO* . . . 
 
 112.9 
 
 0.6958 
 
 20.4 
 
 73.10 
 
 After absorption with KO . HO . . 
 
 108.1 
 
 0.7092 
 
 20.6 
 
 71.29 
 
 Gas transferred 
 
 136.7 
 
 0.3460 
 
 20.6 
 
 43.98 
 
 After explosion with detonating gas 
 
 137.2 
 
 0.3452 
 
 20.7 
 
 44.02 
 
 After addition of hydrogen .... 
 
 190.4 
 
 0.3980 
 
 20.5 
 
 70.49 
 
 \ftcr the explosion 
 
 152.7 
 
 0.3585 
 
 20.3 
 
 50.96 
 
 
 
 
 
 
 After absorption with potash . . . 
 
 148.9 
 
 0.3665 
 
 18.9 
 
 51.04 
 
 Nitrogen 81.81 
 
 Oxygen 14.21 
 
 Carbonic acid 2.44 
 
 Sulphurous acid 1.54 
 
 100.00 
 
 6. HYDROCHLORIC ACID. 
 
 This gas can also be absorbed by a potash ball, like 
 the two preceeding substances, when no other acid gases 
 soluble in water are present. 
 
 The separation of hydrochloric acid from carbonic 
 acid, sulphuretted-hydrogen or sulphurous acid, although 
 it can be completely accomplished, is always attended 
 with some difficulty, particularly when the volume of hy- 
 
90 SPECIAL DETERMINATIONS. 
 
 drochloric acid present is considerable, compared with 
 that of the other gases. 
 
 The hydrochloric acid is first determined after the 
 gas has been completely dried by a ball of phosphoric 
 acid. The absorption of the acid gas may be effected by 
 a ball of oxide of bismuth or oxide of zinc, which has 
 been plastered whilst moist on the bent end of a platinum 
 wire, and then ignited in the flame of a spirit-lamp. With 
 the former of these substances, however, the results ar- 
 rived at are somewhat too small, and with the latter, 
 somewhat too large. More exact results are obtained 
 by employing a neutral salt containing a large quantity 
 of water of crystallization. Sulphate of magnesia, or bo- 
 rax, but especially sulphate of soda answer extremely 
 well for this purpose. A ball of these substances is best 
 made by bending the end of a platinum wire into a coil, 
 and dipping the coil several times into the salt, melted 
 in its own water of crystallization, until a sufficient quan- 
 tity of it adheres to the platinum. If only a small quan- 
 tity of hydrochloric acid is present, this method gives very 
 exact results; but if a large quantity is to be absorbed, it 
 may often happen that the water of crystallization from 
 the sulphate of soda takes up more than a few percenta- 
 ges in weight of hydrochloric acid, and deliquesces to a li- 
 quid, which runs down the sides of the tube, rendering 
 the reading off difficult, and causing small quantities of 
 hydrochloric acid to diffuse with the aqueous vapour into 
 the gas. When this happens, the gas must be dried with 
 phosphoric acid, another ball of sulphate of soda intro- 
 duced, and the gas again dried by phosphoric acid. It 
 is, however, always better to take at first a ball of sul- 
 phate of soda lar^e enough to absorb the whole of the 
 hydrochloric acid in the proper manner. 
 
HYDROCHLORIC ACID. 
 
 m 
 
 After separation of the hydrochloric acid, the sul- 
 phurous acid or sulphuretted - hydrogen is absorbed by 
 binoxide of manganese and phosphoric acid, and the car- 
 bonic acid determined by potash. An experiment con- 
 ducted in this way, gave the following results: 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol at 
 0" C. and 
 1 press. 
 
 Carbonic acid and sulphuretted-hy- 
 drogen, dried by phosphoric acid 
 Alter addition of hydrochloric acid 
 After absorption with sulphate of 
 soda 
 
 104.8 
 167.4 
 
 105.6 
 104.0 
 
 ydrogeL 
 
 0.7187 
 0.7712 
 
 0.7199 
 0.7207 
 
 Emp 
 
 i 5* 
 j.1 
 
 13.7 
 13.7 
 
 13.7 
 132 
 
 loyed. 
 !.34 
 
 .66 
 
 71.72 
 122.94 
 
 72.56 
 71.52 
 
 Found. 
 58.18 
 41.82 
 
 Alter drying with phosphoric acid 
 
 This gives: 
 
 Carbonic acid and sulphuretted-h 
 Hydrochloric acid 
 
 
 100.00 
 
 100.00 
 
 7. HYDROGEN. 
 
 Hydrogen gas can be determined very exactly by 
 combustion with oxygen. This latter gas is best prepared 
 for gasometric purposes in small retorts (Fig. 37) of about 
 Fig. 37. 6 to 10 cubiccentimetre capacity, 
 
 blown before the blowpipe from 
 a glass tube. These retorts are 
 half filled with pulverised dry 
 chlorate of potash, and the end 
 of the tube at a afterwards bent 
 upwards. The air is first ex- 
 
92 SPECIAL DETERMINATIONS. 
 
 pelled by a quick evolution of oxygen, and the gas then 
 allowed to rise immediately into the eudiometer, care 
 being taken not to add more than from three to four times 
 the volume of the hydrogen present. 
 
 The hydrogen amounts to two thirds of the volume 
 which has disappeared after the explosion. If the gas 
 contains absorbable constituents, these are determined be- 
 fore hand, in the absorption tube, and the residual gas 
 then transferred into the combustion eudiometer. In pre- 
 sence of nitrogen, considerable errors may ensue if the 
 temperature of the combustion be not lowered beneath 
 that at which a formation of nitric acid occurs. The re- 
 lation between the volumes of nitrogen and detonating 
 gas burnt, must, therefore, in every case be determined. 
 If this relation is less than 6 to 1, the analysis must be 
 repeated with addition of so much air, that this or a 
 larger proportion is attained. If, on the other hand, the 
 amount of hydrogen is very small, compared with the vo- 
 lume of non- combustible gas, a quantity of electrolytic 
 detonating gas must be added, until the point of com- 
 plete combustion has been reached. This detonating gas 
 disappears completely after the combustion, and therefore 
 does not need to be measured. The hydrogen employed 
 in both the following experiments was prepared by elec- 
 trolysis. 
 
HYDROGEN. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 1" press. 
 
 Air employed 
 
 2G9.4 
 
 0553G 
 
 5 2 
 
 146 36 
 
 
 
 
 
 
 After addition of hydrogen .... 
 
 297.4 
 
 0.580G 
 
 5.4 
 
 169.45 
 
 After the explosion ... ... 
 
 255.1 
 
 0.5386 
 
 5 5 
 
 134 69 
 
 
 
 
 
 
 Employed. Found 
 
 Air 84.23 84.16 
 
 Hydrogen 15.77 15.84 
 
 100.00 
 
 100.00 
 
 A similar degree of accuracy maybe attained in mix- 
 tures containing only a trace of hydrogen. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 Original volume of air . 
 
 269.7 
 
 0.5585 
 
 5.9 
 
 150.49 
 
 
 
 
 
 
 After addition of hydrogen .... 
 
 271.6 
 
 0.5610 
 
 5.9 
 
 152.29 
 
 After addition of detonating gas . 
 
 358.4 
 
 0.6448 
 
 5.9 
 
 226.21 
 
 After the explosion 
 
 268.1 
 
 0.5574 
 
 5.9 
 
 149.37 
 
 
 
 
 
 
 Air . . . 
 Hydrogen 
 
 Employed. Found. 
 
 . 98.82 98.72 
 
 1.18 1.28 
 
 100.00 
 
 100.00 
 
 As an example of a complicated mixture of gases con- 
 taining hydrogen from a natural source, I append an ana- 
 lysis of a gas, which I collected in the summer of 1846, 
 from the great fumarole - fields of the Krafla- and Leyrh- 
 uukr- Volcanoes at Namarfjall in Iceland. 
 
94 
 
 SPECIAL DETERMINATIONS. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 1 press. 
 
 Gas employed 
 
 94 
 
 6945 
 
 13 3 
 
 62 35 
 
 After absorption of the H S . ':,. . . 
 After absorption of the CO 2 . 
 
 73.7 
 46.1 
 
 0.6728 
 0.6502 
 
 13.6 
 13.6 
 
 47.23 
 
 28.55 
 
 Gas transferred 
 After addition of air 
 
 96.8 
 243 
 
 0.3093 
 4534 
 
 13.1 
 13 6 
 
 28.57 
 10506 
 
 After the explosion 
 
 172 
 
 3839 
 
 13 7 
 
 62 88 
 
 After treatment with potash . . . 
 
 168.6 
 
 0.3902 
 
 13.1 
 
 62.78 
 
 Hydrogen 45.07 
 
 Sulphuretted -hydrogen 24.25 
 
 Carbonic acid . . _.^. : . 29.96 
 
 Nitrogen ', -. . ...... . 0.72 
 
 Carbonic oxide . . . . .-...;, ... 0.00 
 
 Hydrocarbons 0.00 
 
 100.00 
 
 8. CARBONIC OXIDE. 
 y. Vol. c + y 2 Vol. o = i vol. 
 
 Carbonic oxide can be separated from light -car- 
 buretted-hydrogen, hydrogen, nitrogen, carbonic acid &c., 
 by means of a concentrated solution of subchloride of 
 copper brought into the tube on a ball of papiermache. 
 The carbonic acid is first determined by a potash - ball, 
 then the carbonic oxide by subchloride of copper, and 
 lastly a potash -ball is again introduced to free the gas 
 from the vapour of hydrochloric acid evolved from the 
 acid chloride. If oxygen is present, it is removed by 
 
CARBONIC OXIDE. 
 
 95 
 
 pyrogallate of potash before the subchloride of copper is 
 introduced. 
 
 The carbonic oxide used in the following experiment 
 was prepared by slightly heating a mixture of formic and 
 sulphuric acids, and to ensure the perfect purity of the 
 gas, it was passed through a concentrated solution of 
 caustic potash. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 . V 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 Original mixture of N, HandCH 2 
 
 80.3 
 
 0.6785 
 
 1.8 
 
 54.32 
 
 After addition of CO 
 
 107 4 
 
 0.71G 9 
 
 05 
 
 76 78 
 
 After absorption with subchloride 
 
 
 
 
 
 of eoDDer . 
 
 80.0 
 
 0.6813 
 
 1.8 
 
 54.35 
 
 
 Employed. Found. 
 
 Gaseous mixture . 
 
 . . . 70.75 70.79 
 
 Carbonic oxide . . 
 
 , . . 29.25 29.21 
 
 100.00 100.00 
 
 Carbonic oxide may be more accurately estimated by 
 combustion with oxygen , and absorption of the carbonic 
 acid produced, by potash. If the mixture is not infla- 
 mable , electrolytic detonating gas must be added until 
 the requisite point of combustibility has been "reached. 
 The gases containing carbonic oxide which escape as 
 products of combustion from the burning materials in a 
 wind furnace, are best analysed according to this latter 
 method. As an example of this process I choose an ana- 
 lysis of a gas collected in 1845 from a boring 6 feet 
 above the hearth in the wall of a blast - furnace of the 
 Schonstein iron works in the Electorate of Hesse , where 
 
9G SPECIAL DETERMINATION'S. 
 
 the fuel used was charcoal. The gas thus collected con- 
 sists entirely of nitrogen, hydrogen and carbonic oxide. 
 
 In order to obtain the amounts of x carbonic oxide 
 and y hydrogen, the following values are to be substituted 
 in the general formula on page 57. 
 
 P total volume of both gases. 
 P\ = volume of carbonic acid formed. 
 a = 1 b = 1 
 a, = 1 bj_ = 
 Hence 
 
 x = P, 
 y = P P!. 
 
 The contraction C observed on the combination of 
 the gases may serve as a control for the correctness of 
 the analysis. 
 
 On combustion of as volumes of carbonic oxide 
 -\- x volumes of carbonic oxide disappear, also 
 -(- !/ 2 x volumes of oxygen disappear, and 
 - os volumes of carbonic acid are produced. 
 
 Hence the contraction from the combustion of the 
 carbonic oxide amounts to 1 / 9 x. On the combustion of 
 y vol. hydrogen, l / 2 y vol. oxygen and y vol. hydrogen dis- 
 appear, or together 1 J /2 y volumes. If the gas really only 
 contains hydrogen and carbonic oxide, we must there- 
 fore have: 
 
 1/2 #+ IVay C= 0. 
 
 The following are the operations,. which must be per- 
 formed. In the first place, the absence of carbonic acid, 
 which would render the combustion - analysis erroneous, 
 must be proved: 
 
CARBONIC OXIDE. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 Gas employed 
 
 98 9 
 
 6313 
 
 9 5 
 
 60 34 
 
 
 
 
 
 
 After absorption with potash . . . 
 
 97.7 
 
 0.6391 
 
 9.7 
 
 60.30 
 
 From this experiment we see that carbonic acid was 
 not present, we have, therefore, only to explode the com- 
 bustible gases with oxygen. If, as in the present case, it 
 is thought that the combustion would not be complete 
 owing to the large excess of nitrogen, a measured quan- 
 tity of hydrogen, or better of electrolytic detonating gas, 
 which, as we have seen, leaves no residue on explosion, 
 must be added. An analysis thus made gave the follow- 
 ing results: 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 1 press 
 
 Gas employed 
 
 149.7 
 
 0.4629 
 
 10.0 
 
 66.85 
 
 Alter addition of hydrogen .... 
 Alter addition of oxygen .... 
 After the explosion 
 
 172.8 
 263.8 
 219.3 
 
 0.4842 
 0.5761 
 0.5317 
 
 9.9 
 9.8 
 9.7 
 
 80.75 
 146.71 
 112.61 
 
 After absorption of the carbonic 
 
 182.8 
 
 05022 
 
 9.7 
 
 88.65 
 
 After addition of hydrogen .... 
 After the explosion 
 
 372.9 
 212.9 
 
 0.6854 
 0.5225 
 
 8.8 
 8.8 
 
 247.62 
 107.77 
 
 
 
 
 
 
 The gas in the four first observations was measured 
 whilst moist, the remaining observations were made after 
 the gas had been dried by a potash-ball. The measure- 
 ment of the latter volumes must be made whilst the gas 
 
 7 
 
98 SPECIAL DETERMINATIONS. 
 
 is perfectly dry, as it often happens that after absorption 
 of the carbonic acid, a certain amount of moisture remains 
 attached to the walls of the eudiometer, and to the mer- 
 cury, which evaporates on admission of hydrogen, but 
 owing to the presence of potash on the side of the tube, 
 cannot attain the amount of tension corresponding to the 
 temperature of the gas. In order to avoid the tedious 
 process of drying the gas, which even with a hard ball of 
 potash takes from 10 to 12 hours, it is adviseable, to 
 transfer a portion of the gas, in which the combustion, 
 and absorption of the carbonic acid has already been 
 made, into another combustion-eudiometer and to analyse 
 the gas, thus freed from contact with potash, in the moist 
 state according to the methods given under oxygen and 
 nitrogen. By means of a simple proportion the amount 
 of oxygen and nitrogen contained in the total volume is 
 then obtained from the analysis of the portion trans- 
 ferred. 
 
 The volume of gas 66.85 originally employed, does 
 not consist of combustible gases alone , but contains 
 a quantity of nitrogen, which has to be determined. 
 The volume 88.65 , after absorption of the carbonic acid, 
 contains no gas besides this nitrogen and so much of 
 the added oxygen as remained after the explosion had 
 occurred. 
 
 The amount of this oxygen is, however, Vs * the 
 contraction ensuing from the combustion with hydrogen, it 
 
 is therefore - - = 46.62. The nitrogen pre- 
 
 o 
 
 sent in the gaseous mixture hence is 88.65 46.62=42.03. 
 This 42.03 subtracted from the original volume 66.85, 
 gives the amount of combustible gases to be 24.82 P. 
 The value of PI from the carbonic acid formed by the 
 
MARSH GAS. 99 
 
 combustion is found to be P l 112.61 88.65 = 23.96, 
 and the contraction occurring from the combustion 
 146.71 112.61 = 34.10. 
 
 This contraction is caused not only by the com- 
 bustible gases originally present, but also by the 13.90 vo- 
 lumes of hydrogen added. This quantity of hydrogen 
 produces a contraction of .% X 13.90 = 20.85 volumes. 
 which must be subtracted from the total contraction 34.10. 
 in order to obtain the contraction C produced by tin- 
 combustible gases originally present; hence 
 C 34.10 20.85 = 13.25. 
 
 The following values of x and y are obtained when 
 the numbers just found are substituted in the respective 
 
 equations. 
 
 x == 23.96 
 
 = 0.86 
 
 Thc mixture of gases, therefore, consists of: 
 Carbonic oxide ..... 35.84 
 
 Hydrogen ....... 1.29 
 
 Nitrogen ....... 62.87 
 
 100.00 
 
 9. LIGHT CARBriJETTEI) -HYDROGEN. 
 MARSH (IAS. 
 
 1 , vol. C -f- 2 vol. H = 1 vol. 
 
 If nitrogen has to be estimated in presence of light 
 rurburetted- hydrogen. care must be taken to dilute the 
 
 \vith so much atmospheric air. that the temperature 
 of the explosion rerun ins low enough to prevent the for- 
 mation of nitric acid. We 1m ve already seen, that on 
 combustion of a mixture of hydrogen and nitrogen the 
 
100 SPECIAL DETERMINATIONS. 
 
 production of nitric acid was prevented, when from 2 to 5 
 parts of non- combustible is present for every part of 
 combustible gas. In the analysis of light carburetted-hy- 
 drogen, as well as of all the hydrocarbons, in which se- 
 veral volumes of hydrogen are condensed into one vo- 
 lume, it is necessary to employ a still greater dilution. 
 
 When from 8 to 12 volumes of air and 2 of oxygen 
 are taken to one of the gas to be examined, accurate re- 
 sults are obtained even when the gas consists of pure 
 light carburetted- hydrogen. If the volume of this latter 
 gas, however, forms only a small fraction of the total quan- 
 tity of gas , the explosion does not occur with this great 
 dilution, and electrolytic detonating gas must be added 
 until the required point of combustibility has been at- 
 tained. The detonating gas must be well mixed with the 
 non - combustible gases before explosion; this is best ac- 
 complished by setting the column of mercury in the eu- 
 diometer into longitudinal vibration. It is unnecessary 
 to measure the exact volume occupied by the detonating 
 gas as it entirely disappears on explosion. Carbonic 
 oxide and hydrogen , when accompanying the marsh gas 
 in presence of nitrogen, can both be determined by a 
 simple combustion. If we call the volume of carbonic 
 oxide tf , that of the marsh gas ?/, and that of the hydro- 
 gen z, we have the following numbers to be substituted 
 in the general formula developed on page 57 : 
 cr=l 6=1 c=l A = 1/2 #== V2 C= 3 A 
 a 1= 1 b l= =l Cl = A!= 8/2 B I= Q = % 
 a,z=i/ 2 6 2 =2 Ca = V2 A 2 = \ B 2 = I C 2 = 
 Hence are derived the following equations, in which P re- 
 presents the volume of the combustible gases, P 2 the oxy- 
 gen combined, and JP, the carbonic acid formed during 
 he combustion. 
 
MARSH GAS. 
 
 101 
 
 y = 
 
 2 P, P 
 
 The following analysis may serve as an example of 
 this process. The gas was collected in July 1848, from 
 the mud of a pond in the Marburg botanical garden, and 
 was freed from carbonic acid by potash before it was 
 analysed. 
 
 & 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Original gas employed 
 
 120.5 
 
 0.3144 
 
 18.6 
 
 35 47 
 
 Alter addition oi' air . 
 
 271 9 
 
 0.4G37 
 
 19 
 
 117 88 
 
 After addition oi' oxygen 
 
 312 2 
 
 05037 
 
 19 2 
 
 146 92 
 
 Alter the explosion 
 
 264.9 
 
 0.4550 
 
 19.4 
 
 112.54 
 
 Alter absorption of carbonic acid . 
 After addition of hydrogen .... 
 After the explosion . . . 
 
 233.6 
 320.3 
 
 278.7 
 
 0.43G6 
 0.5252 
 04670 
 
 19.3 
 19.4 
 19.7 
 
 95.26 
 157.07 
 121 41 
 
 
 
 
 
 
 The quantity af air added amounted to 82.41 vol- 
 umes, in this are contained 65.14 volumes nitrogen and 
 17.27 volumes oxygen, as is calculated in the following 
 manner by means of table VII in the appendix 
 
 80.00 vol. of air contain 
 2.00 
 0.40 
 0.01 
 
 63.2320 vol. nitrogen, 
 1.5808 
 0.3161 
 0.0079 
 
 82.41 vol. of air contain therefore 65.1368 vol. nitrogen. 
 
102 SPECIAL DETERMINATIONS. 
 
 80.00 vol. of air contain .... 16.7680 vol. oxygen, 
 2.00 .... 0.4192 
 0.40 .... 0.0838 
 
 o.oi .... o.oo& -, : 
 
 82.41 vol. of air contain therefore 17.2713" vol. oxygen. 
 
 These 17.27 volumes of oxygen together with the 
 29.04 volumes of that gas added, make a total of 46.31 
 volumes. After the absorption of the carbonic acid formed 
 on combustion, a residual volume of 95.26 was observed, 
 and this could only contain nitrogen and unburnt oxygen. 
 On exploding this gas with excess of hydrogen, a con- 
 traction of 35.66 was found. The third part of tl^s 
 volume, or 11.89, gives the amount of oxygen contained 
 in the 95.26 volumes of residual gas. The difference 
 between 95.26 and 11.89, or 83.37, is the volume of nitrogen 
 originally present in the gas, plus that added as at- 
 mospheric air. By subtracting the volume of nitrogen 
 added in the air, 65.14. from the total quantity of this 
 gas, 83.37, we obtain the amount originally present in 
 the gas, namely 18.23; hence the volume of the com- 
 bustible gases employed in the analysis is found to be 
 17.24 = P. The amount of oxygen combined during the 
 combustion is found, by subtracting the residual amount 
 11.89 from the total amount added, to be 34.42 = P.,. 
 The experiment also gives the volume of carbonic acid 
 formed to be P } = 17.28. By substituting these values 
 in the formula we obtain: 
 
 Marsh gas .... 17.20 
 Nitrogen .... 18.23 
 Carbonic oxide . 0.08 
 
 Hydrogen . . . . - 0.04 
 
 35.47 
 
OLEFIANT GAS. 103 
 
 As the volumes of carbonic oxide and hydrogen are 
 found to be so small that they fall within the limits of 
 experimental error, we may conclude that the gas con- 
 sists entirely of hydrogen and nitrogen. If the experiment 
 had given a large negative value for any constituent, it 
 would show that the gas which has been examined con- 
 tained other gases than those under consideration, and 
 that, therefore, the suppositions upon which these for- 
 mula 1 are founded, are incorrect. 
 
 Therefore, according to analysis, in 100 parts the gas 
 consists of: 
 
 Marsh gas 48.5 
 
 Nitrogen 51.5 
 
 Carbonic oxide ... 0.0 
 
 Hydrogen 0.0 
 
 10. OLEFIAXT GAS. KLAYL. 
 
 1 vol. C 4- 2 vol. H = 1 vol. 
 
 In order to determine the amount of elayl by ab- 
 sorption, a concentrated but still liquid solution of an- 
 hydrous sulphuric acid in monohydrated sulphuric acid 
 is employed. This solution is brought into the dry gas 
 by means of a coke -ball, and thus after the absorption 
 of the elayl is complete, the acid fumes, which have dif- 
 fused throughout the gas, are removed by a ball of 
 potash. 
 
 If the gas contains other absorbable gases, as, for 
 instance, sulphurous acid, carbonic acid, and oxygen, the 
 sulphurous acid must be first determined, then the car- 
 bonic acid, then the elayl, and lastly the oxygen. 
 
104 
 
 SPECIAL DETERMINATIONS. 
 
 As an example I have chosen a mixture of air and 
 olefiant gas. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C 
 
 
 
 
 
 
 l m press. 
 
 Olefiant gas ... . . . 
 
 G7.2 
 
 0.5731 
 
 15.2 
 
 36.48 
 
 After addition of air . 
 
 140 1 
 
 6431 
 
 15 2 
 
 85.35 
 
 After absorption by SO 3 and KO HO 
 
 68.2 
 
 0.5657 
 
 15.2 
 
 36.55 
 
 
 Employed. 
 
 Found. 
 
 Olefiant gas . 
 
 .-.' 57.25 
 
 57.18 
 
 Air . . . . 
 
 42.75 
 
 42.82 
 
 
 
 
 100.00 
 
 100.00 
 
 Olefiant gas may be still more exactly determined 
 by combustion with oxygen. If the quantity of oxygen 
 added be not very much more than that required for 
 combustion, the explosion will be so violent that the 
 eudiometer may be broken. The gas must, therefore, be 
 so diluted with atmospheric air, that for one part of the 
 explosive mixture, about twenty parts of non-combustible 
 gas is added. Very accurate results are then obtained, 
 as may be seen from the following analysis made by 
 Dr. Carius. The olefiant gas employed was prepared by 
 the action of sulphuric acid on alcohol, and to free it 
 from all impurities it was first left in contact with sul- 
 phuric acid, and afterwards with a ball of potash. 
 
OLEFIANT GAS. 
 
 105 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 0C. and 
 l m press. 
 
 36.7 
 311.2 
 339.8 
 318.0 
 290.1 
 
 0.2443 
 0.5183 
 0.5402 
 0.5261 
 0.5130 
 
 12.0 
 12.0 
 12.5 
 12.0 
 11.2 
 
 8.64 
 154.52 
 177.48 
 160.26 
 142.96 
 
 P = 8.64, 
 P l = 17.3, 
 Po = 25.91. 
 
 Original gas 
 
 After addition of air 
 
 After addition of oxygen . . . 
 
 After the explosion 
 
 After absorption of carbonic acid 
 
 These experiments give: 
 
 The volume of gas employed . . . 
 
 the volume of carbonic acid formed 
 
 the volume of oxygen burned . . 
 
 If the gas had still contained two other constituents 
 of known composition, the amounts of these could have 
 been calculated from the three values P, P x , P 2 . If we 
 substitute these values in the formula for elayl, and two 
 other gases, for instance carbonic oxida and marsh gas, 
 the calculation must give the value for the latter gases 
 to be 0, or something very near 0, if the gas consists 
 merely of elayl. 
 
 The equations of condition for a mixture of ,r elayl, 
 y carbonic oxide, and z marsh gas, are found from the 
 following values by means of the general formula pre- 
 viously developed. 
 
 a = 1 b=l c=l .4=+1.5 =-1 (7= 2 
 / 1= =2 &i= 1 cj=l .4!= 1.5 B 1= =l C^ =4-2.5 
 
 x = P! - - P 
 
 2 P l 4- 2 P 2 P 2 
 
 y == 
 
 z = 
 
 3 
 
 4P-f2P 2 
 3 
 
106 SPECIAL DETERMINATIONS. 
 
 By substituting the experimental values of P, Pj, 
 and P 2 we have: 
 
 Elayl . v , 8.66 
 
 Carbonic oxide -f- 0.02 
 Marsh gas . . - 0.04 
 
 It is seen that the amounts of the two last gases fall 
 within the limits of the experimental errors. 
 
 As a second example I cite an analysis made by 
 Dr. M. Hermann, of the remarkable mixture of gases 
 evolved by the action of an alcoholic solution of potash 
 on terbromide of formyl : 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 0C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 Ocis employed ... 
 
 141 4 
 
 1763 
 
 16 9 
 
 23 48 
 
 After addition of oxygen . .'-.'; 
 
 356.8 
 
 0.3857 
 
 16.9 
 
 129.60 
 
 Alter the explosion V; ... . 
 
 325.4 
 
 0.3563 
 
 16.8 
 
 109.23 
 
 After absorption of carbonic acid 
 
 268.7 
 
 0.3159 
 
 17.2 
 
 79.86 
 
 P = 23.48 
 P l = 29.37 
 P 2 = 26.26. 
 
 These values substituted in the formula* give: 
 Elayl . ; v .^ : . '. 5.89 
 Carbonic oxide 17.73 
 Marsh gas . ~~*. - 0.14 
 
 If the nature of the constituents of the gas had been 
 doubtful, the close approximation of the value found for 
 marsh gas to 0, would render it very probable that he 
 assumptions upon which the equations rested were 
 
TETRYLENE. 
 
 107 
 
 correct; that is. that the gas actually was composed of 
 elayl and carbonic oxide alone, and in the following 
 proportion : 
 
 Carbonic oxide . 75.0(i 
 
 Elayl .... 24.94 
 100.00 
 
 11. DITETRYL GAS. TETRYLENE. 
 
 2 vol. C -f 4 vol. H 1-vol. 
 
 Ditetryl gas occurs together with elayl amongst the 
 products of the dry distillation of coal. Like this latter 
 gas, and like almost all the hydrocarbons of the form 
 CiiHn. it is completely absorbed by fuming sulphuric- 
 acid. Even in presence of elayl there is no difficulty in 
 the quantitative estimation of ditetryl. An example will 
 most clearly explain the process adopted in this case. 
 For this purpose, I have chosen Manchester coal gas 
 prepared from cannel coal, containing eight constituents, 
 namely sulphuretted -hydrogen, carbonic acid, nitrogen, 
 carbonic oxide, marsh gas, hydrogen, elayl, and ditetryl. 
 The sulphuretted -hydrogen and carbonic acid are first 
 determined in the absorption tube. The following results 
 were obtained: 
 
 
 Vol. 
 
 Pres- 
 
 I. enip. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 1 press. 
 
 Gas originally employed . . . 
 
 120.5 
 
 0.7250 
 
 2.8 
 
 86.48 
 
 After absorption of sulphtiretted- 
 
 
 
 
 - 
 
 hvdro^eu ... . . -. . 
 
 120.0 
 
 7259 
 
 2.8 
 
 8C>.2;3 
 
 Alter absorption of carbonic acid 
 
 114.4 
 
 0.7341 
 
 3.0 
 
 83.06 
 
108 SPECIAL DETERMINATIONS. 
 
 Hence the composition of the gas is, 
 
 Sulphuretted - hydrogen 
 
 Carbonic acid .' . / 
 
 Elayl 
 
 Ditetryl 
 
 Nitrogen 
 
 Carbonic oxide 
 
 Hydrogeji 
 
 Marsh gas 
 
 . 0.25 
 3.17 
 
 83.0H 
 
 86.48 
 
 The following separate analyses were then made of 
 the residual gas thus freed from sulphuretted - hydrogen 
 and carbonic acid. The total volume of both elayl and 
 ditetryl is determined, in a portion A of the gas, by ab- 
 sorption with fuming sulphuric acid. The residual gas 
 B, remaining after this absorption, is then transferred 
 into the combustion -eudiometer, and analysed by com- 
 bustion with oxygen as previously described. This same 
 combustion - analysis is lastly made with a portion C of 
 the original gas, from which the sulphuretted - hydrogen 
 and carbonic acid, but not the elayl or ditetryl, have 
 been separated. 
 
 Analysis A. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 c. 
 
 
 
 
 
 
 l m press. 
 
 Gas originally employed . . . 
 
 103.1 
 
 0.72G6 
 
 3.3 
 
 74.02 
 
 After absorption with sulphuric 
 
 96.5 
 
 0.7217 
 
 2.4 
 
 69.04 
 
 
 
 
 
 
Hence. 
 
 ANALYSIS OF COAL GAS. 
 b. 
 
 4.98 
 
 109 
 
 Ditetryl) 
 Elayl | 
 Nitrogen 
 Carbonic oxide 
 Hydrogen 
 Marsh gas 
 
 69.04 
 
 74.02 
 
 If this composition is calculated to the volume 83.06 
 of the analysis a. , we have 
 
 c. 
 
 Sulphuretted -hydrogen . . 0.25 
 Carbonic acid ..... 3.17 
 Elayl 
 Ditetryl 
 Nitrogen 
 Carbonic oxide 
 Hydrogen 
 
 Marsh gas 
 
 5.59 
 
 77.47 
 
 86.48 
 
 The composition of the 77.47 volumes of gaseous 
 mixture is found from 
 
 Analysis B. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 C. and 
 
 1 press. 
 
 Original gas employed .... 
 After addition of air ... 
 
 256.0 
 750.7 
 
 0.3395 
 7358 
 
 2.0 
 2.2 
 
 86.28 
 547.90 
 
 After addition of oxygen . . . 
 After the explosion 
 
 814.3 
 688.0 
 
 0.7394 
 0.6754 
 
 2.2 
 2.2 
 
 597.25 
 *460.95 
 
 After absorption of carbonic acid 
 
 645.1 
 
 0.6537 
 
 0.5 
 
 420.94 
 
 After addition of hydrogen . . 
 
 819.0 
 
 0.7490 
 
 0.5 
 
 612.30 
 
 After the explosion .... 
 
 G75.3 
 
 0.6696 
 
 0.6 
 
 451.16 
 
110 SPECIAL DETERMINATIONS. 
 
 Gas employed 83.91 
 
 Oxygen burnt . . 1 . . 92.39 
 
 Carbonic acid formed . . 40.01 
 
 Nitrogen . v- ...' . 2.37 
 
 Nitrogen . . .^ 2.37 
 Carbonic oxide . 6.39 
 Hydrogen . . . 43.90 
 Marsh gas ... 33.62 
 
 S6.28 
 
 Calculated to the 77.47 volumes of analysis c., this 
 
 gives 
 
 d. 
 
 Sulphuretted -hydrogen . . 0.25 
 
 Carbonic acid ."., .1 V ^3.17 
 Elayl ) 
 Ditetryl i 
 
 Nitrogen . . . /." . . 4 ' .''*'' 2.13 
 
 Carbonic oxide . . . ;* ? ' 5.74 
 
 Hydrogen .Jr. ^U'to^. 39.42 
 
 Marsh gas 30.18 
 
 86.48 
 
 In order to determine the relation of the elayl to 
 the ditetryl, an analysis is made with another portion C 
 of the gas , containing all the constituents with the 
 exception of the carbonic acid and sulphuretted - hy- 
 drogen. 
 
ANALYSIS OF COAL GAS. 
 
 Analysis C. 
 
 in 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 Gas employed 
 
 70.5 
 
 0.1593 
 
 3.2 
 
 11.10 
 
 After addition oi' air 
 
 294.1 
 
 0.3583 
 
 2.3 
 
 104.46 
 
 After addition of oxygen . . . 
 
 343.2 
 
 0.4008 
 
 3.0 
 
 136.0G 
 
 After the explosion 
 
 315.9 
 
 0.3775 
 
 3.0 
 
 117.90 
 
 After absorption with potash . . 
 
 297.2 
 
 0.3781 
 
 3.2 
 
 111.07 
 
 The volume of gas employed 11.10 consists there- 
 ore of. 
 
 e. 
 
 0.747 
 
 Elayl I 
 Ditetryl i 
 
 Nitrogen 0.284 
 
 Hydrogen 5.268 
 
 Carbonic oxide .... 0.767 
 
 Marsh gas 4.034 
 
 11.100 
 
 The quantities ol hydrogen, carbonic oxide, and 
 marsh gas contained in these 11.10 volumes, must have 
 given a contraction on combustion of 16.353 volumes, 
 and an amount of carbonic acid equal to 4.801 volumes. 
 The same volume of gas containing 0.747 volumes of elayl 
 and ditetryl gave when burnt, according to analysis C, 
 18.100 volumes contraction, and 6.890 volumes of carbonic 
 acid. The contraction ensuing from the combustion or 
 the elayl and ditetryl, alone amounted therefore to 18.100 
 - 16.353 = 1.747, and the carbonic acid formed from 
 0.747 volumes of the two gases amounted to 6.890 
 
112 SPECIAL DETERMINATIONS. 
 
 - 4.800 = 2.090. Hence the following elements for cal- 
 culation are obtained: 
 
 Volume, of gas employed . . 0.74.7 A, 
 Carbonic acid formed ... 2.0M B, 
 Contraction on combustion . 1.747 C. 
 
 One volume of elayl (1vol. C -f- 2vol. H) gives 2 vol- 
 umes of carbonic acid, and 2 volumes contraction. One 
 volume of ditetryl (2 vol. C -f- 4 vol. H) gives 4 volumes 
 of carbonic acid, and a contraction of 3 volumes. 
 
 The proportion between the two gases calculated 
 from the sum of their volumes A, and from the amount 
 of carbonic acid produced on their combustion /?, is 
 found by the following equations in which x represents 
 the amount of the elayl and y that of the ditetryl. 
 
 1) x + y = A, 
 
 2) 2 x + 4 y = B, 
 
 ' ? B 2 A 
 
 y-- -y--, 
 
 B 2 A 
 
 TT 
 
 By substitution of the experimental values of A and 
 B we have, 
 
 Ditetryl 0.298 
 
 Elayl 0.449 
 
 0.747 
 
 The contraction C gives a third formula 
 
 3) 2 a + 3 y = <7, 
 
 which combined with equation 1) gives the values of x 
 
 and y to be 
 
 y = C 2 A, 
 
 x = A C2 A. 
 
ANALYSIS OF COAL GAS. 113 
 
 The composition derived from these values is, 
 
 Ditetryl .... 0.253 
 
 Elayl 0.494 
 
 0.747 
 
 The close agreement in the numbers of both these 
 determinations, may be regarded as a confirmation of 
 the supposition that the gases consisted entirely of a 
 mixture of elayl and ditetryl. The mean of these two 
 determinations calculated for the 5.59 volumes of elayl 
 and ditetryl found in analysis d., gives the following as 
 the composition of the coal gas. 
 
 Nitrogen 2.13 
 
 Sulphuretted -hydrogen . . 0.25 
 
 Carbonic acid 3.17 
 
 Elayl 3.53 
 
 Ditetryl 2.06 
 
 Carbonic oxide 5.74 
 
 Hydrogen 39.42 
 
 Marsh gas 30.18 
 
 86.48 
 or in 100 parts 
 
 Hydrogen 45.58 
 
 Marsh gas . . 34,90 
 
 Carbonic oxide 6.64 
 
 Elayl 4.08 
 
 Ditetryl 2.38 
 
 Sulphuretted -hydrogen . . 0.29 
 
 Nitrogen 2.46 
 
 Carbonic acid 3.67 
 
 100.00 
 
 This gas thus contains 8 constituents, and among these 
 6 are combustible. If another hydrocarbon absorbable 
 
 8 
 
114 SPECIAL DETERMINATIONS. 
 
 by sulphuric acid were present as the ninth constituent, 
 it could also be determined by means of formulae 1, 2, 
 and 3. Even if another non-absorbable hydrocarbon be 
 present as tenth constituent, it can be estimated when 
 the carbonic oxide has been previously removed by sub- 
 chloride of copper. Lastly, another equation is obtained, 
 by help of which an eleventh constituent may be deter- 
 mined, when the volume of aqueous vapour generated 
 during the combustion is measured according to the 
 method previously described. 
 
 As the quantity of oxygen contained in such a 
 mixture of gases can be easily determined by absorption 
 with pyrogallate of potash, it is seen that by means of 
 gasometric analysis, twelve gases, some of them com- 
 bustible and some non- combustible, can be completely 
 separated from each other. 
 
 12. M T H Y L. 
 
 . 2 vol. C -j- 5 vol. H = 1 vol. 
 
 The analysis of sethyl, and of all the gaseous hydro- 
 carbons which contain their constituents in a very con- 
 densed state, can be made like that of elayl and ditetryl; 
 but in proportion as the condensation becomes greater, 
 must the amount of air added be increased. Thus, for 
 example , in order to burn 1 volume of ffithyl containing 
 7 volumes of carbon and hydrogen, it is necessary to 
 add a volume of air from 20 to 24 times as great as the 
 volume of sethyl, and from 6 to 7 times the same volume 
 of oxygen. It is, therefore, most convenient to employ 
 for such analysis an eudiometer from 0.8 to 1.0 metre in 
 length. 
 
jETHYL GAS. 
 
 115 
 
 As an example of an analysis of pure sethyl I cite 
 an experiment made some time ago by Professor Frank- 
 land in my laboratory. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 1 press. 
 
 
 91.8 
 
 0.1186 
 
 12.8 
 
 10.40 
 
 
 471.2 
 
 0.5215 
 
 13.0 
 
 234.56 
 
 After addition of oxygen . . . 
 
 535.1 
 
 0.5800 
 
 12.9 
 
 296.35 
 
 
 498.8 
 
 0.5461 
 
 12.8 
 
 260.19 
 
 After absorption of carbonic acid 
 
 454.3 
 
 0.5043 
 
 13.0 
 
 218.69 
 
 After admission of hydrogen . . 
 
 644.7 
 
 0.6769 
 
 13.1 
 
 416.41 
 
 After the explosion 
 
 532.7 
 
 0.5770 
 
 13.0 
 
 293.39 
 
 Gas employed . . 
 Oxygen burnt . . 
 Carbonic acid formed 
 
 Found. 
 10.40 
 67.26 
 41.50 
 
 Calculated. 
 10.36 
 67.35 
 41.45 
 
 The close agreement between the numbers found by 
 experiment, and those calculated from the formula 
 2 vol. C -)- 5 vol. H = 1 vol., shows that the gas under 
 examination consisted of pure sethyl. 
 
11G DETERMINATION OF THE 
 
 SPECIFIC GRAVITY OF GASES. 
 
 A he specific gravities of various gases are represented 
 by the weights which equal volumes of these gases 
 possess. As the volume occupied by a given weight of 
 any gas, is dependant upon the variations of the force 
 of gravity accompanying change of geographical latitude, 
 or elevation above the sea's level, all gases, of which the 
 absolute volumes are required, must be reduced to the 
 same latitude and elevation above the sea, and to the 
 same barometric pressure and temperature. 
 
 According to the most accurate experiments, for 
 which we are indebted to the classical labours of Reg- 
 nault, one gramme of atmospheric air at the level of the 
 sea, in the 45th degree of latitude, at 0C., and under 
 a pressure of O m 76 of mercury, occupies a volume of 
 773.526 cubic -centimetres. For a latitude qp, and at an 
 elevation of h toises * above the mean level of the sea, 
 this volume is found from the following expression; 
 
 7=773.520. 
 
 1 _ 0.0025935 cos 2 <p ' 
 
 * A toise is equal to 1.9491 metres pretty nearly equal to an 
 english fathom. 
 
SPECIFIC GRAVITIES OF GASES. 117 
 
 in which the number 3266322 signifies the length of the 
 earths radius in toises. 
 
 In the latitude 52 36', as, for instance, in Berlin, a 
 gramme of dry air at 0C., and under a pressure of O m 76 
 occupies exactly 773 cubic -centimetres. 
 
 The accuracy of gasometric determinations is seldom 
 so great, that the differences resulting from the variation 
 of gravitation extend beyond the limit of the possible 
 observational errors. Hence, excepting in normal de- 
 terminations when the greatest accuracy is required, the 
 volume of 1 grm. of dry air .at C., and O m 76 pressure 
 of mercury, may be represented in our latitudes by 
 773 cubic - centimetres ; and the specific gravity of a gas 
 may be defined to be, the weight in grammes of gas 
 which, under the same conditions, occupies a space of 
 773 cubic - centimetres. 
 
 The vertical column of table V in the appendix 
 headed ,,Spec. grav." contains the specific gravities of the 
 more common gases and their constituents. The numbers 
 for oxygen, hydrogen, and nitrogen are those found by 
 Regnault from direct experiment, the remainder are cal- 
 culated from the following atomic weights according to 
 Gay-Lussac's law of volumes. 
 
 = 100.00 Fl = 120.00 
 S = 200.00 Sb = 806.25 
 Se = 491.20 As = 468.75 
 Te = 806.50 Ph = 193.75 
 Cl = 221.87 Si = 266.25 
 Br = 489.40 Bo = 136.25 
 
 1 = 794.37 C = 75.00 
 
 The basis of this calculation is founded upon Reg- 
 nault's fundamental experiment, according to which 1000 
 
118 
 
 METHODS OF DETERMINING 
 
 cubic - centimetres of oxygen in latitude 52 36', at the 
 mean sea's level, and at 0C. and 0.76 pressure of mer- 
 cury, weigh 1.43028 grammes. 
 
 The determination of the specific gravity of gases 
 and gaseous mixtures is a very important operation in 
 gasometric researches. 
 
 In cases in which a normal determination is not 
 required, a common light flask, g, Fig. 38, is employed 
 for measuring the volume of gas of which the specific 
 
 Fig. 38. 
 
 gravity is to be estimated. The volume of the flask should 
 be about 200 or 300 cubic - centimetres , and the neck a, 
 thickened before the glass blowpipe, must be drawn out 
 so as to have an aperture of the thickness of a straw, 
 into which a glass stopper is ground air-tight by means 
 of emery and turpentine. Through this neck, which is 
 furnished with an etched scale in millimetres, mercury 
 is poured, by means of a funnel reaching to the bottom 
 of the flask, until the whole is filled. As soon as this 
 
THE SPECIFIC GRAVITIES OF GASES. 119 
 
 is accomplished, the flask is transferred, with its mouth 
 downwards, into the mercury trough A A, and gas is 
 allowed to enter, until the level of mercury in the neck 
 of the flask stands a few millimetres higher than that in 
 the trough. In order to secure the absence of all gaseous 
 impurities, this gas is evolved from as small a vessel as 
 possible, and allowed to enter the flask through a narrow 
 delivery tube and in the moist state. The gas is dried 
 in the flask itself by a small piece of fused chloride of 
 calcium 6, which had previously been made to crystallise 
 on the side of the flask by bringing if in contact with a 
 single drop of water, and alternately heating and cooling 
 the glass. This small piece of chloride of calcium serves 
 also to free the mercury and the sides of the flask from 
 all adhering moisture. In order to be able to close the 
 flask at any time without warming it with the hand, the 
 little lever cf is employed. On the lower end /of this 
 lever the stopper is so fastened in a cork, that it passes 
 into the neck of the flask without closing it, and the 
 lever is held in its right place by a wedge d, pushed 
 under the finger plate c. As soon as the apparatus has 
 attained the constant temperature t at the barometric 
 pressure P, the volume V of the gas , and the height p 
 of the column of mercury rising above the level of the 
 metal in the trough, are observed with the cathetometer 
 telescope. If the observed volume of gas in cubic -centi- 
 metres reduced from a table of capacity, be represented 
 by F n this volume at 0C. and 0.76 pressure becomes in 
 cubic - centimetres : 
 
 v 
 
 " 
 
 0.76 (1 + 0.00366 t) 
 
 It is now only necessary to determine the weight G 2 
 of this volume K 2 . This is obtained in the following 
 
120 
 
 METHODS OF DETERMINING 
 
 Fig. 39. 
 
 manner: the wedge d is taken away, the flask is thereby 
 closed, and by withdrawing the pin e, it can then be 
 removed, together with the lever c/, from the trough. 
 After having been most carefully freed from all adhering 
 matters, and having attained the temperature ^ of the 
 balance, by the pressure Pj, the flask can be weighed. 
 Let G represent the weight in grammes thus found. The 
 
 glass stopper is now re- 
 moved and replaced by a 
 caoutchouc tube connect- 
 ed with a drying tube 6, 
 Fig. 39. The apparatus 
 thus arranged is placed 
 under the receiver of an 
 air-pump, and the air 
 so often withdrawn and 
 admitted until all the 
 gas has been replaced by 
 dry air. If this weight 
 amounts to G l grammes, 
 the weight 6r 2 of the vol- 
 ume of gas V 2 measured 
 in the flask is equal to 
 
 Vi Pi 
 
 773 X 0.76 X (1 -f 0.00366 t,) 
 
 From this value G 2 , the specific gravity is obtained 
 by the help of the following formula, 
 
 O r? f? O ^-"2 
 
 o = i (6 -=. 
 
 * The unequal specific gravity of the glass and mercury on the 
 one hand, and the metal weights on the other, is not con- 
 sidered in this calculation, as the inaccuracy thus introduced 
 is inconsiderable in comparison to the observational errors. 
 
THE SPECIFIC GRAVITIES OF GASES. 1*1 
 
 I cite as an example of this determination a vapour- 
 density of gaseous bromide of methyl, made with a small 
 balloon of about 44 cubic -centimetres capacity. Ob- 
 servation gave : 
 
 V l 42 CC 19 G = 7*9465 
 
 P = O m 7464 G l = 7*8397 
 
 p = O m 0243 P l =rO m 7421 
 
 t = 1608 C. t, = 6<>2 C. 
 
 The specific gravity calculated from these numbers 
 is 3.253. According to the chemical composition it should 
 have been 3.224, for 
 
 2 X 773 cbc. carbon vapour . . . = 1.6584 
 
 6 X 773 hydrogen ..... = 0.4156 
 
 2X773 bromine vapour . . =10.8217 
 
 4 X 773 bromide of methyl . = 12.8957 
 
 1X773 bromide of methyl . = p = 3.2239 
 
 It often happens that only a few cubic -inches of gas 
 are placed at the disposal of the analysist. The amount 
 of material remaining after the necessary analyses have 
 been made, is therefore often insufficient for the deter- 
 mination of the specific gravity of the gas according to 
 the process just described. In such cases I employ an- 
 other method which gives results of sufficient accuracy 
 even with two cubic -inches of gas. 
 
 This method is based on the fact that the specific 
 gravity of two gases, which stream out of a fine opening 
 in a thin plate, are very nearly proportional to the square 
 of the time of effusion. If a gas of specific gravity s requires 
 the time ?, and another gas of specific gravity s 1 requires 
 the times ^, the relation between the times of effusion, 
 and the specific gravities is represented by the equation 
 
122 
 
 METHODS OF DETERMINING 
 
 - = -^-. If s, or the specific gravity ol one gas, be 
 made equal to 1, the specific gravity of the other is found 
 
 2 
 
 from the formula s { = -. 
 
 Fig. 40 represents the apparatus which is employed 
 Fig 40 f r these determinations. The glass tube 
 
 a a of about 70 cbc. capacity, and open 
 at bottom, is furnished with a glass stop- 
 cock at c, into which the small glass tube 
 e is ground air-tight at d. This small 
 tube is closed at the upper end by a thin 
 piece of platinum foil melted on to the 
 glass, and pierced by a very small aper- 
 ture. In order to render the foil as thin 
 as possible, and the opening extremely 
 small, a hole is bored through the metal 
 with a fine needle, and the platinum, 
 thus pierced, beaten out with a polished 
 hammer on a steel anvil until the hole 
 is not perceptible to the ordinary eye, 
 and is only just seen when the foil is 
 held close between the eye and a bright 
 flame. The foil is then cut into a small 
 round disk in the centre of which is 
 placed the fine aperture. This small disk 
 of metal is easily melted on the upper 
 end of the small tube ed, by laying it 
 upon the blown -out end of the tube, and 
 allowing the edges of glass to fall 
 together over the metal by heating the 
 tube in the blowpipe flame. 
 
 In order that the gases under exami- 
 
THE SPECIFIC GRAVITIES OF GASES. 123 
 
 nation should issue from the aperture e under precisely 
 the same conditions of pressure, a float 66, made as 
 light as possible, of thin glass, is placed in the tube a a. 
 This float carries at a small bead of black glass, to 
 which a thread of white glass is attached; and at ft and 
 ft are placed two other threads of black glass which, 
 like the black bead , serve as marks of level. 
 
 If the tube containing the gas to be examined, and 
 the glass float, be dipped so deep in mercury that the 
 level of the mercury outside , coincides with a mark y on 
 the tube, the float is not visible to a telescope directed 
 on to the mark y. The stop -cock c can now be opened, 
 and the gas thus allowed to escape through the aperture 
 e, so that the float 66 rises with the level of the mercury 
 inside the tube. During this time the experimenter must 
 observe the level of the mercury through the telescope, 
 and after a little time the white thread appears, giving 
 notice that before long the black bead will rise to the 
 level //. At the moment when the bead becomes visible 
 the observations of time must be made with a pendulum 
 vibrating half -seconds, previously verified by a chrono- 
 meter. These observations of time are concluded at the 
 instant the black thread ft appears in the field of view 
 of the telescope, the thread ft gives, as before, warning 
 as to the approach of the end of the experiment. 
 
 By means of these observations, the time of effusion 
 of a column of gas is obtained having a constant length of 
 from /3 to ft reckoning from y on the tube, and issuing 
 tinder pressures the sum of which remains always constant. 
 This time of effusion, determined for various gases, raised 
 to the square gives the relation of the specific gravities 
 of the gases. 
 
124 METHODS OF DETERMINING 
 
 The arrangement represented in Fig. 41, serves to 
 hold the instrument. The tube is fastened to the arm b 
 which is moveable on the standard a a ; by means of this 
 
 Fig. 41. 
 
 arm the tube can be sunk into a hole in the block J, 
 until, when the stop-cock is open, the mercury completely 
 fills the instrument. As soon as the tube is filled with 
 mercury, it is raised out of the mercurial trough, and, as 
 the glass float is already contained in the tube, the gas 
 is allowed to enter in the usual manner from below. If 
 a large amount of gas is placed at the disposal of the 
 
THE SPECIFIC GRAVITIES OF GASES. 
 
 125 
 
 experimenter, it is more convenient to remove the little 
 glass tube d, and to allow the gas to enter the instrument 
 from above and to expel the air by the lower end of the 
 tube which dips under the surface of the mercurial trough. 
 The arrival of the marks on the float above the level of 
 mercury is observed through the plate glass sides h h of 
 the trough. For the sake of greater accuracy it is ad- 
 viseable to take the mean of several series of observations. 
 It is scarcely necessary to mention that the gases must 
 be employed in the dry state, and that all oxidation of 
 the mercury, which would retard the motion of the float 
 must be most carefully avoided. 
 
 The following experiments show the degree of ac- 
 curacy which can be attained by this method. The first 
 column t contains the times of effusion of a volume of air, 
 the second column t the times of effusion of an equal vol- 
 ume of gas , the third and fourth columns the square of 
 these observed times, and the fifth column the specific 
 gravities calculated from these squares. 
 
 Air 
 
 Hydrogen 
 
 . t* 
 
 *i* 
 
 /,* 
 
 t 
 
 *i 
 
 
 
 t* 
 
 105.5 
 
 29.7 
 
 11130 
 
 882.09 
 
 0.0792 
 
 105.0 
 
 30.0 
 
 11025 
 
 900.00 
 
 0.0816 
 
 105.5 
 
 29.5 
 
 11130 
 
 870.25 
 
 0.0782 
 
 105.6 
 
 29.3 
 
 11151 
 
 858.48 
 
 0.0770 
 
 105.5 
 
 
 11130 
 
 
 
126 
 
 SPECIFIC GRAVITY. 
 
 Air 
 
 Oxygen 
 
 t* 
 
 i 2 
 
 *, 2 
 
 t 
 
 h 
 
 
 
 t 2 
 
 102.5 
 
 108.5 
 
 10506 
 
 11772 
 
 1.1205 
 
 103.0 
 
 109.0 
 
 10609 
 
 11881 
 
 1.1199 
 
 102.8 
 
 108.5 
 
 10961 
 
 11772 
 
 1.1140 
 
 Air 
 
 Carbonic acid 
 
 
 
 *, 2 
 
 t 
 
 n 
 
 
 
 r! 
 
 102.7 
 
 127.0 
 
 10547 
 
 16129 
 
 1.5292 
 
 
 127.5 
 
 
 16257 
 
 1.5414 
 
 Air 
 t 
 
 Electrolytic 
 deton. gas 
 <i 
 
 t* 
 
 i 2 
 
 *. 2 
 t* 
 
 117.9 
 
 75.4 
 
 13900 
 
 568.52 
 
 0.4090 
 
 117.0 
 
 75.5 
 
 13689 
 
 570.03 
 
 0.4164 
 
 117.9 
 
 75.5 
 
 13900 
 
 570.03 
 
 0.4101 
 
 117.6 
 
 75.6 
 
 13830 
 
 571.54 
 
 0.4133 
 
 
 75.9 
 
 
 576.08 
 
 0.4166 
 
 Air 
 t 
 
 1 vol. CO 
 -f- 1vol. CO 2 
 *i 
 
 2 
 
 , 2 
 
 tS 
 t* 
 
 117.9 
 
 130.5 
 
 13900 
 
 17030 
 
 1.2251 
 
 
 127.0 
 
 
 16129 
 
 1.1603 
 
 
 130.5 
 
 
 17030 
 
 1.2251 
 
SPECIFIC GRAVITY. 
 
 127 
 
 The mean specific gravities calculated from these 
 experiments are collected in the following table. The 
 first column contains the experimental results, the 
 second column the same values calculated from the 
 atomic weights. 
 
 Gases. 
 
 I. 
 
 II. 
 
 Difference. 
 
 Air . . 
 
 1.000 
 
 1 000 
 
 
 Carbonic acid . . . . 
 1 vol. CO + 1 vol. CO 2 
 
 1.535 
 1.203 
 1 118 
 
 1.520 
 1.244 
 1 106 
 
 -f- 0.015 
 0.041 
 _j_ o 012 
 
 Electrolytic deton. gas 
 Hydrogen .... 
 
 0.414 
 0.079 
 
 0.415 
 0.069 
 
 - 0.001 
 
 4- o.oio 
 
 
 
 
 
 It is seen that the agreement between the experimental 
 and calculated values is very close. For technical pur- 
 poses, as, for instance, the determination of the specific 
 gravity of coal gas, this method is peculiarly applicable 
 from its extreme simplicity. 
 
128 LAWS OF THE ABSORPTION. 
 
 ABSORPTION OF GASES IN LIQUIDS. 
 
 (jraseous bodies are absorbed by liquids, on which 
 they exert no chemical action, in quantities dependant 
 upon 
 
 1st the essential nature of the gas and of the absorbing 
 
 liquid ; 
 
 2nd the temperature; 
 3rd the pressure, to which the gas is subjected. 
 
 The volume of gas, reduced to C. and O m 76 pres- 
 sure of mercury, which is absorbed by the unit volume 
 of a liquid, under the pressure of O m 76 of mercury, is 
 called the absorption-coefficient, or coefficient 
 of absorption. 
 
 The value of this absorption - coefficient in general 
 decreases with increase of temperature, in a ratio depen- 
 dant upon the chemical nature of the absorbed gas and 
 absorbing liquid. The values of the absorption - coeffi- 
 cients for varying temperatures can only be empirically 
 determined. 
 
 An exact relation is, however, found to exist between 
 
OF GASES IN LIQUIDS. 129 
 
 the volumes of absorbed gas *, and the pressures, under 
 which the absorption takes place: The quantity of gas 
 absorbed varies directly as the pressure. 
 
 The coefficient of absorption of any gas is therefore 
 known, when the following quantities are given: 1st, the 
 volume V before the absorption, reduced to C. and obser- 
 ved under the pressure P\ 2nd, the volume Fi, remaining af- 
 ter the absorption, reduced to C. and standing under the 
 pressure PI ; and 3rd, the volume hi of the absorbing liquid. 
 
 The quantity of gas absorbed by this volume hi of 
 liquid under the pressure P l , is equal to the difference 
 between the volume of gas originally taken, and that re- 
 maining unabsorbed: 
 
 VP _ \\Pi 
 0.76 " 0.76 ' 
 
 If the pressure during the absorption had not been 
 PI but 0.76, the amount of gas absorbed would have been 
 according to the above law, 
 VP 
 
 - F - 
 
 Hence it follows, that the coefficient of absorption, 
 i. e. the quantity of gas absorbed in the unit volume of 
 liquid under the pressure 0.76, is 
 
 When this coefficient a. is known, the quantity of gas 
 g absorbed in li volumes of liquid under a pressure P is 
 given by the equation : 
 
 * The expressions quantity of gas " or reduced volume " are 
 henceforward to be understood to signify the volume of gas, 
 reduced to C. and 0.7G pressure of mercury. 
 
 9 
 
130 LAWS OF THE ABSORPTION 
 
 If two or more gases are mixed together, the ab- 
 sorption of the constituent parts is proportional to the 
 pressures, to which these parts are severally subjected. 
 Let the volumes v l v 2 v n , Fig. 42, of different gases, each 
 Fi s- 42 - under the pressure P, remain un- 
 
 mixed one above the other, sepa- 
 rated by the diaphragms ii, ^ij, 
 each of the gases exerting a pressure 
 P against the inclosing diaphragm; 
 withdraw the diaphragm and re- 
 move the resistance opposing the 
 action of the pressure, and the par- 
 ticles of v l will, in virtue of the 
 pressure P, penetrate into the ga- 
 ses 2 u B , which offer no resistance. 
 The motion of the particles of the gas v l ends with a 
 state of equilibrium , which ensues when the pressure 
 exerted by v^ has become equally great at every point of 
 the space v -j- v 2 -\- v, that is, when the gas v 1 has uni- 
 formly extended itself throughout this whole space. The 
 pressure on i^ is therefore, according to the law of Mariotte : 
 
 *>1 V 2 
 
 In like manner it is found, that the gases v 2 and v n , 
 when equilibrium has ensued, are subject to a pressure of 
 
 - rJ*- P and - . '" , P. 
 
 Vl + V 2 -)- V n ^1+^2+ V n 
 
 From these pressures of the constituent parts the 
 total pressure of the mixture is found to be 
 
 p\ __ * p \ 
 
 ' 
 
 Vl + V 2 -f- V n V l -f- V 2 -|- V n ' V 1 -f- V 2 -\- V n 
 
 The quantity of each constituent gas absorbed, is pro- 
 portional to the pressure on that constituent part 
 
OF GASES IN LIQUIDS. 131 
 
 ^3 _ p. 
 
 + J. , 
 
 V * + V n 
 
 and these pressures may be distinguished as partial 
 pressures", in contradistinction to the ,,total pressures" of 
 the whole mixture. 
 
 If a mixture of gases , the constituents of which are 
 supposed not appreciably altered by absorption, consists 
 of two or more volumes of chemically different gases 
 v i V 2 v n > the amount of each gas dissolved in h volumes of 
 liquid under the pressure P, when a t 2 a n are the respec- 
 tive absorption -coefficients of the different gases at the 
 observed temperature, is of the first gas, 
 
 j 1l P Vi 
 
 0.71) (i ?1 +*,+,)'' 
 of the second gas, 
 
 of the 7ith gas, 
 
 a n h P v n 
 
 0.76 (v, + v, + v n ) 
 
 The unit volume of the absorbed gaseous mixture 
 therefore contains , of the first gas 
 
 ?/! = 
 
 of the second 
 
 2 = 
 U 
 
 of the nth 
 
 If, on the contrary, the quantities of the separate ga- 
 ses ?/! u 2 . . . contained in the unit of absorbed gas are 
 known, the composition of the gas used for the absorp- 
 
132 LAWS OF THE ABSORPTION 
 
 tion, supposing that its constituents remain in a constant 
 relation during the experiment, is found from the follow- 
 ing equations. 
 
 The unit of free gas contains of the first gaseous 
 constituent, 
 
 ^+^+- -t 
 
 of the second 
 
 v. 2 = 
 
 i , U 2 U n 
 
 -- u. -4- . . . _) -- 
 
 ' 
 
 of the third 
 
 i_ , a. , i _-. 
 
 1 2 
 
 These formula} are only strictly true on the suppo- 
 sition, that the relation originally existing between the 
 volumes of the constituent gases is not appreciably dis- 
 turbed in consequence of the absorption; they are there- 
 fore, accurately speaking, only applicable in the case in 
 which a gaseous mixture of constant composition, either 
 infinitely large or continually renewed, acts upon a finite 
 volume of liquid. If the volume of liquid employed, is 
 appreciable compared with the volume of gas, the altera- 
 tion which the absorption causes in the composition of 
 the unabsorbed gas, must be brought into the calcula- 
 tion. 
 
 Let us next consider the alterations which a mix- 
 ture of two gases undergoes by absorption, supposing 
 that all the volumes of gas are reduced to C. 
 
OF GASES IN LIQUIDS. 133 
 
 Let the total volume of gas under the pressure P be 
 V\ in the unit volume of this gas let there be v volumes 
 of the first gas, and i\ of the second. Let the absorption- 
 coefficient of the first gas at the observed temperature be 
 a, and that of the second 0, and the volume of absorbing 
 liquid h. Further, let the total volume of the gas remain- 
 ing after the absorption be V l under the pressure P l ; 
 and, lastly, let the unit volume of this residual gas con- 
 tain u volumes of the first, and w x volumes of the second gas. 
 
 The volume V contains v V volumes of the first gas 
 
 vVP 
 
 at the pressure P, or volumes at O m 76. This volume 
 
 is separated by absorption into two parts: the first part, 
 ,c, remains behind after the absorption a free gas ; the 
 second, ^, is that absorbed by the w&kex^ The quantity 
 of this latter is determined by the law of absorption; the 
 unit of liquid absorbs the volume a under the pressure 
 O m 76 ; hence under the pressure PI , h volumes of water 
 
 will absorb 
 
 ah Pi 
 0.76 ' 
 
 As, however, the first gas is expanded by mixing 
 
 V P 
 
 with the second from x to * /r , the quantity of gas ab- 
 
 sorbed by h is, by virtue of the partial pressure, 
 alix 
 
 Hence 
 
 or 
 
 vVP 
 
 ahx v V P 
 ~'~ : ~~' 
 
134 LAWS OF THE ABSORPTION 
 
 and by similar reasoning, the volume of the second gas is 
 
 0,6 (l + f J 
 
 Hence when 
 
 ,, 
 
 we obtain 
 
 (AB l + A#) ~~ + y~ 
 
 A n 
 ^--y^nt ... (6) 
 
 It is clear that, vice versa, the unknown composition 
 of a gaseous mixture may be found from the change of 
 volume ensuing on absorption by a liquid. In this way 
 it is possible to analyse mixtures of gases by a purely 
 physical experiment, unassisted by chemical decomposi- 
 tion. Such absorptiometric determinations, as I term 
 them, are, under certain conditions, scarcely less correct 
 than a chemical analysis, and often much more simple 
 and convenient. Frequently, indeed, this mode of analysis 
 is of immense importance, as solving questions, which by 
 other methods are not determinable. 
 
 Let us next consider the case, in which two gases are 
 given whose relation to each other is to be determined 
 by an absorptiometric experiment. 
 
 Let # be the original volume of the first gas reduced 
 to the pressure 1 ; 
 
 Let #' be the volume of the same gas unabsorbed, 
 also reduced to the pressure 1 ; 
 
 Let v be the volume of the unabsorbed gaseous mix- 
 ture at the pressure P' ; 
 
OF GASES IN LIQUIDS. 135 
 
 r' 
 
 The pressure of the unabsorbed gas 1 is then --T*/ 
 
 1 {/ 
 If the absorbed quantity of the gas 1 be reduced to this 
 
 pressure, the volume is ah: reduced to the pressure 1, it 
 is therefore: 
 
 17 * 
 
 and hence 
 
 or 
 
 ah 
 
 Hence the pressure of the unabsorbed gas 1 is 
 x 
 
 v' + a h 
 
 If y and y' represent the same values for the gas 2, 
 which x and x' did for the gas 1 , the pressure of the un- 
 absorbed gas 2 is 
 
 y 
 
 v' + flh' 
 As P' is the pressure of the mixture, we get 
 
 p.- __ _ i 
 ~ 
 
 ah v' + fih 
 If P is the pressure under which the mixture origi- 
 nally occupied the volume V, we have 
 
 PJL i _i_ 
 V V 
 
 (also obtained when h = 0). We have then 
 
 1 - x J- 
 
 = ./ / " / 
 
 . _J i 
 - V p T 
 
136 LAWS OF THE ABSORPTION 
 
 If we place 
 
 VP= w; 
 
 (P-f- ah) P* = A, 
 
 we obtain 
 
 x W B A 
 
 y = A - - W ' B ' 
 
 or the volumes of the first and second gases in the unit 
 volume of the mixture are 
 
 ~^~+~y == T~-^~B ' ~W ' ' ' ' (? ) 
 
 y A W B 
 
 ~aT+~y " ~A~- ^~B ' ~W ' 
 
 For the case in which n gases are to be determined, 
 n equations are required, easily obtained by observing 
 for particular temperatures if, t- L ,t%,...,t n _ l , or for different 
 volumes of liquid A, A l7 A 2 , . . ., A n _i, the corresponding 
 gaseous volumes V, F x , F>, . . ., F w _ n at various pressures 
 P, PI , P>, . . ., P H _ r Thus for a mixture of three gases 
 whose volumes are x -f- y -)- z the following equations 
 are obtained : 
 
 _ i I __ 
 
 ^ ^ VP 9 
 
 j 
 
 i _ i_ i * 
 
 If we substitute , 6, c for the coefficients -r= in 
 
 the first equation, a 1? &j, c'j for 7^ - in the 
 
 (l/j -f- 
 
 second, and a. 2 , ^/ 25 z ^' or TTT i - 7 . in the third, 
 
 ( V-2 - 
 
 we obtain: 
 
it' ^i 6j C 2 U-2 GI + 
 
 b. 2 G 6' 2 + GI DI G 
 
 y B ac* 2 ac\ + ci] 
 z C ci LI a b<) + (- 
 
 + f 5 
 6(2 GI Cl<2 G 
 
 y B ci Co ci GI | c 
 or 
 
 y _ 
 
 B 
 
 X 
 
 A 
 
 z 
 
 + B + C 
 C 
 
 x 
 
 The determination of the coefficients of absorption 
 is of the greatest importance in gasometric investigations. 
 The experiments are conducted in an absorptiometer, the 
 arrangement of which is seen in Fig. 43 (see p. 138). 
 
 The absorption - tube e, Fig. 43, divided into milli- 
 metres and calibrated, has a small iron band 6, Fig. 44, 
 furnished with a screw, luted on to its lower and open 
 end; this fits into another screw attached to the small 
 iron stand a a , Fig. 44. By this arrangement the open 
 end of the tube can be screwed down against a plate of 
 caoutchouc covering the bottom of the stand, and the 
 tube thus completely closed. On each side of the stand 
 are fixed two steel springs cc, which fit into two vertical 
 grooves in the inside of the wooden foot of the apparatus 
 /, Fig. 43, so that the little iron stand a a, Fig. 44, can be 
 raised or depressed, but not turned on its axis to the right 
 or left. The outer cylinder gg, Fig. 43, is not cemented 
 into the wooden foot /, or into the iron rim A, but the 
 screws ii press the ground -glass edges of the cylinder 
 against caoutchouc rings placed to receive them. The 
 tubes rr serve to pour in mercury, so that any desired 
 pressure is obtained in the absorption-tube by raising or 
 
138 METHOD OF DETERMINING 
 
 Fig. 43. 
 
 44. 
 
THE COEFFICIENTS OF ABSORPTION. 139 
 
 depressing the level of mercury in the inner glass cylin- 
 der. The temperature of the surrounding water is deter- 
 mined by the small thermometer k. The upper end of 
 the outer cylinder is closed by an iron lid having a 
 hinge at one side, and fastened clown by means of a nut 
 and screw attached to the iron rim /&, fitting into a small 
 slit p, in the side of the lid. In the inside of the lid there 
 is a raised rim of iron, over which a thick sheet of caout- 
 chouc is extended and fastened by a screwed ring s. This 
 distended caoutchouc serves as a spring against which 
 the top of the tube can be pressed, keeping it in a fixed 
 position during the violent agitation necessary during the 
 process of absorption. 
 
 The experiment itself is conducted in the following 
 manner: A volume of the gas to be examined is first 
 collected in the tube over mercury, and the usual pre- 
 cautions taken in reading off &c. , as in the processes of 
 gasometric analysis. A measured .volume of water per- 
 fectly free from air is next admitted under the mercury 
 into the tube, which is then screwed tightly against the 
 caoutchouc plate, and the tube thus closed, placed in the 
 cylinder gg containing some mercury, and over that a 
 quantity of water. As soon as the pressure within and 
 without has been equalised by slightly turning the tube, 
 it is again closed, and the whole apparatus rapidly agi- 
 tated for about a minute. This agitation with opening 
 and closing of the tube is continued many times, until no 
 further change of volume is perceptible. The obser- 
 vations necessary for the measurement and reduction of 
 the residual gas are then repeated. Besides the tempe- 
 rature t and the barometric pressure p, four readings 
 from the divided tube are required: 
 
140 EXAMPLE OF THE CALCULATION. 
 
 1. The lower level of the mercury in the outer cylinder 
 at a. 
 
 2. The upper surface of mercury in the absorption-tube 
 at b. 
 
 3. The upper surface of water in the absorption -tube 
 . at c. 
 
 4. The upper surface of water in the outer cylinder at J. 
 
 The method of calculation is best explained by an 
 example. For this purpose, I select an experiment for 
 the determination of the absorption -coefficient of nitro- 
 gen for water at 19 C. 
 
 ELEMENTS OF THE CALCULATION.. 
 
 1. Observations before the absorption. 
 
 Lower surface of mercury in outer cylinder . . . a = 423. G mm 
 
 Upper surface of mercury in absorption -tube * . . & 124.1 
 
 Barometric pressure p = 746.9 
 
 Temperature of the absorptiometer t 192 C. 
 
 Temperature of the barometer i 190 
 
 2. Observations after the absorption. 
 
 'mm 
 
 Lower surface of mercury in outer cylinder . * . . a t = 352. 2* 
 
 Upper surface of mercury in absorption -tube . . &j = 350.7 
 
 Upper surface of water in absorption - tube . . . c x = G5.5 
 
 Upper surface of water in outer cylinder . . . . d v = 8.0 
 
 Barometric pressure p l = 74G.3 
 
 Temperature of the absorptiometer . . . . . . t Y = 190 C. 
 
 Temperature of the barometer t l = 189 
 
 * In this first series of observations the absorptiometer contained 
 only mercury and no water. 
 
NITROGEN IN WATER, HI 
 
 REDUCTION OF THESE ELEMENTS. 
 
 1. Before the absorption. 
 
 Surface of mercury at a = 423. G 
 
 Surface of mercury at & = 124.1 
 
 Column of mercury in the absorption - tube . . (a &) = 299.5 
 
 Ditto reduced to C n = 298.0 ,. 
 
 The barometric pressure (p 0.7469) reduced 
 
 to C TT, = 744.4 
 
 The pressure on mercury on the gas reduced 
 
 to C (TT I TI) = 445.9 
 
 Tension of aqueous vapour at 192 C. to be sub- 
 tracted = 1G.G 
 
 Pressure of the dry nitrogen P = 429.3 
 
 The volume of gas corrected from the calibra- 
 tion read off at 6 = 124.1 at 192 C. . . . =34.90 
 
 Ditto reduced to C F= 82.608 
 
 2. After the absorption. 
 
 Barometric pressure p, = 74G.3 reduced to C. ef = 743.8 n " 
 
 Surface of mercury at a t = 352.2 
 
 Surface of mercury at b r =. 350 7 
 
 Column of mercury in tube at 190 JD. . . . (a t fti) = 1.5 
 
 Ditto at C tf , = 1.5 
 
 Lower surface of water in absorption -tube at 2^=350.7 
 
 Upper surface of water in absorption - tube at c t = G5.5 
 
 Column of water in the absorption -tube . (?> t c,) = tt7 = 285.2 
 Lower surface of water in outer cylinder ... a^ = 352.2 
 
 Upper surface of water in outer cylinder ... d l = 8.0 
 
 Column of water in outer cylinder . . . (a, d l ')-=zw l =344.2 
 Column of water (u\ w) acting in opposition 
 
 to the barometer = 59.0 
 
 Ditto reduced to pressure of mercury .... q = 4.4 
 
 The pressure reduced to C (f ^ 9) = 746.8 
 
 Tension of aqueous vapour at 19 C. to be sub- 
 tracted = 1G.3 
 
 Pressure of the unabsorbed nitrogen .... PI = 730.5 ,, 
 
142 
 
 EXAMPLE OF CALCULATION. 
 
 The residual volume of gas corrected from cali- 
 bration read off at division c x = 65.5 .... = 17.G7 mm 
 
 Ditto reduced to C . F, == 16.52 
 
 The corresponding volume to division 6 X = 350.7 = 200.04 
 
 Volume of absorbing liquid ^ = 182.37 
 
 The value of the absorption -coefficient, as obtained 
 from these numbers by equation No. 1, is 
 
 = ^- ^- K = 0.01448. 
 
 The accuracy of these determinations depends in a 
 great measure upon the water employed being perfectly 
 free from air. This is best accomplished by boiling the 
 water briskly for several hours, and then causing it to 
 pass whilst still boiling into a flask , the neck of which 
 has been drawn out to a fine point before the blowpipe 
 (see Fig. 45). The water is then again boiled in this 
 
 Fig. 45. 
 
WATER FREED FROM AIR. 143 
 
 flask for half an hour , and the end of the tuhe hermeti- 
 cally sealed, access of air being prevented during the 
 closing by pressing a caoutchouc tube a attached to the 
 extremity. When the water thus freed from air (which 
 should strike against the glass like a water-hammer), is 
 required for experiment, the closed end of the neck is 
 moistened with solution of corrosive sublimate, and broken 
 under mercury, and the water admitted directly into the 
 absorption -tube. Before transferring the water into the 
 tube, one must be convinced that no bubble of air has 
 appeared in the flask, which would show imperfect 
 boiling. 
 
 The following coefficients of absorption were deter- 
 mined according to this method, partly by myself and 
 partly by Messrs. Carius, Pauli, and Schb'nfeld in my 
 laboratory. The alcohol employed for the experiments 
 had a specific gravity of 0.792 at 20 C. The corrections 
 for the tension of the vapour of alkohol were made from 
 the experiments of Muncke. 
 
 Table III of the appendix contains these tensions 
 calculated from the far more accurate experiments of 
 Regnault. 
 
144 NITROGEN IN WATER. 
 
 No. 1. NITROGEN IN WATER. 
 The gas was prepared by passing dry air, freed from 
 carbonic acid and ammonia, over red-hot copper turnings. 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 9. 
 
 
 1 
 
 4.0 
 
 0.01843 
 
 0.01837 
 
 O.OOOOG 
 
 2 
 
 G.2 
 
 0.01751 
 
 0.01737 
 
 0.00014 
 
 3 
 
 12.G 
 
 0.01520 
 
 0.01533 
 
 -f- 0.00013 
 
 4 
 
 17.7 
 
 0.0143G 
 
 0.01430 
 
 O.OOOOG 
 
 5 
 
 23.7 
 
 0.01392 
 
 0.01384 
 
 0.00008 
 
 
 | 
 
 
 
 By combination of the experiments 1, 2, 3; 2, 3, 4; 
 and 3, 4, 5, we obtain the interpolation formula 
 
 c = 0.020346 0.00053887 -f- 0.000011156 *? . (9) 
 
 No. 2. NITROGEN IN ALCOHOL. 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 10. 
 
 
 1 
 
 1.9 
 
 0.12561 
 
 0.12567 
 
 -j- O.OOOOG 
 
 2 
 
 6.3 
 
 0.12384 
 
 0.12393 
 
 -f- 0.00009 
 
 3 
 
 11.2 
 
 0.12241 
 
 0.12241 
 
 0.00000 
 
 4 
 
 14.G 
 
 0.12148 
 
 0.12152 
 
 -}- 0.00004 
 
 5 
 
 19.0 
 
 0.12053 
 
 0.12056 
 
 -f- 0.00003 
 
 G 
 
 23.8 
 
 0.11973 
 
 0.11979 
 
 -f O.OOOOG 
 
 By combination of experiments 1, 2; 3,4 and 5, 6, 
 we obtain the interpolation formula 
 
 c = 0.126338 0.000418 1 -f 0.0000060 /? . . (10) 
 
HYDROGEN IN WATER. 
 
 145 
 
 No. 3. HYDROGEN IN WATER. 
 
 This gas was prepared from pure zinc and dilute 
 sulphuric acid. 
 
 No. of the 
 experiment. 
 
 C. 
 
 Coefficient 
 found. 
 
 Difference 
 from mean 
 value. 
 
 1 
 
 4.0 
 
 0.0185 
 
 0.0008 
 
 2 
 3 
 
 7.0 
 9.G 
 
 0.0205 
 0.019G 
 
 -|- 0.0012 
 
 -f o.oooi^ 
 
 4 
 
 12.8 
 
 0.018G 
 
 0.0007 
 
 5 
 
 15.5 
 
 0.0197 
 
 -|- 0.0003 
 
 G 
 
 18.8 
 
 0.0188 
 
 0.0005 
 
 7 
 
 23.G 
 
 0.0194 
 
 -j- 0.0001 
 
 From these experiments it is seen that the mean 
 coefficient of absorption 0.0193 of hydrogen is constant 
 for temperatures between and 20 C. 
 
 No. 4. HYDROGEN IN ALCOHOL. 
 
 No. of the 
 experiment. 
 
 C. 
 
 Coefficient 
 found. 
 
 Coefficient 
 from formula 
 11. 
 
 Difference. 
 
 1 
 
 1.0 
 
 0.06916 
 
 0.06910 
 
 0.00006 
 
 2 
 
 5.0 
 
 0.06847 
 
 0.06853 
 
 -|- 0.00006 
 
 3 
 
 11.4 
 
 0.06765 
 
 0.06769 
 
 + 0.00004 
 
 4 
 
 14.4 
 
 0.06726 
 
 0.06732 
 
 -f 0.00006 
 
 5 
 
 19.9 
 
 O.OGGG8 
 
 0.06669 
 
 -f 0.00001 
 
 6 
 
 23.7 
 
 0.06633 
 
 0.06629 
 
 - 0.00004 
 
 By combination of the experiments 1, 2, 3 ; 2, 3, 4, 5 
 
 and 4, 5, 6 the following interpolation formula is obtained: 
 
 c = 0.06925 0.0001487 / -f- 0.000001 <* . . (11) 
 
 10 
 
14G 
 
 ABSORPTION OF GASES IN LIQUIDS. 
 
 No. 5. METHYL GAS IN WATER. 
 
 For these experiments a quantity of the same sethyl 
 gas was employed, which Professor Frankland prepared 
 in my laboratory some years ago , and of which he gave 
 the analysis in his researches on the organic radicals. 
 
 No. of the 
 experiment. 
 
 C. 
 
 Coefficient 
 found. 
 
 Coefficient 
 from formula 
 12. 
 
 Difference. 
 
 1 
 
 5.8 
 
 0.02637 
 
 0.02G2G 
 
 4- 0.0011 
 
 2 
 
 8.7 
 
 0.02393 
 
 0.02428 
 
 0.0035 
 
 3 
 
 4 
 5 
 
 14.0 
 17.2 
 21.8 
 
 0.02199 
 0.02103 
 0.0202G 
 
 0.02175 
 0.02092 
 0.020G1 
 
 -f- 0.0024 
 -j- 0.0011 
 0.0035 
 
 By combination of the experiments 1, 2, 3; 2, 3, 4, 
 
 and 3, 4, 5, the following interpolation formula is found: 
 
 c = 0.031474 0.0010449 t -f- 0.000025066/2 . (12) 
 
 No. 6. CARBONIC OXIDE IN WATER. 
 
 The gas was prepared by heating sulphuric acid with 
 pure formiate of magnesia ; treatment with a potash-ball 
 showed that the gas was perfectly pure. 
 
 No. of the 
 experiment. 
 
 C. 
 
 Coefficient 
 found. 
 
 Coefficient 
 from formula 
 13. 
 
 Difference. 
 
 1 
 
 5.8 
 
 0.028G3G 
 
 0.028691 
 
 -j- 0.000055 
 
 2 
 
 8.6 
 
 0.027125 
 
 0.027069 
 
 0.000056 
 
 3 
 
 9.0 
 
 0.02G855 
 
 0.026857 
 
 -\- 0.000002 
 
 4 
 
 17.4 
 
 0.023854 
 
 0.023642 
 
 - 0.000212 
 
 5 
 
 18.4 
 
 G.023147 
 
 0.023414 
 
 -\- 0.000267 
 
 6 
 
 22.0 
 
 0.022907 
 
 0.022863 ' 
 
 0.000044 
 
CARBONIC OXIDE IN ALCOHOL. 147 
 
 If the mean values from 1, 2, 3, from 2, 3, 4, 5, and 
 from 4, 5, 6, be taken for the calculation of the constants, 
 we obtain the following formula : 
 
 c = 0.032874 0.00081632 1 + 0.000016421 t* . (13) 
 
 No. 7. CARBONIC OXIDE IN ALCOHOL. 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Variation 
 from mean 
 
 experiment. 
 
 
 found. 
 
 value. 
 
 1 
 
 2.0 
 
 0.2035G 
 
 0.00087 
 
 2 
 
 7.0 
 
 0.20526 
 
 -f 0.00083 
 
 3 
 
 12.9 
 
 0.2041G 
 
 0.00027 
 
 4 
 
 1G.2 
 
 0.205GG 
 
 -f 0.00123 
 
 5 
 
 12.9 
 
 0.20341 
 
 0.00102 
 
 G 
 
 24.0 
 
 0.20452 -f- 0.00009 
 
 The coefficient of carbonic oxide and alcohol remains 
 the same between and 25 C.; the mean value is 
 0.20443. 
 
 No. 8. LIGHT CARBURETTED-HYDROGEN IN WATER. 
 
 I have used for this determination a gas, preserved 
 in hermetically closed tubes, which is found in the mud- 
 volcanoes of Bulganak in the Crimea, where it occurs un- 
 der similar circumstances as at Baku on the Caspian Sea. 
 This gas was employed because it appeared from my ex- 
 periments to be the purest which occurs naturally. By 
 treatment with a potash -ball, it was freed from a trace 
 of carbonic acid, and it contained as the following ana- 
 lysis shows, neither nitrogen, oxygen, nor defiant gas: 
 
 10* 
 
148 
 
 MARSH GAS IN WATER. 
 
 
 Vol. 
 
 C. 
 
 Press, 
 in me- 
 tres. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Original volume of gas 
 After admission af air 
 
 127. G 
 499-0 
 537.4 
 495.4 
 4GG.2 
 
 4.8 
 4.8 
 4.8 
 4.5 
 4.6 
 
 0.159G 
 5151 
 0.5500 
 0.5115 
 0.4994 
 
 20.01 
 252.60 
 290.47 
 249.29 
 228.97 
 
 After admission of oxygen .... 
 After the explosion 
 
 After absorption of carbonic acid . 
 
 After addition of hydrogen .... 
 After the explosion 
 
 G09.3 
 478.8 
 
 Foui 
 20 
 
 4.3 
 4.3 
 
 ad. Gal 
 01 2 
 82 2 
 18 4 
 18 4 
 
 O.G284 
 0.5105 
 
 lulated. 
 0.45 
 0.45 
 0.90 
 0.90 
 
 376.95 
 240.64 
 
 Gas employed 
 
 Carbonic acid formed 
 Contraction 
 
 . . 20. 
 . . 41. 
 . . 41. 
 
 Oxygen consumed . . 
 
 This gas gives the following absorptiometric values: 
 
 No. of the 
 experiment. 
 
 C. 
 
 Coefficient 
 found. 
 
 Coefficient 
 from formula 
 14. 
 
 Difference. 
 
 1 
 
 6.2 
 
 0.04742 
 
 0.04757 
 
 0.00015 
 
 *2 
 
 9.4 
 
 0.04451 
 
 0.04430 
 
 -f- 0.00021 
 
 3 
 
 12.5 
 
 0.04126 
 
 0.04134 
 
 0.00008 
 
 4 
 
 18.7 
 
 0.03586 
 
 0.03600 
 
 0.00014 
 
 5 
 
 25.6 
 
 0.03121 
 
 0.03100 
 
 + 0.00021 
 
 The mean from 1, 2, 3, from 2, 3, 4, and from 3,4,5, 
 gives the interpolation formula 
 
 c = 0.05449 0.0011807 / -|- 0.000010278 1* . (14) 
 
MARSH GAS IN ALCOHOL. 
 
 149 
 
 No. 9. 
 LIGHT CARBURETTED- HYDROGEN IN ALCOHOL. 
 
 The gas was prepared by heating acetate of potash 
 with hydrate of potash, and from the following analysis 
 is seen to be pure. 
 
 
 Vol. 
 
 Temp. 
 
 Press, 
 in me- 
 tres. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Original volume of gas 
 
 75.2 
 
 5.0 
 
 0.2983 
 
 22.32 
 
 
 After addition of air 
 
 352.2 
 
 5.0 
 
 0.5736 
 
 201.04 
 
 Alter addition of oxygen 
 
 399.3 
 
 5.3 
 
 0.6183 
 
 242.19 
 
 
 After the explosion 
 
 352.2 
 
 5.2 
 
 0.5728 
 
 197.97 
 
 
 Alter absorption of carbonic acid . 
 
 325.0 
 
 5.6 
 
 0.5538 
 
 176.37 
 
 Found. Calculated. 
 
 Cras employed 22 
 
 32 22.11 
 
 
 Carbonic acid produced . 22.25 22.11 
 
 Contraction 44.22 44.22 
 
 Oxygen employed .... 44.22 44.22 
 
 Absorption gave the following elements: 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 15. 
 
 
 1 
 
 2.0 
 
 0.51721 
 
 0.51691 
 
 0.00030 
 
 2 
 
 6.4 
 
 0.50382 
 
 0.50483 
 
 -|- 0.00101 
 
 3 
 
 11.0 
 
 0.49264 
 
 0.49278 
 
 -|- 0.00014 
 
 4 
 
 15.0 
 
 0.48255 
 
 0.48280 
 
 -f 0.00025 
 
 5 
 
 19.0 
 
 0.47290 
 
 0.47327 
 
 -|-. 0.00037 
 
 6 
 
 23.5 
 
 0.46290 
 
 0.46309 
 
 -f 0.00019 
 
 By combination of experiments 1, 2, 3 ; 2, 3, 4, 5, and 
 4, 5, 6, the following interpolation formula is obtained: 
 c = 0.522586 0.0028655 1 + 0.0000142 f> . (15) 
 
150 METHYL GAS IN WATER. 
 
 No. 10. METHYL GAS IN WATER. 
 
 For this experiment, a specimen of methyl gas, sealed 
 up in a glass tube, was used, which Professor Frankland 
 prepared from iodide of methyl, and analysed some years 
 ago at Marburg: 
 
 No. of the 
 
 c. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 16. 
 
 
 1 
 
 4.6 
 
 0.072884 
 
 0.073084 
 
 0.000200 
 
 2 
 
 7.8 
 
 0.064732 
 
 0.064839 
 
 0.000107 
 
 3 
 
 12.1 
 
 0.055788 
 
 0.055703 
 
 -}- 0.000085 
 
 4 
 
 15.2 
 
 0.050722 
 
 0.050500 
 
 -}- 0.000222 
 
 5 
 
 19.8 
 
 0.045715 
 
 0.044915 
 
 -}- 0.000800 
 
 6 
 
 24.2 
 
 0.040817 
 
 0.041960 
 
 0.001143 
 
 If the arithmetical mean of 1, 2, 3, 4, of 3, 4, 5, and 
 4, 5, 6, are used for the equations for the interpolation 
 formula, we get: 
 
 c = 0.0871 0.0033242* -f- 0.0000603 * . (16) 
 
 No. 11. OLEFIANT GAS IN WATER. 
 
 The gas was prepared with the well known pre- 
 cautions from alcohol and sulphuric acid. To free it 
 from the vapour of alcohol and aether, and from traces 
 of other hydrocarbons polymeric with elayl, a ball of 
 coke, saturated with concentrated, but not fuming sul- 
 phuric acid, was placed in the gas until nearly the half 
 of it was absorbed; a ball of potash was afterwards 
 introduced, and left in contact with the gas for some 
 
OLEFIANT GAS IN WATER. 
 
 151 
 
 time. The following analysis showed the perfect purity 
 of the gas : 
 
 
 
 Pressure 
 
 Vol. at 
 
 
 Vol. i C. 
 
 
 C. and 
 
 
 
 
 in metres. 
 
 
 
 
 
 
 l m press. 
 
 Original volume of gas . . . 
 
 36.7 
 
 12.0 
 
 0.2443 
 
 8.64 
 
 After addition of air . . . . 
 
 311.2 
 
 12.0 
 
 0.5183 
 
 154.52 
 
 After addition of oxygen . . 
 
 339.8 
 
 12.5 
 
 0.5462 
 
 177.48 
 
 After the explosion .... 
 
 318.0 
 
 12.0 
 
 0.5261 
 
 160.26 
 
 After absorption of carbon, acid 
 
 290.1 
 
 11.2 
 
 0.5130 
 
 142.96 
 
 Found. Calculated. 
 
 Gas employed 8.64 8.61 
 
 Carbonic acid produced . 17.31 17.22 
 
 Contraction 17.22 17.22 
 
 Oxygen consumed . . . 25.91 25.83 
 
 Absorptiometric experiment gave: 
 
 No. of the 
 
 n c. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 17. 
 
 
 i 
 
 
 
 
 1 
 
 4.6 
 
 0.21870 
 
 0.21824 
 
 -|- 0.00046 
 
 2 
 
 9.6 
 
 0.18398 
 
 0.18592 
 
 0.00194 
 
 3 
 
 14.0 
 
 0.16673 
 
 0.16525 
 
 -1- 0.00148 
 
 4 
 
 18.0 
 
 0.15324 
 
 0.15278 
 
 -}- 0.00046 
 
 5 
 
 20.6 
 
 0.14597 
 
 0.14791 
 
 0.00194 
 
 The following interpolation formula is obtained from 
 the mean of 1, 2, 3, and 2, 3, 4, and 3, 4, 5: 
 
 c = 0.25629 0.00913631 1 + 0.000188108 **. (17) 
 
152 CARBONIC ACID IN WATER. 
 
 No. 12. OLEFIANT GAS IN ALCOHOL. 
 
 No. of the 
 
 c. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 18. 
 
 
 1 
 
 0.8 
 
 3.5344 
 
 3.5484 
 
 -f- 0.0140 
 
 2 
 
 5.4 
 
 3.3109 
 
 3.3033 
 
 0.0076 
 
 3 
 
 10.9 
 
 3.0431 
 
 3.0469 
 
 -f- 0.0038 
 
 4 
 
 15.4 
 
 28G45 
 
 2.8679 
 
 -f- 0.0034 
 
 5 
 
 19.3 
 
 2.7302 
 
 2.7348 
 
 + 0.0046 
 
 G 
 
 23.8 
 
 2.6048 
 
 2.6072 
 
 4- 0.0024 
 
 The following interpolation formula is obtained from 
 the mean of 1, 2, and 3, 4, and 5, 6: 
 
 c = 3.59498 0.057716* + 0.0006812*2. . (18) 
 
 No. 13. CARBONIC ACID IN WATER. 
 
 This gas was prepared by the action of strong sul- 
 phuric acid upon chalk, a few drops of water being 
 added to the mixture. The gas, thus steadily evolving, 
 was washed by being passed through boiled water. The 
 experiment gave : 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 19. 
 
 
 1 
 
 4.4 
 
 1.4698 
 
 1.4584 
 
 -f 0.0114 
 
 2 
 
 8.4 
 
 1.2426 
 
 1.2607 
 
 0.0181 
 
 3 
 
 13.8 
 
 1.0654 
 
 1.0385 
 
 -f- 0.0269 
 
 4 
 
 16.6 
 
 0.9692 
 
 0.9610 
 
 -f 0.0082 
 
 5 
 
 19.1 
 
 0.8963 
 
 0.9134 
 
 - 0.0171 
 
 6 
 
 22.4 
 
 0.8642 
 
 0.8825 
 
 0.0183 
 
OXYGEN IN WATER. 
 
 153 
 
 The three equations formed from the mean of 1, 2, 
 3, 4, of 2, 3, 4, and of 3, 4, 5, 6, give the interpolation 
 formula : 
 
 c = 1.7967 0.07761 1 + 0.0016424?2. . (19) 
 
 No. 14. CARBONIC ACID IN ALCOHOL. 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 20. 
 
 
 1 
 
 3.2 
 
 4.0442 
 
 4.0416 
 
 0.0026 
 
 2 
 
 6.8 
 
 ...7374 
 
 3.7480 
 
 -f- 0.0106 
 
 3 
 
 10.4 
 
 3.4875 
 
 3.4866 
 
 0.0009 
 
 4 
 
 14.2 
 
 3.2357 
 
 3.2457 
 
 -f 0.0100 
 
 5 
 
 18.0 
 
 3.0391 
 
 3.0402 
 
 -f 0.0011 
 
 6 
 
 22.6 
 
 2.8277 
 
 2.8396 
 
 -|- 0.0119 
 
 The mean from 1, 2; 3, 4, and 5, 6 gives the inter- 
 polation formula: 
 
 c = 4.32955 0.09395 1 + 0.00124*2. . (20) 
 
 No. 15. OXYGEN IN WATER. 
 
 Oxygen gas, prepared in the usual manner from 
 chlorate of potash, gave the following results: 
 
 No. of the 
 
 c. 
 
 Coefficient. 
 
 experiment. 
 
 
 
 1 
 
 6.0 
 
 0.04609 
 
 2 
 
 8.3 
 
 0.04186 
 
 3 
 
 11.6 
 
 0.03921 
 
 4 
 
 18.1 
 
 0.03715 
 
 5 
 
 22.8 
 
 0.03415 
 
154 
 
 OXYGEN IN WATER. 
 
 During the agitation in the absorptiometer, the water 
 became turbid owing to the formation of a black powder, 
 and it was supposed that the metals dissolved in the 
 mercury had been oxidised at the expense of the oxygen 
 in the water, and hence too large a coefficient obtained. 
 The mercury employed, was therefore freed from all 
 foreign metals, as perfectly as could be effected by 
 several digestions with concentrated nitric acid. The 
 experiment conducted with the purified mercury gave the 
 following results: 
 
 No. of the 
 
 C. 
 
 Coefficient. 
 
 Difference. 
 
 experiment. 
 
 
 
 
 1 
 
 19.4 
 
 0.03109 
 
 -}- 0.00090 
 
 2 
 
 19.G 
 
 0.03199 
 
 -f- 0.00003 
 
 3 
 
 19.4 
 
 0.03202 
 
 -j- 0.00052 
 
 4 
 
 19.5 
 
 0.03254 
 
 0.00009 
 
 5 
 
 19.5 
 
 0.03245 
 
 -f 0.00047 
 
 G 
 
 19.5 
 
 0.03292 
 
 -f- 0.00221 
 
 7 
 
 19.0 
 
 0.03513 
 
 0.00057 
 
 8 
 
 19.0 
 
 0.0345G 
 
 
 The experiment gave therefore, rather a smaller 
 coefficient. In spite, however, of the most careful pu- 
 rification, the mercury always caused a black turbidity 
 in the water, which perceptibly increased with agitation. 
 This circumstance, together with the fact that the coef- 
 ficients determined one after the other in the same liquid, 
 and at the same temperature, always regularly increased, 
 showed that this method was not to be relied upon 
 for exact results. I have, therefore, preferred to de- 
 
INDIRECT METHOD. 155 
 
 termine the coefficient of oxygen in water by an indirect 
 method. 
 
 If atmospheric air, perfectly free from carbonic acid 
 and ammonia, be passed into boiled water, the amount 
 of oxygen F absorbed, and the amount of nitrogen V 
 absorbed, is found from the following equations (No. 3) 
 which we have already deduced : 
 
 aPOV\ V fiPNV l 
 
 ~ 0.76 (N+0) ' ~ 0.76 (N+ 0)' 
 
 The first of these equations divided by the second gives 
 NV 
 
 ov p 
 
 N 
 As the composition of the air, i. e. the proportion y , as 
 
 well as the absorption -coefficient /3 of nitrogen is known, 
 
 Y 
 
 we only require to determine the proportion -=pr , or the 
 
 composition of the air dissolved in the water, in order 
 to calculate a, or the absorption -co efficient of oxygen. 
 The following experiments give the elements required 
 for this calculation. Atmospheric air carefully freed 
 from carbonic acid, and ammonia, was passed in a strong 
 current for half a day through the water, previously well 
 boiled, and kept at a constant temperature by immersion 
 in a water bath. The purification of the water must be 
 conducted with the greatest care. It must not be distilled 
 from a vessel previously used for any organic preparation, 
 as the slightest trace of volatile organic matter is suf- 
 ficient to convert a part of the oxygen into carbonic 
 acid. In order , therefore , to test the correctness of the 
 determination, it is adviseable to prove the absence of 
 carbonic acid in the air boiled out from the water by 
 special experiment. 
 
15G 
 
 AIR IN WATER. 
 
 The gases dissolved in this water were collected by 
 a method which I employed in my investigations upon 
 the gases of the Icelandic springs , and more fully de- 
 scribed by Professor Baumert in his excellent research 
 on the respiration of the Cobitis fossilis. 
 
 Air from water saturated at 1 C. 
 
 
 
 Pressure 
 
 
 Vol. at 
 
 
 Vol. 
 
 
 C. 
 
 C. and 
 
 
 
 in metres. 
 
 
 
 
 
 
 
 l m press. 
 
 Volume of gas employed 
 
 216.85 
 
 0.2G44 
 
 9.7 
 
 55.374 
 
 -\- hydrogen . . . 
 
 37G.1G 
 
 0.4170 
 
 9.8 
 
 151.414 
 
 After the explosion 
 
 289.83 
 
 0.3340 
 
 9.9 
 
 93.420 
 
 Oxygen 
 Nitrogen 
 
 34.91 
 G5.09 
 
 100.00 
 
 Air from water saturated at 13 C. 
 
 
 
 Pressure 
 
 
 Vol. at 
 
 
 Vol. 
 
 
 C. 
 
 0C. and 
 
 
 
 in metres. 
 
 
 
 
 
 
 
 l m press. 
 
 Volume of gas employed 
 
 1G5.99 
 
 0.2198 
 
 9.0 
 
 53.324 
 
 -}- hydrogen . . . 
 
 346.28 
 
 0.3914 
 
 9.5 
 
 130.994 
 
 After the explosion 
 
 288.78 
 
 0.3371 
 
 9.2 
 
 94.180 
 
 Oxygen 
 Nitrogen 
 
 34.73 
 65.27 
 
 100.00 
 
AIR IN WATER. 
 Air from water saturated at 23 C. 
 
 157 
 
 
 
 Pressure 
 
 
 Vol. at 
 
 
 Vol. 
 
 
 C. 
 
 0C. and 
 
 
 
 in metres. 
 
 
 
 
 
 
 
 l m press. 
 
 Volume of gas employed 
 
 206.67 
 
 0.2577 
 
 9.3 
 
 51.497 
 
 -}- hydrogen . . . 
 
 400.29 
 
 0.4437 
 
 9.2 
 
 171.828 
 
 After the explosion . 
 
 323.95 
 
 0.374G 
 
 8.7 
 
 117.608 
 
 Oxygen 
 Nitrogen 
 
 35.08 
 64.92 
 
 100.00 
 
 From these experiments, it is clear that the com- 
 position of the air dissolved in water at various tem- 
 peratures is always constant. The mean composition is: 
 
 Oxygen . ." . 34.91 = V 
 Nitrogen . . 65.09 = V 
 100.00 
 
 Thus we see, that the curve which represents the 
 increase of the absorption -coefficient of oxygen for de- 
 creasing temperatures is parallel to the corresponding 
 curve for nitrogen. 
 
 If we take the following as the true composition of 
 atmospheric air, 
 
 Oxygen . .. , 0.2096 = O 
 ^ _ J_ Nitrogen . . 0.7904 N 
 
 1.0000 
 
 and if we substitute the values of PI, P, 0, and N in the 
 preeceding equation, we obtain, when represents the 
 absorption -coefficient of nitrogen, the value of the coef- 
 ficient of oxygen from the formula : 
 
 a = 2.0225 ft (21) 
 
158 OXYGEN IN ALCOHOL. 
 
 No. 16. OXYGEN IN ALCOHOL. 
 
 As the oxygen which dissolved in alcohol scarcely 
 oxidises the metals contained in solution in the mercury, 
 Dr. Carius has determined the absorption -coefficients in 
 the usual manner with the absorptiometer. 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Variation 
 from mean 
 
 experiment. 
 
 
 found. 
 
 value. 
 
 1 
 
 1.0 
 
 0.28389 
 
 0.00008 
 
 2 
 
 4.5 
 
 0.28588 
 
 -f 0.00191 
 
 3 
 
 9.8 
 
 0.28439 
 
 +- 0.00042 
 
 4 
 
 14.2 
 
 0.28122 
 
 0.00275 
 
 5 
 
 18.8 
 
 0.28373 
 
 - 0.00024 
 
 G 
 
 23.1 
 
 0.284G9 
 
 -f- 0.00072 
 
 Hence it is seen that the coefficients of absorption of 
 oxygen in alcohol are constant for temperatures between 
 and 24. 
 
 No. 17. NITROUS OXIDE IN WATER. 
 The gas was prepared from pure nitrate of ammonia. 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 22. 
 
 
 1 
 
 2.5 
 
 1.1942 
 
 1.1962 
 
 -f- 0.0020 
 
 2 
 
 8.2 
 
 0.9700 
 
 0.9791 
 
 -f 0.0091 
 
 3 
 
 12.0 
 
 0.8432 
 
 0.8588 
 
 -f- 0.015G 
 
 4 
 
 1G.2 
 
 0.7477 
 
 0.7489 
 
 -|- 0.0012 
 
 5 
 
 20.0 
 
 O.G744 
 
 O.G700 
 
 - 0.0044 
 
 G 
 
 24.0 
 
 O.G024 
 
 O.G082 
 
 -j- 0.0058 
 
NITROUS OXIDE IN ALCOHOL. 
 
 159 
 
 From the mean of 1, 2; 3,4, and 5, 6, the following 
 interpolation formula is obtained: 
 
 e = 1.30521 0.045362 * + 0.0006843 /. . (22) 
 No. 18. NITROUS OXIDE IN ALCOHOL. 
 
 No. of the 
 experiment. 
 
 c. 
 
 Coefficient 
 found. 
 
 Coefficient 
 from formula 
 23. 
 
 Difference. 
 
 1 
 
 2.3 
 
 4.0262 
 
 4.0207 
 
 0.0055 
 
 2 
 
 7.0 
 
 3.70G9 
 
 3.7192 
 
 -f 0.0123 
 
 3 
 
 ll.G 
 
 3.4219 
 
 3.4501 
 
 -f- 0.0282 
 
 4 
 
 18.2 
 
 3.1105 
 
 3.1092 
 
 - 0.0013 
 
 5 
 
 23.0 
 
 ; 3.88G1 
 
 ,8.8944 
 
 -f- 0.0083 
 
 The mean of experiments 1, 2 ; 2, 3, 4, and 4, 5, give 
 the interpolation formula: 
 
 c = 4.17805 0.069816 t + 0.000609 #*. . (23) 
 
 No. 19. NITRIC OXIDE IN ALCOHOL. 
 
 In order to obtain pure nitric oxide, this gas evolved 
 from copper and nitric acid, is led into a concentrated 
 solution of protosulphate of iron. The solution thus 
 obtained, when freshly prepared, and sufficiently con- 
 centrated, gives on heating, a gas perfectly free from 
 nitrous oxide and nitrogen, particularly if only the first 
 portions of gas are collected. 
 
160 
 
 SULPHURETTED-HYDROGEN IN ALCOHOL. 
 
 No. of the 
 
 c. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 24. 
 
 
 1 
 
 2.0 
 
 0.30895 
 
 0.30928 
 
 -j- 0.00033 
 
 2 
 
 G.O 
 
 0.29G84 
 
 0.29G90 
 
 -f O.OOOOG 
 
 3 
 
 11.8 
 
 0.28162 
 
 0.28174 
 
 -f- 0.00012 
 
 4 
 
 1G.O 
 
 0.27250 
 
 0.27281 
 
 -f- 0.00031 
 
 5 
 
 20.0 
 
 0.2G573 
 
 0.2G592 
 
 -|- 0.00019 
 
 6 
 
 24.2 
 
 0.2G014 
 
 0.2G038 
 
 - 0.00024 
 
 From experiments 1, 2; 3, 4, and 5, 6, we obtain the 
 interpolation formula : 
 
 c = 0.31606 0.003487 1 + 0.000049 t*. . (24) 
 
 No. 20. SULPHURETTED -HYDROGEN IN ALCOHOL. 
 
 The absorptiometer cannot be used for the deter- 
 mination of the absorption -co efficients of those gases 
 which act upon mercury, nor of those which are extremely 
 soluble in water. In the case of sulphuretted -hydrogen, 
 which in presence of alcohol is decomposed by mercury, 
 another method must be had recourse to. The simplest 
 plan is to saturate the alcohol, at a constant tem- 
 perature, and under a known pressure, with sulphuretted- 
 hydrogen, and to determine the absorbed gas by che- 
 mical means. This saturation is best effected in the 
 apparatus Fig. 46, employed by Messrs. Schonfeld and 
 Carius in the determination of the following coefficients 
 of absorption. 
 
 The flask a a, containing the boiled-out alcohol which 
 is to be saturated, is closed by an air-tight cork with 
 four holes bored through it. In the first hole is placed 
 
SULPHURETTED HYDROGEN IN ALCOHOL. 
 
 161 
 
 the small thermometer 6, dipping into the liquid; the 
 second hole contains the glass delivery tube c reaching 
 to the bottom of the flask ; the third is filled by a short 
 
 Fig. 46. 
 ji o 
 
 exit tube <7, through which the excess of gas escapes; 
 and the fourth contains a syphon -tube e dipping to the 
 bottom of the liquid. A rapid stream of sulphuretted- 
 hydrogen gas, prepared from sulphide of iron and sul- 
 phuric acid, and well washed, is passed for two hours 
 through the liquid from the delivery tube c, whilst the 
 whole apparatus is kept at a constant temperature by 
 immersion in a water -bath. After the current of gas 
 has passed for this period through the liquid, we may 
 presume that the point of saturation has been reached. 
 
 11 
 
1G2 CHEMICAL METHOD. 
 
 The little caoutchouc tube on the end of the tube t/, is 
 next closed by a glass rod, whilst the evolution of gas 
 still continues; the slight increase of pressure ensuing 
 
 from this closing is sufficient to drive out the saturated 
 liquid by the syphon e. This stream of saturated alcohol 
 is allowed to flow on to the bottom of a small stoppered 
 bottle, so as gradually to fill the bottle, and to run over 
 the neck, in order to expel the portions of liquid which 
 have been in contact with the air, by those which flow 
 directly from the saturating flask. The small measure 
 is then quickly closed by its stopper, and after removing 
 the alcohol which remains on the outside, the saturated 
 liquid is emptied into a solution of chloride of copper, 
 
SULPHURETTED -HYDROGEN IN WATER. 
 
 163 
 
 in which the sulphur of the precipitated sulphide is 
 estimated in the usual manner as sulphate of barium. 
 Let A represent the quantity of sulphate of barium found, 
 h the volume of the measure in cubic - centimetres , P the 
 barometric pressure under which the saturation took place, 
 and s the specific gravity of sulphuretted -hydrogen, we 
 obtain the value of the coefficient of absorption from the 
 following formula, the derivation of which is simple 
 
 enough: 
 
 (HS). 773. 0.76 
 
 a = A 
 
 (BaS0 4 ).5.P./i 
 
 Experiments carried on in this manner, gave the 
 following values for the absorption - coefficients of sul- 
 phuretted-hydrogen in alcohol: 
 
 No. of the 
 
 C. 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 25. 
 
 
 1 
 
 1.0 
 
 17.367 
 
 17.242 
 
 0.125 
 
 2 
 
 4.0 
 
 15.198 
 
 15.373 
 
 -|- 0.17.-) 
 
 3 
 
 7.5 
 
 13.246 
 
 13.343 
 
 -|- 0.097 
 
 4 
 
 10.6 
 
 11.446 
 
 11.680 
 
 -}- 0.234 
 
 5 
 
 17.6 
 
 8.225 
 
 8.393 . 
 
 -f 0.168 
 
 G 
 
 22.0 
 
 6.624 
 
 6.659 
 
 -|- 0.035 
 
 From the mean of 1, 2, 3; 2, 3, 4, 5, and 4, 5, 6, the 
 following interpolation formula is obtained: 
 
 c = 17.891 0.65598 / + 0.00661 /. . . (25) 
 
 No. 21. SULPHURETTED -HYDROGEN IN WATER. 
 
 Experiments conducted in a similar manner to those 
 just described, gave the following results: 
 
 11* 
 
164 
 
 SULPHUROUS ACID IN ALCOHOL. 
 
 
 
 
 
 No. of the 
 
 c. 
 
 Coefficient 
 
 Coefficient 
 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 26.. 
 
 
 1 
 
 2.0 
 
 4.2373 
 
 4.2053 
 
 0.0320 
 
 2 
 
 9.8 
 
 3.5446 
 
 3.6006 
 
 -f- 0.0560 
 
 3 
 
 14.G 
 
 3.2651 
 
 3.2599 
 
 0.0052 
 
 4 
 
 19.0 
 
 2.9050 
 
 2.9687 
 
 -f 0.0637 
 
 5 
 
 23.0 
 
 2.7415 
 
 2.7215 
 
 0.0200 
 
 a 
 
 27.8 
 
 2.3735 
 
 2.4470 
 
 -f- 0.0735 
 
 7 
 
 35.G 
 
 1.9972 
 
 2.0521 
 
 -f 0.0549 
 
 8 
 
 43.3 
 
 1.7142 
 
 1.7244 
 
 -|- 0.0102 
 
 The mean of experiments 1, 2, 3, 4; 2, 3, 4, 5, 6, 7, 
 and 5, 6, 7, 8, give the interpolation formula: 
 
 c = 4.3706 0.083687 1 + 0.0005213 t*. . (26) 
 
 No. 22. SULPHUROUS ACID IN ALCOHOL. 
 
 The pure alcohol of spec. grav. 0,792 used in these 
 experiments, was saturated, in a similar apparatus to 
 that described under sulphuretted -hydrogen, with pure 
 sulphurous acid, prepared from pure sulphuric acid, and 
 copper turnings, and carefully washed before saturation. 
 In order to determine the weight of sulphurous acid in 
 the saturated liquid, a measured volume was diluted with 
 so much boiled water, that 1000 parts of the mixture 
 contained less than 4 parts of the acid, and in this diluted 
 solution the sulphurous acid was estimated by the iodine- 
 volumetric method. 
 
 If the weight of an absorbed gas only amounts to 
 a small fraction of that of the absorbing liquid, we may 
 suppose, without any apparent error, that the volume of 
 
ALTERATION OF SPECIFIC GRAVITY. 165 
 
 the liquid before, and after the saturation, has not 
 altered. This is, however, not allowable when so 
 much gas is absorbed, that the specific gravity of the 
 liquid is perceptibly changed. In this case the specific 
 gravities corresponding to the various degrees of sa- 
 turation must be determined, and from these and the 
 volume of the saturated solution, the volume must be 
 calculated which the liquid would have possessed before 
 it took up the gas. 
 
 Let his suppose that experiment showed that p gram- 
 mes of sulphurous acid was contained in V volumes of 
 alcohol , saturated at C., and under a pressure equal to 
 P\ and let the specific gravity of gaseous sulphurous acid 
 be represented by s, that of the saturated alcohol by s t , 
 that of the pure alcohol before saturation by s 2 , we shall 
 then see that the absorption-coefficients, that is, the volume 
 of gas which is absorbed at *, and 0.76 pressure by the 
 unit volume of pure alcohol, is found from the following 
 considerations. The measured volume V of saturated 
 alcohol weighs Vsi, the pure alcohol which is contained 
 in this weight combined with sulphurous acid is therefore 
 
 (Vst p), and occupies the volume i-^ . But this 
 
 ^2 
 
 volume has absorbed S- volumes of sulphurous acid ; 
 
 s 
 
 hence, 1 cbc. alcohol absorbs at P pressure and t tem- 
 perature of saturation, - 7 = '* ' ' cbc. of the gas. 
 
 (Fa, p)s 
 
 Hence the coefficient of absorption c, or the volume of 
 sulphurous acid absorbed by one volume of pure alcohol 
 at the temperature of saturation ?, and under the pres- 
 sure 0.76, hence is 
 
1GG 
 
 ALTERATION OF SPECIFIC GRAVITY. 
 0.76 . 773 . p . s 2 
 
 c = 
 
 (27) 
 
 P(V Sl p)s 
 
 In order to calculate the value of c, the specific 
 gravities of the various saturated volumes of alcohol must 
 be determined. The following experiments served for 
 these determinations: 
 
 No. of the 
 experira. 
 
 Temp, 
 of the 
 saturation 
 
 C. 
 
 Spec. grav. 
 of solution 
 obtained. 
 
 Mean 
 *i- 
 
 Spec, 
 gray, 
 according 
 to formula 
 
 28. 
 
 Difference. 
 
 1 
 
 4.0 
 
 1.0GG4 
 1.0580 
 
 1.0G22 
 
 1.0G71 
 
 -f- 0.0049 
 
 2 
 
 11.6 
 
 0.984G 
 0.9914 
 
 0.9880 
 
 0.990G 
 
 -j- 0.002G 
 
 3 
 
 16.0 
 
 0.9490 
 0.95G4 
 
 0.9527 
 
 0.9597 
 
 -f- 0.0070 
 
 4 
 
 ( 0.9370 
 20.1 
 / 9434 
 
 0.9402 
 
 0.9400 
 
 0.0002 
 
 5 
 
 ( 0.9242 
 23.5 
 / 0.9322 
 
 1 
 
 0.9282 
 
 0.9302 
 
 -}- 0.0020 
 
 The mean from 1, 2; 2, 3, 4, and 4, 5, gives the 
 following interpolation formula: 
 
 c = 1.11937 0.014091 1 + 0.000257 t\ . (28) 
 
 By means of this formula the following table was' 
 calculated: 
 
SULPHUROUS ACID IN ALCOHOL. 
 
 167 
 
 Temp, 
 of 
 saturation 
 
 HX 
 
 Specific 
 gravity. 
 
 Difference. 
 
 Temp, 
 of 
 saturation 
 
 
 
 Specific 
 gravity. 
 
 Difference. 
 
 o 
 
 1.1194 
 
 
 13 
 
 0.9796 
 
 0.0077 
 
 
 
 0.0139 
 
 
 
 0.0071 
 
 i 
 
 1.1055 
 
 
 14 
 
 0.9725 
 
 
 
 
 0.0133 
 
 
 
 0.0067 
 
 2 
 
 1.0922 
 
 
 15 
 
 0.9658 
 
 
 
 
 0.0128 
 
 
 
 0.0061 
 
 3 
 
 1.0794 
 
 
 16 
 
 0.9597 
 
 
 
 
 0.0123 
 
 
 
 0.0056 
 
 4 
 
 1.0671 
 
 
 17 
 
 0.9541 
 
 
 
 
 0.0118 
 
 
 
 0.0051 
 
 5 
 
 1.0553 
 
 
 18 
 
 0.9490 
 
 
 
 
 0.0112 
 
 
 
 0.0046 
 
 6 
 
 1.0441 
 
 
 19 
 
 0.9444 
 
 
 
 
 0.0108 
 
 
 
 0.0040 
 
 7 
 
 1.0333 
 
 
 20 
 
 0.9404 
 
 
 
 
 0.0102 
 
 
 
 0.0036 
 
 8 
 
 1.0231 
 
 
 21 
 
 0.9368 
 
 
 
 
 0.0097 
 
 
 
 0.0030 
 
 9 
 
 1.0134 
 
 
 22 
 
 0.9338 
 
 
 
 
 0.0092 
 
 
 
 0.0026 
 
 10 
 
 1.0042 
 
 
 23 
 
 0.9312 
 
 
 
 
 0.0087 
 
 
 
 0.0020 
 
 11 
 
 0.9955 
 
 0.0082 
 
 24 
 
 0.9292 
 
 0.0015 
 
 12 
 
 0.9873 
 
 
 25 0.9277 
 
 
 From this table are obtained the required values of 
 The other experimental data are found subjoined: 
 
 No. of the 
 experiment. 
 
 t 
 
 c. 
 
 P 
 
 P 
 
 * 
 
 
 1 
 
 3.2 
 
 0.7576 
 
 2.1677 
 
 1.0769 
 
 
 2 
 
 5.8 
 
 0.7458 
 
 1.9432 
 
 1.0463 j 
 
 
 3 
 
 11.0 
 
 0.7566 
 
 1.5663 
 
 0.9955 f 
 
 
 
 
 
 
 I 
 
 v ^^ 400 
 
 4 
 
 14.0 
 
 0.7510 
 
 1.3678 
 
 0.9725 ^ 
 
 4 = 0.792 
 
 5 
 
 17.0 
 
 0.7558 
 
 1.2259 
 
 0.9541 j 
 
 
 6 
 
 20.0 
 
 0.7438 
 
 1.0920 
 
 0.9404 \ 
 
 
 7 
 
 24.4 
 
 0.7536 
 
 0.9698 
 
 0.9286 ' 
 
 
 By substituting these quantities in the preceeding 
 formula (No. 27), we obtain the following values for 
 
1G8 
 
 SULPHUROUS ACID IN WATER. 
 
 the absorption - coefficients of sulphurous acid in al- 
 cohol. 
 
 No. of the 
 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 29. 
 
 
 1 
 
 3.2 
 
 276.62 
 
 277.57 
 
 0.95 
 
 2 
 
 5.8 
 
 240.72 
 
 240.81 
 
 + 0.09 
 
 3 
 
 11.0 
 
 177.84 
 
 179.91 
 
 2.07 
 
 4 
 
 14.0 
 
 149.29 
 
 152.45 
 
 - 3.16 
 
 5 
 
 17.0 
 
 130.12 
 
 130.61 
 
 - 0.49 
 
 6 
 
 20.0 
 
 114.48 
 
 114.38 
 
 H- 0.10 
 
 7 
 
 24.4 
 
 97.54 
 
 100.75 
 
 3.21 
 
 The interpolation formula for these experiments is 
 calculated from the mean of 1, 2; 3, 4, 5, and 6, 7: 
 
 c = 328.62 -16.95 t + 0.3119 1\ " . (29) 
 
 No. 23. SULPHUKOUS ACID IN WATp]R. 
 
 Experiments made in a like manner with water in- 
 stead of alcohol, gave the following results: 
 
 No. of the 
 
 
 Coefficient 
 
 Coefficient 
 from formula 
 
 Difference. 
 
 experiment. 
 
 
 found. 
 
 
 
 
 
 
 30. 
 
 
 1 
 
 4.0 
 
 68.64 
 
 69.89 
 
 -\- 1.25 
 
 2 
 
 10.0 
 
 55.79 
 
 56.65 
 
 -}- 0.86 
 
 3 
 
 15.6 
 
 46.30 
 
 46.25 
 
 0.05 
 
 4 
 
 21.0 
 
 37.02 
 
 37.97 
 
 -|- 0.95 
 
 5 
 
 26.0 
 
 32.13 
 
 31.58 
 
 0.55 
 
 From the mean of 1, 2, 3; 2, 3, 4, and 3, 4, 5, the 
 following interpolation formula is obtained: 
 
 c = 79.789 2.6077 t + 0.02935 
 
 (30) 
 
AMMONIA IN WATER. 169 
 
 The specific gravity s t of the solution, saturated at 
 
 / degrees, was, 
 
 c s\ 
 
 Oo C. 
 
 10 
 20 
 
 1.0609 
 1.0547 
 1.0239 
 
 No. 24. AMMONIA IN WATER. 
 
 The following method, employed by Dr. Carius for 
 the determination of the absorption -coefficients of am- 
 monia, can be generally adopted when the gas under 
 examination is still more soluble than sulphurous acid. 
 
 The ammonia evolved from lime and sal-ammoniac in 
 the iron vessel a, Fig. 48, is purified by passing through 
 a wash -bottle b containing solution of potash, and then 
 
 Fig. 48. 
 
170 METHOD EMPLOYED FOR 
 
 is led into the vessel c containing the boiled -out water 
 which is to be saturated. This vessel c is immersed in 
 a water -bath , the temperature of which is carefully 
 
 Fig. 49. 
 
 kept constant, and observed on the thermometer d. As 
 soon as it is presumed that the liquid is saturated with 
 gas, the lower part of the absorption -vessel, seen in 
 section in Fig. 50, is closed at u by a well ground glass 
 rod m, and the whole of the ammoniacal liquid above u 
 is carefully washed away, the space from u to n being 
 filled with distilled water. On opening the stopper r/i, 
 the saturated solution in v becomes sufficiently diluted 
 with the supernatant water to allow the ammonia to be 
 determined by a volumetric analysis with sulphuric acid. 
 The capacity of the vessel uv measured in cubic -centi- 
 
VERY SOLUBLE GASES. 
 
 171 
 
 metres gives the volume V of the saturated water em- 
 ployed in the experiments; the volumetric analysis gives 
 the weight p of the ammonia ab- 
 Fig. 50. Fig. 51. sorbed at the temperature t of the 
 saturation, and under the pressure 
 P. The specific gravity -^ of the 
 saturated solution of ammonia cannot 
 be determined in a small bottle in 
 the usual way, because the slightest 
 increase of temperature, or even 
 merely pouring out the saturated 
 solution, would cause considerable 
 loss of gas. In order to avoid this 
 source of error, a carefully weighed 
 pipette, previously cooled in a 
 freezing -mixture, is filled up to a 
 mark w, Fig. 51, with the saturated 
 solution of ammonia, the excess of 
 
 which is quickly wiped from the outside, and the pipette 
 is then introduced into a weighed test tube half filled 
 with water, and the whole apparatus again weighed. If 
 the weight of the tube and water, together with that of 
 the pipette, be subtracted from the total weight, we 
 obtain the weight of the measured volume of liquid. The 
 volume of this liquid is found from the known capacity 
 of the pipette. In this way, the following specific gra- 
 vities s-i of the saturated ammouiacal liquid for the tem- 
 perature t , is obtained : 
 
172 
 
 AMMONIA IN WATER. 
 
 
 c. 
 
 Capacity 
 of the 
 pipette 
 in grins. 
 
 Spec. grav. 
 ! found. 
 
 Spec. grav. 
 from formula 
 31. 
 
 Difference. 
 
 1 
 
 0.58 
 
 2.5291 
 
 0.8531 
 
 0.8549 
 
 -j- 0.0018 
 
 2 
 
 4.60 
 
 2.5702 
 
 0.8670 
 
 0.8649 
 
 - 0.0021 
 
 3 
 
 9.54 
 
 2.5992 
 
 0.87G7 
 
 0.8756 
 
 0.0011 
 
 4 
 
 14.11 
 
 2.G2G1 
 
 0.8858 
 
 0.8845 
 
 0.0013 
 
 5 
 
 19.71 
 
 2.6454 
 
 0.8923 
 
 0.8924 
 
 -|- 0.0001 
 
 G 
 
 25.01 
 
 2.6654 
 
 0.8991 
 
 0.8984 
 
 0.0007 
 
 From the mean of 1, 2, 3; 2, 3, 4, 5; 4, 5, 6, we 
 obtain the interpolation formula: 
 
 Sl = 0.85355 + 0.0026269* 0.0000333 <* . (31) 
 
 By means of this formula the following table is cal- 
 culated : 
 
 c. 
 
 Spec, 
 grav. 
 
 Diff. 
 
 c. 
 
 Spec, 
 grav. 
 
 Diff. 
 
 C. 
 
 Spec, 
 grav. 
 
 Diff. 
 
 
 
 
 
 
 0.0021 
 
 
 
 0.0014 
 
 
 
 0.8535 
 
 
 9 
 
 0874G 
 
 
 18 
 
 0.8903 
 
 
 
 
 0.002G 
 
 
 
 0.0020 
 
 
 
 0.0013 
 
 1 
 
 0.8561 
 
 
 10 
 
 0.8766 
 
 
 19 
 
 0.8916 
 
 
 
 
 0.0026 
 
 
 
 0.0019 
 
 
 
 0.0012 
 
 2 
 
 0.8587 
 
 
 11 
 
 0.8785 
 
 
 20 
 
 0.8928 
 
 
 
 
 0.0026 
 
 
 
 0.0019 
 
 
 
 0.0012 
 
 3 
 
 0.8611 
 
 0.0026 
 
 12 
 
 0.8804 
 
 0.0019 
 
 21 
 
 0.8940 
 
 0.0012 
 
 4 
 
 0.8637 
 
 
 13 
 
 0.8823 
 
 
 22 
 
 0.8952 
 
 
 
 
 0.0026 
 
 
 
 0.0018 
 
 
 
 0.0011 
 
 5 
 
 0.8663 
 
 
 14 
 
 0.8841 
 
 
 23 
 
 0.89G3 
 
 
 
 
 0.0026 
 
 
 
 0.0017 
 
 
 
 0.0011 
 
 6 
 
 0.8689 
 
 0.0024 
 
 15 
 
 0.8858 
 
 0.0016 
 
 24 
 
 0.8974 
 
 0.0010 
 
 7 
 
 0.8713 
 
 
 16 
 
 0.8874 
 
 
 25 
 
 0.8984 
 
 
 
 
 0.0022 
 
 
 
 0.0015 
 
 
 
 
 8 
 
 0.8725 
 
 
 17 
 
 0.8889 
 
 
 
 
 
 The experiments conducted according to this method, 
 gave the following values: 
 
AMMONIA IN WATER. 
 
 173 
 
 No. of the 
 experiment 
 
 Temperature 
 *C. of the 
 absorption. 
 
 Barometer 
 P. 
 
 Weight of 
 ammonia/), in 
 V= 5.0764 
 cbc. liquid. 
 
 The same 
 weight p in 
 V= 2.9646 
 cbc. liquid. 
 
 1 
 
 0.53 
 
 0.7553 
 
 1.9010 
 
 1.1127 
 
 2 
 
 4.60 
 
 0.7509 
 
 1.7924 
 
 1.0492 
 
 3 
 
 9.54 
 
 0.7509 
 
 1.6965 
 
 
 
 4 
 
 14.41 
 
 0.7546 
 
 1.6021 
 
 0.9376 
 
 5 
 
 19.71 
 
 0.7546 
 
 1,4988 
 
 0.8751 
 
 G 
 
 25.01 
 
 0.7525 
 
 1.3963 
 
 0.8138 
 
 By substituting these values in formula 27 , together 
 with the constant quantities for ammonia, we obtain the 
 following absorption -coefficients for ammonia in water: 
 
 No. 
 of the 
 exper. 
 
 C. 
 
 Coe 
 
 ^ 
 
 First 
 series. 
 
 'ficients fo 
 
 , -- 
 
 Second 
 series. 
 
 and. 
 
 . 
 Mean 
 from 
 1 and 2. 
 
 Coefficient 
 from formula 
 32. 
 
 Diffe- 
 rence. 
 
 1 
 
 0.53 
 
 1032.3 
 
 1036.0 
 
 1034.1 
 
 1034.1 
 
 0.00 
 
 2 
 
 4.60 
 
 918.9 
 
 922.5 
 
 920.7 
 
 927.3 
 
 -f- 6.54 
 
 3 
 
 9.54 
 
 822.2 
 
 
 
 822.2 
 
 825.4 
 
 -|- 3.14 
 
 4 
 
 14.41 
 
 735.3 
 
 737.7 
 
 736.5 
 
 736.4 
 
 0.10 
 
 5 
 
 19.71 
 
 655.4 
 
 655.2 
 
 655.3 
 
 657.8 
 
 -f 2.54 
 
 6 
 
 25.01 
 
 586.5 
 
 584.8 
 
 585.7 
 
 585.7 
 
 -f 0.02 
 
 The numbers in column 6 are obtained from the 
 formula 
 c = 1049.63 29.496? + 0.67687 1* 0.0095621/3 (32) 
 
 calculated from the experimental values in columns 2 
 and 5. 
 
174 AIR IN WATER. 
 
 No. 25. ATMOSPHERIC AIR IN WATER. 
 
 It has been previously shown that the relative pro- 
 portion in which the constituents of a mixture of gases 
 are absorbed by water does not alone depend upon their 
 several coefficients of absorption, but also upon the re- 
 lative proportions in which they are mixed. If the ab- 
 sorption-coefficients are different, the gases dissolved in 
 the water are not in the same relation as those in the 
 free gas. This last, undergoes therefore an alteration 
 in its composition varying with the relation of the mass 
 of the water to that of the gas. Hence the absorption- 
 coefficient of a mixed gas can only be calculated from 
 the relative proportions of the constituents and their 
 several coefficients of absorption, when the volume of 
 the gas is so great in comparison with the mass of the 
 absorbing liquid, that the alteration effected by the ab- 
 sorption in the composition of the residual gas is in- 
 appreciable. The true coefficient of absorption of at- 
 mospheric air can, therefore, be found in those cases only 
 in which these conditions are fully satisfied. 
 
 If we take the following as the mean composition 
 
 of the air, 
 
 Oxygen , <:> , . . 0.2096 = 
 
 Nitrogen . . . 0.7904 = N 
 1.0000 
 
 we obtain the required coefficient c for air and water 
 from the following equations: 
 
 V . - 
 
 - ~ 
 
 0.76 (N + 0} ~ 0.76 (N + 0) 
 
 and by substituting the values 1 for V l and N -)- O, and 
 
PRACTICAL APPLICATIONS. 175 
 
 0.76 for P, and the numerical values for and JV, we 
 obtain the equation: 
 
 c = 0.2096 a + 0.7904 ft. 
 
 Having thus determined the coefficients of absorption 
 of a series of gases, we may proceed to the practical 
 applications of the law of absorption. 
 
 If the volume of a simple gas, whose coefficient of 
 absorption is a, be twice absorbed by the same volume 
 h of water, at the same temperature, but under two dif- 
 ferent pressures P and P l , the amount of gas absorbed 
 in the two cases is, according to formula 2: 
 
 aPh 
 
 aP 1 h 
 
 0.76 
 
 Hence we have: 
 
 9i 
 
 . 
 
 Pi' 
 
 The following determinations made with the. ab- 
 sorptiometer show, within the limit of observational 
 errors, that the amount of carbonic acid g absorbed in 
 the same volume of water at the same temperature , in- 
 creases proportionally to the corresponding pressure P. 
 
 Carbonic acid at 199 C. 
 
 No. 
 
 P 
 
 g 
 
 P_ 
 
 g 
 
 
 
 
 PI 
 
 9i 
 
 1 0.7255 
 
 38.G1 
 
 
 
 2 
 
 0.5215 
 
 27.24 
 
 1.38 
 
 1.42 
 
 3 
 
 0.5237 
 
 27.08 
 
 1.39 
 
 1.43 
 
 4 0.5231 
 
 27.23 1.39 
 
 1.42 
 
17G 
 
 PRACTICAL APPLICATIONS 
 Carbonic acid at 32 C. 
 
 No. 
 
 P 
 
 g 
 
 P 
 P l 
 
 _9_ 
 <7i 
 
 1 
 
 0.5244 
 
 31.41 
 
 
 
 
 
 2 
 
 O.G467 
 
 38.GG 
 
 0.8109 
 
 0.8125 
 
 3 
 
 O.G470 
 
 38.49 
 
 0.8105 
 
 0.81G1 
 
 This constant ratio between the absorbed gaseous 
 volume and the pressure to which it is subjected, is more 
 clearly seen in cases in which the partial pressures occur, 
 i. e. in which alterations of pressure are effected by 
 dilution with another gas. The formula 7 gives a con- 
 venient statement of this relation : 
 
 x-\-y 
 
 W B 
 A B 
 
 A_ 
 W 
 
 By means of this formula, the composition of a mixture 
 of two gases can be calculated when the following quan- 
 tities are given : j the absorption - coefficient of the first 
 gas; /3 L that of the second; V the common volume of 
 both gases before the absorption, under the pressure P; 
 J 7 ! the residual volume after the absorption, under the 
 pressure P l \ and, lastly, the volume h of the absorbing 
 liquid. If the composition of the mixture calculated from 
 these experimental data coincides with that found by 
 direct eudiometrical analysis, we may conclude that the 
 formulae based upon the original premises are true, and 
 that the law is applicable not only for total, but also for 
 partial pressures. 
 
 The following experiments were made with mixtures 
 of carbonic acid and hydrogen. 
 
OF THE LAW OF ABSORPTION. 
 
 177 
 
 EXPERIMENT I. 
 Eudiometric determination. 
 
 
 
 Pres- 
 
 
 Vol. at 
 
 
 Vol. 
 
 
 C. 
 
 C. and 
 
 
 
 sure. 
 
 
 
 
 
 
 
 l m press. 
 
 
 120.G 
 
 0.7214 
 
 13.6 
 
 82.87 
 
 After addition of carbonic acid 
 
 129.4 
 
 0.7269 
 
 13.5 
 
 89.63 
 
 Composition of the gas in 100 parts: 
 
 Hydrogen .... 92.46 
 Carbonic acid 7.54 
 
 100.00 
 Absorptiometric determination of the same gas. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 C. 
 
 Vol. at 
 0C. 
 
 Volume ol' gas employed . . . 
 After absorption 
 
 180.94 
 122.01 
 
 0.5368 
 0.6809 
 
 15.4 
 5.5 
 
 171.29 
 119.61 
 
 Volume of absorbing water == 356.7 
 
 ,, o5o.l 
 
 Mean . . . 356.4 
 
 From these data we obtain the following elements 
 of the calculation : 
 
 P 0.5368; V = 171.29; 
 
 P l == 0.6809; \\ = 119.61; 
 
 a = 1.4199; ft = 0.0193; 
 
 h = 356.4; 
 
 12 
 
178 
 
 ABSORPTIOMETRIC ANALYSIS 
 
 and hence the composition is found to be : 
 
 Absorptiometric. Eudiometric. 
 
 Hydrogen . . . 0.9207 0.9246 = V 
 
 Carbonic acid , 0.0793 0.0754 = v 
 
 1.0000 
 
 1.0000 
 
 The composition of the gas remaining after the ab- 
 sorption is found by means of the formula? : 
 
 + 
 
 to be: 
 
 ~ x + y "" AB L + A 1 B 
 
 Hydrogen . . . 0.9829 
 Carbonic acid . 0.0171 
 
 1.0000 
 
 As the gaseous mixture after absorption was sub- 
 jected to a^pressure P = O m 6809, the partial pressure 
 upon the carbonic acid was in this experiment: 
 
 u P l = O m 0116, 
 that of the hydrogen : 
 
 M! P l = O m 6692. 
 
 EXPERIMENT II. 
 Eudiometric determination. 
 
 
 
 Pres- 
 
 
 Vol. at 
 
 
 Vol. 
 
 
 c. 
 
 O n C. and 
 
 
 
 sure. 
 
 
 
 
 
 
 
 l m press. 
 
 
 G2.2 
 
 0.0449 
 
 
 39 03 
 
 After admission of carbonic acid 
 
 82.1 
 
 O.GG49 
 
 G.4 
 
 53.34 
 
OF A MIXTURE OF TWO GASES. 
 Composition of the gas : 
 
 Hydrogen . . . 0.7319 
 
 179 
 
 Carbonic acid 
 
 0.2681 
 
 1.0000 
 
 Absorptiometric analysis of the same gas. 
 
 
 Vol. at 
 
 
 
 
 O n C. 
 
 Pressure. 
 
 C. 
 
 Volume of gas employed . . . 
 
 119.03 
 
 0.4951 
 
 6.8 
 
 After first absorption 
 
 72.02 
 
 O.G11G 
 
 5.1 
 
 After second absorption . . . 
 
 G0.39 
 
 0.7297 
 
 12.8 
 
 After third absorption .... 
 
 75.71 
 
 O.G020 
 
 23.3 
 
 Volume of absorbing water: 
 
 206.83 
 206.61 
 206.61 
 207.11 
 
 Mean 
 
 206.79 
 
 Hence we have for the first absorption experiment 
 
 P = 0.4951; T r = 119.03; 
 
 P l = 0.6116; V l = 72.02; 
 
 a = 1.4434; ft = 0.0193; 
 
 h = 206.79; 
 
 For the second Absorption : 
 
 P = 0.4951; 
 
 P, = 0.7297; 
 
 a ad 1.0726; 
 
 h = 206.79; 
 
 V = 119.03; 
 Fi = 60.39; 
 = 0.0193; 
 
 ft 
 
 12* 
 
180 ABSORPTIOMETRIC ANALYSIS 
 
 For the third absorption: 
 
 P = 0.4951; V = 119.03; 
 P l = 0.6020; l\ = . 75.71; 
 a = 0.8555; ft = 0.0193. 
 h =206.79; 
 
 The calculation of the first absorption gives : 
 
 Absorptiometric. Eudiometric. 
 
 Hydrogen . . . 0.7343 0.7319 
 
 Carbonic acid . 0.2657 0.2681 
 
 1.0000 1.0000 
 
 The composition of the residual gas, remaining after 
 absorption, calculated from the eudiometric analysis, is: 
 
 Carbonic acid . '. . 0.0699 
 
 Hydrogen 0.9301 
 
 1.0000 
 
 Hence the partial pressure of the hydrogen is O ni 5688, 
 and of the carbonic acid O m 04275. 
 
 From the second absorption we obtain: 
 
 Absorptiometric. Eudiometric. 
 
 Hydrogen . . . 0.7372 0.7319 
 
 Carbonic acid . 0.2628 0.2681 
 
 1.0000 1.0000 
 
 This gives a residual gas of the composition : 
 
 Carbonic acid . . . -0.07712 
 
 Hydrogen .... 0.92288 
 
 1.00000 
 
 The partial pressure of the carbonic acid is here 
 0-0563, and of the hydrogen 06734. 
 
OF A MIXTURE OF TWO GASES. 181 
 
 The third absorption gives the following results: 
 
 Absorptiometric. Eudiometric. 
 
 Hydrogen . . . 0.7285 0.7319 
 
 Carbonic acid . . 0.2715 0.2681 
 
 1.0000 1.0000 
 
 The residual gas after absorption, was hence found 
 
 to be: 
 
 Carbonic acid . . . 0.1036 
 
 Hydrogen 0.8964 
 
 1.0000 
 
 The pressure of the carbonic acid is, here O m 06236, 
 and of the hydrogen O m 5396. 
 
 The mean of these three determinations compared 
 with the eudiometric analysis, gives: 
 
 Absorptiometric analysis. Eudiometric analysis. 
 
 Hydrogen .... 26.67 26.81 
 
 Carbonic acid . . 73.33 73.19 
 
 100.00 100.00 
 
 It is impossible to determine a priori, the extent 
 beyond the limits already examined, for which the law 
 is true. It is, however, more than probable that in this 
 law, as in the law of Mariotte, a limit exists beyond 
 which the regularity of the action is disturbed by varying 
 molecular influences. The limits of exact action, de- 
 termined experimentally, are, however, quite extensive 
 enough to enable us to draw some very interesting con- 
 clusions from the subject. Eudiometry , for example, 
 gains from the law* of absorption an entirely new field 
 of action, enabling it not only to determine, without any 
 chemical experiments, the simple or complex constitution 
 of a gas , but also to recognize the nature of the com- 
 
182 ABSORPTION IN LIQUIDS 
 
 poneut parts, even indeed to estimate their several pro- 
 portions, when once for all the coefficients of absorption 
 of the gases are known. In order to show that such an 
 absorptiometric determination can serve as a reagent 
 for the detection of gases, I choose an experiment with 
 marsh gas, which satisfactorily proves that results are 
 attainable, even when the values of the absorption -coef- 
 ficients employed in the calculation differ but little from 
 each other. 
 
 Relying on the results of eudiometrical analysis, it 
 has been hitherto supposed that the gas obtained by the 
 action of a hyxlrated alkali upon an alkaline acetate at 
 a high temperature was marsh gas. Although this sup- 
 position has scarcely ever been questioned, still all po- 
 sitive proof of the fact is wanting. Frankland and Kolbe 
 have shown that two volumes of marsh gas by eudio- 
 metrical explosion react exactly as a mixture of equal 
 volumes of hydrogen and methyl. Both give for every 
 volume a volume of carbonic acid, and require for their 
 combustion the double volume of oxygen. Eudiometric 
 analysis leaves it then undecided, whether the gas evolved 
 from the alkaline acetates is to be considered as marsh 
 gas, or as a mixture of methyl and hydrogen. By means 
 of absorptiometric analysis, this question is very readily 
 and decisively answered. If we start from the supposition 
 that the gas in question is a mixture of equal volumes 
 of methyl arid hydrogen , a volume V of the gas , at C., 
 and under O m 76 pressure, measured in the absorptiometer 
 under a pressure P, would consist of 
 
 . methyl , and 
 
 P V 
 
 -r hydrogen. 
 
 2 . 0.76 
 
A NEW REAGENT. 183 
 
 If this gas be agitated with /ij volumes of water, the 
 observed volume of the residual absorbed gas being V l 
 under the pressure P l , the sum of the absorption -coef- 
 ficients at the temperature of absorption (for hydrogen 
 ! and for methyl /3 X ) can be calculated from the ob- 
 servations. If we call the residual hydrogen x { , and the 
 residual methyl yi (both reduced to C. and O m 76), this 
 x l will, iii consequence of its dilution with methyl, be 
 
 subject to the partial pressure - L ' ' . It is, however, 
 
 absorbed under this pressure by the volume 7^ of water. 
 The absorbed volume of hydrogen, reduced to C. and 
 O m 76 pressure, is therefore, according to the law of 
 
 absorption, -~jr a\ hi- This absorbed hydrogen plus the 
 ri 
 
 unabsorbed x^ is equal to the hydrogen originally present, 
 namely : 
 
 PV 
 
 2 . 0.76 l V, 
 
 or 
 
 PV 
 
 2 . 0.76 fl + 
 
 0.76 d 
 
 If the value of ^ is substituted in the expression , 7 - 1 - 1 , 
 
 we obtain for the pressure of the hydrogen in the residual 
 unabsorbed gas 
 
 PV 
 
 2 (V\ + MO ' 
 
 and for the pressure of the methyl in a similar manner, 
 
 PV 
 
 It follows, however, from the law of absorption, that the 
 
184 ABSORPTION IN LIQUIDS 
 
 sum of the two partial pressures is equal to the observed 
 pressure PI. Hence we have : 
 
 P pv pv 
 
 2 (F, + V*,) " 2(F, +ftA,)' 
 or 
 
 PV 2 F! 
 
 "" + ft = : TTkAT ~T 
 
 An experiment made by Dr. Pauli with a gas pre- 
 pared by heating the acetate with hydrate of potash, and 
 carefully freed from elayl and carbonic acid with fuming 
 sulphuric acid and potash, gave the following elements 
 for calculation: 
 Original volume of gas reduced to C. Ji . ! .' . V = 11G.42 
 
 The pressure on this volume P = 0.50G5 
 
 Volume of gas reduced to C. after first absorption V l = 75.18 
 
 Corresponding pressure P l = O.GG15 
 
 Volume of absorbing water ........ A, = 318.11 
 
 Temperature of the absorption .... ."]. ;-. 128 C. 
 
 Absorption -coefficient of hydrogen at 12 8C. . ct*= 0.01930 
 Absorption -coefficient of methyl gas at 128 C. . ft = 0.0544G 
 Absorption -coefficient of marsh gas at 128 C. . y t = 0.0410G 
 The volume after second absorption reduced to C. F n = 79.04 
 Corresponding pressure . . *./ . r; *. ' . . . . . P n = 0.6561 
 
 Volume of absorbing water 7* n = 325.05 
 
 Temperature of absorption t n = 24G C. 
 
 Absorption -coefficient of hydrogen at 246 C. . n = 0.01930 
 Absorption -coefficient of methyl gas at 24G C. . ft, 0.04181 
 Absorption -coefficient of marsh gas at 24G C. . y n = 0.031GG 
 
 When this is calculated , negative values for cq -f- fti 
 and for a n -\- /? are found from both absorptiometric 
 experiments, namely: -- 0.3325 and 0.34807, instead 
 of the sums of the coefficients found in the experiments 
 for methyl and hydrogen: -f- 0.07376 and -f- 0.06111. 
 Hence the gas in question cannot consist of methyl and 
 hydrogen. 
 
A NEW REAGENT. 185 
 
 If, on the contrary, the same elements are used in 
 the calculation of y Y and */, under the supposition that 
 the gas is a pimple one, two absorption - coefficients are 
 obtained, which are almost exactly the same as those 
 found from formula 14 for marsh gas, at the temperatures 
 1208 C. and 24o6 C. The formula 
 VP JV 
 
 gives in fact, according to table VI of the appendix, for 
 the temperature 128 C. the value of the coefficient to be 
 
 yi = 0.0439 
 
 instead of the actual value 0.041 1 ; and for the tempera- 
 ture 2406 C. 
 
 y n = 0.0333 
 
 instead of 0.03166. From this agreement we may con- 
 clude that the marsh gas prepared from acetate of pot- 
 ash is neither a mixture of hydrogen and methyl, nor a 
 body isomeric with natural marsh gas, but that it is ac- 
 tually the same substance which issues from the mud- 
 volcanoes of Bulganak in the Crimea. 
 
 Any general reaction to distinguish between the con- 
 stituents of a gaseous mixture has hitherto been wanting. 
 The quantitative composition of a gas obtained by eudio- 
 metrical analysis, depends almost entirely upon certain 
 suppositions regarding its qualitative constitution. If, for 
 instance, eudiometrical analysis points out the presence 
 of marsh gas, it remains quite undecided, as I have just 
 shown, whether or not this gas is a mixture of equal vo- 
 lumes of methyl and hydrogen. If analysis shows the 
 presence of a mixture of marsh gas and hydrogen , it is 
 uncertain whether we are experimenting upon mixtures 
 of methyl and hydrogen, or of methyl, marsh gas and hy- 
 drogen. All analyses in which the two latter gases occur 
 
180 ABSORPTIOMETRIC ANALYSIS 
 
 together may be calculated according to either of these 
 assumptions, without it having hitherto been possible to 
 prove the accuracy of either one. 
 
 It is easy, by means of the law of absorption, to re- 
 move these doubts, for the absorption -coefficients serve 
 as the reagents which are wanting in gas analysis, and 
 they also present the peculiarity, that they do not only 
 show the qualitative, but at the same time the quantita- 
 tive composition of the gas. Let us, for example, sup- 
 pose that an unknown gas be mixed in an unknown vo- 
 lume or, with an unknown volume y of another unknown 
 gas, we can then, by means of three absorptiometric ex- 
 periments, determine, firstly, what gases are present in the 
 mixture, and secondly, in what proportions they occur. 
 
 The following is the method of solving this problem: 
 A sufficient quantity of the gas to be examined is col- 
 lected in the absorptiometer, and its volume, pressure 
 and temperature observed. 
 
 If the originally observed volume reduced to C. 
 be called F, and its pressure P, we obtain the equation 
 
 x 
 
 '- yp -r yp 
 
 Three absorptions of the gas are first made with the 
 volumes of water h^h^h^ and the corresponding volumes 
 for a constant temperature f, found to be, F x , P l ; F 2 , P 2 ; 
 F 8 , P 3 ; reduced to C. From these observations we ob- 
 tain the following equations, in which a denotes the ab- 
 sorption-coefficient of the first, and /3 that of the second 
 unknown gas at the temperature of the observations t: 
 
 i x i y 
 
OF TWO UNKNOWN GASES. 187 
 
 : TrT i , 7, \ T> I 71 
 
 From these four equations the unknown quantities 
 ., y. a, /3, are easily obtained. These two last are the 
 ordinates of absorption for two gases for the temperature 
 abscissa t. If the numerical values of these are calcu- 
 lated, the gas which has the same coefficient of absorp- 
 tion for corresponding temperatures is found in the 
 tables, and in this way the nature of the mixture determ- 
 ined. The values of x and y give also the relative pro- 
 portions between the constituents. In the case of two 
 gases the determination of a and ft is not difficult. If 
 we place PV = o, P l V l = a,, P 2 V 2 = ,, P 3 F 3 == a* 
 and PI J^ = 6 l7 P 2 h. 2 = 6 2 , P 3 /* 3 = 6 3 , we obtain in the 
 first place, 
 . &A 
 
 _ ,, 6 3 (o a f ) a d & g (a a,,) b t b 3 (g, a 3 ) (a 
 i * 3 (t - .) 
 
 and when the expressions on the right of these equations 
 are represented by A and B, we have, 
 
 a + ft = A ..... Ks->* . (34) 
 
 a P= A--B . ._._. . (35) 
 The sum of these two equations gives the value of a, their 
 difference that of ft. 
 
 By help of these values a and ft , we obtain, lastly, 
 
 (a 2 a -|- a 6 2 ) (q a -f /3 & 2 ) fi 
 
 ^ = 6 2 ( _ ft 
 
 ^^a ^. :; .^. ,,;:;..,. ; . ,,,,-. (37) 
 
 As an example of such a calculation , I select the 
 qualitative and quantitative determination of the gas pre- 
 pared by heating oxalic acid with concentrated sulphuric 
 acid. As this gas always contains an admixture of small 
 
188 
 
 ABSORPTIOMETRIC ANALYSIS 
 
 quantities of sulphurous acid, it was first passed through 
 water containing oxide of manganese in suspension , and 
 the gas was not collected until the water had been com- 
 pletely saturated, and all the air expelled from the 
 apparatus. An eudiometric analysis of the purified gas 
 gave: 
 
 
 
 Pres- 
 
 
 Vol. at 
 
 
 Vol. 
 
 
 C. 
 
 C. and 
 
 
 
 sure. 
 
 
 
 
 
 
 
 l m press. 
 
 Original volume 
 
 142.9 
 
 O.G9G5 
 
 20.2 
 
 92.70 
 
 
 
 
 
 
 After absorption of carbonic acid . 
 
 74.6 
 
 O.GG37 
 
 19.0 
 
 .46.29 
 
 
 
 
 
 
 Carbonic oxide 
 Carbonic acid . 
 
 Found. 
 
 '50.0G 
 
 49.94 
 
 Calculated. 
 50.00 
 50.00 
 
 100.00 
 
 100.00 
 
 The absorptiometric determination, which was so con- 
 ducted that the amount of absorbing water It was in- 
 creased after every observation, gave the following ele- 
 ments : 
 
 
 Vol. at 
 
 Pres- 
 
 
 Volume 
 
 
 
 
 C. 
 
 of water 
 
 
 0C. 
 
 sure. 
 
 
 = h. 
 
 
 
 
 
 
 Gas employed 
 
 500.8 
 
 0.5760 
 
 19.0 
 
 o 
 
 After the first absorption .... 
 
 384.0 
 
 0.6882 
 
 19.0 
 
 81.6 
 
 After the second absorption . . . 
 
 340.0 
 
 0.7015 
 
 19.2 
 
 186.9 
 
 After the third absorption .... 
 
 2833 
 
 0.7415 
 
 19.0 
 
 335.5 
 
 From these elements the value of /? is found, accord- 
 ing to formulae 34 and 35, to be 0.1)248. The table of 
 
OF TWO UNKNOWN GASES. 189 
 
 coefficients VI shows that carhonic acid gas possesses 
 the coefficient of absorption 0.9150 at the temperature 
 190 C. of the experiment, and that it therefore differs but 
 slightly from that just found. We are in the habit of con- 
 cluding from the consistence of a precipitate, from its co- 
 lour, solubility &c. that a certain substance is present. In this 
 case we have a certain definite ordinate of a curve of solu- 
 bility, fixed by previous experiment which serves as a rea- 
 gent in place of the precipitate. As, however, we are ac- 
 quainted with many substances which produce precipitates 
 so much alike that they cannot be employed as a means 
 of recognition, we may also find that these ordinates so 
 approach at a given temperature by which the curves of 
 solubility touch or cut one another, that a second absorptio- 
 metric experiment is necessary. The foregoing experi- 
 ment may serve as an example of this difficulty ; we find 
 the experimental value of a to be 0.0204 ; a number which 
 differs but very inconsiderably from the coefficient of 
 carbonic oxide, as found in the tables for the tempera- 
 ture 19 C., viz 0.0233. The coefficients for both hydro- 
 gen, and sethyl, 0.0193 and 0.0207, differ however, so 
 slightly from this experimental value, that we cannot de- 
 termine with certainty which of these three gases is present. 
 In this case the absorption -coefficient of water is to be 
 compared to a reagent which indicates the presence of a 
 group of bodies. It only remains, to determine by ab- 
 sorptiometric experiments, either at varying temperatures, 
 or with other liquids, which of these three gases is con- 
 tained in the mixture under examination. The deter- 
 mination of the absorption - coefficients of gases for 
 alcohol, for saline solutions, and other liquids, forms 
 therefore an important element in gasometric investi- 
 gations as from these a number of equations are ob- 
 
190 ABSORPTIOMETRIC ANALYSIS 
 
 tainable, each of which possesses the value of a new 
 reagent. 
 
 If the material nature of the gas has been deter- 
 mined from a and /3 by the method described, it is only 
 necessary to substitute these values of a and /3 in the 
 equations 36 and 37, in order to be able to calculate the 
 quantitative relation to which the two gases are mixed. 
 
 This calculation made for the above experiment with 
 the values of a and /3 found in the tables of carbonic acid 
 and carbonic oxide, gives: 
 
 
 
 Eudio- 
 metric. 
 
 First 
 experim. 
 
 Absorpt 
 
 Second 
 experim. 
 
 ioinctric. 
 
 *- ^M^"i 
 
 Third 
 experirn. 
 
 Mean. 
 
 Carbonic acid . 
 Carbonic oxide . 
 
 50.06 
 49.94 
 
 50.00 
 50.00 
 
 50.03 
 49.97 
 
 50.34 
 49.GG 
 
 50.12 
 49.88 
 
 100.00 
 
 100.00 
 
 100.00 
 
 100.00 
 
 100.00 
 
 The same elements which have served to determine 
 the qualitative nature of the mixture of gases, give there- 
 fore the quantitative composition with a degree of accu- 
 racy scarcely surpassed by eudiometric analysis. 
 
 In the following experiment a mixture of carbonic- 
 acid and marsh gas was employed, and the liquid used 
 for the absorption was absolute alcohol. The eudiome- 
 tric analysis gave: 
 
OF TWO UNKNOWN GASES. 
 
 191 
 
 
 Vol. 
 
 Temp. 
 
 Pres- 
 sure. 
 
 Vol. at 
 C. and 
 l m press. 
 
 Carbonic oxide 
 
 185.0 
 
 5.4 
 
 0.5874 
 
 106.56 
 
 After addition of marsh gas . . . 
 
 3335 
 
 5.7 
 
 0.6462 
 
 111.11 
 
 Carbonic oxide 50.48 
 
 Marsh gas 49.52 
 
 100.00 
 
 The elements of the absorptiometric determination 
 were: 
 
 
 Vol. at 
 
 | 
 
 
 Volume 
 
 
 
 Pressure. 
 
 C. : of alcohol 
 
 
 C. 
 
 
 = h. 
 
 Volume of gas employed . 
 
 326.69 0.6462 
 
 5.7 
 
 
 
 After first absorption . . . 
 
 203.44 0.6533 
 
 5.4 
 
 50.7 
 
 After second absorption . . 
 
 197.80 0.6580 
 
 5.4 
 
 74.7 
 
 After third absorption . . 193.42 0.6624 
 
 5.4 
 
 94.4 
 
 Hence the coefficient a is found to be = 0.5084, and 
 ft = 0.2139. The two gases whose coefficients at a tem- 
 perature of 54 C. agree with these numbers are marsh 
 gas and carbonic oxide, as is seen from table VI in the 
 appendix, where the first is found to be 0.5075 and the 
 second 0.2139. As the other tables do not contain any 
 other coefficients which so nearly approach the numbers 
 found, we may consider the qualitative nature of the mix- 
 ture thereby determined. The calculation of the quanti- 
 tative composition gives the following results : 
 
192 
 
 APPLICATIONS OF THE 
 
 
 Eudio- 
 inetric 
 
 Absorptiometric. 
 
 First 
 experim. 
 
 Second 
 experim. 
 
 Third 
 experim. 
 
 Mean. 
 
 Carbonic oxide . 
 Marsh gas . 
 
 50.48 
 49.52 
 
 50.60 
 49.40 
 
 50.59 
 49.41 
 
 50.5G 
 49.44 
 
 50.58 
 49.42 
 
 100.00 
 
 100.00 
 
 100.00 
 
 100.00 
 
 100.00 
 
 Another problem which can be solved by help of the 
 law of absorption, concerns the alterations which a mix- 
 ture of gases undergoes on contact with water. The fol- 
 lowing example of a similar mixture of carbonic acid and 
 carbonic oxide shows how considerable such alterations, 
 even with relatively small amounts of liquid, may under 
 certain circumstances become; and to what serious errors 
 those eudiometric experiments may be subject in which 
 the gases are confined over water, or liquids instead of 
 solids are employed as absorbents. 
 
 The gas employed in this experiment was again that 
 evolved from oxalic and sulphuric acids. The following 
 elements for the calculation were obtained from an ex- 
 periment made by Dr. Atkinson : 
 
 V = 388.4; V, = 247.69; 
 P = 0.6557; P l = 0.7395; 
 
 a =rr 0.9124. 
 
 * == 315.3; 
 ** = 0.02326 ; 
 
 These values substituted in formula 7, gives the following 
 composition of the gas employed: 
 
 * Called 
 ** Called 
 
 in formula 7. 
 in formula 7. 
 
LAW OF ABSORPTION OF GASES. 
 
 193 
 
 Absorptiometric. 
 
 Carbonic acid 49.55 
 
 Carbonic oxide 50.45 
 
 100.00 
 
 Calculated. 
 
 50.00 
 50.00 
 
 100.00 
 
 Absorptiometric analysis, leads therefore, as before, to 
 
 the values V = 0.4955 and V = 0.5045. 
 
 From this is obtained, by means of equation 6, the 
 
 composition of the residual unabsorbed gas : 
 
 Carbonic acid 31.87 
 
 Carbonic oxide 68.13 
 
 100.00 
 
 A eudiometric analysis of the residual gas , made by 
 Dr. Atkinson, agrees in a satisfactory manner with this 
 calculated composition. He found: 
 
 
 Volume. 
 
 Pressure. 
 
 c. 
 
 Vol. at 
 C. and 
 
 
 
 
 l m press. 
 
 Original volume .... 
 
 9G.1 
 
 O.G721 
 
 18 7 
 
 60.45 
 
 After absorption of the 
 carbonic acid .... 
 
 Carbonic aci 
 Carbonic ox 
 
 68.0 
 d 
 
 0.6556 
 
 19.3 
 
 . 31.12 
 
 68.88 
 
 41.64 
 
 de 
 
 
 100.00 
 
 The quantity of carbonic oxide contained in the ga- 
 seous mixture has therefore increased from 50.45 to 68.88. 
 although the volume of absorbing water was not so large 
 as that of the gas. 
 
 The phenomena which accompany the evolution of 
 gas in mineral springs , can only be fully understood by 
 
 13 
 
194 GASES ABSORBED 
 
 the help of the law of absorption. " Among the non - alka- 
 line springs, containing but a small quantity of dissolved 
 salts, there are some whose absorption -coefficients differ 
 but slightly from those of pure water, and contain carbo- 
 nic acid gas alone in solution. If such springs, as is usu- 
 ally the case, are saturated with gas, a certain limit for 
 the amount of contained carbonic acid may be found. 
 This limit of the quantity of carbonic acid, depends: 
 firstly upon the temperature of the spring; secondly on 
 the depth of the shaft of the spring ; thirdly on the height 
 of the spring above the sea. 
 
 Springs of the above description, which are saturated 
 with a stream of chemically pure carbonic acid, and rise 
 without pressure at the level of the sea, give according 
 to their temperature very different amounts of gas. They 
 contain in one litre of water the following amounts of 
 gas for the corresponding temperatures : 
 
 C. Cbc. of gas in 1 litre of water 
 
 1796.7 
 
 5 1449.7 
 
 10 1184.7 
 
 15 1002.0 
 
 20 901.4 
 
 If the same spring , under otherwise similar circum- 
 stances, rose at an elevation above the sea where the 
 average atmospheric pressure was only two - thirds of the 
 mean height of the barometric column , it would contain 
 only two -thirds of the above amount of dissolved car- 
 bonic acid. 
 
 Hence, it will be perceived, that the amount of gas 
 in a spring which is saturated with pure carbonic acid, 
 may be considerably argumented by deepening the spring 
 shaft, and thus increasing the column of water under 
 
IN MINERAL SPRINGS. 195 
 
 which the gas issues from the earth, as Bischoff has in- 
 deed already shewn in his admirable researches on the 
 phenomena of springs. If, for example, the depth of the 
 shaft from the surface of the spring to the ground is 15 
 feet, the water where it bubbles out from the earth will 
 contain one third more carbonic acid than the above 
 amounts shew. The water in rising to the surface loses 
 a part of the dissolved gas in proportion as the pressure 
 diminishes, but the statical equilibrium which ensues, in 
 consequence of the law of absorption , requires a certain 
 time for its restoration. Thus the Peter's Spring in Pe- 
 tersthal in the Schwarzwald, which has a temperature of 
 10 C., contains at the surface of the spring, under a pres- 
 sure O m 735, 1270.4 cbc. of carbonic acid in the litre; 
 whereas, according to the absorption -coefficient of car- 
 bonic acid for 103, it should only contain 1133.3 cbc. 
 under the same pressure. The water is therefore super- 
 saturated with carbonic acid. This excess of gas is seen 
 to escape in small bubbles from the water when a vessel 
 filled at the spring is allowed to stand. By agitation the 
 equilibrium is restored in a few moments, and the gas 
 dissolved in the water reduced to its normal amount. From 
 similar considerations, it is easy to see that many of the 
 statements, with regard to the amount of carbonic acid 
 contained in springs, must be false. Thus , for instance, 
 the amount of carbonic acid contained in the ,,Fursten- 
 Quelle" in Imnau, is given by Sigwart to be 2500 cbc. 
 in the litre. Under the mean pressure, and at the tem- 
 perature of the spring 63 C., the water can, however, ac- 
 cording to the law of absorption, only contain 1373.2 * 
 
 * The small amount of solid constituents contained in the water 
 (not more than 9 grains in the pound), cannot appreciably alter 
 the absorption - coefficients, certainly not increase them. 
 
 13* 
 
19G GASES ABSORBED IN 
 
 cbc. after the equilibrium has been established. The 
 amount of gas 2500, requires a pressure of I m 3836 of 
 mercury, or a column of water of 8 m 449 to be added to 
 the mean barometric pressure. As, however, it is impos- 
 sible to suppose that the Imnau spring rises under the 
 pressure of a column of water at least 25 feet high, and 
 as a saturation of nearly double the amount of gas is as 
 improbable, we are compelled to assume that Sigwart's 
 experiments are erroneous. The falsity of many other si- 
 milar statements may thus be easily shewn. 
 
 The relations which are found to exist between the 
 free and absorbed gases of a spring by means of the law 
 of absorption, give a fixed starting-point from which to 
 estimate the influence which an amount of nitrogen in 
 the free gas in a spring exerts upon the quantity of car- 
 bonic acid dissolved in the water. The second and third 
 columns of the following table , calculated from the pre- 
 ceding formulse, show the percentage amount of carbonic 
 acid and nitrogen in the absorbed gas for the cor- 
 responding percentages of nitrogen in the free gas given 
 in the first column. The temperature of the water is 
 supposed to be 151 C. 
 
 Amount of nitrogen 
 
 Gas absorbed 
 
 in the spring water 
 
 in the free gas. 
 
 -^- " _ 
 nitrogen. 
 
 -^ 
 carbonic acid. 
 
 I. 
 
 II. 
 
 HI. 
 
 10 per cent 
 
 1.613 
 
 98.387 
 
 20 
 
 3.558 
 
 96.442 
 
 30 
 
 5.949 
 
 94.051 
 
 40 
 
 8.958 
 
 91.042 
 
 50 
 
 12.861 
 
 87.139 
 
 60 
 
 18.127 
 
 81.873 
 
 70 
 
 25.623 
 
 74.377 
 
 80 ; 
 
 37.123 
 
 62.877 
 
 90 
 
 57.052 
 
 42.948 
 
MINERAL SPRINGS. 197 
 
 From this table it is plainly seen, that if the gas 
 passing through a spring at 151 C. contains only 10 per 
 cent of carbonic acid with 90 per cent of nitrogen, the 
 gas dissolved in the spring water will contain 42.948 per 
 cent of carbonic acid. In this way it is easy, in analysis 
 of mineral waters, to calculate the composition of the 
 gases contained in the water, if the composition of the 
 gas which is set free in the spring is known by experi- 
 ment. If the composition of both gases is directly deter- 
 mined , and the experimental composition agrees with 
 that found by calculation, we have a most valuable con- 
 firmation of the correctness of both analyses. 
 
 All these deductions from the law of absorption are 
 of course only applicable to cases in which a statical 
 equilibrium between the free and dissolved gases can 
 ensue. This is not only the case in springs through which 
 gases pass, but particularly in rain and dew, and the 
 law is applicable to these with the greatest precision. 
 
198 LAWS OF THE 
 
 DIFFUSION OF GASES. * 
 
 JLf a long vertical tube closed at the lower end, be half 
 filled with hypochlorous acid, or any other coloured gas, 
 a colourless column of air is seen in the upper {>art of 
 the tube resting on the coloured gas below. If a portion 
 of the air be withdrawn before a mixture of the gases 
 has occurred, the surface of contact of the two layers, as 
 seen by the coloured gas , rises in consequence of the in- 
 creasing expansion, and the pressure, measured by a ma- 
 nometer attached to the side of the tube, is altered in a 
 similar manner in all the layers of the two gases. Hence 
 we may conclude that the particles of different gases exert 
 the same pressure on each other as the particles of simi- 
 lar ones. 
 
 Occurring together with, although entirely indepen- 
 dant of these actions of pressure, we observe another 
 phenomenon; namely gaseous diffusion. This pheno- 
 menon depends upon the property of gases mutually to 
 penetrate into each other from their surfaces of contact, 
 with velocities determined by their chemical natures, 
 
 * The results communicated under this heading are derived from 
 an unfinished , and still unpublished research which the author 
 made some years ago in conjunction with Professor Stegmami. 
 
DIFFUSION OF GASES. 199 
 
 until the density of each constituent has become the same 
 throughout the whole mass. If the two gases are sepa- 
 rated by a porous diaphragm, as, for instance, a piece of 
 dried gypsum, whose pores offer so large a fractional re- 
 sistance that the velocity of issue for gases , even when 
 they are forced through under a considerable pressure, 
 remains but small, it is still found that an exchange of 
 gases goes on through such a diaphragm with consider- 
 able rapidity. If the pressure above and below the dia- 
 phragm be always retained the same, it is found that the 
 volumes of the gases which pass through in both directions 
 during the same time are not equal, and therefore, that 
 gases pass through such porous diaphragms with veloci- 
 ties dependant upon their essential natures. It is not 
 possible to determine the diffusion -velocity of two gases 
 whilst they freely communicate with each other, because 
 the motion effected by the diffusion is not the only phe- 
 nomenon observed ; for when two gases penetrate into 
 each other with different velocities, the total pressure 
 thus altered, must adjust itself and effect motions enti- 
 rely independant of those which diffusion alone would 
 have caused in each separate gas. In researches upon 
 diffusion we must therefore especially guard against the 
 disturbing influence of unequal pressure. In order to be 
 able to fulfil these conditions for gases, whose volumes 
 are undergoing continual alteration, we may employ an 
 instrument called the diffusiometer which has the following 
 arrangement. Fig. 52 (seep. 200) a a represents a rod of 
 wood moveable in a vertical direction through the sockets 
 cc, to which the vessel containing the gas, whose pressure 
 is to remain constant, is attached by the small bent iron 
 clamp I. The axis d is fixed between the two arms kk 
 (firmly attached to the rod a a) by means of a piece of 
 
200 
 
 LAWS OF THE 
 
 cat-gut wound round the axis at <j and drawn tight by a 
 violin key at v. By turning the wheel p (which revolves 
 against a steel spring e , and forms the end of the axis 
 c/), either to right or left on its centre, the rod a can 
 
 Fig. 52. 
 
 easily be moved in a vertical direction either upwards or 
 downwards. As this motion is diminished in the propor- 
 tion of the radius of the wheel p to that of the axis d, a 
 relatively large motion of the wheel effects a very slight 
 
DIFFUSION OF GASES. 201 
 
 upward or downward movement of the tube m containing 
 the gas. If this tube be dipped into a cylinder filled with 
 mercury, it is easy to keep the metal in the tube at the 
 same level as that in the cylinder to within O. mm l by 
 turning the wheel p whilst the meniscus is observed 
 through the telescope h h. 
 
 Graham, to whom we are indebted for the important 
 discovery of the phenomena of gaseous diffusion , found 
 that a definite relation existed between the volume of air 
 exchanged for a volume of gas diffusing into the air. 
 through a porous diaphragm and under a constant pres- 
 sure, and the volume of diffused gas itself; and he found 
 that this definite relation more or less nearly approached 
 that of the inverse square - roots of the specific gravities 
 of the gases. A theoretical explanation of this particular 
 numerical relation has been attempted by the supposition 
 that a gas diffuses into another gas of different constitu- 
 tion, according to the same laws which regulate its pene- 
 tration into a vacuous space , and that in the case of dif- 
 fusion of two gases, the motion proceeds with the same 
 relative velocity as it would have done had they both of 
 them diffused into a space free from air. As the velocity 
 of issue of gases into a vacuum is found both by theory 
 and experiment to be inversely proportional to the square- 
 roots of their densities, only when the efflux occurs from 
 fine openings in thin plates, and not through capillary 
 tubes, we see that this theoretical explanation rests on 
 the improbable supposition that a porous diaphragm acts 
 towards gases like a system of fine openings in thin plates. 
 Hence it appeared necessary, in order to test the truth of 
 the generally adopted theory of diffusion, especially to 
 examine the phenomena occurring in the transit of gases 
 through porous diaphragms. For this purpose the appa- 
 
202 LAWS OF THE 
 
 ratus represented by Fig. 53 was employed. The tube d 
 is graduated and calibrated, and closed by the diaphragm 
 of gypsum b. This tube is connected with the head C by 
 
 Fig. 53. 
 
DIFFUSION OF GASES. 203 
 
 an air-tight vulcanised caoutchouc joining Z>, so that a 
 current of gas can be brought , from the delivery tube e 
 by means of the small caoutchouc tube i, immediately 
 above the surface of the porous plate b. The ground 
 glass stopper o serves to shut off the communication be- 
 tween the plate of gypsum and the current of gas, by mov- 
 ing the glass rod w, working air-tight in the vulcanised 
 caoutchouc cap E. In cases in which the gas is required 
 to be withdrawn for analysis at any given period of the 
 experiment, the small exit tube p furnished with a caout- 
 chouc ventile g, may be used. 
 
 The following is the method employed when we have 
 to determine the velocity with which a gas passes through 
 the plug of gypsum. The diffusion -tube just described 
 (Fig. 53) is first fastened on to the bent iron clamp b of 
 the diffusiometer (Fig. 52) ; the stopper o (Fig. 53) is then 
 lifted by means of the glass rod m, which, in order to 
 keep it in its place, is fastened by a thread to a little 
 hook on the wooden rod aa. If the diffusion-tube be now 
 sunk into the mercury by turning the wheel of the diffusio- 
 meter, whilst the ventile q is closed, the air contained in 
 the tube will escape through the porous plug b. If, on 
 the other hand, a continuous current of gas be passed 
 through the head C of the instrument whilst the tube is 
 raised above the mercury, it becomes filled with the gas 
 pressed through the diaphragm. As soon as the atmospheric 
 air has been completely displaced from all parts of the 
 apparatus by successively filling and exhausting, the tube, 
 which dips in mercury up to the exit tube qp, is rapidly 
 drawn up, without discontinuing the evolution of gas 
 through the head C. By this means, the column of mer- 
 cury in the tube is raised above that in the outer cylin- 
 der. In order that this column of mercury should always 
 
204 
 
 LAWS OF THE 
 
 remain at the same height during the entrance of the gas, 
 the float b b , Fig. 54 , resting on the outer level of mer- 
 cury is employed. This float is made of a circular piece 
 
 Fig. 54. 
 
 of cardboard which moves over 
 the glass tube with very little 
 friction and is furnished with 
 more substantial ends cc in order 
 that the circular form should be 
 retained. In this screen six small 
 windows are cut, three on each 
 side opposite to one another ; and 
 the lower edges of these sets of 
 three windows a a, ^a^ a 2 a 2 are 
 all at a known distance from the 
 lower end c of the paper cylinder. 
 As soon as the mercury me- 
 niscus in the inner tube has sunk 
 so far as to coincide with the 
 lower edge of one of the win- 
 dows, this level of mercury is 
 kept constant by turning the 
 wheel of the diffusiometer, and 
 then the length of time observed 
 which elapses until 5 divisions 
 
 on the tube (in which the level of mercury is kept con- 
 stant by turning the wheel) pass across the lower edge of 
 the little window. These observations can be read off to 
 the tenth of a millimetre by means of the telescope hli. 
 
 If the constant height of the column of mercury ex- 
 tending from the end of the cylinder to the lower edge 
 of the window be called p, the volume of the tube corre- 
 sponding to the 5 divisions (determined beforehand by 
 
DIFFUSION OF GASES. 
 
 205 
 
 calibration) F, the height of the barometer P, and the 
 time which elapses until 5 divisions are passed t< the vo- 
 lume V l of gas which passes through in the time 1, and 
 under the pressure 1, is found from the equation: 
 
 The following experiments made with oxygen, hydro- 
 gen, carbonic acid, and air show, that within certain li- 
 mits, the issued volumes of gas, reduced to equal pressure, 
 are proportional to the pressure under which they issue; 
 although it is to be remarked that the rate of issue varies 
 considerably from this law under large amounts of pres- 
 
 sure. 
 
 Oxygen into oxygen. 
 
 II. 
 
 III. 
 
 Temperature 
 
 12C. 
 
 12 C. 
 
 1'2 C. 
 
 Barometric pressure 
 
 O m 7452 
 
 O m 7452 
 
 O m 74T)2 
 
 Time of diffusion in seconds . . 
 
 259 
 
 198 
 
 102 
 
 Diffused gas at l m pressure . . 
 
 25.49 
 
 39.14 
 
 31.19 
 
 Velocity of diffusion V l .... 
 
 0.09841 
 
 0.1977 
 
 0.3058 
 
 Difference of pressure p . . . . 
 
 0"01G7 
 
 O m 0335 ' 
 
 0>0520 
 
 Value of . 
 
 5.893 
 
 5.901 
 
 5.881 
 
 P 
 
 
 
 
20G 
 
 LAWS OF THE 
 
 Hydrogen into hydrogen. 
 
 
 IV. 
 
 V. 
 
 VI. 
 
 Temperature 
 
 14C. 
 
 14C. 
 
 14C. 
 
 
 0^7452 
 
 O m 7452 
 
 O7452 
 
 Time of diffusion in seconds . . 
 
 82 
 
 53 
 
 37 
 
 Diffused gas at l m pressure . . 
 
 21.85 
 
 28.4G 
 
 31.19 
 
 Velocity of diffusion F x .... 
 
 0.26G5 
 
 0.53G9 
 
 0.8431 
 
 Difference of pressure p . . . . 
 
 O m 01G7 
 
 00338 
 
 O m 0520 
 
 Value of l 
 
 1 59 G 
 
 1.589 
 
 1.G21 
 
 P 
 
 
 
 
 Carbonic acid into carbonic acid. 
 
 
 VII. 
 
 VIII. 
 
 Temperature ... 
 
 05 C 
 
 05 C 
 
 Barometric pressure 
 
 O m 7477 
 
 O m 7477 
 
 Time of diffusion in seconds . .' .' 
 Diffused gas at l m pressure . . ** 
 Velocity of diffusion V " ' 
 
 129 
 21.93 
 1700 
 
 41 
 14.29 
 3485 
 
 Difference of pressure p . . . . . 
 Value of l . 
 
 001G7 
 1 018 
 
 00333 
 1 04G 
 
 P 
 
 
 
DIFFUSION OF GASES. 
 
 207 
 
 Air into air. 
 
 
 IX. 
 
 X. 
 
 
 07452 
 254 
 
 12C. 
 07452 
 115 
 
 Barometric pressure 
 Time of diffusion in seconds . . . 
 
 Diffused gas at l m pressure . .7,^ "\ 
 
 21.31 
 
 0.0839 
 O m 0350 
 
 2.397 
 
 20.20 
 0.175G 
 O m 072 
 
 2.439 
 
 Difference of pressure p 
 Value of * 
 
 P 
 
 In experiments I and IV, as in experiments III and 
 IV one and the same porous diaphragm of gypsum was 
 used 46 mm thick and dried at 60 C. 
 
 The rate of issue of oxygen is found for these expe- 
 riments to be to that of hydrogen in the proportion of 
 1 to 2.71, and of 1 to 2.76 or a mean of 1 to 2.73. The 
 velocity with which both gases effuse from fine openings 
 in thin plates is inversely proportional to the square roots 
 of their densities, and the relation instead of being 
 1:2.73, as in the foregoing example, should have been 
 as 1:3.995. Hence it is plain, that the pores of the 
 gypsum do not act towards gases passing through 
 them, as a system of fine openings in thin plates, 
 but as a system of capillary tubes, and that there- 
 fore an explanation of the phenomena of diffusion which 
 is based upon the laws of the rates of effusion of gases 
 from fine openings cannot be correct 
 
 Under these circumstances we thought it adviseable 
 
208 LAWS OF THE 
 
 to return to the experimental data of the original theory 
 of diffusion , and to determine in the first place the fol- 
 lowing questions by new experiments: 
 
 1) Does a specific attraction of the porous surface of 
 the diaphragms through which the gases pass exert 
 a disturbing effect upon the phenomena of diffusion? 
 
 2) Does the relation between the volumes of the ex- 
 changing gases remain constant during the whole 
 course of the experiment? 
 
 3) Do the volumes of two gases which have diffused 
 into each other, stand to each other, as is univer- 
 sally admitted, inversely as the square roots of their 
 densities ? 
 
 In order to decide the first question all we require is 
 to determine whether the pores of the gypsum act simply 
 as an empty space, or whether gases possess determinate 
 absorption - coefficients for gypsum as for liquids. We 
 have therefore, to determine the coefficients of absorption 
 of various gases for a solid body, for gypsum. The fol- 
 lowing was the method employed. 
 
 The diffusion - tube, Fig. 55, is furnished with a lid d 
 which can be hermetically closed by pressure against a 
 plate of caoutchouc ; below the lid, a cake of gypsum from 
 half an inch to an inch in thickness is cast, and a cur- 
 rent of gas is led into the tube immediately below the 
 cake of dried gypsum b (when the lid is closed), until 
 all atmospheric air is expelled from the porous dia- 
 phragm as well as from the diffusion tube. The volume 
 of gas contained between the gypsum and the mercury 
 was then measured under various pressures, which were 
 easily attained by raising the tube in the mercurial 
 trough. The volume V under the pressure P, and the 
 volume V l under the pressure P 1 are thus found. The 
 
DIFFUSION OF GASES. 
 
 209 
 
 volume F, which represents the gas in the tuhe and not 
 that contained in the diaphragm, would, according to 
 Mariotte's law, occupy under the pressure PI a volume 
 
 Fig. 55. 
 
 PV 
 
 equal to -= together with the vo- 
 lume of gas which has issued from 
 the gypsum owing to the diminu- 
 tion of pressure from P to P lf If 
 we call this latter volume 10, we 
 have : 
 
 1) ^+.= F,. 
 
 If now, a represent the absorp- 
 tion - coefficient of the gypsum dia- 
 phragm, i. e. the volume of gas, re- 
 duced to 0.76 pressure and C., 
 which is contained in the unit vo- 
 lume of the gypsum (measured in 
 the volumes of the diffusion tube); 
 and if v represent the volume of the 
 diaphragm, the quantity of gas ab- 
 sorbed by the diaphragm under a 
 
 . Pav 
 
 pressure P is when reduced to 
 
 0.76, and under a pressure PI * 
 
 0.7 b 
 Pav 
 
 also reduced to 0.76. TT^TT therefore represents 
 
 0.7 b <7t^ 
 
 P } av 
 0.76 
 
 ,the volume of gas, reduced to 0.76, which has issued from 
 the porous diaphragm upon the diminution of pressure 
 from P to PI. Under the pressure P l this volume of gas 
 becomes : 
 
 av -r- 1 ) 
 
210 LAWS OF THE 
 
 This value substituted for w in equation 1 gives us : 
 V l P l VP 
 
 p - 
 
 &.V. 
 
 The following experiments show that the value of 
 a v does not materially alter for " various gases. An ex- 
 periment with hydrogen gave : 
 
 V 
 
 p 
 
 V 
 
 20.G 
 
 0.7287 
 
 
 27.7 
 
 O.G344 
 
 27.2 
 
 30.9 
 
 0.5981 
 
 2G.8 
 
 32.7 
 
 0.5802 
 
 2G.7 
 
 37.7 
 
 0.5375 
 
 27.5 
 
 Mean value oi ttv 27.1. 
 
 The first column V contains the volumes of gas, cor- 
 rected according to the table of volumes, and read off 
 on the closed diffusion tube; the second P gives the cor- 
 responding pressures observed ; and the third the cal- 
 culated values of av. In these and the following ex- 
 periments no change of temperature occured. 
 
 A similar experiment repeated with moist atmospheric 
 air, after the same diaphragm had been exposed for 
 some hours to the air, gave the following results: 
 
 V 
 
 P 
 
 V 
 
 33.2 
 
 0.7290 
 
 
 40. "> 
 
 O.G525 
 
 27.75 
 
 47.0 
 
 0.5947 
 
 27.90 
 
 Mean value of ctv 27.82. 
 
DIFFUSION OF GASES. 
 
 211 
 
 Two other experiments with air and carbonic acid 
 made with another diaphragm of gypsum at different 
 temperatures gave: 
 
 Air. 
 
 V 
 
 *C. 
 
 P 
 
 V at C. 
 
 ctv 
 
 1 I 
 
 
 
 150.9 
 
 3.0 
 
 0.7537 
 
 149.3 
 
 
 204.6 
 
 6.8 
 
 0.5750 
 
 200.4 
 
 15.12 
 
 Carbonic acid. 
 
 V 
 
 <c. 
 
 j) 
 
 Fat 0C. 
 
 cev 
 
 141.2 86 
 
 0.7527 13G.9 
 
 
 192.4 
 
 9.3 
 
 0.5689 
 
 186.1 
 
 1523 
 
 From the constant valuej of a v we may therefore 
 conclude, that no actual attraction takes place between 
 the porous surface of the gypsum and the gases contained 
 in the pores, but that these pores act towards the in- 
 closed gases as a simple vacuous space. Hence phenomena 
 of absorption, as exhibited in the action of gases and liquids, 
 cannot occur when gases diffuse through a diaphragm of 
 gypsum. 
 
 Up to the present time the relation between the volume 
 of gas which has entered, and that which has issued 
 from the diffusion tube, has been determined only by as- 
 certaining the volume of the gas before the experiment, 
 and after the exchange was completed. Independently, 
 however, of the fact that the volume of the escaping gas 
 strictly speaking never can reach 0, but only indefinitely 
 
 14* 
 
212 LAWS OF THE 
 
 approaches this limit, a practical difficulty occurs which 
 renders it impossible to recognise the point at which the 
 quantity of the issuing gas even approaches the zero. 
 This difficulty becomes evident when we consider, that 
 the only method by which we can determine whether the 
 diffusion is complete or not, is by observing whether or 
 not the inner level of mercury in the diffusion tube rises to 
 a notable height above the outer level in the cylinder. As 
 soon, however, as the gas in the diffusion tube has been 
 diluted to a certain extent by another gas entering the 
 tube, the rate of issue of the first gas will be so re- 
 tarded, that even an imperceptible column of mercury is 
 sufficient to cause as much gas to enter the tube as dif- 
 fuses out from the interior. No elevation is then ob- 
 served of the mercury in the diffusion tube , although an 
 analysis of the gaseous contents of the tube would give 
 evidence of the presence of a considerable residue of the 
 original gas, proving that the diffusion is by no means 
 completed. Even by employing more accurate means of 
 measurement, so that O.l mm column of mercury or water 
 could be accurately observed, it is impossible to obtain 
 satisfactory accordance in the numerical values for dif- 
 ferent observations. This is clearly shown in the fol- 
 lowing experiments, in which a continually renewed cur- 
 rent of oxygen, was allowed to diffuse into a finite volume 
 of hydrogen contained in the diffusion tube. The ex- 
 periment was conducted with the apparatus represented 
 in Fig. 52. 
 
 EXPERIMENT 1. The original volume of hydrogen 
 amounted to 230.7. The wheel of the diffusiometer was 
 so turned during the experiment, that the inner level of 
 mercury was never elevated above the outer level by the 
 
DIFFUSION OF GASES. 213 
 
 perceptible difference of O.l mm . At the beginning of the 
 experiment the diffusion proceeded at the rate of a di- 
 minution of 5 volumes in 10 seconds. After the expiration 
 of 524 seconds, when the volume of hydrogen in the tube 
 was reduced to 68.3, this same diminution of volume re- 
 quired 112 seconds. Now it required nearly this time 
 (112 seconds) to press 5 volumes of air through the 
 diaphragm under the pressure of O.l mm of mercury. 
 Beyond the volume 68.3, therefore, no further observation 
 was possible. In this way, the diffusion, when followed 
 to its furthest observable limit by help of the most ac- 
 curate measurements, gave a relation between the hy- 
 drogen which had issued, and the oxygen which had 
 
 O1 Q J 
 
 entered, represented by the number PQ ' = 3.127. Ac- 
 
 oo.o 
 
 cording to the previous supposition, namely that this 
 relation is that of the inverse square - roots of the den- 
 sities it should have been 
 
 = 3.995. 
 
 V 0.06926 
 
 EXPERIMENT 2. In order to diminish the original 
 volume of hydrogen 183.5 by 5 volumes, 8 seconds were 
 required. After the volume had become 63.2, and no 
 longer admitted of exact observation a diminution of 
 5.1 volumes required 101 seconds. Under the supposition 
 that the exchange of gases was completed (as further 
 observation was impossible), the number obtained is 2.903 
 instead of 3.995, as required by the former theory. 
 
 In both these experiments, on account of the opacity 
 of the mercury, the inner meniscus in the tube was ob- 
 served about 0.1 mm above the level of the mercury in the 
 outer cylinder, so that the density of the gas contained 
 
214 LAWS OF THE : 
 
 in the tube was very slightly less than that of the sur- 
 rounding atmosphere. This small difference of pressure 
 acted therefore in such a way that the amount of gas 
 remaining in the tube after the diffusion was a little too 
 large. The experiment was therefore repeated, with the 
 difference that a small piece of cardboard was placed 
 on the surface of the mercury within the tube, and 
 this float kept at a level with the outer surface of mer- 
 cury by reading off with the telescope. By this means 
 the internal pressure was necessarily somewhat greater 
 than the external one throughout the experiment. Even 
 under these more favorable circumstances, the relation 
 between the exchanged gases was always found to be 
 below the number 3.995 required by theory. 
 
 EXPERIMENT 3. An attempt was next made to 
 decrease the sources of error necessarily present in the 
 former experiments to the minimum amount, by making 
 use of water as a liquid specifically lighter than mercury, 
 and by increasing the dimensions of the diffusion tube 
 and porous diaphragm. The diffusion tube employed was 
 about 2 feet long, and 1 inch in diameter. It was filled 
 with hydrogen which diffused freely into the atmosphere. 
 The observations of the heights were made with the te- 
 lescope, so that the difference between the meniscus of 
 the water (which was not boiled -out) inside and outside 
 the tube was always kept below one millimetre. The 
 instrument, filled with air, was then placed so that a 
 difference of pressure of 15 mm was kept constant, and the 
 time was observed during which 5 volumes of air had 
 entered. This was found to amount to 12.5 minutes. A 
 difference of pressure of l mm of water would therefore 
 produce an error, from air forced in, of 1 volume in 
 37.5 minutes. 
 
DIFFUSION OF GASES. 215 
 
 In an experiment of this kind, conducted with every 
 precaution, in which hydrogen diffused into air, the 
 original volume of hydrogen at O'O" was 645. After 21 
 seconds it was 635, after the next 21 seconds 625, after 
 the next 26 seconds 615, after 32' 7", and the following 
 times the volumes were: 
 
 Time. 
 
 Volume. 
 
 32' 7" 
 
 225 
 
 33' 27" 
 
 220 
 
 35' 10" 
 
 215 
 
 37' 8" 
 
 210 
 
 39' 53" 
 
 205 
 
 43' 41" 
 
 200 
 
 49'52" 
 
 195 
 
 62' 25" 
 
 193 
 
 74' 44" 
 
 193 
 
 114' 10" 
 
 194 
 
 151' 0" 
 
 195 
 
 The last four observations were made whilst the 
 internal meniscus was l mm higher than the external one. 
 From this experiment it is clearly seen that the diffusion 
 had become inappreciable after the observation at 62' 25", 
 for the two last observations show an increase of volume 
 of 1 for a difference of pressure of l mm in from 39 to 
 37 minutes, which according to the former experiment 
 must occur if the difference of pressure were the sole 
 cause of the alteration of level. If, therefore, we suppose 
 that the diffusion has become infinitely small at a volume 
 of 193, we obtain a relation for the exchanged volumes 
 
 of - J- = 3.34, which still differs considerably from the 
 
 i Jo 
 
 theoretical number = 3.80. 
 
21G 
 
 LAWS OF THE 
 
 From these experiments we are forced to conclude 
 that the diffusive interchange does not occur in the re- 
 lation of the inverse square -roots of the specific gravities. 
 
 We may, therefore, now inquire, what is the true 
 relation between the volumes of gases interchanged during 
 the diffusion, and how far this relation remains constant 
 during the course of the phenomenon. These questions 
 can be answered when the composition of the gas con- 
 tained in the diffusion tube is determined at successive 
 periods of the diffusion. For this purpose, the following 
 experiment was made with hydrogen, and a current of 
 oxygen passing rapidly over the gypsum diaphragm. 
 
 Number 
 of the 
 observations. 
 
 Volume of 
 gas in the 
 . diffusion 
 tube. 
 
 Time 
 in 
 minutes. 
 
 1 
 
 385.2 
 
 9 
 
 2 
 
 381.2 
 
 ? 
 
 3 
 
 376.2 
 
 9 
 
 4 
 
 371.2 
 
 y 
 
 5 
 
 3GG.2 
 
 12.98 
 
 6 
 
 3G1.2 
 
 16.38 
 
 7 
 
 356.2 
 
 19.96 
 
 8 
 
 351.2 
 
 23.55 
 
 9 
 
 346.2 
 
 27.25 
 
 10 
 
 341.2 
 
 30.95 
 
 11 
 
 336.2 
 
 34.71 
 
 12 
 
 331.3 
 
 38.70 
 
 13 
 
 326.3 
 
 42.16 
 
 14 
 
 321.4 
 
 46.16 
 
 15 
 
 316.5 
 
 50.25 
 
 Gas collected. 
 
DIFFUSION OF GASES. 
 
 217 
 
 Number 
 of the 
 observations. 
 
 Volume of 
 gas in the 
 diffusion 
 tube. 
 
 Time 
 
 in 
 minutes. 
 
 16 
 
 192.3 
 
 o-.o 
 
 17 
 
 184.2 
 
 7.40 
 
 18 
 
 179.4 
 
 11.72 
 
 19 
 
 174.6 
 
 16.05 
 
 20 
 
 169.8 
 
 20.53 
 
 21 
 
 164.9 
 
 25.25 
 
 22 
 
 160.1 
 
 30.18 
 
 23 
 
 155.3 
 
 35.22 
 
 24 
 
 150.6 
 
 40.48 
 
 25 
 
 145.8 
 
 46.20 
 
 Gas collected. 
 
 Immediately after the 15th observation, the dif- 
 fusion tube was closed by the stopper, and a sample 
 of gas collected, which gave the following analytical 
 results. 
 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 C. 
 
 Vol. at 
 0C. and 
 l m press. 
 
 Original cas 
 
 187.9 
 
 0.4180 
 
 2.2 
 
 79 18 
 
 After the explosion 
 
 149.3 
 
 0.3806 
 
 22 
 
 57 28 
 
 
 
 
 
 
 Hydrogen 
 Oxygen . 
 
 The whole 316.5 volumes of gas at the fifteenth ob- 
 servation contains, therefore, 29.18 oxygen and 287.32 
 
218 
 
 LAWS OF THE 
 
 hydrogen. The original volume before the diffusion con- 
 sisting solely of hydrogen amounted to 385.2. For 29.18 
 volumes of oxygen which had entered 385.2 287.32 
 = 97.88 volumes of hydrogen had issued. The relation 
 between the volumes at the fifteenth observation was 
 
 P7 oo 
 
 therefore ' = 3.354, a result widely differing from 
 
 the value 3.995 required by the theory which has been 
 hitherto considered correct, but agreeing very closely 
 with the results which were found in the experiment 
 made with water. 
 
 In order to ascertain whether the relation of the 
 interchanging gases remains constant during a continued 
 diffusion, the volume of residual gas in the diffusion tube 
 was again accurately measured, the diffusion continued, 
 and another sample of gas collected after the twenty-fifth 
 observation. The analysis gave : 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 Original gas ... ... 
 
 129.5 
 
 0.3615 
 
 -M 
 
 47.06 
 
 .Ai'tcr the explosion 
 
 38 5 
 
 273G 
 
 1 6 
 
 10 GO 
 
 
 
 
 
 
 II. 
 
 Hydrogen 
 Oxygen . 
 
 34.91 
 12.15 
 
 47.06 
 
 The volume of gas read off at the 16th observation 
 amounted to 192.3 volumes, and consisted, according to 
 analysis I, of 174.57 hydrogen and 17.73 oxygen. The 
 observation twenty -five made 46.2 minutes later gave a 
 volume equal to 145.8. According to analysis II this 
 
DIFFUSION OF GASES. 219 
 
 volume contains 108.16 hydrogen and 37.64 oxygen. The 
 amount of hydrogen which had diffused out during these 
 46.2 minutes was therefore 174.57 108.16 = 66.41 vol- 
 umes ; and the amount of oxygen which had entered the 
 tube was 37.64 17.73 = 19.91. The relation between 
 the two interchanging volumes during this time was 
 
 / J * -j 
 
 ' = 3.336, a value agreeing very nearly with that 
 
 ly.t) i 
 
 found for the first period of the diffusion. From these 
 experiments we may conclude, that the volume of oxygen 
 which enters the tube, is to the volume of hydrogen which 
 issues from the tube, as 1 to 3.345, and that this proportion 
 remains constant during the whole course of the diffusion. 
 
 Having thus proved that within certain limits the 
 rate at which any gas traverses a porous diaphragm is 
 proportional, 
 
 1st to the difference of pressure to which the gas is 
 exposed above, and below the diaphragm, and 
 
 2ndly to a coefficient of friction which is dependent 
 upon the nature of the gas, and of the diaphragm, 
 we will now proceed to show that the phenomena of ga- 
 seous diffusion really depend upon the fact that these two 
 conditions are also applicable to the partial pressures of 
 mixed gases, restricted however within certain limits. In 
 order to prove this fact, the alteration of volume was 
 observed which a known amount of dry hydrogen under- 
 went (whilst the pressure was retained constant), when 
 a current of dry oxygen was passed over the diaphragm ; 
 and during this alteration the time \\as noted. Let us 
 suppose that the volume of hydrogen originally contained 
 in the diffusion tube was H Q under the pressure 1 ; and 
 that on the outside of the diaphragm an infinitely large, 
 or continually renewed atmosphere of oxygen was present, 
 
220 LAWS OF THE 
 
 also under the pressure 1 ; and let us suppose that after 
 the lapse of the time t a volume of oxygen had entered 
 the tube, whilst the original volume of hydrogen had 
 diminished to H, so that HQ // under the pressure 1 
 represents the volume of hydrogen which had escaped, 
 whilst H -}- is the volume occupied by both gases. 
 Now as the volume of oxygen expands to the volume 
 H -\- 0, the pressure of the oxygen in the diffusion tube 
 
 amounts to . ( , and hence the difference of pres- 
 sure of the oxygen inside and outside the diaphragm is 
 represented by the equation 
 
 ! H 
 
 - H + Q H+ 0' 
 
 and the amount of oxygen entering in the infinitely small 
 space of time dt is found from the expression: 
 
 (1) dO = H 
 
 in which t denotes the coefficient of friction in the 
 gypsum diaphragm, to be determined for hydrogen. On the 
 other hand, however, the volume 11 of hydrogen present, 
 
 has expanded into the volume H -\- 0, hence . . 
 
 represents the pressure which we must consider to be 
 the motive power in respect to the rate of issue of the 
 hydrogen. And as the diffusion apparatus was so ar- 
 ranged that the moment any hydrogen had diffused out 
 it was immediately carried away by the current of oxygen, 
 so that no other partial pressure was opposed to that of 
 
 the hydrogen within the tube, namely - . /o we find 
 that the volume of hydrogen which escapes in the time 
 
DIFFUSION OF GASES. 221 
 
 dt is represented by the equation (bearing in mind that 
 the volume // decreases with increase of f) 
 
 H 
 
 in which 02 is again a coefficient dependent upon the 
 nature of the gas and diaphragm. 
 
 The first conclusion which is arrived at on comparing 
 these two equations (1) and (2), concerns the constant 
 relation which exists during the whole length of the dif- 
 fusion between the amount of oxygen dO entering at 
 every moment, and the amount of hydrogen dH issuing 
 at the same time, a relation which is represented by 
 
 a i 
 
 = y. 
 
 a, 
 
 In order to bring this explanation of the fundamental 
 principles of the phenomena of gaseous diffusion to the 
 test of experiment, we must endeavour to determine the 
 volumes of gas diffused after any finite time , together 
 with the observed volume in the diffusion tube H-\- 0= V 
 as function of the time. From equations (1) and (2) we 
 obtain 
 
 and hence by integration 
 
 -)- = consianl. 
 
 Now as the volume of hydrogen originally contained in 
 the diffusion tube was = H Q , and at the commencement 
 of the diffusion = 0, the unknown constant of the 
 
 former equation is found to be -, and we have 
 
 O 
 
222 IAWS OF THE 
 
 By substituting the value = y (PI Q PI) in equation 
 (2) we obtain: 
 
 dPI = - 
 
 a 2 Pl 
 
 and therefore 
 
 -a 2 dt = (l -- 
 
 and the integral of this, because when t = we have 
 also // = HQ , is 
 
 <M == (1 -r) (#0 -H) + yff<, log. e. . 
 
 As J/ = = - - we obtain by substituting this 
 value for PI: 
 
 (3) , = // - F+ y H, log. e. 
 
 If F, Fj , . . . , F n .denote the volumes in the diffusion 
 tube observed in the times t. ? 1? . . .. < B , we have: 
 
 (4) a, (, - = F- F, + y H log. e. 
 
 This equation No. 4 is best suited for the direct 
 experimental verification of the foregoing theory of dif- 
 fusion. The values of a 2 are calculated from the ob- 
 servational quantities, that is, for each reading of F, 
 Fj, . . ., F n , and the corresponding time tf, ^, . . ., t n \ 
 the mean of these values of a^ is then substituted in the 
 equation, and thus the alteration of volume V n F n _|_i 
 in the spaces of time t n t nJrl calculated. If these cal- 
 culated values do not differ from the experimental results 
 by a larger quantity than that incurred in the unavoidable 
 errors of observation, we may presume that the equation 
 was correct, and hence that the theory upon which the 
 equation is founded is also true. 
 
DIFFUSION OF GASES. 223 
 
 In order to conduct the observations under the 
 most favorable circumstances, hydrogen and oxygen 
 were used in the experiments as being the two gases 
 whose rates of diffusion are the most different. The 
 amount of gas contained in the gypsum diaphragm was 
 added to the quantity of dry hydrogen contained in the 
 tube , and care was taken that the oxygen which passed 
 over the diaphragm should be completely dried. The value 
 0.2989 given for y was that obtained in the foregoing 
 experiments by direct analysis , as the mean of the two 
 
 determinations ^ and found on pages 218 
 
 and 219. 
 
 The first observations are excluded from the cal- 
 culation because they are accompanied by errors of ob- 
 servation which can neither be eliminated nor allowed 
 for. The gypsum diaphragm at the beginning of the 
 experiment is completely filled with hydrogen; hence 
 diffusion begins on the surface of the diaphragm exposed 
 to the current of oxygen. This must necessarily cause 
 the phenomena of diffusion to be limited to the internal 
 mass of the gypsum, and hence the oxygen will only 
 gradually penetrate the porous substance, and after lapse 
 of a certain time reach the surface in contact with the 
 hydrogen. During the time in which the diffusion is 
 confined to the porous gypsum no alteration of volume 
 occurs in the diffusion tube, and thus the remarkable 
 fact is explained that on opening the tube a few moments 
 elapse before any diminution in the volume of the gas is 
 observed. From this cause, the observations for about 
 the first 48 seconds are inaccurate, but after lapse of this 
 time the gases have penetrated throughout the diaphragm 
 and the rise of the liquid in the tube proceeds regularly. 
 
224 LAWS OF THE 
 
 For another reason we must also reject the last ob- 
 servations as incorrect. If the partial pressure of the 
 hydrogen diminishes so much towards the end of the 
 experiment, that the small differences of pressure within 
 and without the tube necessary for the observation, begin 
 to have a finite relation to this partial pressure, the ob- 
 servations, as we have shown, become untrustworthy. 
 Besides this, another error renders the latter observations 
 inaccurate, for, during the whole course of the observations 
 a small quantity of oxygen has entered the tube in con- 
 sequence of the slight difference of internal and external 
 pressure, and this quantity of oxygen pressed in is con- 
 tinually increasing, and causes the diffusion at the end of 
 the experiment to be retarded very much more than 
 would have been the case without this cause of error. 
 
 This uncertainty concerning the exactitude of the 
 later observations may be partly explained by the sup- 
 position that the simple relation between the partial 
 pressures and the rates of diffusion only strictly exists 
 within certain limits. 
 
 The following tables give the results of such a series 
 of observations made with the diffusiometer. The first 
 column contains the numbers of the observations; the 
 second the volume of gas read off, corrected according 
 to the table of capacity of the tube , and the capacity of 
 the porous diaphragm ; the third contains the time in 
 seconds at which the observations were made; the fourth 
 the values of a. 2 calculated from each single observation ; 
 the fifth the times which elapsed between each obser- 
 vation, and the last contains the same times calculated 
 from the mean value of a. 
 
DIFFUSION OF GASES. 
 
 225 
 
 IT 
 
 III 
 
 IV 
 
 VI I VII 
 
 
 
 No. 
 of the 
 obser- 
 vation. 
 
 Observed 
 volume 
 V. 
 
 Cor- 
 responding 
 time in 
 seconds t. 
 
 f 
 
 Observed 
 tn M-l. 
 
 Calculated 
 t n t n +l 
 , = 0.4969 
 
 Diffe- 
 rence. 
 
 1 
 
 133.5 0.0 
 
 
 
 
 
 2 
 
 178.5 8.0 
 
 
 
 
 
 3 
 
 173.6 20.5 
 
 
 
 
 
 4 
 
 168.5 :U.o 
 
 
 
 
 
 5 
 
 163.5 
 
 48.0 
 
 
 
 
 
 G 
 
 158.0 
 
 62.0 
 
 0.5140 
 
 15.0 
 
 15.5 
 
 -4-0.5 
 
 7 
 
 153.6 
 
 77.0 
 
 o..".340 
 
 15.0 
 
 16.1 
 
 + 1.1 
 
 8 
 
 148.5 
 
 92.0 
 
 0.4994 
 
 16.0 
 
 16.1 
 
 + 0.1 
 
 9 
 
 143.5 
 
 108.0 
 
 0.5038 
 
 16.0 
 
 16.2 
 
 + 0.2 
 
 i(r 
 
 138.5 
 
 124.0 
 
 0.5230 
 
 16.0 
 
 16.9 
 
 + 0.9 
 
 11 
 
 133.5 
 
 140.0 
 
 0.4878 
 
 18.0 
 
 17.7 
 
 0.3 
 
 12 
 
 128.4 
 
 158.0 
 
 0.4922 
 
 18.0 
 
 17.8 
 
 0.2 
 
 13 
 
 123.4 
 
 17G.O 
 
 0.5500 
 
 17.0 
 
 18.8 
 
 + 1.8 
 
 14 
 
 118.3 
 
 193.0 
 
 0.4529 
 
 21.0 
 
 19.1 
 
 1.9 
 
 15 
 
 1133 
 
 214. (I 
 
 0.4725 
 
 20.0 
 
 19.0 
 
 - 1.0 
 
 1C 
 
 108.4 
 
 234.0 
 
 0.4818 
 
 22.0 
 
 21.3 
 
 0.7 
 
 17 
 
 103.3 
 
 256.0 
 
 0.4778 
 
 23.0 
 
 22.1 
 
 0.9 
 
 18 
 19 
 20 
 
 98.3 
 93.3 
 88.4 
 
 279.0 
 302.0 
 328.0 
 
 0.5095 
 0.4765 
 0.4779 
 
 23.0 
 26.0 
 29.0 
 
 23.6 
 24.9 
 27.9 
 
 + 0.6 
 - 1.1 
 1.1 
 
 21 
 22 
 
 83.4 
 
 78.4 
 
 357.0 
 391.0 
 
 
 
 
 23 
 24 
 
 73.4 
 68.3 
 
 428.0 
 474.0 
 
 
 
 
 
 25 
 
 63.2 
 
 553.0 
 
 
 
 2G 
 
 58.2 
 
 636.0 
 
 
 
 
 
 
 
 
 I 
 
 
22G 
 
 LAWS OF THE 
 
 I 
 
 II 
 
 III 
 
 IV 
 
 V 
 
 VI 
 
 VII 
 
 No. 
 of the 
 obser- 
 vation. 
 
 Observed 
 volume 
 V. 
 
 Cor- 
 responding 
 time in 
 seconds t. 
 
 a, 
 
 Observed 
 t n tn+l. 
 
 Calculated 
 tn t n +l 
 ^=0.6310 
 
 Diffe- 
 rence. 
 
 1 
 
 213.6 
 
 
 
 
 
 
 
 2 
 
 208.6 
 
 10 
 
 
 
 
 
 8 
 
 203.6 
 
 20 
 
 
 
 
 
 4 
 
 198.6 
 
 31 
 
 
 
 
 
 5 
 
 193.6 
 
 41 
 
 
 
 
 
 
 
 188.6 
 
 52 
 
 0.6347 
 
 12 
 
 12.1 
 
 -f-0.1 
 
 7 
 
 183.6 
 
 64 
 
 0.7165 
 
 11 
 
 12.5 
 
 + 1.5 
 
 8 
 
 178.5 
 
 75 
 
 0.6421 
 
 12 
 
 12.2 
 
 -f 0.2 
 
 9 
 
 173.5 
 
 87 
 
 0.6653 
 
 12 
 
 12.7 
 
 + 0.7 
 
 10 
 
 168.5 
 
 99 
 
 0.6775 
 
 12 
 
 12.9 
 
 -f 0.9 
 
 11 
 
 163.5 
 
 111 
 
 0.6310 
 
 13 
 
 13.0 
 
 0.0 
 
 ' 12 
 
 158.6 
 
 124 
 
 0.6047 
 
 14 
 
 13.4 
 
 0.6 
 
 13 
 
 153.6 
 
 138 
 
 0.6800 
 
 13 
 
 14.0 
 
 -f 1.0 
 
 14 
 
 148.5 
 
 151 
 
 0.6353 
 
 14 
 
 14.1 
 
 + 0.1 
 
 15 
 
 143.5 
 
 165 
 
 0.6532 
 
 14 
 
 14.5 
 
 + 0.5 
 
 1C 
 
 138.5 
 
 179 
 
 0.6016 
 
 16 
 
 15.3 
 
 0.7 
 
 17 
 
 133.4 
 
 195 
 
 0.6514 
 
 15 
 
 15.5 
 
 + 0.5 
 
 18 
 
 128.4 
 
 210 
 
 0.6346 
 
 17 
 
 16.1 
 
 0.9 
 
 19 
 
 123.4 
 
 227 
 
 0.6368 
 
 17 
 
 17.2 
 
 + 0.2 
 
 20 
 
 118,3 
 
 244 
 
 0.6198 
 
 18 
 
 17.7 
 
 0.3 
 
 21 
 
 113.8 
 
 262 
 
 0.5440 
 
 21 
 
 18.1 
 
 2.9 
 
 22 
 
 108.4 
 
 283 
 
 0.6131 
 
 21 
 
 20.4 
 
 0.0 
 
 23 
 
 103.3 
 
 304 
 
 0.5693 
 
 24 
 
 21.7 
 
 2.3 
 
 24 
 
 '98.3 
 
 328 
 
 0.5793 
 
 26 
 
 23.9 
 
 -2.1 
 
 25 
 
 93.3 
 
 354 
 
 0.6345 
 
 
 
 
 2G 
 
 88.4 
 
 384 
 
 
 
 
 
 27 
 
 83.4 
 
 420 
 
 
 
 
 
 28 
 
 78.4 
 
 463 
 
 
 
 
 
 29 
 
 73.3 
 
 524 
 
 
 
 
 
 30 
 
 68.3 
 
 636 
 
 
 
 
 
DIFFUSION OF GASES. 227 
 
 From these tables it is seen that the accordance 
 between the experimental and theoretical values is as 
 close as can be expected considering the possible ob- 
 servational errors. The agreement would have been still 
 more complete if the diffusion had not taken place so 
 quickly. For the theory assumes, that the gas entering 
 the diffusion tube, expands into the whole space of the 
 tube with a rapidity compared with which the rate of 
 passage of the gas through the diaphragm can be re- 
 garded as inappreciable. This strictly speaking is never 
 the case. 
 
 The condition required by the theory can be most 
 nearly complied with, by diminishing the rate at which 
 the gases traverse the diaphragm, and not allowing the 
 dimensions of the diffusion tube to be too large. This 
 retardation was effected in the following experiments 
 (from which the value of y employed in the former cal- 
 culations was obtained), by using a diaphragm of dense 
 gypsum of considerable length and small section. 
 
 The first part of this series of experiments was cal- 
 culated according to formula 3. A sample of gas was 
 taken between the first and second parts, from the 
 analysis of which on page 217 we see that the original 
 volume 192.3 with which the 16th observation is made 
 consists of 174.5 hydrogen to 17.8 oxygen. The formula 
 for the calculation of the second part of the analysis is 
 derived from the following considerations. If we suppose 
 that represents the amount of oxygen present in the 
 gas at the 16th observation, and H the amount of hy- 
 drogen present at the same time, and if thfc volumes of 
 these two gases present in a volume V observed at a 
 later time, be called and //, we have in the first 
 place : 
 
 15* 
 
228 LAWS OF THE 
 
 H*-H ^. 
 
 O 0o ' " </i " 
 
 Further by substitution in former equation No. 2 the 
 value = + y (#0 JT ) we obtain : 
 
 = 
 
 and 
 
 (0 + ? #o) ~- 
 
 and tbe integral of tbis is: 
 
 (/ , f = (i _ y ) (J/ - - //) -f (0 
 
 If we substitute tbe value of 
 ; F _ - 
 
 - 
 
 in tbis last equation, we have: 
 (5) a, /= 
 
 according to which formula the hitter observations from 
 16 to 2.5 are calculated. 
 
DIFFUSION OF GASKs. 
 
 229 
 
 I 
 
 II JII IV 
 
 
 
 VI 
 
 ! 
 
 No. of 
 
 Observed 
 
 
 Calculated 
 
 
 
 Observed 
 
 
 
 time in 
 
 
 the ob- , 
 
 volume. 
 
 time in a, 
 
 minutes *<*- 
 
 servation. 
 
 
 minutes. , = 020702 
 
 1 
 
 385.2 
 
 o 
 
 
 
 
 2 
 
 v 
 
 y 
 
 
 
 
 3 
 
 -.' 
 
 
 
 
 
 
 4 
 
 ? 
 
 y 
 
 
 
 
 5 
 
 366.2 
 
 13.0 
 
 0.2109 
 
 13.2 
 
 -|- 0.2 
 
 
 
 
 
 
 
 6 
 
 361.2 
 
 16.4 0.2118 
 
 16.7 
 
 -f- 0.3 
 
 7 
 
 356.2 
 
 20.0 
 
 0.2105 
 
 20.3 
 
 -{- 0.3 
 
 8 
 
 351.2 
 
 23.6 
 
 0.2098 
 
 23.9 
 
 4- 0.3 
 
 
 
 346.2 
 
 27.:: 
 
 0.2033 
 
 26.7 
 
 0.6 
 
 10 
 
 341.2 
 
 31." 
 
 02081 
 
 31.1 
 
 -f- 0.1 
 
 11 
 
 336.2 
 
 34.7 
 
 0.2078 
 
 ;54.7 
 
 0.0 
 
 12 
 
 99113 
 
 38.7 
 
 0.2056 
 
 :j8.3 0.4 
 
 
 
 
 
 13 
 
 326.3 
 
 42.2 . 0.2068 
 
 42.0 - 0.2 
 
 14 
 
 321.4 
 
 46.2 0.2054 
 
 45.7 _ o.:, 
 
 M 
 
 816.5 
 
 5fc3 .2"3!> 
 
 49.4 0.9 
 
 Interrupted in order to collect a sample of jius. 
 
 16 
 
 192.3 
 
 
 2 = 1.76<;9 
 
 
 17 
 
 184.2 
 
 7.4 1.7434 
 
 7.3 
 
 - 0.1 
 
 18 
 
 179.4 
 
 11.7 1.7699 
 
 11.7 
 
 0.0 
 
 19 
 
 174.6 
 
 16.1 1.7796 
 
 16.2 
 
 + 0.1 
 
 20 
 
 169.8 
 
 20,5 1.7923 20 7 + 0.2 
 
 21 
 
 164.9 
 
 25.3 1.7855 25.6 
 
 + 0.3 
 
 22 
 
 160.1 
 
 30.1 1.7808 j 30.3 
 
 + 0.2 
 
 23 
 
 155.3 
 
 35.2 1.7682 
 
 35.2 
 
 0.0 
 
 24 
 
 150.6 
 
 40.5 1.7509 
 
 40.1 
 
 0.4 
 
 25 
 
 145.8 
 
 46. 2 
 
 1.7317 
 
 45.3 
 
 0.9 
 
230 APPLICATION OF GASEOUS DIFFUSION. 
 
 In the former experiments the time which elapsed 
 until the original volume of gas had diminished 17.8 per 
 cent amounted to 1.4 minutes, in these experiments 36.2 
 minutes were required. 
 
 Oil comparing the results of this series of slower 
 diffusions with the more rapid diffusions in the preceed- 
 ing experiments a much closer approximation to the 
 theoretical numbers is perceived. 
 
 We must, however, not forget that a smaller value of 
 2 is found from the second part of the last series of ob- 
 servations than was obtained from the first part. This 
 shows that the diffusion -velocity is only approximately 
 proportional to the partial pressures, and that deviations 
 from this simple relation occur for partial pressures, just 
 as we have seen that the passage of gases through ca- 
 pillary tubes is only proportional to the total pressures 
 within certain definite limits. 
 
 We can now pass from these theoretical consider- 
 ations to the important application which can be made 
 of gaseous diffusion in many questions occurring in gaso- 
 metric investigations. 
 
 One of the most difficult questions which we are 
 called upon to decide, is, whether a given gas consists of 
 a single gas or of a mixture of several gases. If the pro- 
 ducts of combustion stand in no simple volumetric rela- 
 tion to one another there can be no doubt that we are 
 experimenting upon a mixture of gases, but the inverse 
 of this is by no means true , and we cannot always con- 
 clude from the simple relation existing between the vol- 
 umes of the products of combustion that a simple gas is 
 present, for we are acquainted with many chemical de- 
 compositions in which two or more gases are evolved in 
 their simple atomic proportions. 
 
IN GASOMETRIC INVESTIGATIONS. 
 
 231 
 
 
 This difficulty is chiefly felt with mixtures of hydro- 
 gen and hydrocarbons, or generally with these numerous 
 mixtures of gases whose constituents cannot he separated 
 by absorbants or detected by any reagent. 
 
 In such cases two methods are available. The first 
 consists in submitting the gas to an absorptiometric ana- 
 lysis, and determining the volume of gas absorbed by a 
 volume of liquid, under various pressures and at a con- 
 stant temperature. If this amount of absorbed gas is 
 found to be proportional to the pressures, it must, accord- 
 
 Fig. 56. 
 
 ing to the laws of absorption, con- 
 sist of one gas and not of a mix- 
 ture of several. 
 
 In the second method, which is 
 equally as applicable as the first, 
 "^^ the gas is allowed to diffuse with 
 I' MiH atmospheric air, and on subsequent 
 
 analysis it is seen whether or not 
 any alteration in the relation be- 
 tween the products of combustion 
 has ensued. If ho alteration in this 
 relation is observed, we may con- 
 clude that the gas is not a mixture. 
 For this experiment the diffusion- 
 tube Fig. 56 is employed. The gra- 
 duated tube is closed at one end by 
 a plug of gypsum b from 8 to 10 mm 
 in thickness, and above this dia- 
 phragm the iron lid d can be screwed 
 tightly down, so that a very small 
 space is left between the upper sur- 
 face of the gypsum and the caout- 
 chouc plate covering the inside of the iron lid. 
 
232 
 
 METHOD EMPLOYED. 
 
 This vessel, with the lid screwed down, is then filled 
 under mercury with the gas to be examined, and trans- 
 ferred from the mercurial -trough to a cylinder hy means 
 
 of the small iron spoon pp. After 
 the diffusion has continued for 
 some time, the lid being open 
 and the inner and outer level 
 of mercury kept equal during the 
 experiment, the lid is again shut, 
 the tube transferred back to the 
 trough with the spoon, and a 
 portion of the gas, now diluted 
 with air, filled into a eudiometer 
 for analysis. 
 
 As an example of the applica- 
 tion of diffusion in gas analysis, 
 we select the hydride of methyl 
 obtained on heating an acetate 
 with a hydrated alkali. It has 
 already been shown (p. 182) that 
 a simple analysis cannot decide 
 whether this consists of a mix- 
 ture or a chemical compound of 
 equal volumes of methyl and hy- 
 drogen. 
 
 The following experiment on diffusion , shows , in con- 
 firmation of the absorptiometric determination, that the 
 second supposition is the correct one, and that the methyl 
 contained in the gas is not simply mixed, but chemically 
 combined with the hydrogen. 
 
DIFFUSION OF HYDRIDE OF METHYL. 233 
 
 The analysis of the gas before diffusion gave : 
 
 Vol. 
 
 Pres- 
 sure. 
 
 Temp. 
 
 C. 
 
 Vol. at 
 
 0C. and 
 1 press. 
 
 
 104.5 
 
 0.3123 
 
 5.7 
 
 32.0 
 
 Ditto -{- air 
 
 390.2 
 
 0.6009 
 
 5.7 
 
 229.7 
 
 4- oxvffen 
 
 429-0 
 
 O.G400 
 
 5.4 
 
 269.3 
 
 alter the explosion . . . 
 
 3G1.G 
 
 0.5711 
 
 5.4 
 
 202.5 
 
 carbonic acid .... 
 
 323.1 
 
 0.5388 
 
 5.8 
 
 170.2 
 
 
 39G.2 
 
 0.6136 
 
 5.7 
 
 238.1 
 
 after the explosion . . . 
 
 350-1 
 
 0.5G24 
 
 5.7 
 
 192.9 
 
 Combustible gas. Oxygen burnt. Carbonic acid formed. 
 
 32.0 : G5.9 : 32.3 
 
 1 : 2.08 : 1.01 
 
 Marsh gas alone, or a mixture of equal volumes of 
 methyl and hydrogen should give the relation of 1:2:1. 
 
 The same gas was allowed to diffuse into air until 
 the total volume had diminished from 205 to 170. 
 
 The analysis of the gas thus obtained gave : 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 
 
 
 
 
 Original gas 
 
 126.8 
 
 0.3444 
 
 4.5 
 
 42.96 
 
 \- oxygen and air 
 
 280.6 
 
 0.4962 
 
 4.8 
 
 136.81 
 
 
 
 
 
 
 After the explosion .... 
 
 231.8 
 
 0.4473 
 
 4.8 
 
 101.90 
 
 Alter absorption of carbonic acid 
 
 201.8 
 
 0.4260 
 
 4.8 
 
 84.48 
 
 After admission of hydrogen . . 
 
 510.0 
 
 0.7359 
 
 5.2 
 
 368.30 . 
 
 Alter the explosion 
 
 422.9 
 
 0.6375 
 
 5.2 
 
 264.57 
 
 
 
 
 
 
234 DIFFUSION OF GASES. 
 
 These observations cannot be calculated according 
 to the formula generally used because the relation be- 
 tween the constituents of the atmospheric air has altered 
 during the course of the diffusion. Another method must 
 therefore be employed. 
 
 If x denote the volume of the methyl-gas , y that of 
 the hydrogen, z that of the oxygen and n that of the ni- 
 trogen; and further if A represent the original volume 
 employed = x-\-y-\-z-}-n, C the carbonic acid formed 
 by the combustion, R the volume of residual oxygen found 
 on combustion with hydrogen after the removal of the 
 carbonic acid, and lastly N the volume of residual nitro- 
 gen and oxygen found after removal of the carbonic acid 
 we have: 
 
 n = N R 
 x = V C 
 
 _ A + 2R -f- 3 C n 
 
 y = A (oc -\- y 4- n). 
 / \ i j i / 
 
 Hence experiment gives A =. 136.84, C = 17.42, 
 R = 34.58 and N 84.48. Whence we obtain: 
 Methyl ... 8.71 
 Hydrogen . . 8.78 
 Oxygen . . . 69.45 
 Nitrogen . . 49.90 
 
 136.84 
 
 A mixture of methyl arid hydrogen would before and 
 after diffusion exhibit different volumetric relations. As, 
 however, we find this not to be the case we have a direct 
 proof that the gas did not consist of a mixture of methyl 
 and hydrogen , but of a chemical compound of these two 
 gases. 
 
COMBUSTION OF GASES. 235 
 
 PHENOMENA OF THE COMBUSTION 
 
 OF GASES. 
 
 \v hen a jet of gas burns in an atmosphere of another 
 gas, the phenomena occurring in the resulting flame are 
 of a most complicated nature, as the mixture of the com- 
 bining substances proceeds gradually, and hence the com- 
 position of each layer of the body of the flame is different. 
 In order to obtain a clear insight into the nature of com- 
 bustive phenomena we must commeDce with the study 
 of homogeneous flames, ensuing from the ignition of a 
 gaseous mixture of constant composition. In the follow- 
 ing pages we shall solely consider such simple cases. 
 
 One of the most important relations which we meet 
 with in the combustion of gases, regards 
 
 1) The heat of combustion. It is customary to de- 
 signate under this title the amount of heat which is 
 liberated by the chemical union of two or more bodies. 
 This amount of heat is independent of the time during 
 which the combustion occurs, but entirely depends upon 
 the chemical nature and quantity of the combining bo- 
 dies. In order to be able to measure the amount of the 
 heat evolved from the unit of weight of the substance , a 
 
23(! HEAT OF COMBUSTION. 
 
 unit of heat is taken as the quantity required to raise 
 one part by weight of water from C. to 1 C. Thus 
 the number 2240 representing the heat of combustion of 
 sulphur signifies, that by the combustion of one part of 
 sulphur to sulphurous acid 2240 parts of water can be 
 raised from C. to 1 C., or what is the same thing, one 
 part of water heated from C. to 2240 C., when the 
 specific heat of water at all temperatures is considered 
 the same as at 0C, and when all evaporation is avoided. 
 We are indebted to Favre and Silbermann for a re- 
 cent research, carried out with all due precautions, upon 
 the heat of combustion, and as these results deserve more 
 reliance than the older experiments we shall make them 
 the starting point in the present chapter. Favre and 
 Silbermann found that, 
 
 Units of heat. 
 
 Hydrogen burning to water gave out .... 34462 
 
 hydrochloric acid gave out 23783 
 Carbon from "wood burning to carbonic oxide 
 
 gave out 2474 
 
 Ditto burning to carbonic acid gave out . . . 8080 
 
 Carbonic oxide burning to carbonic acid gave out 2403 
 Marsh gas burning to carbonic acid and water 
 
 gave out 13063 
 
 Olefiant gas burning to carbonic acid and water 
 
 gave out 11858 
 
 Sulphur burning to sulphurous acid gave out . 2240 
 Bisulphide of carbon burning to sulphurous and 
 
 carbonic acid gave out 3400 
 
 Sulphuretted -hydrogen burning to sulphurous 
 
 acid and water gave out 2741 
 
 By means of these numbers we can calculate the 
 heat of combustion of a gaseous mixture of known com- 
 
HEAT OF COMBUSTION. 
 
 237 
 
 position. Let w , 0j, w? 2 , . . ., ? represent the amount of 
 heat liberated by each single constituent when the weights 
 of these constituents are # , g l , # 2 , . . ., r/ H , we have for 
 the heat of combustion W of the whole mixture the fol- 
 lowing expression: 
 
 ^ WQ (Jo ~h Wi ffi + + w n <jn m 
 
 </o 4- g\ + - - + 9* 
 
 As an example of such a calculation I select the 
 heat of combustion of a mixture of gases which was 
 obtained from the shaft of a blast-furnace at Vecker- 
 hagen at depth of two feet under the surface of the fuel. 
 
 Composition Composition 
 according to according to 
 
 
 volume. 
 
 weight. 
 
 
 
 
 
 9 
 
 w 
 
 tog 
 
 Nitrogen 
 
 6078.0 
 
 7.6375 
 
 0.0 
 
 0.0 
 
 Garb, acid 
 
 874.0 
 
 1.7188 
 
 0.0 
 
 0.0 
 
 Garb, oxide 
 
 2629.0 
 
 3.2902 
 
 2403.0 
 
 7906.3 
 
 Hydrogen 
 
 196.0 
 
 0.0175 
 
 34462.0 
 
 603.0 
 
 Mnrsh gas 
 
 223.0 
 
 0.1596 
 
 13063.0 
 
 2084.9 
 
 1000.0 12.8236 
 
 Swg _ 10594.2 
 -Sf - 12*236- 
 
 Hence if the weight of gas issuing from the furnace 
 in the unit of time be represented by 6r, and if W stand 
 for its heat of combustion , we have the value G Wt for 
 the amount of heat lost in the time t in the unburnt 
 gases which escape. 
 
 As the average quantity of gases, of the composition 
 above given, issuing from the blast-furnace upon which 
 the experiments were made, amounted to 12 kilogrammes 
 per minute, the quantity of heat lost from this imperfect 
 combustion per hour is found to be 
 
 60 X 826 . 1 X 12 = 594792 units of heat. 
 
238 HEAT OF COMBUSTION. 
 
 And as 1 kilogramme of coals is capable of heating 1 ki- 
 logramme of water up to 8080 C., the combustible mate- 
 
 594792 
 
 rials which issue unburnt are equal to 0/^0^ = 73.6 ki- 
 logrammes of coal per hour. 
 
 The weight of a given volume of gas is found from 
 table VIII. The first horizontal column contains the vo- 
 lumes in cubic - centimetres , the remaining columns the 
 weight in grammes of the corresponding volumes of the 
 gas mentioned at the beginning of the column. If, for 
 example, it is required to determine the weight of 1407.3 
 cubic - centimetres of carbonic acid we find from this 
 table, that 
 
 1000 cbc. weigh . . . 1.96663 
 
 400 : ... 0.78665 
 
 7 ... 0.01376 
 
 0.3 . . 0.00037 
 
 hence 1407.3 ... 2.76741 
 
 We must now distinguish between the heat of com- 
 bustion, and 
 
 2) The temperature of the combustion. This is the tem- 
 perature which exists in the interior of a burning mass, 
 and may be deduced from the heat of combustion when 
 we know the specific heat of the products of combustion 
 compared with that of water as unity. The following 
 values of the specific heats of the most important gases 
 required in these calculations, are taken from the latest 
 determinations of Regnault. 
 
TEMPERATURE OF COMBUSTION. 239 
 
 Specific heats by constant pressure. 
 
 (Specific heat of water = 1.) 
 
 Oxygen 0.2182 
 
 Nitrogen 0.2440 
 
 Hydrogen 3.4046 
 
 Chlorine 0.1214 
 
 Carbonic oxide 0.2479 
 
 Carbonic acid 0.2164 
 
 Sulphuretted -hydrogen . . 0.2423 
 
 Sulphurous acid .... 0.1553 
 
 Hydrochloric acid . ... 0.1845 
 
 Olefiant gas 0.3694 
 
 Marsh gas 0.5929 
 
 Vapour of water .... 0.4750 
 
 Air 0.2370 
 
 If the constituents of a gaseous mixture weigh 
 h, . . ., g n before the combustion, and if theire respective 
 amounts of heat of combustion are W Q , u\ , . . ., iv n , the 
 heat of combustion of the mixture, as we have seen, is 
 
 jp #0 W -\~ 9l Wl -f" ' "t" 9n W n 
 
 that is , the mixture gives off an amount of heat capable 
 of raising 1 part by weight of water J! = H "degrees of 
 
 temperature. If the products of combustion were simply 
 water in the liquid state, this water would possess a tem- 
 perature jL The products of combustion are , how- 
 ever, gaseous bodies having a specific heat different from 
 that of water. Hence the temperature ^ will be to 
 the temperature of the gaseous products of combustion, 
 
240 TEMPERATURE OF COMBUSTION. 
 
 inversely as the specific heat of water, to the specific heat 
 of the products of combustion; or (because the specific 
 
 'r-^ 
 
 heat of water = 1) as the temperature v - divided by 
 
 the specific heat of the gaseous products. This is easily 
 found from the composition of the products of combustion. 
 If we represent by p Q , p\ , . . . , p n the weights of the con- 
 stituent parts of the gaseous products, and by s , S\T>-> * 
 their respective specific heats, we obtain for the value of 
 <S, the specific heat of the total product : 
 
 [ | [ 
 
 and hence for the temperature of combustion T: 
 
 T 
 " 
 
 and, because the weight of the unburnt constituents (j 
 is equal to the sum of the constituents which have un- 
 dergone combustion Z?p, we have: 
 
 ,_ 2gw 
 
 2 ps ' 
 
 The 12 kilogr. or more correctly 12.8236 kilogr. of 
 gas, of the given composition, issuing from the blast - fur- 
 nace, requires for its complete combustion 2. 65817 kilogr. 
 of oxygen. These 2.65817 correspond to 11.46478 kilogr. 
 of air containing 8.80661 nitrogen. Hence we have the 
 composition of this gas before and after the com- 
 bustion. 
 
TEMPERATURE OF COMBUSTION. 
 Before the combustion: 
 
 241 
 
 
 g 
 
 tp 
 
 wg 
 
 Nitrogen . . 
 
 16.444 
 
 
 
 
 
 Carbonic acid . 
 
 1.719 
 
 
 
 
 
 Oxygen . . . 
 
 2.658 
 
 
 
 
 
 Carbonic oxide 
 
 3.290 
 
 2403 
 
 7906.3 
 
 Hydrogen . . 
 
 0.018 
 
 34462 
 
 603.0 
 
 Marsh gas . . 
 
 0.160 
 
 13063 
 
 2084.9 
 
 lg = 24.289 Ztcg __ 10594.2 
 24.2884 
 
 S?= ir= 436018. 
 
 After the combustion: 
 
 Nitrogen . . 16.444 
 Carbonic acid 7.328 
 Aqueous vapour 0.517 
 
 JP* 
 
 0.2440 4.0123 
 0.2164 1.5858 
 0.4750 0.2456 
 
 = 24.289 
 
 Eps 
 
 5.8437 
 24.289 
 
 = S = 0.2406. 
 
 Hence the temperature of the combustion 
 
 f = -=1818.9 a 
 
 Zips S 
 
 This calculation is founded upon the assumption 
 that the specific heat of gases is not alterable with the 
 temperature as in the case with liquids and solids ; this 
 assumption has been proved by Reguault to hold good 
 for temperatures varying from 30 C. to -J- 225 C., 
 and Clausius has shown the correctness of this view from 
 purely theoretical considerations. 
 
 The following table gives the temperature of com- 
 bustion for several gases, calculated according to the 
 preceeding method. 
 
 16 
 
242 TEMPERATURE OF COMBUSTION 
 
 Hydrogen (burned with chlorine) . . 3532 C. 
 
 Carbonic oxide (burned with oxygen) 7067 C. 
 
 Marsh gas 7851 C. 
 
 Hydrogen 8061 C. 
 
 Olefiant gas 9187 C. 
 
 Carbonic oxide (burned with air) . . 3042 C. 
 
 Marsh gas 5329 C. 
 
 Hydrogen 3259 C. 
 
 Olefiant gas 5413 C. 
 
 These numbers represent the temperatures which the 
 various gases attain on combustion with exactly the re- 
 quisite amount of chlorine, oxygen, or air, supposing that 
 the inflamed gases can freely expand as is the case in an 
 open flame. If, on the contrary, the combustion occurs 
 in a closed space, under circumstances in which the vol- 
 ume, and not the pressure of the gas remains constant, 
 the temperature of the combustion will be totally different. 
 In order to calculate the temperature in this case, we 
 must substitute the value of the specific heats for con- 
 stant volume for those by constant pressure. If we as- 
 sume, in accordance with Dulong's experiments, that the 
 relation of the specific heats by constant pressure and by 
 constant volume is 1.421 for air, we obtain the specific 
 heat c by constabt volume, for any given gas, from the 
 specific heat c v under constant pressure, from the follow- 
 ing equation in which s represents the specific gravity of 
 the gas compared with air as unity: 
 
 0.070216 
 
 G = 6*1 
 
 S 
 
 The specific heats for constant volume and varying 
 pressure are thus found for the preceeding gases : 
 
EXPLOSIVE .FORCE OF GASES. 243 
 
 Oxygen 0.1547 
 
 Nitrogen 0.1717 
 
 Hydrogen 2.3910 
 
 Chlorine 0.0928 
 
 Carbonic oxide . . . . 0.1753 
 
 Carbonic acid 0.1702 
 
 Sulphuretted-hydrogen . . 0.1826 
 
 Sulphurous acid .... 0.1236 
 
 Hydrochloric acid .."j'. 0.1288 
 
 Olefiant gas . .: j . , r,, J . 0.5204 
 
 Marsh gas ,**.,..',:* '*Q. $i 0.2425 
 
 Aqueous vapour .... 0.3621 
 
 Air 0.1668 
 
 By means of these values we obtain the following 
 temperatures when the gases are burned in closed vessels. 
 
 Hydrogen with chlorine . . . 5059 C. 
 
 Carbonic oxide with oxygen . 8986 C. 
 
 Marsh gas 10183 C. 
 
 Hydrogen 10575 C. 
 
 Olefiant gas. 11853C. 
 
 Intimately connected with these temperatures of 
 combustion is 
 
 3) The explosive force of gases. When the tempe- 
 rature of the combustion and the volume of the pro- 
 ducts formed thereby are known, we can arrive at certain 
 conclusions regarding the amount of the mechanical action 
 which accompanies the combustion of explosive gaseous 
 mixtures. For this purpose we merely require to cal- 
 culate, firstly, the alteration of volume which the unit 
 amount of the unburned gas undergoes in consequence 
 of the combustion, and, secondly, the heat evolved during 
 the process. 
 
 16* 
 
244 EXPLOSIVE FORCE OF GASES. 
 
 For instance, one volume of a gaseous mixture of 
 2/3 vol. carbonic oxide and J /3 v l- oxygen gives on com- 
 bustion 2 /3 v l- carbonic acid. If the gas cannot expand 
 during this combustion it is heated (according to the 
 calculations of the temperature of combustion), to 8986 C. 
 2 /3 vol. carbonic acid occupies at 8986 C. the volume 
 2/ 3 (1 -f 0.00366 X ^986) = 22.59. AS the gas could 
 not expand, these 22.59 volumes are compressed into a 
 volume equal to 1. Hence, according to Mariotte's law, 
 if the gas before the combustion was measured at 0C., 
 and under a pressure of one atmosphere, the pressure 
 exerted during the combustion on the inner surface of a vessel 
 containing the gas must have been 22.59 atmospheres. 
 
 In this way, the pressures which the following mix- 
 tures of detonating gases exert upon their inclosing sur- 
 faces are calculated, supposing that the gases are com- 
 .pletely burned in closed vessels at 0C., and under the 
 normal atmospheric pressure. 
 
 1. Hydrogen with chlorine . . . 19.5 atmospheres 
 
 2. Carbonic oxide with oxygen . . 22.6 
 
 3. Hydrogen 26.5 
 
 4. Marsh gas 38.3 
 
 5. Olefiant gas 44.4 
 
 6. Ditetryl 88.8 
 
 Experience teaches us, in accordance with this cal- 
 culation, that the detonating gases 1 and 2 can be ex- 
 ploded without danger in thin flasks, that No. 3 requires 
 somewhat more substantial vessels, and that even narrow 
 eudiometers of thick glass are shattered by exploding 4 
 and 5, whilst it is scarcely possible to obtain a eudio- 
 meter strong enough to resist the shock ensuing from 
 the combustion of ditetryl. Hence we see that in gas 
 
EXPLOSIVE FORCE OF GASES. 245 
 
 analyses it is always necessary before combustion to dilute 
 with some indifferent gas any one which contains its con- 
 stituents in a very condensed state. If all these ex- 
 plosive gases be detonated in a thin flask surrounded by 
 cloths and held in the hand scarcely any shock is felt- 
 when the flask is broken by explosion with the gases 
 1 and 2 ; with Nos. 3 and 4 the detonation is more per- 
 ceptible; and with 5 and 6 the explosion takes place in 
 so violent a manner that the shock can scarcely be 
 endured. 
 
 In all these phenomena, we must remember that it 
 seldom happens that the total pressure of the exploding 
 gases comes into play. If the combustion commences at 
 one point, a certain time is required before it is trans- 
 mitted throughout the mass. This time appears to depend 
 upon the chemical nature of the mixture undergoing 
 combustion. Thus the combustion of carbonic oxide can 
 be followed by the eye, whilst this is not possible with 
 other detonating gases. 
 
 If a column of detonating gas be ignited at its upper 
 extremity, the combustion does not reach the lower end 
 of the column until a certain quantity of heat has been 
 lost by radiation and conduction. When the detonating 
 gas is diluted with an indifferent gas nearly up to its 
 limit of inflamability . a ball of fire is frequently seen to 
 start from the point of ignition and to move slowly 
 downwards to the lower end of the column of gas. In 
 this case, the combustion at the top of the column is at 
 an end, whilst at the bottom the action is still proceeding. 
 The combustibility of any detonating gas is therefore 
 diminished by addition of an indifferent gas not only 
 because the temperature of the combustion becomes lower, 
 but also because the rate of transmission of the com- 
 
246 TEMPERATURE OF IGNITION OF GASES. 
 
 bustion decreases. Hence we see, that the total pressure 
 can be exerted only when the combustion of the whole 
 mass takes place simultaneously. This fact explains 
 the singular fact that the same chlorous acid accord- 
 ing as it is ignited, or explodes spontaneously, either 
 gives a slight report, or else detonates most violently, 
 producing extraordinary mechanical effects; and that a 
 glass containing a mixture of chlorine and hydrogen is 
 shattered when the gas is exposed to the direct sun- 
 light, whereas if an electric spark be passed through the 
 mixture the vessel remains unbroken. 
 
 4) Temperature of ignition of gases. If an explosive 
 mixture of gases is diluted with a large quantity of a 
 non - combustible gas, a limit is reached, beyond which 
 the mixture ceases to be capable of ignition. This 
 limit can be so closely approached that the smallest 
 addition of a non -combustible gas is sufficient to cause 
 a gaseous mixture which was before perfectly infiamable 
 to become as perfectly non -combustible. 
 
 A gas which has thus become non-inflamable regains 
 its combustibility if it is prevented from expanding freely 
 during the ignition, or when its temperature has been 
 increased. The limit of dilution at which this sudden 
 check is given to the inflamability is essentially dependent 
 upon the nature of the gases used as diluents. 
 
 The following experiments show the influence which 
 the presence of oxygen, hydrogen or carbonic acid exert 
 upon the limits of inflamability of the oxyhydrogen de- 
 tonating gas *. 
 
 * All the combustions detailed in these experiments were con- 
 ducted in closed eudiometers, and hence in the calculations 
 founded upon these experiments , the specific heats of the 
 gases for constant volumes are employed. 
 
TEMPERATURE OF IGNITION OF GASES. 
 Non-inflamable mixture. 
 
 247 
 
 
 VOL Pres - 
 
 sure. 
 
 Temp., VoLat 
 1 0C. and 
 
 l m press. 
 
 Original volume of oxygen . . 
 Alter addition of hydrogen . . 
 Alter passage of spark .... 
 
 194.0 
 202.9 
 203.5 
 
 0.7111 
 0.7203 
 0.7173 
 
 6.3 
 5.7 
 5.7 
 
 137.81 
 146.15 
 145.97 
 
 Inflamable mixture. 
 
 Original volume of oxygen . . 
 After addition of hydrogen . . 
 Alter passage of spark .... 
 
 191.0 
 201.7 
 192.8 
 
 0.708G 
 6.7172 
 0.7000 
 
 5.8 
 5.8 
 5.8 
 
 135.54 
 144.66 
 134.96 
 
 Non-inflamable mixture. 
 
 Original volume of hydrogen . . 
 Alter addition of oxygen . . . 
 
 189.2 
 200.0 
 
 0.7070 
 0.7"173 
 
 6.0 
 6.0 
 
 133.8 
 t !34.5 
 
 Inflamable mixture. 
 
 Original volume of hydrogen . . 
 After addition of oxygen . . . 
 
 188.2 
 200.4 
 
 0.7031 
 0.7164 
 
 7.0 
 7.0 
 
 132.3 
 143.2 
 
 Non-inflamable mixture. 
 
 Original volume carbonic acid 
 Alter addition of detonating gas 
 
 122.4 
 156.9 
 
 0.6780 
 0.7128 
 
 5.7 
 5.7 
 
 81.29 
 109.39 
 
 Inflamable mixture. 
 
 Original volume carbonic acid 
 After addition of detonating gas 
 
 122.4 
 15G.1 
 123.9 
 
 0.6780 
 0.7191 
 0.6807 
 
 5.7 
 5.3 
 5.5 
 
 81.29 
 110.12 
 82.73 
 
 
248 LIMIT OF INFLAMABILITY. 
 
 These experiments show: 
 
 i.* 
 
 That 1 vol. of deton. gas with 2.82 carbonic acid is inflamable 
 1 3.37 hydrogen 
 1 9.35 oxygen 
 
 II. 
 
 That 1 vol. of deton. gas with 2.89 carbonic acid is non - inflamable 
 1 >, 3.93 hydrogen 
 
 1 10.08 oxygen 
 
 The temperature of combustion calculated for the 
 first inflamable mixture of one volume of detonating gas 
 to 2.82 volumes of carbonic acid, amounted to 18088 C. ; 
 the same for the non - inflamable mixture with 2.89 vol- 
 umes of carbonic acid is found to be 17724C. 
 
 In order to understand the processes which occur 
 on these combustions, let us suppose a column of mixture 
 Fig. 58. No. 1 at 0C. divided into a number of 
 equal -sized infinitely thin layers a, a^ 
 ct 2 , . . . We shall find that the following 
 phenomena occur during the ignition of 
 these layers, not considering for the mo- 
 ment the other physical relations. 
 
 As soon as the first layer a is raised, 
 by any outward cause, to the temperature 
 of ignition x, the combustion occurs, ac- 
 companied by an increase of temperature 
 of the layer from x to x -f- 18088, in consequence of 
 the heat of combustion. This temperature is communi- 
 cated to the adjacent equally large, infinitely thin layer 
 i , until an equilibrium is established , and each layer 
 
 x -f 180808 
 has arrived at the temperature ' . Owing to 
 
LIMIT OF INFLAMABILITY. 249 
 
 conduction and radiation, and by the alteration of the 
 capacity of heat of the products of combustions, these 
 
 layers must lose a certain quantity of the amount 
 
 of heat they originally contained. The temperature of 
 the layers a and a t is therefore 
 
 ) 
 
 - 1808Q8 \ 
 
 2 Jr 
 
 As this temperature is sufficient to ignite the layer 
 ai it must certainly be as great if not greater than x. 
 
 If we repeat these considerations in the case of the 
 second mixture of 1 vol. detonating gas to 2.89 of car- 
 bonic acid, we obtain for the temperature of the layer a v 
 
 the value 
 
 17724\ 
 
 / J_\ /* 
 \ n}\ 
 
 As, however, this mixture did not ignite, and therefore 
 the combustion was not transmitted to the layer j . the 
 
 / 1 \ ( x _l_ 1772<4\ 
 
 value (1 ) ( - o~ ) mu t be smaller than x. 
 
 The difference of these two temperatures is : 
 
 Hence, if we add the temperature (l - -J 182 to 
 
 the temperature ( 1 -J (- ^ -j the value of a-, 
 that is of the temperature of ignition, is attained or 
 
 exceeded. 
 
250 LIMIT OF INFLAMABILITY. 
 
 The gaseous mixture is, therefore, not inflamable 
 without this additional temperature f 1 - j 182, but 
 
 with this increased amount of heat it becomes com- 
 bustible. As this number less than 182 may be con- 
 sidered to be infinitely small when compared to the tem- 
 perature of ignition #, upwards of 1000, we may assume, 
 without any perceptible error, that the limit of com- 
 bustibility, or what in this case is the same, viz the tem- 
 perature of ignition, is equal to 
 
 / iw,+.m*4x 
 
 V 1 T/ \ 2 / 
 
 Hence we have: 
 
 or 
 
 x = l 17906. 
 
 A similar calculation applied to the remaining ex- 
 periments gives the following results, for the various 
 temperatures of ignition: 
 
 1) of deton. gas and hydrogen (l --- ) 21168 = x 
 
 \ ^o / 
 
 2) carb. acid (l -- -) 17906 = x l 
 
 \ MI / 
 
 3) oxygen . (l - -L) 857<>3 = ^ 
 
 \ "2 / 
 
 The variations seen in these three numbers may arise 
 from three different causes. Either, in the first place, 
 the temperature of ignition x is a invariable quantity, and 
 
 hence the coefficient of loss of heat must vary with 
 
 n 
 
PECULIAR ACTION OF DILUENTS. 251 
 
 the nature of the gas added in excess ; or , in the second 
 place, the coefficient - - is constant, and the temperature 
 
 of ignition is altered by the mere presence of the diluent 
 which does not enter into combination; or, thirdly, both 
 these causes act together. 
 
 Let us now examine whether the difference between 
 the calculated temperatures can be explained by the 
 first supposition , viz : that the temperature of ignition x 
 has a constant value. If x = x l = x 2 we have : 
 
 and hence 
 
 -<-<-. 
 
 n-2 n^ * TI O 
 
 The fraction th of the total increase of temperature 
 
 which is lost by radiation, conduction &c. is therefore 
 less in the oxygen mixture No. 3, than in the carbonic 
 acid mixture 2, and less in this latter case than in the 
 hydrogen mixture 1. Let us now see if this be really 
 the case. 
 
 In the first place , an explanation of the loss of tem- 
 perature may be given in the fact, that the specific heat 
 of the products of combustion contained in layer a, is 
 different from the specific heat of the gases in layer ! 
 which are not yet burned. The relation between the cal- 
 culated specific heats of the gases which have, and which 
 have not undergone combustion, is given in the following 
 table, 
 
 In the oxygen mixture . . (3) as 1 : 1.009 
 carbonic acid mixture (2) 1 : 1.020 
 hydrogen mixture . (1) 1 : 1,023 
 
252 DIATHERMANOUS PROPERTIES OF GASES 
 
 This relation is certainly in the direction <<- 
 
 n% ^ r f*i n 
 
 which the theory requires, but the difference between 
 each value is so small that its influence upon the tem- 
 perature of ignition is inappreciable, and may be con- 
 sidered to fall within the limits of observational error. 
 The great differences observed in the temperatures of 
 ignition do not therefore arise from this relation of the 
 specific heats. 
 
 Another much more important source of unequal 
 cooling , exists in the radiation and conduction of heat 
 in the various gases. If the radiation and conduction of 
 heat proceeds more rapidly in one gas than in another, 
 the loss of heat accompanying the equalisation of tem- 
 perature in layers a and a must necessarily vary during 
 the combustion. As no data exist concerning the dia- 
 thermanous properties of gases, I have endeavoured to 
 determine the question by direct experiment. 
 
 For this purpose, a galvanic current of gradually 
 increasing intensity was passed through two platinum 
 wires of equal length and thickness a % , Fig. 59 , one of 
 which a was surrounded by carbonic acid, and the other 
 % with oxygen, in the two glass tubes AA^ As soon as 
 the current had attained, a certain intensity, the first 
 wire a become red-hot, and after the strength of the 
 current had been still further increased, the first symptoms 
 of glow were observed in the wire a surrounded by 
 oxygen ; and this . latter wire was always visibly less 
 heated than the former. If the direction of the current 
 was reversed, or the contents of the tubes changed, the 
 glow was always first observed in the atmosphere of 
 carbonic acid. Now as the same current passing through 
 two wires of equal dimensions, produces in each an equal 
 
INFLUENCE OF DILUENTS. 
 
 253 
 
 amount of heat , and as the capacity of heat of oxygen 
 and carbonic acid is almost exactly the same under equal 
 pressure, the only reason which can be assigned for the 
 
 Fig. 59. 
 
 fact that the wire becomes always first red-hot in the 
 carbonic acid, is that this gas gives off its heat by ra- 
 diation and conduction with greater difficulty than oxygen 
 
 gas. Accordingly the loss of heat - in the carbonic 
 
 711 
 
 acid mixture (2) ought to be less than the loss in 
 
 n 2 
 
 the oxygen mixture (3) if the equation x = x l == x 2 is 
 correct. In reality, however, we find from the experiment 
 
 that <~ ; hence we must consider that the sup- 
 
 2 - ni 
 
 position that x is invariable is not correct, and we 
 may fairly conclude , that the temperature of ignition 
 of a gaseous mixture varies according to the nature of the 
 gases present, whether they take pa ft in the chemical action 
 or not. 
 
254 IMPORTANT BEARINGS OF THESE 
 
 A knowledge of these remarkable phenomena ne- 
 cessitate a consideration of the mode of action of affinity 
 from a new point of view. For, according to these ex- 
 periments, we see that the temperature of ignition, or 
 the point at which the chemical attraction of the mole- 
 cules is so increased that combination can take place, is 
 not only dependent upon the relative attractions of the 
 molecules undergoing combination, but also upon those 
 particles which are present but do not take any active 
 part in the decomposition. Hence we are obliged to 
 admit that chemical affinity is the resultant of the at- 
 tractive forces exerted by all the molecules within the 
 sphere of the chemical attraction, whether these mole- 
 cules take part in the chemical action or not. By this 
 supposition alone can we satisfactorily account for the 
 observed phenomena. 
 
 If a mixture of one part of detonating gas with 2.85 
 parts of carbonic acid is raised to a temperature some- 
 what below that necessary to ignite the detonating gas, the 
 gas will immediately explode if the carbonic acid be re- 
 placed by oxygen; although neither the carbonic acid 
 nor the oxygen take any part in the chemical combination. 
 
 From these observations we cannot doubt that the 
 so called catalytic decompositions may be explained in 
 the same way; and that, far from depending upon any 
 extraordinary causes, they are simply the common effects 
 of affinity. Just as a volume of detonating gas in the 
 sphere of attraction of molecules of carbonic acid is not 
 combustible at a given temperature, but when in the 
 sphere of the molecules of oxygen the gas becomes com- 
 bustible at the same temperature, we also find that the 
 elements of peroxide of hydrogen are retained combined 
 in the sphere of attraction of the atoms of water, but do 
 
FACTS ON THE ACTION OF AFFINITY. 255 
 
 not remain combined in the sphere of attraction of the 
 atoms of black -oxide of manganese or metallic platinum. 
 
 Nor should we be astonished at the fact, that a small 
 quantity of platinum is able to decompose an unlimited 
 amount of peroxide of hydrogen. For wherever a piece 
 of platinum touches peroxide of hydrogen the affinity in 
 the nearest layer is so weakened that the peroxide in 
 this layer, but only in this layer, decomposes into oxygen 
 and water. The chemical action of the platinum here 
 ends; and it is only when the products of decomposition 
 thus formed, are removed by foreign forces, such as gra- 
 vitation, capillarity, expansion &c., and by means of these 
 foreicfn forces new peroxide of hydrogen brought in contact 
 with the platinum, that the phenomenon is repeated. 
 
 Hence it is seen, that the catalytic action produced 
 by the platinum or oxide of manganese, is not equi- 
 valent to an unlimited amount of labour, but that for 
 every decomposition effected, an equivalent amount of 
 force is absorbed, just as in the case of^a weight raised 
 by a falling body, a force is expended exactly equivalent 
 to the work done. 
 
 I have just shown that the temperature of ignition 
 of two chemically different molecules of a homogeneous 
 gaseous mixture, depends upon the total number of mo- 
 lecules lying within the sphere of attraction, and that 
 therefore, this temperature must be altered by the presence 
 of other particles of the same or different material pro- 
 perties. This catalytic action which the excess of mo- 
 lecules present taking no part in the decomposition exert 
 upon the combining molecules, is seen in a most remarkable 
 manner in the volumetric relation between the products 
 formed by the combustion, and brings to light a singular 
 law which appears to be of fundamental importance in 
 
256 SIMPLE VOLUMETRIC RELATION 
 
 the mode of action of affinity. If, namely the particles 
 a of a homogeneous gaseous mixture have the choice of 
 combination between the particles b and c of two other 
 gases present in excess, a certain equilibrium ensues 
 between the attractions of all the particles , so that the 
 compounds (a -\- b) and (a -f- c), formed by the union 
 of a with b and c, stand in a simple relation to one an- 
 other, dependent upon the amount of the particles re- 
 maining uncombined, and undergoing discontinuous al- 
 teration on gradual increase of these- particles. Suppose, 
 for instance, that we have a gaseous mixture of 30 atoms 
 of oxygen, 30 of hydrogen, and 119 atoms of carbonic 
 oxide, the proportion between the atoms of carbonic acid, 
 and water, which can be thus combined is represented 
 by n HO and 30 -- n CO 2 when n represents all the 
 whole numbers from to 30. That is : 
 
 either 30 atoms water to atoms carbonic acid 
 r 29 1 
 
 1 9Q 
 
 ii ii ii ii u *' 11 11 11 
 
 11 11 n 11 ^^ 11 11 11 
 
 According to the preceeding law, however, only those 
 cases of these 31 are possible in which 1, 2, 3 atoms of 
 the one product are formed together with 1, 2, 3, 4 . . . 
 of the other. In the experiment before us, the atomic 
 relation between the water and carbonic acid formed, is 
 as 1 : 1. If the volume of carbonic oxide present be 
 gradually diminished, the relation of HO : CO 2 suddenly 
 changes to that of 2 HO : CO 2 as soon as the proportion 
 of carbonic oxide has sunk to 86 atoms. 
 
BETWEEN THE PRODUCTS OF COMBUSTION. 257 
 
 The following experiments, conducted with electro- 
 lytic detonating gas and carbonic oxide, may serve to 
 illustrate this law. 
 
 EXPERIMENT 1. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 0C. and 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 l m press. 
 
 1 1 
 
 
 
 Electrolytic detonating gas . . 
 
 42.7 
 
 0.6232 
 
 22.2 
 
 24.G1 
 
 After addition of carbonic oxide 
 
 132.0 
 
 0.7350 
 
 22.2 
 
 89.73 
 
 Employed for combustion: 
 
 Volume of gas employed . . . 
 After the combustion .... 
 
 145.8 
 124.1 
 
 0.7338 
 0.7318 
 
 22.3 
 22.4 
 
 98.92 
 83.92 
 
 EXPERIMENT 2. 
 
 Electrolytic detonating gas . . 
 After addition of carbonic oxide 
 After the explosion 
 
 123.6 
 261.1 
 220.1 
 
 ENT 
 
 0.3210 
 0.4527 
 0.4130 
 
 3. 
 
 3.4 
 3.3 
 3.0 
 
 40.04 
 116.79 
 89.99 
 
 EXPERIM 
 
 Electrolytic detonating gas . . 
 After addition of carbonic oxide 
 
 57.6 
 130.3 
 
 0.6422 
 0.7085 
 
 22.4 
 22.5 
 
 34.19 
 85.32 
 
 Employed for th< 
 Gas employed 
 
 2 coml 
 
 119.5 
 
 87.2 
 
 >ustior 
 
 0.7293 
 0.7293 
 
 L: 
 
 22.5 
 22.5 
 
 80.52 
 58.76 
 
 After the combustion .... 
 
 EXPERIMENT 4. 
 
 Electrolytic detonating gas . . 
 After addition of carbonic oxide 
 After the explosion . . 
 
 120.4 
 193.0 
 134.7 
 
 0.3084 
 0.3806 
 0.3308 
 
 5.3 
 
 4.7 
 3.8 
 
 17 
 
 36.43 
 72.21 
 43.94 
 
 
258 
 
 SIMPLE VOLUMETRIC RELATION 
 EXPERIMENT 5. 
 
 
 Vol. 
 
 Pres- 
 
 Temp. 
 
 Vol. at 
 C. and 
 
 
 
 sure. 
 
 C. 
 
 
 
 
 
 
 l m press. 
 
 Electrolytic detonating gas . . 
 
 104.0 
 
 O.G713 
 
 22.3 
 
 64.55 
 
 After addition of carbonic oxide 
 
 150.0 
 
 0.7358 
 
 22.5 
 
 101.98 
 
 Employed for the combustion: 
 
 
 113.4 
 58.2 
 
 0.7234 
 0.6667 
 
 22.0 
 
 22.7 
 
 After the combustion .... 
 
 EXPERIMENT G. 
 
 Electrolytic detonating gas . . 
 After addition of carbonic oxide 
 After the combustion 
 
 121.3 
 152.9 
 67.2 
 
 ENT 
 
 0.3182 
 0.3523 
 0.2766 
 
 7. 
 
 3.0 
 
 2.6 
 2.8 
 
 EXPERIM 
 
 Electrolytic detonating gas . . 
 After addition of carbonic oxide 
 After the explosion 
 
 123.4 
 147.4 
 61.3 
 
 ENT 
 
 0.3229 
 0.3436 
 0.2589 
 
 8. 
 
 2.4 
 2.3 
 1.9 
 
 EXPERIM 
 
 Electrolytic detonating gas . . 
 After addition of hydrogen . . 
 After addition of carbonic oxide 
 
 65.7 
 98.0 
 151.9 
 
 0.6321 
 0.6645 
 0.7165 
 
 22.7 
 22.8 
 23.0 
 
 Employed for the combustion: 
 Gas employed . 168.6 0.7194 23.0 
 
 After the combustion . . 
 
 112.4 
 ENT 
 
 0.7206 
 9. 
 
 23.0 
 
 EXPERIM 
 
 Electrolytic detonating gas . . 
 After addition of carbonic oxide 
 
 119.3 
 139.9 
 52.9 
 
 0.3004 
 0.3207 
 0.2421 
 
 6.5 
 7.0 
 5.3 
 
 
BETWEEN THE PRODUCTS OF COMBUSTION. < 259 
 
 According to these analyses the composition of these 
 mixtures which underwent combustion was the following : 
 
 Expt. 1. Expt. 2. Expt. 3. Expt. 4. Expt. 5. 
 
 Vol. of oxygen .... 100.0 100.0 100.0 100.0 100.0 
 hydrogen . . . 200.0 200.0 200.0 200.0 200.0 
 carhonic oxide 793.8 575.0 448.6 294.7 174.0 
 
 Expt. 6. Expt. 7. Expt. 8. Expt. 9. 
 
 Vol. of oxygen .... 100.0 100.0 100.0 100.0 
 t hydrogen . . . 200.0 200.0 370.3 200.0 
 carbonic oxide 119.3 80.7 315.1 74.0 
 
 In order to calculate the quantity of hydrogen and oxy- 
 gen which combined with these 100 volumes of oxygen in 
 the foregoing mixtures, we only require to know the vol- 
 ume of gas which has disappeared on exploding the various 
 mixtures, as found from the experiments. If we call this 
 contraction C, and the amount of oxygen burnt 100 = 0, 
 we find the volume of carbonic acid formed c, and that 
 of the aqueous vapour w produced from the following 
 equation : 
 
 3 C = c, 
 
 C = w. 
 
 The following values for and C are obtained from 
 the experiments: 
 
 
 Expt. 1. 
 
 Expt. 2. 
 
 Expt. 3. 
 
 Expt. 4. 
 
 Expt. 5. 
 
 . 
 
 . 100.0 
 
 100.0 
 
 100.0 
 
 100.0 
 
 100.0 
 
 c . 
 
 . 165.7 
 
 200.72 
 
 202.3 
 
 232.7 
 
 250.0 
 
 
 Expt. 6. 
 
 Expt. 7. 
 
 Expt. 8. 
 
 Expt. 9.' 
 
 
 . 
 
 . 100.0 
 
 100.0 
 
 100.0 
 
 100.0 
 
 
 c . 
 
 251.7 
 
 261.2 
 
 260.9 
 
 266.5 
 
 
 Hence the following amounts of carbonic acid and 
 water in the various experiments are calculated: 
 
 17* 
 
2GO 
 
 SIMPLE VOLUMETRIC RELATION. 
 
 
 
 Expt. 1. 
 
 Expt. 2. 
 
 Expt. 3 
 
 . Expt. 4. 
 
 Expt. 5. 
 
 Carbonic 
 
 acid 
 
 67 
 
 50 
 
 51 
 
 34 
 
 25 
 
 Aqueous 
 
 vapour . 
 
 33 
 
 50 
 
 49 
 
 66 
 
 75 
 
 
 
 100 
 
 100 
 
 100 
 
 100 
 
 100 
 
 
 
 Expt. 6. 
 
 Expt. 7. 
 
 Expt. 8 
 
 . Expt. 9. 
 
 
 Carbonic 
 
 acid . . 
 
 24 
 
 19 
 
 20 
 
 17 
 
 
 Aqueous 
 
 vapour . 
 
 76 
 
 81 
 
 80 
 
 83 
 
 
 100 100 100 100 
 
 The numbers in the second horizontal division of 
 the following table represent the relation between car- 
 bonic acid and water which must ensue if the compound 
 in the first division is formed by the combustion : 
 
 Expt. 1. Expt. 2. Expt. 3. Expt. 4. Expt. 5. 
 
 
 HO 2 CO 2 
 
 HO CO 2 
 
 HO CO 2 
 
 2 HO CO 2 
 
 2 HO CO 2 
 
 Carbonic acid 
 
 67 
 
 50 
 
 50 
 
 33 
 
 25 
 
 Aqueous vapour 
 
 33 
 
 50 
 
 50 
 
 G7 
 
 75 
 
 
 100 
 
 100 
 
 100 
 
 100 
 
 100 
 
 Expt. 6. Expt. 7. Expt. 8. Expt. 9. 
 
 
 3 HO CO 2 
 
 4 HO CO 2 
 
 4 HO CO 2 
 
 5 HO CO 2 
 
 
 Carbonic acid 
 
 25 
 
 20 
 
 20 
 
 17 
 
 
 Aqueous vapour 
 
 75 
 
 80 
 
 80 
 
 83 
 
 
 
 
 100 
 
 100 
 
 100 
 
 100 
 
 
 The proportion between the constituents of these simple 
 formulae corresponds almost exactly with the volumetric 
 relation found in the products of combustion which the 
 
BETWEEN THE PRODUCTS OP COMBUSTION. 201 
 
 oxygen formed, when divided between the two gases pre- 
 sent in excess. 
 
 In each of the nine mixtures which we have con- 
 sidered, a regular system of molecular attractions has 
 been formed as the resultant of the respective attractions 
 of the non- combustible, as well as of the combustible 
 particles ; and this system of attractions is of such a kind 
 that the atoms exposed to it arrange themselves so as 
 to form the six most simple hydrates of carbonic acid. 
 

 TABLES 
 
 FOR 
 
 THE CALCULATION OF ANALYSES. 
 

TABLE OF THE TENSION OF THE VAPOUR OF WATER. 265 
 
 I. 
 
 Table of the tension of aqueous vapour for temperatures 
 from 2 to -j-35C., according to Regnault. 
 
 C. Tension. 
 
 C. 
 
 Tension. 
 
 C. 
 
 Tension. 
 
 C. 
 
 Tension. 
 
 
 2.0 
 
 3.955 
 
 
 -f-2.0 
 
 mm 
 
 5.302 
 
 
 -{-6.0 
 
 mm 
 
 6.998 
 
 
 -4- 10.0 
 
 mm 
 
 9.165 
 
 1.9 
 
 3.985 
 
 2.1 
 
 5.340 
 
 6.1 
 
 7.047 
 
 10.1 
 
 9.227 
 
 1.8 
 
 4.016 
 
 2.2 
 
 5.378 
 
 6.2 
 
 7.095 
 
 10.2 
 
 9.288 
 
 1.7 
 
 4.047 
 
 2.3 
 
 5.416 
 
 6.3 
 
 7.144 
 
 10.3 
 
 9.350 
 
 1.6 
 
 4.078 
 
 2.4 
 
 5.454 
 
 6.4 
 
 7.193 
 
 10.4 
 
 9.412 
 
 1.5 
 
 4.109 
 
 2.5 
 
 5.491 
 
 6.5 
 
 7.242 
 
 10.5 
 
 9.474 
 
 1.4 
 
 4.140 
 
 2.6 
 
 5.530 
 
 6.6 
 
 7.292 
 
 10.6 
 
 9.537 
 
 1.3 
 
 4.171 
 
 2.7 
 
 5.569 
 
 6.7 
 
 7.342 
 
 10.7 
 
 9.601- 
 
 1.2 
 
 4.203 
 
 2.8 
 
 5.608 
 
 6.8 
 
 7.392 
 
 10.8 
 
 9.665 
 
 1.1 
 
 4.235 
 
 2.9 
 
 5.647 
 
 6.9 
 
 7.442 
 
 10.9 
 
 9.728 
 
 1.0 
 
 4.267 
 
 3.0 
 
 5.687 
 
 7.0 
 
 7.492 
 
 11.0 
 
 9.792 
 
 0.9 
 
 4.299 
 
 3.1 
 
 5.727 
 
 7.1 
 
 7.544 
 
 11.1 
 
 9.857 
 
 0.8 
 
 4.331 
 
 3.2 
 
 5.767 
 
 7.2 
 
 7.595 
 
 11.2 
 
 9.923 
 
 0.7 
 
 4.364 
 
 3.3 
 
 5.807 
 
 7.3 
 
 7.647 
 
 11.3 
 
 9.989 
 
 0.6 
 
 4.397 
 
 3.4 
 
 5.848 
 
 7.4 
 
 7.699 
 
 11.4 
 
 10.054 
 
 0.5 
 
 4.430 
 
 3.5 
 
 5.889 
 
 7.5 
 
 7.751 
 
 11.5 
 
 10.120 
 
 0.4 
 
 4.463 
 
 3.6 
 
 5.930 
 
 7.6 
 
 7.804 
 
 11.6 
 
 10.187 
 
 0.3 
 
 4.497 
 
 3.7 
 
 5.972 
 
 7.7 
 
 7.857 
 
 11.7 
 
 10.255 
 
 0.2 
 
 4.531 
 
 3.8 
 
 6.014 
 
 7.8 
 
 7.910 
 
 11.8 
 
 10.322 
 
 0.1 
 
 4.565 
 
 3.9 
 
 6.055 
 
 7.9 
 
 7.964 
 
 11.9 
 
 10.389 
 
 0.0 
 
 4.600 
 
 4.0 
 
 6.097 
 
 8.0 
 
 8.017 
 
 12.0 
 
 10.457 
 
 + 0.1 
 
 4.633 
 
 4.1 
 
 6.140 
 
 8.1 
 
 8.072 
 
 12.1 
 
 10.526 
 
 0.2 
 
 4.667 
 
 4.2 
 
 6.183 
 
 8.2 
 
 8.126 
 
 12.2 
 
 10.596 
 
 0.3 
 
 4.700 
 
 4.3 
 
 6.226 
 
 8.3 
 
 8.181 
 
 12.3 
 
 10.665 
 
 0.4 
 
 4.733 
 
 4.4 
 
 6.270 
 
 8.4 
 
 8.236 
 
 12.4 
 
 10.734 
 
 0.5 
 
 4.767 
 
 4.5 
 
 6.313 
 
 8.5 
 
 8.291 
 
 12.5 
 
 10.804 
 
 0.6 
 
 4.801 
 
 4.6 
 
 6.357 
 
 8.6 
 
 8.347 
 
 12.6 
 
 10.875 
 
 0.7 
 
 4.836 
 
 4.7 
 
 6.401 
 
 8.7 
 
 8.404 
 
 12.7 
 
 10.947 
 
 0.8 
 
 4.871 
 
 4.8 
 
 6.445 
 
 8.8 
 
 8.461 
 
 12.8 
 
 11.019 
 
 0.9 
 
 4.905 
 
 4.9 
 
 6.490 
 
 8.9 
 
 8.517 
 
 12.9 
 
 11.090 
 
 1.0 
 
 4.940 
 
 5.0 
 
 6.534 
 
 9.0 
 
 8.574 
 
 13.0 
 
 11.162 
 
 1.1 
 
 4.975 
 
 5.1 
 
 6.580 
 
 9.1 
 
 8.632 
 
 13.1 
 
 11.235 
 
 1.2 
 
 5.011 
 
 5.2 
 
 6.625 
 
 9.2 
 
 8.690 
 
 13.2 
 
 11.309 
 
 1.3 
 
 5.047 
 
 5.3 
 
 6.671 
 
 9.3 
 
 8.748 
 
 13.3 
 
 11.383 
 
 1.4 
 
 5.082 
 
 5.4 
 
 6.717 
 
 '9.4 
 
 8.807 
 
 13.4 
 
 11.456 
 
 1.5 
 
 5.118 
 
 5.5 
 
 6.763 
 
 9.5 
 
 8.865 
 
 13.5 
 
 11.530 
 
 1.6 
 
 5.155 
 
 5.6 
 
 6.810 
 
 9.6 
 
 8.925 
 
 13.6 
 
 11.605 
 
 1.7 
 
 5.191 
 
 5.7 
 
 6.857 
 
 9.7 
 
 8.985 
 
 13.7 
 
 11.681 
 
 1.8 
 
 5.228 
 
 5.8 
 
 6.904 
 
 9.8 
 
 9.045 
 
 13.8 
 
 11.757 
 
 1.9 
 
 5.265 
 
 5.9 
 
 6.951 
 
 9.9 
 
 9.105 
 
 13.9 
 
 11.832 
 
266 
 
 TABLE OF THE TENSION 
 
 c. 
 
 Tension. 
 
 C. 
 
 Tension. C. 
 
 Tension. C. 
 
 Tension. 
 
 
 -}- 14.0 
 
 ll!908 
 
 
 + 18.0 
 
 mm 
 
 15.357 
 
 
 
 + 22.0 
 
 mm 
 
 19.659 
 
 
 + 26.0 
 
 mm 
 
 24.988 
 
 14.1 
 
 11.986 
 
 18.1 
 
 15.454 
 
 22.1 
 
 19.780 
 
 26.1 
 
 25.138 
 
 14.2 
 
 12.064 
 
 18.2 
 
 15.552 
 
 22.2 
 
 19.901 
 
 26.2 
 
 25.288 
 
 14.3 
 
 12.142 
 
 18.3 
 
 15.650 
 
 22.3 
 
 20.022 
 
 26.3 
 
 25.438 
 
 14.4 
 
 12.220 
 
 18.4 
 
 15.747 
 
 22.4 
 
 20.143 
 
 26.4 
 
 25.588 
 
 14.5 
 
 12.298 
 
 18.5 
 
 15.845 
 
 22.5 
 
 20.265 
 
 26.5 
 
 25.738 
 
 14.6 
 
 12.378 
 
 18.6 
 
 15.945 
 
 22.6 
 
 20.389 
 
 26.6 
 
 25.891 
 
 14.7 
 
 12.458 
 
 18.7 
 
 16.045 
 
 22.7 
 
 20.514 
 
 26.7 
 
 26.045 
 
 14.8 
 
 12.538 
 
 18.8 
 
 16.145 
 
 22.8 
 
 20.639 
 
 26.8 
 
 26.198 
 
 14.9 
 
 12.619 
 
 18.9 
 
 16.246 
 
 22.9 
 
 20.763 
 
 26.9 
 
 26.351 
 
 15.0 
 
 12.699 
 
 19.0 
 
 16.346 
 
 23.0 
 
 20.888 
 
 27.0 
 
 26.505 
 
 ' 15.1 
 
 12.781 
 
 19.1 
 
 16.449 
 
 23.1 
 
 21.016 
 
 27.1 
 
 26.663 
 
 15.2 
 
 12.864 
 
 19.2 
 
 16.552 
 
 23.2 
 
 21.144 
 
 27.2 
 
 26.820 
 
 15.3 
 
 12.947 
 
 19.3 
 
 16.655 
 
 23.3 
 
 21.272 
 
 27.3 
 
 26.978 
 
 15.4 
 
 13.029 
 
 19.4 
 
 16.758 
 
 23.4 
 
 21.400 
 
 27.4 
 
 27.136 
 
 15.5 
 
 13.112 
 
 19.5 
 
 16.861 
 
 23.5 
 
 21.528 
 
 27.5 
 
 27.294 
 
 15.6 
 
 13.197 
 
 19.6 
 
 16.967 
 
 23.6 
 
 21.659 
 
 27.6 
 
 27.455 
 
 15.7 
 
 13.281 
 
 19.7 
 
 17.073 
 
 23.7 
 
 21.790 
 
 27.7 
 
 27.617 
 
 15.8 
 
 13.366 
 
 19.8 
 
 17.179 
 
 23.8 
 
 21.921 
 
 27.8 
 
 27.778 
 
 15.9 
 
 13.451 
 
 19.9 
 
 17.285 
 
 23.9 
 
 22.053 
 
 27.9 
 
 27.939 
 
 16.0 
 
 13.536 
 
 20.0 
 
 17.391 
 
 24.0 
 
 22.184 
 
 28.0 
 
 28.101 
 
 16.1 
 
 13.623 
 
 20.1 
 
 17.500 
 
 24.1 
 
 22.319 
 
 28.1 
 
 28.267 
 
 16.2 
 
 13.710 
 
 20.2 
 
 17.608 
 
 24.2 
 
 22.453 
 
 28.2 
 
 28.433 
 
 16.3 
 
 13.797 
 
 20.3 
 
 17.717 
 
 24.3 
 
 22.588 
 
 28.3 
 
 28.599 
 
 16.4 
 
 13.885 
 
 20.4 
 
 17.826 
 
 24.4 
 
 22.723 
 
 28.4 
 
 28.765 
 
 16.5 
 
 13.972 
 
 20.5 
 
 17.935 
 
 24.5 
 
 22.858 
 
 28.5 
 
 28.931 
 
 16.6 
 
 14.062 
 
 20.6 
 
 18.047 
 
 24.6 
 
 22.996 
 
 28.6 
 
 .29.101 
 
 16.7 
 
 14.151 
 
 20.7 
 
 18.159 
 
 24.7 
 
 23.135 
 
 28.7 
 
 29.271 
 
 16.8 
 
 14.241 
 
 20.8 
 
 18.271 
 
 24.8 
 
 23.273 
 
 28.8 
 
 29.441 
 
 16.9 
 
 14.331 
 
 20.9 
 
 18.383 
 
 24.9 
 
 23.411 
 
 28.9 
 
 29.612 
 
 17.0 
 
 14.421 
 
 21.0 
 
 18.495 
 
 25.0 
 
 23.550 
 
 29.0 
 
 29.782 
 
 17.1 
 
 14.513 
 
 21.1 
 
 18.610 
 
 25.1 
 
 23.692 
 
 29.1 
 
 29.956 
 
 17.2 
 
 14.605 
 
 21.2 
 
 18.724 
 
 25.2 
 
 23.834 
 
 29.2 
 
 30.131 
 
 17.3 
 
 14.697 
 
 21.3 
 
 18.839 
 
 25.3 
 
 23.976 
 
 29.3 
 
 30.305 
 
 17.4 
 
 14.790 
 
 21.4 
 
 18.954 
 
 25.4 
 
 24.119 
 
 29.4 
 
 30.479 
 
 17.5 
 
 14.882 
 
 21.5 
 
 19.069 
 
 25.5 
 
 24.261 
 
 29.5 
 
 30.654 
 
 17.6 
 
 14.977 
 
 21.6 
 
 19.187 
 
 25.6 
 
 24.406 
 
 29.6 
 
 30.833 
 
 17.7 
 
 15.072 
 
 21.7 
 
 19.305 
 
 25.7 
 
 24.552 
 
 29.7 
 
 31.011 
 
 17.8 
 
 15.167 
 
 21.8 
 
 19.423 
 
 25.8 
 
 24.697 
 
 29.8 
 
 31.190 
 
 17.9 
 
 15.262 
 
 21.9 
 
 19.541 
 
 25.9 
 
 24.842 
 
 29.9 
 
 31.369 
 
OF THE VAPOUR OF WATER. 
 
 267 
 
 c. 
 
 Tension. 
 
 C. 
 
 Tension. 
 
 C. 
 
 Tension. 
 
 C. 
 
 Tension. 
 
 
 -j-30.0 
 
 31.148 
 
 
 -j-32.0 
 
 35J359 
 
 
 -f-33.0 
 
 37.410 
 
 
 -f-34.0 
 
 mm 
 
 39.565 
 
 30.1 
 
 31.729 
 
 32.1 
 
 35.559 
 
 33.1 
 
 37.621 
 
 34.1 
 
 39.786 
 
 30.2 
 
 31.911 
 
 32.2 
 
 35.760 
 
 33.2 
 
 37.832 
 
 34.2 
 
 40.007 
 
 30.3 
 
 32.094 
 
 32.3 
 
 35.962 
 
 33.3 
 
 38.045 
 
 34.3 
 
 40.230 
 
 30.4 
 
 32.278 
 
 32.4 
 
 36.165 
 
 33.4 
 
 38.258 
 
 33.4 
 
 40.455 
 
 30.5 
 
 32. 4G3 
 
 32.5 
 
 36.370 
 
 33.5 
 
 38.473 
 
 34.5 
 
 40.680 
 
 30.6 
 
 32.650 
 
 32.6 
 
 36.576 
 
 33.6 
 
 38.689 
 
 34.6 
 
 40.907 
 
 30.7 
 
 32.837 
 
 32.7 
 
 36.783 
 
 33.7 
 
 38.906 
 
 34.7 
 
 41.135 
 
 30.8 
 
 33.026 
 
 32.8 
 
 3G.991 
 
 33.8 
 
 39.124 
 
 34.8 
 
 41.364 
 
 30.9 
 
 33.215 
 
 32.9 
 
 37.200 
 
 33.9 
 
 39.344 
 
 34.9 
 
 41.595 
 
 
 
 
 
 
 
 35.0 
 
 41.827 
 
 31.0 
 
 33.405 
 
 
 
 
 
 
 
 31.1 
 
 33.596 
 
 
 
 
 
 
 
 31.2 
 
 33.787 
 
 
 
 
 
 
 
 31.3 
 
 33.980 
 
 
 
 
 
 
 
 31.4 
 
 34.174 
 
 
 
 
 
 
 
 31.5 
 
 34.368 
 
 
 
 
 
 
 
 31.6 
 
 34.564 
 
 
 
 
 
 
 
 31.7 
 
 34.761. 
 
 
 
 
 
 
 
 31.8 
 
 34.959 
 
 
 
 
 
 
 
 31.9 
 
 35.159 
 
 
 
 
 
 
 
268 TABLE FOR THE CALCULATION 
 
 II. 
 
 Table for the calculation of the value of 1 + 0.00366 t. 
 
 t. 
 
 Num. 
 
 Log. 
 
 t. 
 
 Num. 
 
 Log. 
 
 
 
 
 
 
 
 
 
 2.0 
 
 0.99268 
 
 9.99681 
 
 -(-2.0 
 
 1.00732 
 
 0.00317 
 
 1.9 
 
 0.99305 
 
 9.99697 
 
 2.1 
 
 1.00769 
 
 0.00333 
 
 L.8 
 
 0.99341 
 
 9.99713 
 
 2.2 
 
 1.00805 
 
 0.00349 
 
 1.7 
 
 0.99378 
 
 9.99729 
 
 2.3 
 
 1.00842 
 
 0.00365 
 
 1.6 
 
 0.99414 
 
 9.99745 
 
 2.4 
 
 1.00878 
 
 0.00381 
 
 1.5 
 
 0.99451 
 
 9.99761 
 
 2.5 
 
 1.00915 
 
 0.00397 
 
 1.4 
 
 0.99488 
 
 9.99777 
 
 2.6 
 
 1.00952 
 
 0.00412 
 
 1.3 
 
 9.99524 
 
 9.99793 
 
 2.7 
 
 1.00988 
 
 0.00428 
 
 1.2 
 
 0.99561 
 
 9.99809 
 
 2.8 
 
 1.01025 
 
 0.00444 
 
 1.1 
 
 0.99597 
 
 9.99825 
 
 2.9 
 
 1.01061 
 
 0.00459 
 
 1.0 
 
 0.99634 
 
 9.99841 
 
 3.0 
 
 1.01098 
 
 0.00474 
 
 0.9 
 
 0.99671 
 
 9.99857 
 
 3.1 
 
 1.01135 
 
 0.00490 
 
 0.8 
 
 0.99707 
 
 9.99873 
 
 3.2 
 
 1.01171 
 
 0.00506 
 
 0.7 
 
 0.99744 
 
 9.99888 
 
 3.3 
 
 1.01208 
 
 0.00521 
 
 0.6 
 
 0.99780 
 
 9.99904 
 
 3.4 
 
 1.01244 
 
 0.00537 
 
 0.5 
 
 0.99817 
 
 9.99920 
 
 3.5 
 
 1.01281 
 
 0.00553 
 
 0.4 
 
 0.99854 
 
 9.99937 
 
 3.6 
 
 1.01318 
 
 0.00568 
 
 0.3 
 
 0.99890 
 
 9.99952 
 
 3.7 
 
 1.01354 
 
 0.00584 
 
 0.2 
 
 0.99927 
 
 9.99968 
 
 3.8 
 
 1.01391 
 
 0.00600 
 
 0.1 
 
 0.99968 
 
 9.99984 
 
 3.9 
 
 1.01427 
 
 0.00615 
 
 0.0 
 
 1.00000 
 
 0.00000 
 
 4.0 
 
 1.01464 
 
 0.00631 
 
 + 0.1 
 
 1.00037 
 
 0.00016 
 
 4.1 
 
 1.01501 
 
 0.00647 
 
 0.2 
 
 1.00073 
 
 0.00032 
 
 4.2 
 
 1.01537 
 
 0.00663 
 
 0.3 
 
 1.00110 
 
 0.00048 
 
 4.3 
 
 1.01574 
 
 0.00678 
 
 0.4 
 
 1.00146 
 
 0.00063 
 
 4.4 
 
 1.01610 
 
 0.00694 
 
 0.5 
 
 1.00183 
 
 0.00079 
 
 4.5 
 
 1.01647 
 
 0.00710 
 
 0.6 
 
 1.00220 
 
 0.00095 
 
 4.6 
 
 1.01684 
 
 0.00725 
 
 0.7 
 
 1.00256 
 
 0.00111 
 
 4.7 
 
 1.01720 
 
 0.00741 
 
 0.8 
 
 1.00293 
 
 0.00127 
 
 4.8 
 
 1.01757 
 
 0.00756 
 
 0.9 
 
 1.00329 
 
 0.00143 
 
 4.9 
 
 1.01793 
 
 0.00772 
 
 1.0 
 
 1.00366 
 
 0.00159 
 
 5.0 
 
 1.01830 
 
 0.00788 
 
 1.1 
 
 1.00403 
 
 0.00175 
 
 5.1 
 
 1.01867 
 
 0.00803 
 
 .2 
 
 1.00439 
 
 0.00191 
 
 5.2 
 
 1.01903 
 
 0.00819 
 
 1.3 
 
 1.00476 
 
 0.00207 
 
 5.3 
 
 1.01940 
 
 0.00834 
 
 .4 
 
 1.00512 
 
 0.00222 
 
 5.4 
 
 1.01976 
 
 0.00850 
 
 1.5 
 
 1.00549 
 
 0.00238 
 
 5.5 
 
 1.02013 
 
 0.00865 
 
 1.6 
 
 1.00586 
 
 0.00254 
 
 5.6 
 
 1.02050 
 
 0.00881 
 
 1.7 
 
 1.00622 > 
 
 0.00270 
 
 5.7 
 
 1.02086 
 
 0.00896 
 
 1.8 
 
 1.00659 
 
 0.00285 
 
 5.8 
 
 1.02123 
 
 0.00912 
 
 1.9 
 
 1.00695 
 
 0.00301 
 
 5.9 
 
 1.02159 
 
 0.00927 
 
OF 1 -f 0.0036G L 
 
 2G9 
 
 L 
 
 i 
 
 Num. 
 
 Log. 
 
 /. 
 
 Num. 
 
 Log. 
 
 
 
 
 
 
 
 
 
 -j-G.O 
 
 1.02196 
 
 0.00943 
 
 -}- 10.0 
 
 1.03660 
 
 0.01561 
 
 6.1 
 
 1.02233 
 
 0.00959 
 
 10.1 
 
 1.03697 
 
 0.01577 
 
 6.2 
 
 1.02269 
 
 0.00975 
 
 10.2 
 
 1.03733 
 
 0.01592 
 
 6.3 
 
 1.02306 
 
 0.00991 
 
 10.3 
 
 1.03770 
 
 0.01607 
 
 6.4 
 
 1.02342 
 
 0.01006 
 
 10.4 
 
 1.03806 
 
 0.01623 
 
 6.5 
 
 1.02379 
 
 0.01022 
 
 10.5 
 
 1.03843 
 
 0.01639 
 
 6.6 
 
 1.02416 
 
 0.01038 
 
 10.6 
 
 1.03880 
 
 0.01653 
 
 6.7 
 
 1.02452 
 
 0.01054 
 
 10.7 
 
 1.03916 
 
 0.016G9 
 
 6.8 
 
 1.02489 
 
 0.01069 
 
 10.8 
 
 1.03953 
 
 0.01683 
 
 6.9 
 
 1.02525 
 
 0.01084 
 
 10.9 
 
 1.03989 
 
 0.01698 
 
 7.0 
 
 1.02562 
 
 0.01099 
 
 11.0 
 
 .04026 
 
 0.01714 
 
 7.1 
 
 1.02599 
 
 0.01115 
 
 11.1 
 
 .04063 
 
 0.01729 
 
 7.2 
 
 1.02635 
 
 0.01131 
 
 11.2 
 
 .04099 
 
 0.01744 
 
 7.3 
 
 1.02672 
 
 0.01147 
 
 11.3 
 
 .04136 
 
 0.01759 
 
 7.4 
 
 1.02708 
 
 0.01162 
 
 11.4 
 
 .04172 
 
 0.01775 
 
 7.5 
 
 1.02745 
 
 0.01177 
 
 11.5 
 
 .04209 
 
 0.01790 
 
 7.6 
 
 1.02782 
 
 0.01193 
 
 11.6 
 
 .04246 
 
 0.01805 
 
 7.7 
 
 1.02818 
 
 0.01208 
 
 11.7 
 
 .04282 
 
 0.01820 
 
 7.8 
 
 1.02855 
 
 0.01223 
 
 11.8 
 
 .04319 
 
 0.01836 
 
 7.9 
 
 1.02891 
 
 0.01238 
 
 11.9 
 
 .04355 
 
 0.01851 
 
 8.0 
 
 1.02928 
 
 0.01253 
 
 12.0 
 
 .04392 
 
 0.01867 
 
 8.1 
 
 1.02965 
 
 0.01269 
 
 12.1 
 
 .04429 
 
 0.01882 
 
 8.2 
 
 1.03001 
 
 0.01284 
 
 12.2 
 
 .04465 
 
 0.01897 
 
 8.3 
 
 1.03038 
 
 0.01300 
 
 12.3 
 
 .04502 
 
 0.01912 
 
 8.4 
 
 1.03074 
 
 0.01315 
 
 12.4 
 
 .04538 
 
 0.01928 
 
 8.5 
 
 1.03111 
 
 0.01330 
 
 12.5 
 
 .04575 
 
 0.01943 
 
 8.6 
 
 1.03148 
 
 0.01346 
 
 12.6 
 
 .04612 
 
 0.01958 
 
 8.7 
 
 1.03184 
 
 0.01361 
 
 12.7 
 
 .04648 
 
 0.01973 
 
 8.8 
 
 1.03221 
 
 0.01377 
 
 12.8 
 
 .04685 
 
 0.01989 
 
 8.9 
 
 1.03257 
 
 0.01392 
 
 12.9 
 
 .04721 
 
 0.02004 
 
 9.0 
 
 1.03294 
 
 0.01407 
 
 13.0 
 
 1.04758 
 
 0.02019 
 
 9.1 
 
 1.03331 
 
 0.01423 
 
 13.1 
 
 1.04795 
 
 0.02034 
 
 9.2 
 
 1.03367 
 
 0.01438 
 
 13.2 
 
 1.04831 
 
 0.02049 
 
 9.3 
 
 1.03404 
 
 0.01454 
 
 13.3 
 
 1.04868 
 
 0.02064 
 
 9.4 
 
 1.03440 
 
 0.01469 
 
 13.4 
 
 1.04904 
 
 0.02079 
 
 9.5 
 
 1.03477 
 
 0.01484 
 
 13.5 
 
 1.04941 
 
 0.02095 
 
 9.6 
 
 1.03514 
 
 0.01500 
 
 13.6 
 
 1.04978 
 
 0.02110 
 
 9.7 
 
 1.03550 
 
 0.01515 
 
 13.7 
 
 1.05014 
 
 0.02125 
 
 9.8 
 
 1.03587 
 
 0.01530 
 
 13.8 
 
 1.05051 
 
 0.02140 
 
 9.9 
 
 1.03G23 
 
 0.01545 
 
 13.9 
 
 1.05087 
 
 0.02155 
 
270 
 
 TABLE FOR THE CALCULATION 
 
 t. 
 
 Num. 
 
 Log. 
 
 t. 
 
 Num. 
 
 Log. 
 
 
 -|-14.0 
 
 1.05124 
 
 0.02170 
 
 
 + 18.0 
 
 1.06588 
 
 0.02771 
 
 14.1 
 
 1.05161 
 
 0.02185 
 
 18.1 
 
 1.06625 
 
 0.02786 
 
 14.2 
 
 1.05197 
 
 0.02200 
 
 18.2 
 
 1.00661 
 
 0.02801 
 
 14.3 
 
 1.05234 
 
 0.02215 
 
 18.3 
 
 1.06698 
 
 0.02816 
 
 14.4 
 
 1.05270 
 
 0.02230 
 
 18.4 
 
 1.06734 
 
 0.02831 
 
 14.5 
 
 1.05307 
 
 0.02246 
 
 18.5 
 
 1.06771 
 
 0.02846 
 
 14.6 
 
 1.05344 
 
 0.02261 
 
 18.6 
 
 1.06808 
 
 0.02861 
 
 14.7 
 
 1.05380 
 
 0.02276 
 
 18.7 
 
 1.06844 
 
 0.02876 
 
 14.8 
 
 1.05417 
 
 0.02291 
 
 18.8 
 
 1.06881 
 
 0.02891 
 
 14.9 
 
 1.05453 
 
 0.02306 
 
 18.9 
 
 1.06917 
 
 0.02906 
 
 15.0 
 
 1.05490 
 
 0.02321 
 
 19.0 
 
 1.06954 
 
 0.02921 
 
 15.1 
 
 1.05527 
 
 0.02336 
 
 19.1 
 
 1.06991' 
 
 0.02936 
 
 15.2 
 
 1.05563 
 
 0.02351 
 
 19.2 
 
 1.07027 
 
 0.02951 
 
 15.3 
 
 1.05600 
 
 0.02366 
 
 19.3 
 
 1.07064 
 
 0.02965 
 
 15.4 
 
 1.05636 
 
 0.02381 
 
 19.4 
 
 1.07100 
 
 0.02980 
 
 15.5 
 
 1.05673 
 
 0.02396 
 
 19.5 
 
 1.07137 
 
 0.02995 
 
 15.6 
 
 1.05710 
 
 0.02411 
 
 19.6 
 
 1.07174 
 
 0.03009 
 
 15.7 
 
 1.05746 
 
 0.02426 
 
 19.7 
 
 1.07210 
 
 0.03024 
 
 15.8 
 
 1.05783 
 
 0.02441 
 
 19.8 
 
 1.07247 
 
 0.03039 
 
 15.9 
 
 1.05819 
 
 0.02456 
 
 19.9 
 
 1.07283 
 
 0.03053 
 
 16.0 
 
 1.05856 
 
 0.02471 
 
 20.0 
 
 1.07320 
 
 0.03068 
 
 16.1 
 
 1.05893 
 
 0.02486 
 
 20.1 
 
 1.07357 
 
 0.03083 
 
 16.2 
 
 1.05929 
 
 0.02501 
 
 20.2 
 
 1.07393 
 
 0.03098 
 
 16.3 
 
 1.05966 
 
 0.02516 
 
 20.3 
 
 1.07430 
 
 0.03113 
 
 16.4 
 
 1.06002 
 
 0.02531 
 
 20.4 
 
 1.07466 
 
 0.03128 
 
 16.5 
 
 1.06039 
 
 0.02546 
 
 20.5 
 
 1.07503 
 
 0.03142 
 
 16.6 
 
 1.06076 
 
 0.02561 
 
 20.6 
 
 1.07540 
 
 0.03157 
 
 16.7 
 
 1.06112 
 
 0.02576 
 
 20.7 
 
 1.07576 
 
 0.03172 
 
 16.8 
 
 1.06149 
 
 0.02591 
 
 20.8 
 
 1.07613 
 
 0.03187 
 
 16.9 
 
 1.06185 
 
 0.02606 
 
 20.9 
 
 1.07649 
 
 0.03201 
 
 17.0 
 
 1.06222 
 
 0.02621 
 
 21.0 
 
 1.07686 
 
 0.03216 
 
 17.1 
 
 1.06259 
 
 0.02636 
 
 21.1 
 
 1.07723 
 
 0.03231 
 
 17.2 
 
 1.06295 
 
 0.02651 
 
 21.2 
 
 1.07759 
 
 0.03246 
 
 17.3 
 
 1.06332 
 
 0.02666 
 
 21.3 
 
 1.07796 
 
 0.03261 
 
 17.4 
 
 1.06368 
 
 0.02681 
 
 21.4 
 
 1.07832 
 
 0.03275 
 
 17.5 
 
 1.06405 
 
 0.02696 
 
 21.5 
 
 1.07869 
 
 0.03290 
 
 17.6 
 
 1.06442 
 
 0.02711 
 
 21.6 
 
 1.07906 
 
 0.03305 
 
 17.7 
 
 1.06478 
 
 0.02726 
 
 21.7 
 
 1.07942 
 
 0.03320 
 
 17.8 
 
 1.06515 
 
 0.02741 
 
 21.8 
 
 1.07979 
 
 0.03334 
 
 17.9 
 
 1.06551 
 
 0.02756 
 
 21.9 
 
 1.08015 
 
 0.03349 
 
OF 1 -f 0.003G6 t. 
 
 271 
 
 t. 
 
 Num. 
 
 Log. 
 
 /. 
 
 Num. 
 
 Log. 
 
 
 
 
 
 
 
 
 
 -j- 22.0 
 
 1.08052 
 
 0.03363 
 
 -j-26.0 
 
 1.09516 
 
 0.03948 
 
 2-2.1 
 
 1.08089 
 
 0.03378 
 
 26.1 
 
 1.09553 
 
 0.03963 
 
 22.2 
 
 1.08125 
 
 0.05393 
 
 26.2 
 
 1.09589 
 
 0.03977 
 
 22.3 
 
 .08162 
 
 0.03408 
 
 26.3 
 
 1.09626 
 
 0.03992 
 
 22.4 
 
 .08198 
 
 0.03422 
 
 26.4 
 
 1.09662 
 
 0.04006 
 
 22.5 
 
 .08235 
 
 0.03437 
 
 26.5 
 
 1.09699 
 
 0.04021 
 
 22.6 
 
 .08272 
 
 0.03452 
 
 26.6 
 
 1.09736 
 
 0.04035 
 
 2-J.7 
 
 .08308 
 
 0.03466 
 
 26.7 
 
 1.09772 
 
 0.04050 
 
 22.8 
 
 1.08345 
 
 0.03481 
 
 26.8 
 
 1.09809 
 
 0.04064 
 
 22.9 
 
 1.08381 
 
 0.03496 
 
 26.9 
 
 1.09845 
 
 0.04079 
 
 23.0 
 
 1.08418 
 
 0.03510 
 
 27.0 
 
 1.09882 
 
 0.04093 
 
 23.1 
 
 1.08455 
 
 0.03525 
 
 27.1 
 
 1.09919 
 
 0.04107 
 
 23.2 
 
 1.08491 
 
 0.03539 
 
 27.2 
 
 1.09955 
 
 0.04122 
 
 23.3 
 
 1.08528 
 
 0.03554 
 
 27.3 
 
 1.09992 
 
 0.04136 
 
 23.4 
 
 1.08564 
 
 0.03568 
 
 27.4 
 
 1.10028 
 
 0.04150 
 
 23.5 
 
 .1.08601 
 
 0.03583 
 
 27.5 
 
 1.10065 
 
 0.04165 
 
 23.6 
 
 1.08638 
 
 0.03598 
 
 27.6 
 
 1.10102 
 
 0.04179 
 
 23.7 
 
 1.08674 
 
 0.03612 
 
 27.7 
 
 1.10138 
 
 0.04193 
 
 23.8 
 
 1.08711 
 
 0.03627 
 
 27.8 
 
 1.10175 
 
 0.04208 
 
 23.9 
 
 1.08747 
 
 0.03642 
 
 27.9 
 
 1.10211 
 
 0.04222 
 
 24.0 
 
 1.08784 
 
 0.03656 
 
 28.0 
 
 1.10248 
 
 0.04237 
 
 24.1 
 
 1.08821 
 
 0.03671 
 
 28.1 
 
 1.10285 
 
 0.04251 
 
 24.2 
 
 1.08857 
 
 0.03685 
 
 28.2 
 
 1.10321 
 
 0.04266 
 
 24.3 
 
 .08894 
 
 0.03700 
 
 28.3 
 
 1.10358 
 
 0.04280 
 
 24.4 
 
 .08930 
 
 0.03714 
 
 28.4 
 
 1.10394 
 
 0.04295 
 
 24.5 
 
 .08967 
 
 0.03729 
 
 28.5 
 
 1.10431 
 
 0.04309 
 
 24.6 
 
 .09004 
 
 0.03744 
 
 28.6 
 
 1.10468 
 
 0.04323 
 
 24.7 
 
 .09040 
 
 0.03758 
 
 28.7 
 
 1.10504 
 
 0.04338 
 
 24.8 
 
 .09077 
 
 0.03772 
 
 28.8 
 
 1.10541 
 
 0.04352 
 
 24.9 
 
 .09113 
 
 0.03787 
 
 28.9 
 
 1.10577 
 
 0.04367 
 
 25.0 
 
 .09150 
 
 0.03802 
 
 29.0 
 
 1.10614 
 
 0.04381 
 
 25.1 
 
 .09187 
 
 0.03817 
 
 29.1 
 
 1.10651 
 
 0.04395 
 
 25.2 
 
 .09223 
 
 0.03831 
 
 29.2 
 
 1.10G87 
 
 0.04410 
 
 25.3 
 
 .09260 
 
 0.03846 
 
 29.3 
 
 1.10724 
 
 0.04424 
 
 25.4 
 
 .09296 
 
 0.03860 
 
 29.4 
 
 1.10760 
 
 0.04438 
 
 25.5 
 
 .09333 
 
 0.03875 
 
 29.5 
 
 1.10797 
 
 0.04453 
 
 25.6 
 
 .09370 
 
 0.03889 
 
 29.6 
 
 1.10834 
 
 0.04467 
 
 25.7 
 
 .09406 
 
 0.03904 
 
 29.7 
 
 ' 1.10870 
 
 0.044S2 
 
 25.8 
 
 1.09443 
 
 0.03918 
 
 29.8 
 
 1.10907 
 
 0.04496 
 
 25.9 
 
 1.09479 
 
 0.03933 
 
 29.9 
 
 1.10943 
 
 0.04510 
 
272 
 
 TABLE FOR THE CALCULATION 
 
 t. 
 
 Num. 
 
 Log. 
 
 t. 
 
 Num. 
 
 Log. 
 
 
 -j-30.0 
 
 1.10980 
 
 0.04524 
 
 
 -f- 34.0 
 
 1.12444 
 
 0.05094 
 
 30.1 
 
 1.11017 
 
 0.04538 
 
 34.1 
 
 1.12481 
 
 0.05108 
 
 30.2 
 
 1.11053 
 
 0.04552 
 
 34.2 
 
 1.12517 
 
 0.05122 
 
 30.3 
 
 1.11090 
 
 0.04567 
 
 34.3 
 
 1.12554 
 
 0.05136 
 
 30.4 
 
 1.11126 
 
 0.04581 
 
 34.4 
 
 1.12590 
 
 0.05150 
 
 30.5 
 
 1.11163 
 
 0.04595 
 
 34.5 
 
 1.12627 
 
 0.05164 
 
 30.6 
 
 1.11200 
 
 0.04610 
 
 34.6 
 
 1.12664 
 
 0.05178 
 
 30.7 
 
 1.11236 
 
 0.04624 
 
 34.7 
 
 1.12700 
 
 0.05193 
 
 30.8 
 
 1.11273 
 
 0.04638 
 
 34.8 
 
 1.12737 
 
 0.05207 
 
 30.9 
 
 1.11309 
 
 0.04653 
 
 34.9 
 
 1.12773 
 
 0.05221 
 
 31.0 
 
 1.11346 
 
 0.04667 
 
 35.0 
 
 1.12810 
 
 0.05235 
 
 31.1 
 
 1.11383 
 
 0.04681 
 
 35.1 
 
 1.12847 
 
 0.05249 
 
 31.2 
 
 1.11419 
 
 0.04695 
 
 35.2 
 
 1.12883 
 
 0.05263 
 
 31.3 
 
 1.11456 
 
 0.04710 
 
 35.3 
 
 1.12920 
 
 0.05277 
 
 31.4 
 
 1.11492 
 
 0.04724 
 
 35.4 
 
 1.12956 
 
 0.05291 
 
 31.5 
 
 1.11529 
 
 0.04738 
 
 35.5 
 
 1.12993 
 
 0.05305 
 
 31.6 
 
 1.11566 
 
 0.04753 
 
 35.6 
 
 1.13030 
 
 0.05319 
 
 31.7 
 
 1.11602 
 
 0.04767 
 
 35.7 
 
 1.13066 
 
 0.05333 
 
 31.8 
 
 1.11639 
 
 0.04781 
 
 35.8 
 
 1.13103 
 
 0.05347 
 
 31.9 
 
 1.11675 
 
 0.04796 
 
 35.9 
 
 1.13139 
 
 0.05361 
 
 32.0 
 
 1.11712 
 
 0.04810 
 
 3G.O 
 
 1.13176 
 
 0.05375 
 
 32.1 
 
 1.11749 
 
 0.04824 
 
 36.1 
 
 1.13213 
 
 0.05389 
 
 32.2 
 
 1.11785 
 
 0.04838 
 
 36.2 
 
 1 13249 
 
 0.05403 
 
 32.3 
 
 1.11822 
 
 0.04852 
 
 36.3 
 
 1.1328G 
 
 0.05417 
 
 32.4 
 
 1.11858 
 
 0.04866 
 
 36.4 
 
 1.13322 
 
 0.05431 
 
 32.5 
 
 1.11895 
 
 0.04881 
 
 36.5 
 
 1.13359 
 
 0.05446 
 
 32.6 
 
 1.11932 
 
 0.04895 
 
 36.6 
 
 1.13396 
 
 0.05460 
 
 32.7 
 
 1.11968 
 
 0.04909 
 
 36.7 
 
 1.13432 
 
 0.05474 
 
 32.8 
 
 1.12005 
 
 0.04923 
 
 36.8 
 
 1.13469 
 
 0.05488 
 
 32.9 
 
 1.12041 
 
 0.04938 
 
 36.9 
 
 1.13505 
 
 0.05502 
 
 33.0 
 
 1.12078 
 
 0.04952 
 
 37.0 
 
 1.13542 
 
 0.05516 
 
 33.1 
 
 1.12115 
 
 0.04966 
 
 37.1 
 
 1.13579 
 
 0.05530 
 
 33.2 
 
 1.12151 
 
 0.04980 
 
 37.2 
 
 1.13615 
 
 0.05544 
 
 33.3 
 
 1.12188 
 
 0.04994 
 
 37.3 
 
 1.13652 
 
 0.05558 
 
 33.4 
 
 1.12224 
 
 0.05008 
 
 37.4 
 
 1.13688 
 
 0.05572 
 
 33.5 
 
 1.12261 
 
 0.05022 
 
 37.5 
 
 1.13725 
 
 0.05585 
 
 33.6 
 
 1.12298 
 
 0.05036 
 
 37.6 
 
 1.13762 
 
 0.05599 
 
 33.7 
 
 1.12334 
 
 0.05050 
 
 37.7 
 
 1.13798 
 
 0.05613 
 
 33.8 
 
 1.12371 
 
 0.05065 
 
 37.8 
 
 1.13835 
 
 0.05627 
 
 33.9 
 
 1.12407 
 
 0.05079 
 
 37.9 
 
 1.13871 
 
 0.05641 
 
OF 1 -f- 0.003GG t. 
 
 t. 
 
 Num. 
 
 Log. 
 
 < 
 
 Num. 
 
 Log. 
 
 
 
 
 
 
 
 
 
 -j-38.0 
 
 1.13908 
 
 0.05655 
 
 -j-39.0 . 
 
 1.14274 
 
 0.05795 
 
 38.1 
 
 1.13945 
 
 0.05669 
 
 39.1 
 
 1.14311 
 
 0.05809 
 
 38.2 
 
 1.13981 
 
 0.05683 
 
 39.2 
 
 1.14347 
 
 0.05823 
 
 38.3 
 
 1.14018 
 
 0.05697 
 
 39.3 
 
 1.14384 
 
 0.05837 
 
 38.4 
 
 1.14054 
 
 0.05711 
 
 39.4 
 
 1.14420 
 
 0.05850 
 
 38.5 
 
 1.14091 
 
 0.05725 
 
 39.5 
 
 1.14457 
 
 0.05864 
 
 38.6 
 
 1.14128 
 
 0.05739 
 
 39.6 
 
 1.14494 
 
 0.05878 
 
 38.7 
 
 1.14164 
 
 0.05753 
 
 39.7 
 
 1.14530 
 
 0.05892 
 
 38.8 
 
 1.14201 
 
 0.05767 
 
 39.8 
 
 1.14567 
 
 0.05905 
 
 38.9 
 
 1.14237 
 
 0.05781 
 
 39.9 
 
 1.14603 
 
 0.05919 
 
 
 
 
 40.0 
 
 1.14640 
 
 0.05933 
 
274 TABLE OF THE TENSION OF THE VAPOUR 
 
 HI. 
 
 Table of the tension of the vapour of absolute alcohol, 
 according to Regnault. * 
 
 .* 
 
 Tension 
 
 a" 
 
 Tension. C. 
 
 Tension 
 
 c. 
 
 Tension. 
 
 
 
 mm 
 
 
 
 mm 
 
 
 
 mm 
 
 
 
 mm 
 
 0.0 
 
 12.73 
 
 4.0 
 
 16.62 
 
 8.0 
 
 21.31 
 
 12.0 
 
 27.19 
 
 0.1 
 
 12.82 
 
 4.1 
 
 16.73 
 
 8.1 
 
 21.45 
 
 12.1 
 
 27.36 
 
 0.2 
 
 12.91 
 
 4.2 
 
 16.84 
 
 8.2 
 
 21.58 
 
 12.2 
 
 27.53 
 
 0.3 
 
 13.01 
 
 4.3 
 
 16.95 
 
 8.3 
 
 21.72 
 
 12.3 
 
 27.70 
 
 0.4 
 
 13.10 
 
 4.4 
 
 17.05 
 
 8.4 
 
 21.85 
 
 12.4 
 
 27.87 
 
 0.5 
 
 13.19 
 
 4.5 
 
 17.16 
 
 8.5 
 
 21.99 
 
 12.5 
 
 28.04 
 
 0.6 
 
 13.28 
 
 4.6 
 
 17.27 
 
 8.6 
 
 22.12 
 
 12.6 
 
 28.21 
 
 0.7 
 
 13.37 
 
 4.7 
 
 17.38 
 
 8.7 
 
 22.25 
 
 12.7 
 
 28.38 
 
 0.8 
 
 13.46 
 
 4.8 
 
 17.48 
 
 8.8 
 
 22.39 
 
 12.8 
 
 28.55 
 
 0.9 
 
 13.56 
 
 4.9 
 
 17.59 
 
 8.8 
 
 22.52 
 
 12.9 
 
 28.72 
 
 1.0 
 
 13.65 
 
 5.0 
 
 17.70 
 
 9.0 
 
 22.66 
 
 13.0 
 
 28.89 
 
 1.1 
 
 13.74 
 
 5.1 
 
 17.82 
 
 9.1 
 
 22.80 
 
 13.1 
 
 29.07 
 
 1.2 
 
 13.84 
 
 5.2 
 
 17.93 
 
 9.2 
 
 22.94 
 
 13.2 
 
 29.25 
 
 1.3 
 
 13.93 
 
 5.3 
 
 18.04 
 
 9.3 
 
 23.08 
 
 13.3 
 
 29.43 
 
 1.4 
 
 14.03 
 
 5.4 
 
 18.16 
 
 9.4 
 
 23.23 
 
 13.4 
 
 29.61 
 
 1.5 
 
 14.12 
 
 5.5 
 
 18.27 
 
 9.5 
 
 23.37 
 
 13.5 
 
 29.79 
 
 1.6 
 
 14.22 
 
 5.6 
 
 18.38 
 
 9.6 
 
 23.51 
 
 13.6 
 
 29.97 
 
 1.7 
 
 14.31 
 
 5.7 
 
 18.50 
 
 9.7 
 
 23.65 
 
 13.7 
 
 30.15 
 
 1.8 
 
 14.41 
 
 5.8 
 
 18.61 
 
 9.8 
 
 23.79 
 
 13.8 
 
 30.23 
 
 1.9 
 
 14.50 
 
 5.9 
 
 18.73 
 
 9.9 
 
 23.94 
 
 13.9 
 
 30.51 
 
 2.0 
 
 14.60 
 
 6.0 
 
 18.84 
 
 10.0 
 
 24.08 
 
 14.0 
 
 30. G9 
 
 2.1 
 
 14.70 
 
 6.1 
 
 18.96 
 
 .10.1 
 
 24.23 
 
 14.1 
 
 30.88 
 
 2.2 
 
 14.79 
 
 6.2 
 
 19.08 
 
 10.2 
 
 24.38 
 
 14.2 
 
 31.07 
 
 2.3 
 
 14.89 
 
 6.3 
 
 19.20 
 
 10.3 
 
 24.53 
 
 14.3 
 
 31.26 
 
 2.4 
 
 14.99 
 
 6.4 
 
 19.32 
 
 10.4 
 
 24.68 
 
 14.4 
 
 31.45 
 
 2.5 
 
 15.09 
 
 6.5 
 
 19.44 
 
 10.5 
 
 24.83 
 
 14.5 
 
 31.64 
 
 2.6 
 
 15.19 
 
 6.6 
 
 19.56 
 
 10.6 
 
 24.99 
 
 14.6 
 
 31.84 
 
 2.7 
 
 16.29 
 
 6.7 
 
 19.68 
 
 10.7 
 
 25.14 
 
 14.7 
 
 32.03 
 
 2.8 
 
 15.39 
 
 6.8 
 
 19.80 
 
 10.8 
 
 25.29 
 
 14.8 
 
 32.22 
 
 2.9 
 
 15.49 
 
 6.9 
 
 19.92 
 
 10.9 
 
 25.44 
 
 14.9 
 
 32.41 
 
 3.0 
 
 15.59 
 
 7.0 
 
 20.04 
 
 11.0 
 
 25.59 
 
 15.0 
 
 32.60 
 
 3.1 
 
 15.69 
 
 7.1 
 
 20.17 
 
 11.1 
 
 25.75 
 
 15.1 
 
 32.80 
 
 3.2 
 
 15.79 
 
 7.2 
 
 20.30 
 
 11.2 
 
 .25.91 
 
 15.2 
 
 33.01 
 
 3.3 
 
 15.90 
 
 7.3 
 
 20.43 
 
 11.3 
 
 26.07 
 
 15.3 
 
 33.21 
 
 3.4 
 
 16.00 
 
 7.4 
 
 20.55 
 
 11.4 
 
 26.23 
 
 15.4 
 
 33.41 
 
 3.5 
 
 16.10 
 
 7.5 
 
 20.68 
 
 11.5 
 
 26.39 
 
 15.5 
 
 33.61 
 
 3.6 
 
 16.21 
 
 7.6 
 
 20.81 
 
 11.6 
 
 26.55 
 
 15.6 
 
 33.82 
 
 3.7 
 
 16.31 
 
 7.7 
 
 20.93 
 
 11.7 
 
 26.71 
 
 15.7 
 
 34.02 
 
 3.8 
 
 16.41 
 
 7.8 
 
 21.06 
 
 11.8 
 
 26.87 
 
 15.8 
 
 34.22 
 
 3.9 
 
 16.52 
 
 7.9 
 
 21.19 
 
 11.9 
 
 27.03 
 
 15.9 
 
 34.42 
 
 * This table is calculated from recent experiments of Regnault. 
 
OF ABSOLUTE ALCOHOL, ACCORDING TO REGNAULT. 275 
 
 y c. 
 
 Tension. 
 
 C. 
 
 Tension. 
 
 C. 
 
 Tension. 
 
 C. 
 
 Tension. 
 
 
 16.0 
 
 mm 
 
 34.62 
 
 
 20.0 
 
 mm 
 
 44.00 
 
 
 24.0 
 
 mm 
 
 55.70 
 
 
 28.0 
 
 7002 
 
 16.1 
 
 34.84 
 
 20.1 
 
 44.27 
 
 24.1 
 
 56.04 
 
 28.1 
 
 70.49 
 
 16.2 
 
 35.05 
 
 20.2 
 
 44.54 
 
 24.2 
 
 56.37 
 
 28.2 
 
 70.89 
 
 16.3 
 
 35.27 
 
 20.3 
 
 44.81 
 
 24.3 
 
 56.70 
 
 28.3 
 
 71.29 
 
 16.4 
 
 35.48 
 
 20.4 
 
 45.08 
 
 24.4 
 
 57.03 
 
 28.4 
 
 71.69 
 
 16.5 
 
 35.70 
 
 20.5 
 
 45.35 
 
 24.5 
 
 57.37 
 
 28.5 
 
 72.09 
 
 16.6 
 
 35.91 
 
 20.6 
 
 45.61 
 
 24.6 
 
 57.70 
 
 28.6 
 
 72.49 
 
 16.7 
 
 36.13 
 
 20.7 
 
 45.88 
 
 24.7 
 
 58.03 
 
 28.7 
 
 72.89 
 
 16.8 
 
 36.34 
 
 20.8 
 
 46.15 
 
 24.8 
 
 58.36 
 
 28.8 
 
 73.29 
 
 16.9 
 
 36.56 
 
 20.9 
 
 46.42 
 
 24.9 
 
 58.70 
 
 28.9 
 
 73.69 
 
 17.0 
 
 36.77 
 
 21.0 
 
 46.69 
 
 25.0 
 
 59.03 
 
 29.0 
 
 74.09 
 
 17.1 
 
 37.00 
 
 21.1 
 
 46.98 
 
 25.1 
 
 59.38 
 
 29.1 
 
 74.53 
 
 17.2 
 
 37.23 
 
 21.2 
 
 47.26 
 
 25.2 
 
 59.73 
 
 29.2 
 
 74.96 
 
 17.3 
 
 37.45 
 
 21.3 
 
 47.55 
 
 25.3 
 
 60.08 
 
 29.3 
 
 75.39 
 
 17.4 
 
 37.68 
 
 21.4 
 
 47.83 
 
 25.4 
 
 60.43 
 
 29.4 
 
 75.82 
 
 17.5 
 
 37.91 
 
 21.5 
 
 48.12 
 
 25.5 
 
 60.78 
 
 29.5 
 
 76.25 
 
 17.6 
 
 38.14 
 
 21.6 
 
 48.40 
 
 25.6 
 
 61.13 
 
 29.6 
 
 76.68 
 
 17.7 
 
 38.36 
 
 21.7 
 
 48.69 
 
 25.7 
 
 61.48 
 
 29.7 
 
 77.12 
 
 17.8 
 
 38.59 
 
 21.8 
 
 48.97 
 
 25.8 
 
 61.83 
 
 29.8 
 
 77.55 
 
 17.9 
 
 38.82 
 
 21.9 
 
 49.26 
 
 25.9 
 
 62.18 
 
 29.9 
 
 77.98 
 
 
 
 
 
 
 
 30.0 
 
 78.41 
 
 18.0 
 
 39.05 
 
 22.0 
 
 49.54 
 
 26.0 
 
 62.53 
 
 
 
 18.1 
 
 39.29 
 
 22.1 
 
 49.84 
 
 26.1 
 
 62.90 
 
 
 
 18.2 
 
 39.53 
 
 22.2 
 
 50.14 
 
 26.2 
 
 63.27 
 
 
 
 18.3 
 
 39.77 
 
 22.3 
 
 50.44 
 
 26.3 
 
 63.64 
 
 
 
 18.4 
 
 40.01 
 
 22.4 
 
 50.74 
 
 26.4 
 
 64.01 
 
 
 
 18.5 
 
 40.25 
 
 22.5 
 
 51.04 
 
 26.5 
 
 64.37 
 
 
 
 18.6 
 
 40.49 
 
 22.6 
 
 51.34 
 
 26.6 
 
 64.74 
 
 
 
 18.7 
 
 40.73 
 
 22.7 
 
 51.64 
 
 26.7 
 
 65.11 
 
 
 
 18.8 
 
 40.97 
 
 22.8 
 
 51.94 
 
 26.8 
 
 65.48 
 
 
 
 18.9 
 
 41.21 
 
 22.9 
 
 52.24 
 
 26.9 
 
 65.85 
 
 
 
 19.0 
 
 41.45 
 
 23.0 
 
 52.54 
 
 27.0 
 
 66.22 
 
 
 
 19.1 
 
 41.71 
 
 23.1 
 
 52.86 
 
 27.1 
 
 66.60 
 
 
 
 19.2 
 
 41.96 
 
 23.2 
 
 53.17 
 
 27.2 
 
 66.99 
 
 
 
 19.3 
 
 42.22 
 
 23.3 
 
 53.49 
 
 27.3 
 
 67.38 
 
 
 
 19.4 
 
 42.47 
 
 23.4 
 
 53.81 
 
 27.4 
 
 67.77 
 
 
 
 19.5 
 
 42.73 
 
 23.5 
 
 54.12 
 
 27.5 
 
 68.15 
 
 
 
 19.6 
 
 42.98 
 
 23.6 
 
 54.44 
 
 27.6 
 
 68.54 
 
 
 
 19.7 
 
 43.24 
 
 23.7 
 
 54.75 
 
 27.7 
 
 68.93 
 
 
 
 19.8 
 
 43.49 
 
 23.8 
 
 55.07 
 
 27.8 
 
 69.31 
 
 
 
 19.9 
 
 43.75 
 
 23.9 
 
 55.38 
 
 27.9 
 
 69.70 
 
 
 
 In the text (p. 143 & c.) the older determinations of Muncke 
 have been employed. 
 
 18* 
 
276 
 
 TABLE FOR THE REDUCTION 
 
 O 
 o 
 O 
 
 O 
 
 43 
 
 tJD 
 
 1 
 
 <D 
 
 P^ 
 
 iO THCOGMt^COGO'^05 iO r-ICOC^l^COCO^OS iO i * CO OJ t^ CO GO 
 
 OOOOOOOOOO o^-it-lr-HT^i-lr^^T-lT^ T-H'-lScNCN 
 
 dodddddodd oododooodo d d d d d 
 
 OOOOOOOOOO OOOOOOOOOO 050505C5GO 
 
 OOOO^OOOOOO c J. 1 - | '- <1 ~i 1 ~3 T ~i 1 ~i'~i r ^ T-J T-I ,H T-H ,-< 
 
 dodddddo'dd dooooooodd doddd 
 
 OOOOOOOOOO OOOOrHT-ii-lT-lr-jT-H ,_i,_i^2 
 
 ddddddodoo oddddddddd ddddc 
 
 050505050505050505CO COCOCOCOCOCOCOCOt-t> t>t>t^St^ 
 
 OOOOOOOOOO OOOOOO > i-lr-li-J^H 2222^^ 
 
 dodddddodd dodddddddd ddddc 
 
 OOOOO>OOOOO OOOOOOOOOrH rH^^^r- 
 
 dddddddodd oddddddddd ddddc 
 
 oooooooooo oooooooooo o o o TH r- 
 
 odoodooodd ddddddodoo ddddd 
 
 OOOOOOOOO f O OOOOOOOOOC5 OOOOC 
 
 ddddddodoo ddddddddo'd ddddc 
 
 iOt-icocNco^tiO5Oi ico <N oo eo 05 "3 o <.> i i t- co c5"*oeoTH 
 
 OOOi li IT IT (GMG^GN C^COCOCOCO^t 1 "^'^^ iO lO 1 C iO r ^ O 
 
 OOOOOOOOOO OOOOOOOOOO O O O O O 
 
 doddoododd dddddddodd odddo 
 
 l> ^t* T I CO iO (7^1 O5 O CO ' ( GO vO C?^ O5 CO CO O CO xO ^1 O5 CO CO O t^ 
 
 OOOOOOOOOO OOOOOOOOOO O O O O O 
 
 dddddddodd oddddddddd o'ddoo 
 
 OOOOOOOOOO Oi-t^(Hr-lvHi-lT-li-(iH ^H ^1 rH (N <M 
 
 oooooooooo oooooooooo c ?; o . c . c ; 
 
 dddddddddd dodddddddd ddodo 
 
 
OF BAROMETRIC OBSERVATIONS TO 0C, 277 
 
 r - ~4i~cocc^c5iooc><N i^eooo cs o o o 1-1 i cooo^Ci>ootD--it^co 
 
 -N c: :r. x to xocosNGGsr^tcvococ^ o n i -,o T so GN o as i-- o--*ico*HOCit>.cD-+ico 
 
 s>j cc co TT o ot>-xa5Cso-H<raco-*i o O to >> ab o O -<<* co-*T>ocoi>.i>.cooiO' < 
 
 c* ff> SN s^ ff* (NCXc>jGM(NcococQcQco eocococoeocoTj<TtiT}<Tti -*t & & & -4* ^ -^ Jm ^ \o 
 
 d d c d odddddo'ddd dddddddddd dddodddddd 
 
 f. f. f- "f. 'f- OO GO QO CO QO 00 CO CO CO GO CO CO CO X O l^. t^. l>. I- l>. t- l^ !> t- t> I> l> t^ t^ l 
 
 1-1 00 O 7-1 O> CCCOO1 -fii IXOCMCJ COCOOl^rti-HCOOGMOS O OS O t TJH I GO HO CM Ci 
 
 O l> x-O ST. O XCO-r CS[>--* I SNOI-- O C~ X O <# -^ Ci l>- ^ GMOCOOCOT-HCCCD-'tfi-H 
 
 o o TI co cc -r i^ vr i~ x> cs o o i i CNT coeo-^iooot^-co OSOO-HCNCOCO-^IIOO 
 
 2g M Tl 7-1 > T-l^IJMCNCMS^GMGMCOCO COCOCCCOeOCOCOeOeOCO eO-^->Tl-^i-<*i-^JiTji-^i'^i-<ji 
 
 ddddd ddddoddodd dddddddddd dddddddddd 
 
 & C-. -T X -N O liOO-*C5COCOfNO O 10 O5 rhi CO CO l^ 7-1 "^CSCOCOCMt^i-HeDOT^ 
 
 C- L^ ^ CO T * O X !> xO CO7^OC^I>- O ""S^ C^ *" * C5 CO CC xO CO CM O X t>- xO -^ 7^ ~^ CTS CO CD 
 
 l.^T-IX)iO IMCiiOtMOOeOOcrcO Ol-^-*-Ht-.-<!tl-HOOOCN OiOfMCSOCOOtOCOO 
 
 t-cociCio -Ht-i5<icoeo^foo<iOt>. coccosoo' ICMCMCO-* -^ooot^cocscsOT-i 
 
 ^r-i^i^-iGM CMGM'M'M7I'M7-1(M7-13M GNJCNC^COCOCOCOCOeOCO COCOCOCOCOCOcOCO^-^i 
 
 c c d d o* dddddddddd dddddddddd ddddddddod 
 
 r. i-->o 
 
 iC tt I - I - XOiOSOOi Iff^C^ICOCO -^OiOOtOI^.XXC5CS Ot ir-lfN5MCO'*i->*l>OO 
 
 (pt^i^^^^^-i T-I^-HT-IJNCMCNCNJCNOIT-I CMCMCMCMCMS^CNJGNCNJS^ eocococococococococo 
 ddddd dddddddddd dddddddddd dddddddddd 
 
 r* :t -r 1 o otocDt^t^aoaoooo i i^^cM-McocoTf-^uoio c^coi>-i->.xaociO5OO 
 
 ddddd dddddddddd dddddddddd dddddddddd 
 
 IMC. t^O-M ^ X ?T SO ' n t^ -*< !M O CO^5-*-lCSI>iO<MOt> lOCO^OOtC^i-ICSIr^O 
 
 occi-i^t^csGNioac^ co to 7-1 T i* = c ao i^t^OTT-iidcoococo 
 
 T-l^-^iOCiCOXT-l^-H tOACOCOC4OrH)OaCQ CO(MOOiOC5COCO(MtO 
 
 ddddd ddd ddd 
 
 XCT. ~. riO OO-^^^i-<!MSMCOCOCO ^^^IxOiCiOO^tDlr-. t-.tCOCOOOC5C5OOO 
 
 ddddd dddddddddd dddddddddd dddddddddd 
 
 tT C". \Z O 7-1 rJH t>- Cl 7-1 rr t-- O 7<I xO t^. O 7-1 lO X O CO iO X O CO ~~2 CO TH CO O CO i-4 CO 
 
 CC I >. I>- l>- t*- CO X CO COCTiCTiOOO O O '^ *^ '^ f T ' 7-1 7-1 7-1 *M COCOCOCO^^^^iO i3 
 
 o o o o o OOOOOOOO-H^ 1 ~ ( '^'~ ll ~l r ^ T ^'~i'~l T ~i'~i T ^'~i'~i 1 ^ T ^'~J T ^'~i'~J'~ l 
 
 ddddd dddddddddd dddddddddd d d d d'd d d d d d 
 
 C50000 OOOOOOOOOO OO.OOC5OOOOO 00000 00. i-H T- 
 
 
 - ifl O ^ it^T-lCC^CSKOO-OCN t^cOCO-^050O?r>T-l|- 7<IX^cT5tOOOr-lt^CO 
 
 T-i - r-. x to va so 7-1 o c: i- -^ .~ so <N oot^o^eocMOCit^ OTfico^oost^co^co 
 
 71 '.~ '.~ i~ L- X ~. ~. ~ 71 CO -^ "3 O iT t^- CO CS O t-< 1-1 <N CO Tji lO to t> t CO OS O -H 
 
 ff-1 7-1 71 7-1 7-1 71 71 7-1 71 7-1 CO CO CO CO CO CO CO CO CO CO SO T* * * -* 1 -* T 1 * ^ ^f "=f ^ ^ ^O vO 
 
 OOOC:~ OOOOOOOOOO OOOOOOOOOO OOOOOOOOOO 
 
 do' odd dddddddddd dddddddddd dddddddddd 
 
278 
 
 TABLE FOR THE REDUCTION 
 
 dodddddddd ddddddddoo dodo" odd o' o' c 
 
 OtO(MOaOiOCOT-lcO O -<*l <7<l C5 t- O GM O OO O CO * C5 CO 
 
 dddddddddd o do doddddd oddd 
 
 t> 
 
 dddodddddd dddddddddd ddddddddo'c 
 
 CO GNJ GM GMGMC^^IC^G^l' * T^THI I^HT-HT (r^^-HOO OOOOOOCiQSC 
 
 dddodddddd dddodddddd oddddddddc 
 
 CO CO CO GO CO COCOCi'^CS ^C^TfC^'^O xO O lO O O OCOiiCOrHcOrHCC^ 
 
 cocococococoeoeococo coeocoeococoeoTtiTttTt< ^^^TH-*'^(^I^I^<^ 
 
 dddodddddd dddodddddd dddodddddd 
 
 eocococococoeococoeo cocoeoeoeococococort 
 
 dddodddddd ddddddoddd dddodddddd 
 
 TflCOO'i ICOOCCOCN^t 1 COCOT-HCOiOCOOGM'^'CD COOCOiCb-OCN^COOC 
 
 C^GMGMCNGMGNIGMCNGMtT^ CMGMGMCNG^GNIGNIOIC^G'^ GM^lC^JCMGMiTslC^COCCW 
 
 dddodddddd ddodddddo'o' ddddddddo'c 
 
 lOiOCOCOCOCOI^-Ol t- COCOCOCOO5CSO5OOO O-^-^'-H'-l 
 
 T-HrHi IT- IT-HT-II-HT li-Hil ^^^-li-Hi ii li li-H(M(J<IO:i O15<l(M!MCM(Nl?4(NCN!^ 
 
 dddddddodd dddodddddd dddodddddd 
 
 71 K 
 
 OOOO-<Hi-li-4rHT-( CN<N<N<M(NCOeOCOCOCO eO.-Ti^-^f'*'^^^^ 
 
 odododdddo dddddddodd odo'do'do'ddo 
 
 OOOOOOOOOO OOC5OOOOOOO OOC5 
 
 dddodddddd ddddddoddd do* do 
 
 xOOOOiOOiOOiOO 
 
 O5Dcot>-i>.ooooa3O5O 
 cocococoeococococo'^ 1 
 
OF BAROMETRIC OBSERVATIONS TO C. 279 
 
 xxxacccaacicscjc; c; ~. ~. n ~. ~ ~ ~ o o 
 dddddddddd oooooo-H*4 
 
 lit LO O lO lO lO lO O O lO lO lO lO lO ^ ^J 1 ^ ^ ^ "^ "^* ^ ^ ^ "^ ^ ^ "^ "^ ^ 
 
 r co c t~ ^r xut^jcs ir?cot^ x.-^j :-:ot^^ ioooc^d 
 
 ox'-sit ciso^reNO t^ o cc o x tr c.t . -M ~ L- i- r: x o ec 
 
 co <N co <*( ie o o t^aocioo. -i(Mcoec-o OtDt^t^ooosoO^^i 
 
 t* t>- L^ i- t- i- t- i^ i>- t^ i^ t>- t>- cc ac ac ac x cc x cc co GC cc cc cc ci ci ri r; 
 
 cc'dooooooo docJooooocJo ddddodddoo 
 
 ooooo 
 
 o ~ r. ~. ~. x x x x x x; cc cc cc t~ t>- t-- t> t> t>- t 
 
 ~--DSMQO'^'OCi(MX) *J<OO<MCCTt<Oee<MaC -*OO(MCO-^OtCCNX 
 
 TTr^OOCCt^aCCCO5Ci O'-^'-HCM<NC<5'^^fOiO St^t>-aCCCCsOO 
 
 in xc o ic o 10 c 10 10 >--: -^ -~ - ~ -~ - - - -- --s CD co t> t> t>. i> 
 
 dddddddddd dddddddddd dddddddddd 
 
 -. Eooooiooio 
 
 
 ri C-: x d ~- -J: . t^ d :: i~-~ x ^- -r rj 5<i 10 ao o cc o as ~-i ^ t^ o co 
 ~. c- r^ GN cc O Tii c; co t> (N<OO-*O>oOt--tOO ^ -. c- t -- -_DO-*Cico 
 
 X -. - O - --- ^J<M COCO-^T}H^iOO--r-^:t^ t>l>.QOQCOC5OOO i 
 
 . o 
 
 icc~. Mioci^trrieotc cicooocooocot-o 
 
 "^f "^- iO lO iO CDCCCOt^-t^ t'-CCCOC^CiC^ O O O 
 
 cocococococococococo cocoeococoeo-^-^'-r 
 
 
 O <M 3C <M X O X 
 
 o tcJNcccooioo 
 
 COtSX CC" X-^-^T 
 
 <M (7 ?J (N <M (M C S^l (M CO CO CO CO 
 
 
 iO iOiO^**^Ct^ t^-t^t^t^t^COOOOO GO GC GCO^CiOO^OOOO 
 
 dddddodddd dddddddddd dddddddddd 
 
 oooooooooo oooooooooo oooooooooo 
 
 \f2 O iO O O O id O O O iC O \fl O i5 O tO O tft O iC O iO O iO O iO O >ft O 
 
280 
 
 TABLE FOR THE REDUCTION 
 
 OOOOOOOOr-l 
 
 =f co eo co co co co eococo eo co co co co co co 
 
 oooo ooooo 
 
 05 o oooooooooo ooS2^^2^i u 2 
 
 ^S>cccoSco2oco! S^ff^Sas?*" 500 '^^ ^ <*> ^ =c eo t-- .^ - c 
 
 ^^^aOj-ggOicotMos cocoot^coot^^Scc o 2< oo S ^ 
 
 QOGOaOQOGOOOCOGOCOCO 00050505050505050505 0505050505C50OO- 
 
 ooooocdodoo oooooooooo ooooddr^rH'rt 
 
 CO CO 1C C 1C 1C >0 1C 1C 1C rH ^ ^ ^ ^ ^ ^H rj, ^, CO CO CO CO CO ... 
 
 ^COCO^'SiCCD''c : oS! G 2 "*OcOC-lCO-*iOCO(MOO ^OCOG^CO^fiocSJNi 
 
 ^ l " ^ "^ l ^I L> : "^ ^ l ": ^ !>; t>- !> 00 GO 90 CO 00 CO CO CO CO CO CC CO OD 00 00 CO X 
 
 oooooooooo oooooooooo 6 6 6 6 6 6 6 o d q 
 
 ococoococoococoai 
 
 O<T<ICOiCCOt>.a5O! I (N 
 i 1 Cl i 1 CO i 1 CO r-l l^ CM I,. 
 
 oooooooooo oooooodocdo 
 
 ooooo 
 
 OTtiCCCOt^i-HCOO^tlCO COt~-^H 
 
 C5 'N 1C 00 O CO C 
 
 iO lO iC iO --O iO vO iC O O 
 
 oooooooooo 
 
 oooooooooo 
 
 o o i i I-H <N 
 
 oooooooooo 
 
 *t^O^Ht>T 1 Tfl OO TH Tjt 
 
 '-lT-i(M(M(M e o e oeO^Tt* 
 
 '^^'^^f^fTtl-rt'Th'^-^ 
 
 OOOOOOC5OOO 
 
 <7<ll>.' iiCO5-*COC<ICOO iCO5COl--i-ICOO^COM 
 ^liCiCiCCOCOCOl>.l^L>. COCOQOO5O5O5OOO 
 
 oooooooooo oooodddddo 
 
 10 i-l GO UC5 r-l ' t^ TtH O l> TH 
 
 iOi icoijqGoecasiooco 
 
 OCOiOOOOCOiCOOi ICO 
 'i 1 > I'-HI !(MiJ<|<M{McOjf5 
 
 cocococococoeocococo 
 oooooooooo 
 
 cOcoSTOtc^S 1 " 11 ^ 10 CO'^OiCi-lt-'NX^ 
 
 cocoeocococoeocococo cocococococococococ; 
 oooooooooo ooodddddcd 
 
 O l> Tfi i iGOiOCOOr-rtl 
 t 00 O <? >CO 1T3 t> OS ~O <N 
 OOi IT- 11 li lili-H(M<7<j 
 04 O4 94 4 (N 94 G4 C4 ,<N G4 
 
 oooooooooo 
 
 222222^^' ^^2^^21^222 ScaSSS^S^^^ 
 
 oooooooooo oooooooooo 
 
 ooooo ooooo 
 
 
 iCOiCOiCOiCOiCO iCOiCOiCOiCOiCO 
 
 2- fi E5 S C S- 2 Sf.S'?9 iccocoi^i^coaoososo 
 
 2 
 
 t 
 
OF BAROMETRIC OBSERVATIONS TO 0C. 281 
 
 O ~" t^- ?N X CO Ci ^ O tO ~^ CC G^l t** CO 00 ^ Ci *5 OCOi-^t^- ^QOCOCyS^O 
 
 ~. ~~ N:~ I^-.T-.C i^ x n o ^i -M co ^r o co t oo CO O> O ^^ e* CO 00 
 
 e oo eo eo oo co eo oo eo cc " -t c- T-I Tr * ^ ^ -^ ^ -* ^r -<j< t- * 10 o o 10 o 
 
 ^r 1-1 o5t>o^ooooco-HaD o^s^ot-O'MOccKO 
 C4CQ co-*ioot^t>aoc50O -HtNCOco^iioot^t^cc 
 i i ^ <M CM c^ s<i c^ <N<MC^(N<N<NN<Mcoco cococoeococococococo 
 
 OOOOOOOOOO 
 
 Cl C~. ~. ~. ~. C". ~. C: O O O OOOOOOOOOO 
 
 i^. x x cr. ~. o c: i H !M c^eceo-^'-n'ioio^- t>- t^ocxcicnooi I-^<N 
 o- i- t^- [> i- x x x x co ac oo oc x x x x x oc oo ac ex cc ao GO ci ci ci-o o 
 eooooooooo oooooooodd dododddood 
 
 i~ C -7 X t- t> -^ O O * GCfMt^.-^iCO'^'X^It^ -^iOO-^QOC^r--lir5CS 
 
 ~ut-jrcst-t-coao ccc5Ooo^H-i-HC^(N eceo^rTfTrioioooo 
 
 -_r :r - -,; v; -^: -^ r O cs ^ ^ i>. t> t>- t^ i> r>- t>- i> t>- t> i> t>- t>- t> t>- t>. t- 
 
 dcdodddodd dddddddddo dodddddddd 
 
 i^ ir: uo u-; u-: ir: o ^ ut o o u-t ut 10 o 10 o o 10 o o o a o >o o o c: --r ^r 
 d d d d d d o" d d d dddddododd dodddddddd 
 
 t-^ it^r^ot r t- -rr t r t^ctO t^^Ot^^Ot^eoOt^ 
 
 x^ 71 X "t . i^ O O C^ t^- CO O "^T* " t^CO QO^Oi^' !t-C^OO^CS 
 
 tOdiOt<Oe4iO(*O COiOCCOCO^X'-^COO CC **<& Z2 ~. -r--r~ . 
 
 X r: ~ ~. r: C O O O I Oi G4 C* C4~CO CO OQ CO-^i^ti-^i-^riOiOiOino 
 
 OOOOOOOOOO dodddddddd dodddddddd 
 
 u- -= vr -j: - - - t> i^. i^ o t> t^ x oc x x x x n cs o o as o o o o o o 
 
 N -M -M -M 7-1 <M_ <N (N <N O] CM <N C^ (>l (M_ <N ^ (?a (N CN C^ C<J C^ C^ ff^ CO CO CO CO CO 
 
 D o o o o o* o O o o dodddddddd doddddddod 
 
 AO^teie^oo^aQ o t>- ac x c; O < ?i :: ?t 
 dddddddo dodddddddd 
 
282 REDUCTION OF BAROMETRIC OBSERVATIONS. 
 
 ^^l^H^HOOOOOO OOOOOOOOOO 
 
 HT '~Hi li-^ifT iHT li I i I^HT-HT I i-H rH r IT IT IT < 
 
 <MT-^OCOI>O-*COCNH oo5cot>io^co<M^o 
 
 OCSCiGCCCGCCCCOGCCC COIt--t>-t^l>-t>.t>.l>l^. 
 
 C^C^C^O^OO^CiO^OOS OG^CiC^OOOOOO 
 
 OOOOOOOOOO cSoOOT^THT-HrHt-^^' 
 
 I>.t>t>-l>-l>.l>-t>.GOGOGO COOOOOOOCOOOOOCOGOCC 
 
 o'ooooooooo ooo'oooooocs 
 
 oooooo'oooo oooooooooo 
 
 ^*<oi>"*oi~coooeo ot^coot>cooocoo 
 
 iO ^f CD (?<l GO CO C5 tO OO CMt^-COCS^O^C^-Ht^-CO 
 
 oooooooooo oooooooooo 
 
 cocococococococococo cocococoeocococococo 
 
 OOOOOOOOOO OOG5OOOOOOO 
 
 00000000*00 oooooooooo 
 
TABLE OF THE SPECIFIC GRAVITIES &c. 
 
 V. 
 
 Table of the specific gravities and composition by 
 volume of gases. 
 
 283 
 
 No. 
 
 Name of the gas. 
 
 Formula. 
 
 Volume of the 
 constituents in 1 vol- 
 ume of gas. 
 
 Specif, 
 grav. 
 
 1 
 
 Atmospheric air 
 
 
 0.2096 O-f 0.7904 N 
 
 1.00000 
 
 2 
 
 /Ethyl .... 
 
 C 4 H 5 
 
 2 vol. C -f 5 vol. H 
 
 2.00477 
 
 3 
 
 Ammonia . . . 
 
 NH 3 
 
 %vol.N + iy a vol.H 
 
 0.58957 
 
 4 
 
 Antimony . . . 
 
 Sb 
 
 
 17.82796 
 
 5 
 
 Antiinoniuretted- 
 hydrogen . . 
 
 SbH 3 
 
 y 4 vol.Sb+lV 2 vol.H 
 
 4.56090 
 
 6 
 
 Arsenic .... 
 
 As 
 
 
 10.36510 
 
 7 
 
 Arseniuretted - hy- 
 drogen . . 
 
 AsH, 
 
 y.vol.As+lV.voLH 
 
 2.69518 
 
 8 
 
 Boron .... 
 
 Bo 
 
 
 1.50639 
 
 9 
 
 Bromine .... 
 
 Br 
 
 
 5.41085 
 
 10 
 
 Carbon .... 
 
 C 
 
 
 0.82921 
 
 11 
 
 Carbonic oxide . 
 
 CO 
 
 y,voi.c-|-y 2 voi.o 
 
 0.96741 
 
 12 
 
 Carbonic acid 
 
 CO, 
 
 '/ a vol.C + Ivol.O 
 
 1.52021 
 
 13 
 
 Chlorine . . . 
 
 Cl 
 
 
 2.45307 
 
 14 
 
 Chloride of acetyl 
 
 C 4 H 3 C1 
 
 lvol.C-|-iy 2 vol.H 
 
 -f % vol. Cl 
 
 2.15965 
 
 15 
 
 Chloride of boron 
 
 BoCl 3 
 
 y 4 vol.Bo-flV 2 vol.Cl 
 
 4.05620 
 
 16 
 
 Chloride of cyanogen 
 
 C 2 NC1 
 
 y 2 voi.c-|-y 2 voi.N 
 
 -p/ 2 vol.Cl 
 
 2.12681 
 
 17 
 
 Chloride of methyl 
 
 C 8 H 3 C1 
 
 %vol.C-j-iy 2 vol.H 
 
 1.74504 
 
 18 
 
 Cyanogen . . . 
 
 C,N 
 
 Ivol.C -|- Ivol.N 
 
 1.80055 
 
 19 
 20 
 
 Ditetryl .... 
 Elayl 
 
 C 8 H 8 
 C 4 H 4 
 
 2vol.C -|- 4vol.H 
 Ivol.C 4- 2vol.H 
 
 1.93550 
 0.96775 
 
 21 
 
 Fluorine .... 
 
 v ^4 4 
 
 Fl 
 
 
 1.32673 
 
 22 
 
 Fluoride of boron 
 
 BoFl 3 
 
 1 /4 vol.Bo+l 1 Avol.Fl 
 
 2.36669 
 
 23 
 
 Fluoride of silicon 
 
 SiFl 3 
 
 V 3 vol.Si-{-2voLFl 
 
 3.63469 
 
 24 
 
 Hydrogen . . . 
 
 H 
 
 
 0.06927 
 
284 
 
 TABLE OF THE SPECIFIC GRAVITIES &c. 
 
 No. 
 
 Name of the gas. 
 
 Formula. 
 
 Volume of the 
 constituents in 1 vol- 
 ume of gas. 
 
 Specif, 
 grav. 
 
 25 
 
 Hydrobromic acid 
 
 HBr 
 
 y s vol.Br-f y a vol.H 
 
 2.7400G 
 
 20 
 
 Hydrochloric acid 
 
 HC1 
 
 y a voi.ci + y 8 voLH 
 
 1.26117 
 
 27 
 
 Hydrofluoric acid 
 
 HF1 
 
 y a voi.Fi + y a voi.H 
 
 O.G9800 
 
 28 
 
 Hydriodic acid . 
 
 HI 
 
 Va VOl.I -fV 2 vol. H 
 
 4.42598 
 
 29 
 
 Iodine .... 
 
 I 
 
 
 8.78269 
 
 30 
 
 Marsh gas . . . 
 
 C 4 H t 
 
 y 2 vol. C-f 2vol.H 
 
 0.55314 
 
 31 
 
 Methyl .... 
 
 C 2 H 3 
 
 1 vol. C -1- 3 vol. H 
 
 1.03702 
 
 32 
 
 Methyl -JEther . 
 
 C 2 H a O 
 
 1 vol. C + 3 vol. H 
 + 1 /, vol.0 
 
 1.58982 
 
 33 
 
 Nitrogen . . . 
 
 N 
 
 
 0.97134 
 
 34 
 
 Nitrous oxide 
 
 NO 
 
 1 vol. N-fy a vol.0 
 
 1.52414 
 
 35 
 
 Nitric oxide . . 
 
 N0 2 
 
 1 / 2 vol.N-l- 1 / 2 vol.O 
 
 1.03847 
 
 3G 
 
 Oxygen .... 
 
 O 
 
 
 1.10561 
 
 37 
 
 Phosgene gas 
 
 CC10 
 
 y 2 vol. c-f y 2 voi.o 
 
 H-lvol.Cl 
 
 3.42048 
 
 38 
 
 Phosphorus. . . 
 
 Ph 
 
 
 4.28424 
 
 39 
 
 Phosphuretted-hy- 
 drogen . . . 
 
 PhH 3 
 
 1 / 4 vol.Ph+l 1 / 2 vol.H 
 
 1.17496 
 
 40 
 
 Selenium ... 
 
 Se 
 
 
 5.43076 
 
 41 
 
 Seleniuretted - hy- 
 drogen . . . 
 
 SeH 
 
 y 2 vol.Se-l-lvol.H 
 
 2.78465 
 
 42 
 
 Silicon .... 
 
 Si 
 
 
 2.94369 
 
 43 
 
 Sulphur .... 
 
 s 
 
 
 6.63366 
 
 44 
 
 Sulphurous acid . 
 
 S0 2 
 
 y e vol. S -j- 1 vol. O 
 
 2.21122 
 
 45 
 
 Sulphuretted -hy- 
 drogen . . . 
 
 SH 
 
 y 6 vol.S + lvol.H 
 
 1.17488 
 
 4G 
 
 Tellurium . . . 
 
 Te 
 
 
 8.91674 
 
 47 
 
 Telluretted-hydro- 
 gen . . . . 
 
 HTe 
 
 y 2 vol.Te + lvol.H 
 
 4.52764 
 
 48 
 
 Vapour of water 
 
 HO 
 
 y a vol.O-|-lvol.H 
 
 0.62207 
 
TABLE FOR THE REDUCTION OF THE BAROMETER. 285 
 
 Table for the reduction of the pressure of a column 
 of water to a column of mercury. 
 
 Pressure 
 of water 
 in Mm. 
 
 Pressure 
 of mercury 
 in Mm. 
 
 Pressure 
 of water 
 in Mm. 
 
 Pressure 
 of mercury 
 in Mm. 
 
 Pressure 
 of water 
 in Mm. 
 
 Pressure 
 of mercury 
 in Mm. 
 
 1 
 
 0.07 
 
 41 
 
 3.03 
 
 81 
 
 5.98 
 
 2 
 
 0.15 
 
 42 
 
 3.10 
 
 82 
 
 6.05 
 
 3 
 
 0.22 
 
 43 
 
 3.17 
 
 83 
 
 6.13 
 
 4 
 
 0.30 
 
 44 
 
 3.25 
 
 84 
 
 6.20 
 
 5 
 
 0.37 
 
 45 
 
 3.32 
 
 85 
 
 6.27 
 
 6 
 
 0.44 
 
 46 
 
 3.39 
 
 86 
 
 6.35 
 
 7 
 
 0.52 
 
 47 
 
 3.47 
 
 87 
 
 6.42 
 
 8 
 
 0.59 
 
 48 
 
 3.54 
 
 88 
 
 6.49 
 
 9 
 
 0.66 
 
 49 
 
 3.62 
 
 89 
 
 6.57 
 
 10 
 
 0.74 
 
 50 
 
 3.69 
 
 90 
 
 6.64 
 
 11 
 
 0.81 
 
 51 
 
 3.76 
 
 91 
 
 6.72 
 
 12 
 
 0.89 
 
 52 
 
 3.84 
 
 92 
 
 6.79 
 
 13 
 
 0.96 
 
 53 
 
 3.91 
 
 93 
 
 6.86 
 
 14 
 
 1.03 
 
 54 
 
 3.99 
 
 94 
 
 6.94 
 
 15 
 
 1.12 
 
 55 
 
 4.06 
 
 95 
 
 7.01 
 
 16 
 
 1.18 
 
 56 
 
 4.13 
 
 96 
 
 7.08 
 
 17 
 
 1.26 
 
 57 
 
 4.21 
 
 97 
 
 7.16 
 
 18 
 
 1.33 
 
 58 
 
 4.28 
 
 98 
 
 7.23 
 
 19 
 
 1.40 
 
 59 
 
 4.35 
 
 99 
 
 7.31 
 
 20 
 
 1.48 
 
 60 
 
 4.43 
 
 100 
 
 7.38 
 
 21 
 
 1.55 
 
 61 
 
 4.50 
 
 200 
 
 14.76 
 
 22 
 
 1.62 
 
 62 
 
 4.58 
 
 300 
 
 22.14 
 
 23 
 
 1.70 
 
 63 
 
 4.65 
 
 400 
 
 29.52 
 
 24 
 
 1.77 
 
 64 
 
 4.72 
 
 500 
 
 36.90 
 
 25 
 
 1.84 
 
 65 
 
 4.80 
 
 600 
 
 44.28 
 
 26 
 
 1.92 
 
 66 
 
 4.87 
 
 700 
 
 51.66 
 
 27 
 
 1.98 
 
 67 
 
 4.94 
 
 800 
 
 59.04 
 
 28 
 
 2.07 
 
 68 
 
 5.02 
 
 900 
 
 66.42 
 
 29 
 
 2.14 
 
 69 
 
 5.09 
 
 1000 
 
 73.80 
 
 30 
 
 2.21 
 
 70 
 
 5.17 
 
 
 
 31 
 
 2.29 
 
 71 
 
 5.24 
 
 
 
 32 
 
 2.36 
 
 72 
 
 5.31 
 
 
 
 33 
 
 2.44 
 
 73 
 
 5.39 
 
 
 
 34 
 
 2.51 
 
 74 
 
 5.46 
 
 
 
 35 
 
 2.58 
 
 75 
 
 5.54 
 
 
 
 36 
 
 2.66 
 
 76 
 
 5.61 
 
 
 
 37 
 
 2.73 
 
 77 
 
 5.68 
 
 
 
 38 
 
 2.80 
 
 78 
 
 5.76 
 
 
 
 39 
 
 2.88 
 
 79 
 
 5.83 
 
 
 
 40 
 
 2.95 
 
 80 
 
 5.90 
 
 
 
28G 
 
 TABLE OF THE COEFFICIENTS OF ABSORPTION 
 
 VI. Table of the coefficients of absorption 
 
 , 
 
 Nitrogen 
 
 Hydrogen 
 
 Oxygen 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 
 
 0.02035 
 
 0.12634 
 
 0.01930 
 
 0.06925 
 
 0.04114 
 
 0.28397 
 
 1 
 
 0.01981 
 
 0.12593 
 
 0.01930 
 
 0.06910 
 
 0.04007 
 
 0.28397 
 
 2 
 
 0.01932 
 
 0.12553 
 
 0.01930 
 
 0.06896 
 
 0.03907 
 
 0.28397 
 
 3 
 
 0.01884 
 
 0.12514 
 
 0.01930 
 
 0.06881 
 
 0.03810 
 
 0.28397 
 
 4 
 
 0.01838 
 
 0.12476 
 
 0.01930 
 
 0.06867 
 
 0.03717 
 
 0.28397 
 
 5 
 
 0.01794 
 
 6.12440 
 
 0..01930 
 
 0.06853 
 
 0.03628 
 
 0.28397 
 
 6 
 
 0.01752 
 
 0.12405 
 
 0.01930 
 
 0.06839 
 
 0.03544 
 
 0.28397 
 
 7 
 
 0.01713 
 
 0.12371 
 
 0.01930 
 
 0.06826 
 
 0.03465 
 
 0.28397 
 
 8 
 
 0.01675 
 
 0.12338 
 
 0.01930 
 
 0.06813 
 
 0.03389 
 
 0.28397 
 
 9 
 
 0.01640 
 
 0.12306 
 
 0.01930 
 
 0.06799 
 
 0.03317 
 
 0.28397 
 
 10 
 
 0.01607 
 
 0.12276 
 
 0.01930 
 
 0.06786 
 
 0.03250 
 
 0.28397 
 
 11 
 
 0.01577 
 
 0.12247 
 
 0.01930 
 
 0.06774 
 
 0.03189 
 
 0.28397 
 
 12 
 
 0.01549 
 
 0.12219 
 
 0.01930 
 
 0.06761 
 
 0.03133 
 
 0.28397 
 
 13 
 
 0.01523 
 
 0.12192 
 
 0.01930 0.06749 
 
 0.03082 
 
 0.28397 
 
 14 
 
 0.01500 
 
 0.12166 
 
 0.01930 0.06737 
 
 0.03034 
 
 0.28397 
 
 15 
 
 0.01478 
 
 0.12142 
 
 0.01930 0.06725 
 
 0.02989 
 
 0.28397 
 
 16 
 
 0.01458 
 
 0.12119 
 
 0.01930 
 
 0.06713 
 
 0.02949 
 
 0.28397 
 
 17 
 
 0.01441 
 
 0.12097 
 
 0.01930 
 
 0.06701 
 
 0.02914 
 
 0.28397 
 
 18 
 
 0.01426 
 
 0.12076 
 
 0.01930 
 
 0.06690 
 
 0.02884 
 
 0.28397 
 
 19 
 
 0.01413 
 
 0.12056 
 
 0.01930 
 
 0.06679 
 
 0.02858 
 
 0.28397 
 
 20 
 
 0.01403 
 
 0.12038 
 
 0.01930 
 
 0.06668 
 
 0.02838 
 
 0.28397 
 
 21 
 
 
 0.12021 
 
 0.01930 
 
 0.06657 
 
 
 
 22 
 
 
 0.12005 
 
 0.01930 
 
 0.06646 
 
 
 
 23 
 
 
 0.11990 
 
 0.01930 
 
 0.06686 
 
 
 
 24 
 
 
 0.11976 
 
 0.01930 
 
 0.06626 
 
 
 
 
 
 
 
 
 
 
OF VARIOUS GASES IN WATER AND ALCOHOL. 
 
 287 
 
 of various gases in water and alcohol. 
 
 Carbonic acid 
 
 Carbonic oxide 
 
 Nitrous oxide 
 
 Nitric oxide 
 
 in 
 alcohol. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 1.7967 
 
 4.3295 
 
 0.03287 
 
 0.20443 
 
 1.3052 
 
 4.1780 
 
 0.31606 
 
 1.7207 
 
 4.2368 
 
 0.03207 
 
 0.20443 
 
 1.2605 
 
 4.1088 
 
 0.31262 
 
 1.6481 
 
 4.1466 
 
 0.03131 
 
 0.20443 
 
 1.2172 
 
 4.0409 
 
 0.30928 
 
 1.5787 
 
 4.0589 
 
 0.03057 
 
 0.20443 
 
 1.1752 
 
 3.9741 
 
 0.30604 
 
 1.5126 
 
 3.9736 
 
 0.02987 
 
 0.20443 
 
 1.1346 
 
 3.9085 
 
 0.30290 
 
 1.4497 
 
 3.8908 
 
 0.02920 
 
 0.20443 
 
 1.0954 
 
 3.8442 
 
 0.29985 
 
 1.3901 
 
 3.8105 
 
 0.02857 
 
 0.20443 
 
 1.0575 
 
 3.7811 
 
 0.29690 
 
 1.3339 
 
 3.7327 
 
 0.02796 
 
 0.20443 
 
 1.0210 
 
 3.7192 
 
 0.29405 
 
 1.-2809 
 
 3.6573 
 
 0.02739 
 
 0.20443 
 
 0.9858 
 
 3.6585 
 
 0.29130 
 
 1.2311 
 
 3.5844 
 
 0.02686 
 
 0.20443 
 
 0.9520 
 
 3.5990 
 
 0.28865 
 
 1.1847 
 
 3.5140 
 
 0.02635 
 
 0.20443 
 
 0.9196 
 
 3.5408 
 
 0.28609 
 
 1.1416 
 
 3.4461 
 
 0.02588 
 
 0.20443 
 
 0.8885 
 
 3.4838 
 
 0.28363 
 
 1.1018 
 
 3.3807 
 
 0.02544 
 
 0.20443 
 
 0.8588 
 
 3.4279 
 
 0.281-27 
 
 1.0653 
 
 3.3178 
 
 0.02504 
 
 0.20443 
 
 0.8304 
 
 3.3734 
 
 0.27901 
 
 1.0321 
 
 3.2578 
 
 0.02466 
 
 0.20443 
 
 0.8034 
 
 3.3200 
 
 0.27685 
 
 1.0020 
 
 3.1993 
 
 0.0243-2 
 
 0.20443 
 
 0.777s 
 
 3.2678 
 
 0.17478 
 
 0.9753 
 
 3.1438 
 
 0.02402 
 
 0.20443 
 
 0.7535 
 
 3.2169 
 
 0.27281 
 
 0.9519 
 
 3.0908 
 
 0.02374 
 
 0.20443 
 
 0.7306 
 
 3.1672 
 
 0.27094 
 
 0.9318 
 
 3.0402 
 
 0.02350 
 
 0.20443 
 
 0.7090 
 
 3.1187 
 
 0.26917 
 
 0.9150 
 
 2.9921 
 
 0.02329 
 
 0.20443 
 
 0.6888 
 
 3.0714 
 
 0.26750 
 
 0.9014 
 
 2.9465 
 
 0.02312 
 
 0.20443 
 
 0.6700 
 
 3.0253 
 
 0.26592 
 
 
 2.9034 
 
 
 
 0.6525 
 
 2.9805 
 
 0.26444 
 
 
 2.8628 
 
 
 
 0.6364 
 
 2.9368 
 
 0.26306 
 
 
 2.8247 
 
 
 
 0.6216 
 
 2.8944 
 
 0.26178 
 
 
 2.7890 
 
 
 
 0.6082 
 
 2.8532 
 
 0.26060 
 
TABLE OF THE COEFFICIENTS OF ABSORPTION 
 
 c. 
 
 Marsh gas 
 
 Olefiant gas 
 
 ^Ethyl 
 
 in 
 water. 
 
 Methyl 
 
 in 
 water. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 
 
 0.05449 
 
 0.52259 
 
 0.2563 
 
 3.5950 
 
 0.03147 
 
 0.0871 
 
 1 
 
 0.05332 
 
 0.51973 
 
 0.2473 
 
 3.5379 
 
 0.03040 
 
 0.0838 
 
 2 
 
 0.05217 
 
 0.51691 
 
 0.2388 
 
 3.4823 
 
 0.02947 
 
 0.0807 
 
 3 
 
 0.05104 
 
 0.51412 
 
 0.2306 
 
 3.4280 
 
 0.02856 
 
 0.0777 
 
 4 
 
 0.04993 
 
 0.51135 
 
 0.2227 
 
 3.3750 
 
 0.02770 
 
 0.0748 
 
 5 
 
 0.04885 
 
 0.50861 
 
 0.2153 
 
 3.3234 
 
 0.02689 
 
 0.0720 
 
 6 
 
 0.04778 
 
 0.50590 
 
 0.2082 
 
 3.2732 
 
 0.02613 
 
 0.0693 
 
 7 
 
 0.04674 
 
 0.50322 
 
 0.2018 
 
 3.2243 
 
 0.02541 
 
 0.0668 
 
 8 
 
 0.04571 
 
 0.50057 
 
 0.1952 
 
 3.1768 
 
 0.02474 
 
 0.0644 
 
 9 
 
 0.04470 
 
 0.49795 
 
 0.1893 
 
 3.1307 
 
 0.02412 
 
 0.0621 
 
 10 
 
 0.04372 
 
 0.49535 
 
 0.1837 
 
 3.0859 
 
 0.02355 
 
 0.0599 
 
 11 
 
 0.04275 
 
 0.49278 
 
 0.1786 
 
 3.0425 
 
 0.02303 
 
 0.0578 
 
 12 
 
 0.04180 
 
 0.49024 
 
 0.1737 
 
 3.0005 
 
 0.02257 
 
 0.0559 
 
 13 
 
 0.04088 
 
 0.48773 
 
 0.1693 
 
 2.9598 
 
 0.02216 
 
 0.0541 
 
 14 
 
 0.03997 
 
 0.48525 
 
 0.1652 
 
 2.9205 
 
 0.02179 
 
 0.0524 
 
 15 
 
 0.03909 
 
 0.48280 
 
 0.1615 
 
 2.8825 
 
 0.02147 
 
 0.0508 
 
 16 
 
 0.03823 
 
 0.48037 
 
 0.1583 
 
 2.8459 
 
 0.02121 
 
 0.0493 
 
 17 
 
 0.03739 
 
 0.47798 
 
 0.1553 
 
 2.8107 
 
 0.02100 
 
 0.0480 
 
 18 
 
 0.03657 
 
 0.47561 
 
 0.1528 
 
 2.7768 
 
 0.02084 
 
 0.0468 
 
 19 
 
 0.03577 
 
 0.47327 
 
 0.1506 
 
 2.7443 
 
 0.02073 
 
 0.0457 
 
 20 
 
 0.03499 
 
 0.47096 
 
 0.1488 
 
 2.7131 
 
 0.02065 
 
 0.0447 
 
 21 
 
 
 0.46867 
 
 
 2.6833 
 
 
 
 22 
 
 
 0.46642 
 
 
 2.6549 
 
 
 
 23 
 
 
 0.46419 
 
 
 2.6279 
 
 
 
 24 
 
 
 0.46199 
 
 
 2.6022 
 
 
 
OF VARIOUS GASES IN WATER AND ALCOHOL. 
 
 289 
 
 ulphuretted-hydrogen 
 
 Sulphurous acid 
 
 Ammonia 
 
 in 
 water. 
 
 Atmospheric 
 air 
 in 
 water. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 in 
 water. 
 
 in 
 alcohol. 
 
 4.3706 17.891 
 
 68.861 328.62 
 
 1049.6 
 
 0.02471 
 
 4.2874 
 
 17.242 
 
 67.003 
 
 311.98 
 
 1020.8 
 
 0.02406 
 
 4.2053 
 
 16.606 
 
 65.169 
 
 295.97 
 
 993.3 
 
 0.02345 
 
 '.4.1243 
 
 15.983 
 
 63.360 , 280.58 
 
 907.0 
 
 0.02287 
 
 
 
 
 
 
 
 4.0442 
 
 15.373 
 
 61.576 
 
 265.81 
 
 941.9 
 
 0.02237 
 
 j 3.9652 
 
 14.776 
 
 59.816 
 
 251.67 
 
 917.9 
 
 0.02179 
 
 3.8872 
 
 14.193 
 
 5SO&0 238.16 
 
 895.0 
 
 0.02128 
 
 3.8103 
 
 13.623 
 
 56.369 225.25 
 
 873.1 
 
 0.0200 
 
 3.7345 
 
 13.066 
 
 54.683 
 
 212.98 
 
 852.1 
 
 0.02034 
 
 3.659G 
 
 12.523 
 
 53.021 
 
 201.33 
 
 832.0 
 
 0.01992 
 
 3.5858 11.992 
 
 51.383 
 
 190.31 
 
 812.8 
 
 0.01953 
 
 3.5132 11.475 
 
 49.770 
 
 179.91 
 
 794.3 
 
 0.01916 
 
 3.4415 
 
 10.971 
 
 48.182 
 
 170.13 
 
 776.6 
 
 0.01882 
 
 3.3708 
 
 10.480 
 
 46.618 
 
 160.98 
 
 759.6 
 
 0.01851 
 
 3.3012 
 
 10.003 
 
 45.079 
 
 152.45 
 
 743.1 
 
 0.01822 
 
 3.2326 
 
 9.539 
 
 43.564 
 
 144.55 
 
 727.2 
 
 0.01795 
 
 3.1651 
 
 9.088 
 
 42.073 
 
 ' 137.27 
 
 711.8 
 
 0.01771 
 
 3.098G 
 
 8.650 
 
 40.608 130.61 
 
 696.9 
 
 0.01750 
 
 
 
 1 
 
 
 
 3.0331 | 8.227. 
 
 39.165 
 
 124.58 
 
 682.3 
 
 0.01732 
 
 2.9687 
 
 7.814 
 
 37.749 
 
 119.17 
 
 668.0 
 
 0.01717 
 
 2.9053 
 
 7.415 
 
 36.216 
 
 114.48 
 
 654.0 
 
 0.01704 
 
 - 2.8430 
 
 7.030 
 
 34.986 
 
 110.22 
 
 640.2 
 
 
 : 2.7817 
 
 6.659 
 
 33.910 106.68 
 
 626.5 
 
 
 2.7215 
 
 6.300 
 
 32.847 103.77 
 
 613.0 
 
 
 : 2.6623 
 
 5.955 
 
 31.800 
 
 101.47 
 
 599.5 
 
 
 19 
 
290 CALCULATION OF THE COMPOSITION OF THE ATMOSPHE1 
 VII. Table for the calculation of the proportioi 
 
 Volume of the atmospheric air. 
 
 100.00. 
 
 200.00. 
 
 300.00. 
 
 Volume of nitrogen contained .... 
 
 79.04 
 
 158.08 
 
 237.12 
 
 Volume of oxygen contained .... 
 
 20.96 
 
 41.92 
 
 62.88 
 
 VIII. ' Table for the calculatio: 
 
 Name of the gas. i Formula. 1000 CC. 
 
 2000 CC. 3000 CC. 
 
 Atmospheric air . . . 
 
 
 Grammes. 
 1.29366 
 
 Grammes. 
 
 2.58732 
 
 Grammes. 
 
 3.8809* 
 
 /Ethyl ....... 
 
 C 4 H 5 
 
 2.59349 
 
 5.18698 
 
 7.78047 
 
 
 NH. 
 
 0.76271 
 
 1.52542 
 
 2.28813 
 
 A.ntimonv ... 
 
 Sb 
 
 23.06332 
 
 46.12664 
 
 69.18996 
 
 
 Antimoniuretted hydrogen 
 
 SbH 3 
 
 5.90026 
 
 11.80052 
 
 17.70078 
 
 A VQPYllf* 
 
 As 
 
 13.40892 
 
 : 26.81784 
 
 40.2267'> 
 
 Arseniuretted hydrogen 
 
 AsH 3 
 
 3.48665 
 
 6.97330 
 
 10.45995 
 
 Boron * 
 
 Bo 
 
 1.94876 
 
 S 897*9 
 
 5.84628 
 
 
 Br 
 
 6.99990 13.99980 
 
 20.99970 
 
 
 c 
 
 1.07272 
 
 9 14-644 
 
 3.21816 
 
 Carbonic oxide . . . 
 
 CO 
 
 1.25150 2.50300 
 
 3.75450 
 
 Carbonic acid .... 
 
 C0 2 
 
 1.96664 3.93328 
 
 5.8999:' 
 
 Chlorine ... 
 
 Cl 
 
 3.17344 6.34688 
 
 9.52032 
 
 Chloride of acetyl . . 
 
 C 4 H 4 C1 
 
 2.79386 5.58772 
 
 8.38158 
 
 Chloride of boron . . 
 
 BoCl 3 
 
 5.24735 
 
 10.49470 
 
 15.74205 
 
 Chloride of cyanogen . 
 
 C 2 NC1 
 
 2.75137 
 
 5.50274 
 
 8.25411 
 
 Chloride of methyl . . 
 
 C 2 H 3 C1 
 
 2.25749 4.51498 
 
 6.77247 
 
 Cyanogen 
 
 C 2 N 
 
 2.32930 4.65860 
 
 G.98790 
 
 
 Ditetryl 
 
 C 8 P 8 
 
 2.50388 5.00776 
 
 7.61164 
 
 
 Elayl 
 
 C.H, 
 
 1.25194 2.50388 
 
 3.7W82 
 
 Fluorine 
 
 V 4 -*4 
 
 Fl 
 
 1.71634 3.43268 
 
 5.14902 
 
 
CALCULATION OF THE WEIGHTS OF GASES. 
 
 291 
 
 >f oxygen and nitrogen contained in the air. 
 
 400.00. 
 
 500.00. 
 
 600.00. 
 
 700.00. 
 
 800.00. 
 
 900.00. 
 
 316.16 
 
 395.20 474.24 
 
 553.28 632.32 
 
 711.36 
 
 83.84 
 
 104.80 
 
 125.76 
 
 146.72 
 
 167.68 
 
 188.64 
 
 of the weight of gases from their volume. 
 
 4000 CC. 
 
 5000 CC. 
 
 6000 CC. 
 
 7000 CC. 
 
 8000 CC. 
 
 9000 CC. 
 
 1 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 5.17464 
 
 6.46830 
 
 7.76196 
 
 9.05562 
 
 10.34928 
 
 11.64294 
 
 ' 10.37396 
 
 12.96745 
 
 15.56094 
 
 18.15443 
 
 20.74792 
 
 23.34141 
 
 3.05084 
 
 3.81355 
 
 4.57626 
 
 5.33897 
 
 6.10168 
 
 6.86439 
 
 92.25328 
 
 115.31660 
 
 138.37992 
 
 1(51.44324 
 
 184.50656 
 
 207.56992 
 
 23.60104 
 
 29.50130 
 
 35.40156 
 
 41.30182 
 
 47.20208 
 
 53.10234 
 
 53.63568 
 
 67.04460 
 
 80.45352 
 
 93.86244 
 
 107.27136 
 
 120.68028 
 
 13.94660 
 
 17.43325 
 
 20.91990 
 
 24.40655 
 
 27.89320 
 
 31.37985 
 
 7.79504 
 
 9.74380 
 
 11.69256 
 
 13.64132 
 
 15.59008 
 
 17.53884 
 
 27.99960 
 
 34.99950 
 
 41.99940 
 
 48.99930 
 
 55.99920 
 
 62.99910 
 
 4.29088 
 
 5.36360 
 
 6.43632 
 
 7.50904 
 
 8.58176 
 
 9.6544* 
 
 5.00600 
 
 6.25750 
 
 7.50900 
 
 8.76050 
 
 10.01200 
 
 11.26350 
 
 7.86656 
 
 9.83320 
 
 11.79984 
 
 13.76648 
 
 15.73312 
 
 17.69976 
 
 12.69376 
 11.17544 
 
 15.86720 
 13.96930 
 
 19.04064 
 16.76316 
 
 22.21408 
 19.55702 
 
 25.38752 
 22.35088 
 
 28.56096 
 25.14474 
 
 20.98940 
 
 26.23675 
 
 31.48410 
 
 36.73145 
 
 41.97880 
 
 47.22615 
 
 11.00548 
 
 13.75685 
 
 16.50822 
 
 19.25959 
 
 22.01096 
 
 24.76233 
 
 9.02996 
 
 11.28745 
 
 13.54494 
 
 15.80243 
 
 18.05992 
 
 20.31741 
 
 9.31720 
 
 11.64650 
 
 13.97580 
 
 16.30510 
 
 18.63440 
 
 20.96370 
 
 10.01552 
 
 12.51940 
 
 15.02328 
 
 17.52716 
 
 20.03104 
 
 22.53492 
 
 5.00776 
 
 6.25970 
 
 7.51164 
 
 8.76356 
 
 10.01552 
 
 11.26746 
 
 6.86536 
 
 8.58170 
 
 10.29804 
 
 12.01438 
 
 13.73072 
 
 15.44706 
 
292 
 
 TABLE FOR THE CALCULATION 
 
 Name of the gas. 
 
 Formula. 
 
 1000 CO. 
 
 2000 CO. 
 
 3000 CC. 
 
 
 
 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 Fluoride of boron . . 
 
 BoFla 
 
 3.06166 
 
 6.12332 
 
 9.18498 
 
 Fluoride of silicon . . 
 
 SiFl 3 
 
 4.70206 
 
 9.40412 
 
 14.10618 
 
 Hydrogen 
 
 H 
 
 0.08961 
 
 0.17922 
 
 0.26883 
 
 
 
 
 
 
 Hydrobromic acid . . 
 
 HBr 
 
 3.54471 
 
 7.08942 
 
 10.63413 
 
 Hydrochloric acid . . 
 
 HC1 
 
 1.63153 
 
 3.26306 
 
 4.89459 
 
 Hydrofluoric acid . . 
 
 HF1 
 
 0.90298 
 
 1.80596 
 
 2.70894 
 
 Hydriodic acid . . . 
 
 HI 
 
 5.72573 
 
 11.45146 
 
 17.17719 
 
 
 1 
 
 11.36180 
 
 22.72360 
 
 34.08540 
 
 Marsh gas ... 
 
 C 9 H 4 
 
 0.71558 
 
 1.43116 
 
 2.14674 
 
 Methyl .... 
 
 2 *- A 4 
 
 Co Ho 
 
 1.34152 
 
 2.68304 
 
 4.02456 
 
 Methyl aether .... 
 
 VI *-^8 
 
 C 2 H 3 
 
 2.05669 
 
 4.11338 
 
 6.17007 
 
 Nitrogen 
 
 N 
 
 1.25658 
 
 2.51316 
 
 3.76974 
 
 Nitrous oxide .... 
 
 NO 
 
 1.97172 
 
 3.94344 
 
 5.91516 
 
 Nitric oxide .... 
 
 NO 2 
 
 1.34343 
 
 2.68686 
 
 4.03029 
 
 Oxygen 
 
 o 
 
 1.43028 
 
 2.86056 
 
 4.29084 
 
 Phosgene gas .... 
 
 CC1O 
 
 4.42494 
 
 8.84988 
 
 13.27482 
 
 Phosphorus 
 
 Ph 
 
 5.54230 
 
 11.08460 
 
 16.62690 
 
 
 
 
 
 
 Phosphuretted hydrogen 
 
 PhH 3 
 
 1.52000 
 
 2.04000 
 
 4.56000 
 
 Selenium 
 
 Sc 
 
 7.02556 
 
 14.05112 
 
 21.07668 
 
 Seleuiuretted hydrogen 
 
 Sell 
 
 3.60239 
 
 7.20478 
 
 10.80717 
 
 
 Si 
 
 3.80814 
 
 7.61628 
 
 11.42442 
 
 Sulphur .... 
 
 S 
 
 17.16336 
 
 34.32672 
 
 51.49008 
 
 Sulphurous acid . . . 
 
 S0 2 
 
 2.86056 
 
 5.72112 
 
 8.58168 
 
 Sulphuretted hydrogen 
 
 SH 
 
 1.51991 
 
 3.03982 
 
 4.55973 
 
 
 Te 
 
 11.53525 
 
 23.07050 
 
 34.60575 
 
 Telluretted hydrogen . 
 
 HTe 
 
 5.85723 
 
 11.71446 
 
 17.57169 
 
 Vapour of water . . . 
 
 HO 
 
 0.80475 
 
 1.60950 
 
 2.41425 
 
OF THE WEIGHTS OF GASES FROM THEIR VOLUMES. 293 
 
 4000 CC. 
 
 5000 CC. 6000 CC. 
 
 7000 CC. 
 
 8000 CC. 
 
 9000 CC. 
 
 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 Grammes. 
 
 1-2.24664 
 
 15.30830 
 
 18.36996 
 
 21.43162 
 
 24.49328 
 
 27.55494 
 
 18.80824 
 
 23.51030 
 
 28:21236 
 
 32.91442 
 
 37.61648 
 
 42.31854 
 
 0.35844 
 
 0.44805 
 
 0.53766 
 
 0.62727 
 
 0.71688 
 
 0.80649 
 
 14.17884 
 
 17.72355 
 
 21.26826 
 
 24.81297 
 
 28.35768 
 
 31.90239 
 
 6.52612 
 
 8.15765 
 
 9.78918 
 
 11.42071 
 
 13.05224 
 
 14.68377 
 
 3.61192 
 
 4.51490 
 
 5.41788 
 
 6.32086 
 
 7.22384 
 
 8.12682 
 
 22.90292 
 
 28.62865 
 
 34.35438 
 
 40.08011 
 
 45.80584 
 
 51.53157 
 
 45.44720 
 
 56.80900 
 
 68.17080 
 
 79.53260 
 
 90.89440 
 
 102.25620 
 
 2.86232 
 
 3.57790 
 
 4.29348 
 
 5.00906 
 
 5.72464 
 
 6.44022 
 
 5.36608 
 
 6.70760 
 
 8.04912 
 
 9.39064 
 
 10.73216 
 
 12.07368 
 
 8.22676 
 
 10.28345 
 
 12.34014 
 
 14.39683 
 
 16.45352 
 
 18.51021 
 
 5.026*2 
 
 6.28290 
 
 7.53948 
 
 8.79606 
 
 10.05264 
 
 11.30922 
 
 7.88688 
 
 9.85860 
 
 11.83032 
 
 13.80204 
 
 15.77376 
 
 17.74548 
 
 5.37372 
 
 6.71615 
 
 8.06058 
 
 9.40301 
 
 10.74744 
 
 12.09087 
 
 5.72112 
 
 7.15140 
 
 8.58168 
 
 10.01196 
 
 11.44224 
 
 12.87252 
 
 I7.6997ti 
 
 -2-2.12470 
 
 26.54964 
 
 30.9745* 
 
 35.39952 
 
 39.82446 
 
 22.16920 
 
 -27.71150 
 
 33.25380 
 
 38.79610 
 
 44.33840 
 
 49.88070 
 
 6.08000 
 
 7.60000 
 
 I). 12000 10.64000 
 
 12.16000 
 
 13.68000 
 
 28.10224 
 
 35.12780 
 
 42.15336 49.17892 
 
 56.20448 
 
 63.23004 
 
 14.40956 
 
 18.01195 
 
 21. 61434: -j."). -21673 
 
 28.81912 
 
 32.42151 
 
 15.23-256 
 
 19.04070 
 
 22.84884 
 
 26.65698 
 
 30.46512 
 
 34.27326 
 
 68.65344 
 
 So. 81680 
 
 102.98016 
 
 120.14352 
 
 137.30688 
 
 154.47024 
 
 11.442-24 
 
 14.30280 
 
 17.16336 
 
 20.02392 
 
 22.88448 
 
 25.74504 
 
 6.07964 
 
 7.59955 
 
 9.11946 
 
 10.63937 12.15928 
 
 13.67919 
 
 46.14100 
 
 67.67625 
 
 69.21150 i 80.74675 
 
 92.28200 
 
 103.81725 
 
 23.42*92 29.28615 ! 35.14338 I 41.00061 
 
 46.85784 
 
 52.71507 
 
 3.21 1>UU 4.02375 4.82850 
 
 5.63325 
 
 6.43800 
 
 7.24275 
 
294 COMPARISON OP THERMOMETRIC SCALES. 
 
 IX. 
 
 Table for the comparison of the centigrade thermometer 
 with Fahrenheit's scale from + 140 to -f- 20 Fah. 
 
 w Fah. = Vo ( w 32 ) C - 
 w o C. = % ^ -\- 32 Fah. 
 
 lo Fah. == 055 C. 01 Fah. = 0055 C. 
 
 Fahrenheit. 
 
 Centigrade. 
 
 Fahrenheit. 
 
 Centigrade. 
 
 Fahrenheit. 
 
 Centigrade. 
 
 -f 140 
 
 60.00 
 
 -j- 99 
 
 37.22 
 
 -j- 58 
 
 14.44 
 
 139 
 
 59.44 
 
 98 
 
 36.67 
 
 57 
 
 13.89 
 
 138 
 
 58.89 
 
 97 
 
 36.11 
 
 56 
 
 13.33 
 
 137 
 
 58.33 
 
 96 
 
 35.55 
 
 55 
 
 12.78 
 
 136 
 
 57.78 
 
 95 
 
 35.00 
 
 54 
 
 12.22 
 
 135 
 
 57.22 
 
 94 
 
 34.44 
 
 53 
 
 11.67 
 
 134 
 
 56.67 
 
 93 
 
 33.89 
 
 52 
 
 11.11 
 
 133 
 
 56.11 
 
 92 
 
 33.33 
 
 51 
 
 10.55 
 
 132 
 
 55.55 
 
 91 
 
 32.78 
 
 50 
 
 10.00 
 
 131 
 
 55.00 
 
 90 
 
 32.22 
 
 49 
 
 9.44 
 
 130 
 
 54.44 
 
 .89 
 
 31.67 
 
 48 
 
 8.89 
 
 129 
 
 53.89 
 
 88 
 
 31.11 
 
 47 
 
 8.33 
 
 128 
 
 53.33 
 
 87 
 
 30.55 
 
 46 
 
 7.78 
 
 127 
 
 52.78 
 
 86 
 
 30.00 
 
 45 
 
 7.22 
 
 126 
 
 52.22 
 
 85 
 
 29.44 
 
 44 
 
 6.67 
 
 125 
 
 51.67 
 
 84 
 
 28.89 
 
 43 
 
 6.11 
 
 124 
 
 51.11 
 
 83 
 
 28.33 
 
 42 
 
 5.55 
 
 123 
 
 50.55 
 
 82 
 
 27.78 
 
 41 
 
 5.00 
 
 122 
 
 50.00 
 
 81 
 
 27.22 
 
 40 
 
 4.44 
 
 121 
 
 49.44 
 
 80 
 
 26.67 
 
 39 
 
 3.89 
 
 120 
 
 48.89 
 
 79 
 
 26.11 
 
 38 
 
 3.33 
 
 119 
 
 48.33 
 
 78 
 
 25.55 
 
 37 
 
 2.78 
 
 118 
 
 47.78 
 
 77 
 
 25.00 
 
 36 
 
 2.22 
 
 117 
 
 47.22 
 
 76 
 
 24.44 
 
 35 
 
 1.67 
 
 116 
 
 46.67 
 
 75 
 
 23.89 
 
 34 
 
 1.11 
 
 115 
 
 46.11 
 
 74 
 
 23.33 
 
 33 
 
 0.55 
 
 114 
 
 45.55 
 
 73 
 
 22.78 
 
 32 
 
 0.00 
 
 113 
 
 45.00 
 
 72 
 
 22.22 
 
 31 
 
 -f- 0.55 
 
 112 
 
 44.44 
 
 71 
 
 21.67 
 
 30 
 
 1.11 
 
 111 
 
 43.89 
 
 70 
 
 21.11 
 
 29 
 
 1.67 
 
 110 
 
 43.33 
 
 69 
 
 20.55 
 
 28 
 
 2.2 
 
 109 
 
 42.78 
 
 68 
 
 20.00 
 
 27 
 
 2.78 
 
 108 
 
 42.22 
 
 67 
 
 19.44 
 
 26 
 
 3.33 
 
 107 
 
 41.67 
 
 66 
 
 18.89 
 
 25 
 
 3.89 
 
 106 
 
 41.11 
 
 65 
 
 18.33 
 
 24 
 
 4.44 
 
 105 
 
 40.55 
 
 64 
 
 17.78 
 
 23 
 
 5.00 
 
 104 
 
 40.00 
 
 63 
 
 17.22 
 
 22 
 
 5.55 
 
 103 
 
 39.44 
 
 62 
 
 16.67 
 
 21 
 
 6.11 
 
 102 
 
 38.89 
 
 61 
 
 16.11 
 
 20 
 
 6.67 
 
 101 
 
 38.33 
 
 60 
 
 15.55 
 
 
 
 100 
 
 37.78 
 
 59 
 
 15.00 
 
 
 
REDUCTION OF BAROMETER SCALE. 
 
 X. 
 
 Table for the reduction of the barometer scale from 
 millimetres into English inches. 
 
 Millimetres 
 
 Inches. 
 
 Millimetres 
 
 Inches. 
 
 Millimetres 
 
 Inches. 
 
 700 
 
 27.560 
 
 730 
 
 28.741 
 
 760 29.922 
 
 701 
 
 27.590 
 
 731 
 
 28.780 
 
 761 
 
 29.961 
 
 702 
 
 27.638 
 
 732 
 
 28.819 
 
 762 
 
 30.000 
 
 703 
 
 27.678 
 
 733 
 
 28.859 
 
 763 
 
 30.040 
 
 704 
 
 27.717 
 
 734 
 
 28.898 
 
 764 30.079 
 
 705 
 
 27.756 
 
 735 
 
 28.938 
 
 765 30.119 
 
 706 
 
 27.795 
 
 786 
 
 28.977 
 
 766 
 
 30.158 
 
 707 
 
 27.835 
 
 737 
 
 29.016 
 
 767 
 
 30.197 
 
 708 
 
 27.876 
 
 738 
 
 29.056 
 
 768 
 
 30.237 
 
 709 
 
 27.914 
 
 739 
 
 29.059 
 
 769 
 
 30.27G 
 
 710 
 
 27.953 
 
 740 
 
 29.134 
 
 770 
 
 30.315 
 
 711 
 
 27.992 
 
 741 
 
 29.174 
 
 7/1 
 
 30.355 
 
 712 
 
 28.032 
 
 742 
 
 29.213 
 
 772 
 
 30.384 
 
 713 
 
 28.071 
 
 743 
 
 29.252 
 
 773 
 
 30.434 
 
 714 
 
 28.111 
 
 744 
 
 29 292 
 
 774 
 
 30.473 
 
 715 
 
 28.150 
 
 745 
 
 29.331 
 
 775 
 
 30.512 
 
 716 
 
 28.189 
 
 746 
 
 29.371 
 
 776 
 
 30.552 
 
 717 
 
 28.229 
 
 747 
 
 29.410 
 
 777 
 
 30.591 
 
 718 
 
 28.268 
 
 748 
 
 29.449 
 
 778 
 
 30.631 
 
 719 
 
 28.308 
 
 749 
 
 29.489 
 
 779 
 
 30.670 
 
 720 
 
 28.347 
 
 750 
 
 29.528 
 
 780 j 30.709 
 
 721 
 
 28.386 
 
 751 
 
 29.567 
 
 781 
 
 30.749 
 
 722 
 
 28.426 
 
 752 
 
 29.607 
 
 782 
 
 30.788 
 
 723 
 
 28.465 
 
 753 
 
 29.646 
 
 783 
 
 30.827 
 
 724 
 
 28.504 
 
 754 
 
 29.685 
 
 784 
 
 30.867 
 
 725 
 
 28.543 
 
 755 
 
 29.725 
 
 785 
 
 30.906 
 
 726 
 
 28.583 
 
 756 
 
 29.71-4 
 
 786 
 
 30.945 
 
 7-27 
 
 28.622 
 
 757 
 
 29.804 
 
 787 
 
 30.985 
 
 728 
 
 28.661 
 
 758 
 
 29.843 
 
 788 
 
 31.024 
 
 729 
 
 28.701 
 
 759 
 
 29.882 
 
 789 
 
 31.063 
 
 28 inches = 711.187 millimetres. 
 
 29 ,, = 736.587 
 
 30 = 761.986 
 
 31 = 787.386 
 
 1 millimetre = 0.03937 inch. 
 U.I = 0.00394 ,. 
 0.01 = 0.00039 
 
 1 inch = 25.39954 millimetres. 
 
 0.1 = 2.53995 
 
 0.01 = 0.25400 
 
 0.001 = 0.02540 
 
29G 
 
 REDUCTION OF FRENCH MEASURES 
 XL Table for converting French decimal measures 
 
 
 1 
 
 2 
 
 3 
 
 Metre. 
 English yards 
 
 1 093f>3 
 
 1. M 
 
 2 18727 
 
 e a s u r e s 
 
 3 28090 
 
 feet 
 
 3 28090 
 
 6 56180 
 
 9 84270 
 
 inches 
 
 39 37080 
 
 78.74158 
 
 118 IPoG 
 
 Decimetre. 
 Feet 
 
 32809 
 
 65618 
 
 98427 
 
 Inches 
 
 3.93708 
 
 7 87416 
 
 11 81124 
 
 Centimetre. 
 Inches 
 
 39371 
 
 78742 
 
 1 18U2 
 
 Millimetre. 
 Inches .... 
 
 0.03937 
 
 0.07874 
 
 11811 
 
 Litre. 
 English cuoic inch 
 
 61.02711 
 
 2. M 
 
 122 05429 
 
 e a s u r e s 
 183 08133 
 
 .. cubic foot 
 
 0.035317 
 
 0.070633 
 
 0.105950 
 
 imp. gallons 
 quarts 
 Dints 
 
 0.22.017 
 0.8806(5 
 1 7G133 
 
 0.44033 
 1.76133 
 2 52266 
 
 0.66050 
 2.64199 
 5 28399 
 
 Cubic centimetre. 
 
 0.06103 
 
 12205 
 
 18308 
 
 Kilogramme. 
 Cwt ... 
 
 01970 
 
 03939 
 
 3. 
 0.05909 
 
 Ib. (avoir- du-poids) 
 
 2.20486 
 
 4 40971 
 
 6.61457 
 
 Kilogramme. 
 
 Ib. (troy) 
 
 2.67951 
 
 5 35903 
 
 8 03854 
 
 Gramme. 
 Grains . 
 
 15.44242 
 
 30 88484 
 
 46 32726 
 
 Decigramme. 
 Grains ... 
 
 1.54424 
 
 3 08848 
 
 4.63273 
 
 Centigr am me. 
 Grains . 
 
 0.15442 
 
 30885 
 
 46327 
 
 Milligramme. 
 Grains 
 
 0.01544 
 
 0.03089 
 
 0.04633 
 
 
 
 
 
AND WEIGHTS INTO ENGLISH MEASURES AND WEIGHTS. 297 
 nd weights into English measures and weights. 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 of 1 e n g 1 
 
 h. 
 
 
 
 
 
 4.37453 
 13.12360 
 157.48315 
 
 5.46816 
 16.40450 
 196.85394 
 
 6.56180 
 19.68539 
 236.22473 
 
 7.65543 
 22.96629 
 275.59552 
 
 8.74906 
 20.24719 
 314.96630 
 
 9.84270 
 29.52809 
 354.33709 
 
 1.31236 
 15.74832 
 
 1.64045 
 19.68539 
 
 1.96854 
 23.62247 
 
 2.29663 
 27.55955 
 
 2.62472 
 31.49663 
 
 2.95281 
 35.43371 
 
 1.57483 
 
 1.96854 
 
 2.36225 
 
 2.75596 
 
 3.14966 
 
 3.54337 
 
 0.15748 
 
 0.19685 
 
 0.23623 
 
 0.27560 
 
 0.31497 
 
 0.35434 
 
 o i' c a p a 
 
 ei t y. 
 
 
 
 
 244.10844 
 0.141266 
 0.88066 
 3.52266 
 7.04531 
 
 305.13555 
 0.176583 
 1.10083 
 4.40332 
 8.80664 
 
 366.16266 
 0.211900 
 1.32100 
 5.28398 
 10.56797 
 
 427.18977 
 0.247216 
 1.54116 
 6.16465 
 12.32930 
 
 488.21688 
 0.282532 
 1.76133 
 7.04531 
 14.09062 
 
 549.24399 
 0.317849 
 1.98149 
 7.92598 
 15.85195 
 
 0.24411 
 
 0.30514 
 
 0.36616 
 
 0.42719 
 
 0.48822 
 
 0.54924 
 
 Weigh 
 
 t s. 
 
 
 
 
 
 0.07879 
 8.81943 
 
 0.09848 
 11.02428 
 
 0.11818 
 13.22914 
 
 0.13788 
 15.43400 
 
 0.15758 
 17.63886 
 
 0.17727 
 19.84371 
 
 10.71805 
 
 13.39757 
 
 16.07708 
 
 18.75659 
 
 21.43610 
 
 24.11562 
 
 61.76968 
 
 77. -2 12 10 
 
 92.65352 
 
 108.09694 
 
 123'.53936 
 
 138.98178 
 
 6.17697 
 
 7.72121 
 
 9.26535 
 
 10.80969 
 
 12.35394 
 
 13.89818 
 
 0.61770 
 
 0.77212 
 
 0.92654 
 
 1.08097 
 
 1.23539 
 
 1.38982 
 
 0.06177 
 
 0.07721 
 
 0.09265 
 
 0.10810 
 
 0.12354 
 
 0.13898 
 
 
 
 
 
 19* 
 
 
298 REDUCTION OF FRENCH TO ENGLISH WEIGHTS. 
 
 The mode of using this table is exactly the same as for table 
 VIII as explained on page 238. An example may serve as illu- 
 stration. 
 
 Let it be required to find how many grains are equal to 87.435 
 grammes. 
 
 By column 8 line 4 of Nr. 3 
 
 we have 80 
 
 By column 7 line 4 of Nr. 3 
 
 we have 7 
 
 grammes = 1235.3936 grains. 
 108.0969 
 
 By column 4 line 5 of Nr. 3 
 we have 0.4 
 
 By column 3 line 6 of Nr. 3 
 
 we have 0.03 
 
 By column 5 line 7 of Nr. 3 
 
 we have . 0.005 
 
 = 6.1770 
 
 = 0.4633 
 
 0.0772 
 
 87.435 grammes = 1350.2080 grains. 
 
 One English foot = 0.30476 metre log. 0.30476 1.4839580. 
 One English inch m 25.3996 millimetres tog. 25.3996 = 1.4048269. 
 One English cubic -foot == 28.31 litres tog. 28.31 = 1.451940. 
 One English cubic- inch = 16.381 cbc. tog. 16.381 = 1.214340. 
 One English Imp. gallon =P 4.542 litres tog. 4.542 = 0.657247. 
 One English avoir -du-poids Ib. 
 
 = 453.598 grammes tog. 453.598 = 2.656673. 
 One English troy Ib. = 373.246 grammes tog. 373.246 2.571999. 
 
ERRATA. 
 
 Page 70 line 12 i'rom bottom for subtract read add. 
 
 70 
 
 11 
 
 11 
 
 M 
 
 11 
 
 from 
 
 
 to. 
 
 
 70 
 
 ,. 8 
 
 11 
 
 11 
 
 11 
 
 subtracting 
 
 read 
 
 adding. 
 
 70 
 
 7 
 
 n 
 
 11 
 
 11 
 
 from 
 
 11 
 
 
 to. 
 
 102 
 
 i, * 
 
 11 
 
 top 
 
 11 
 
 0.0002 
 
 11 
 
 
 0.0021. 
 
 102 
 
 11 5 
 
 11 
 
 11 
 
 11 
 
 17.2712 
 
 11 
 
 
 17.2731. 
 
 112 
 
 4 
 
 11 
 
 11 
 
 11 
 
 2.089 B 
 
 11 
 
 
 2.090 B. 
 
 133 
 
 i, 14 
 
 11 
 
 11 
 
 i 
 
 water 
 
 11 
 
 
 liquid. 
 
 134 
 
 and 135 for 
 
 v l read 
 
 K, 
 
 throughout. 
 
 
 
 
 145 
 
 line 8 
 
 from 
 
 top for 
 
 0.0003 read 0.0004. 
 
 1 *\f 
 
 Q 
 
 
 
 V 
 
 ?PNV l 
 
 ff\nf\ 
 
 r pPN V l 
 
 100 
 
 157 
 
 5 
 
 11 
 
 bottom 
 
 for 
 
 V l read F . 
 
 rCdvl 
 
 0.76(^0) 
 
 159 
 
 12 
 
 11 
 
 top 
 
 11 
 
 3.8861 1 3.8944 
 
 read 2.8861(2.8944. 
 
 167 
 
 10 
 
 
 
 bottom 
 
 11 
 
 S l read ^. 
 
 
 
 
 167 
 
 1m Q 
 
 6 
 
 11 
 
 11 
 
 11 
 
 "2 11 '^2' 
 
 y 
 
 10 
 
 183 
 
 
 ,1 2 
 
 11 
 11 
 
 top 
 
 11 
 
 11 
 11 
 
 absorbed read unabsorbed. 
 
 193 
 
 5 
 
 11 
 
 11 
 
 11 
 
 V and Vi read 
 
 
 ^ 1 y 
 
 X 
 
 
 220 
 
 11 
 
 11 
 
 bottom 
 
 11 
 
 hydrogen read 
 
 oxygen. 
 
 222 
 
 3 
 
 11 
 
 top 
 
 11 
 
 (i 4- y) 
 
 
 (1 
 
 -y). 
 

 A DH tThf*i , r^ == r ===: ==^ _ 
 
s a 
 
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