S 
 
 593 
 J7 
 1856 
 
FOR THE 
 
 ANALYSIS OF SOILS, LIMESTONES, 
 
 AND 
 
 M A. N U H E S. 
 
 BY 
 
 JAMES F. W. JOHNSTON, 
 
 M.A., F.K.S8. L. & E., AC. 
 
 Author of " Lectures OQ Agrrcultural Chemistry and Geology," 
 " Catechism of Agricultural Chemistry and Geology," 
 
 " The Chemistry of Common Life, Ac." 
 
 THIRD EDITION. 
 
 S. B. SHAW, 
 
 PUBLISHER, OLEVKT, AND, OHIO, 
 1856. 
 
HARRIS, FAIRBANKS & CO., PRINTERS, CLEVELAND. 
 
PREFACE TO THE THIRD ENGLISH EDITION. 
 
 THIS little work is not intended to compete with treatises on 
 chemical analysis, such as those of Rose and Fresenius, which are 
 the text-books of the accomplished analyst. Originally published 
 as an Appendix to my Lectures OH Agricultural Chemistry and 
 Geology, it has been much in demand also in a separate form. I 
 have, therefore, given to this third edition a more widely practical 
 bearing, by including limestones, clays, ironstones, manures, and 
 natural waters, among the substances to be analysed. I have 
 briefly explained, also, the principles on which analysis by meas- 
 ure is founded a method which is susceptible of many simple 
 practical applications. The Instructions are as few and simple as 
 the subject well admits of, and the advancing student will proceed 
 from this little manual to the many larger works which are within 
 his reach. 
 
 To the schoolmaster, the farmer, the pharmaceutical chemist 
 and druggist, the youthful student, and to the rural, the training 
 or normal school, and the agricultural laboratory, I offer it as a 
 
 FIRST HELP TO PRACTICAL AND ECONOMICAL CHEMICAL ANALYSIS. 
 
 Though small in size, it will materially aid them in those chemical 
 investigations which, in connection with agriculture and the arts, 
 are every day becoming more sought for, and more necessary. 
 With a Tiew to easy reference, I have added a copious Index. 
 March 1855. 
 
AMERICAN PUBLISHER'S PREFACE. 
 
 THE want in this country of just such a work as Prof. John- 
 ston has here given to the world, there being nothing of the kind 
 in the United States, has induced the publisher to issue an edition 
 of it for the benefit of the farmers of America, in a cheap form. 
 The importance to the Agriculturist of a thorough knowledge of 
 all branches of his business, and of the fundamental principles 
 which govern the development of vegetation, and its perfect 
 growth, need not be dwelt upon. Every man who understands 
 his own interests, desires a knowledge of everything which will 
 promote them, and I have not a remote doubt that a careful study 
 of this little book, aided by experiments in accordance with its 
 instructions, will redound in large benefits to the student. Few 
 and simple as the Instructions are, they yet form one of the most 
 valuable aids to the science of Agriculture, which have ever been 
 published. 
 
CONTENTS. 
 
 CHAT. PAGE. 
 
 I. PHYSICAL PROPERTIES OF THE SOIL, HOW DETER- 
 MINED, . ... . . . .7 
 
 II. ORGANIC MATTER OF THE SOIL, HOW ESTIMATED, 16 
 
 III. SALINE MATTER OF THE SOIL, HOW EXAMINED, . 24 
 
 IV. ESTIMATION OF THE SALINE MATTERS (NATURAL 
 
 WATERS), . . . ' . '' . . .31 
 
 V. EARTHY MATTERS OF THE SOIL (TILE AND FIRE 
 
 CLAYS), ..43 
 
 VI. ANALYSIS BY MEASURE (OKES OF IRON), . . 59 
 
 VII. GENERAL REMARKS ON THE ANALYSIS OF SOILS 
 
 PRACTICAL SUGGESTIONS, . . . .67 
 
 VIII. ANALYSIS OF LIMESTONES AND MARLS, . . 73 
 IX. ANALYSIS OF SALINE MANURES, . .- . 78 
 
 X. EXAMINATION OF BONE MANURES, GUANOS, AND 
 
 OIL-CAKES, , 87 
 
INSTRUCTIONS 
 
 FOR THE 
 
 ANALYSIS OF SOILS, LIMESTONES, 
 MANURES, &c. 
 
 CHAPTER I. 
 PHYSICAL PROPERTIES OF THE SOIL. 
 
 Why a soil should be analysed. Usefulness of knowing the proportions of 
 lime, organic matter, and sand or clay inn soil. More refined inquiries. 
 How to select a soil for examination. To determine the physical properties 
 of a soil; its density, absolute weight, proportions of sand and gravel ; its 
 absorbing power; its power of retaining water ; rapidity with which it dries; 
 power of absorbing heat from the sun; and rapidity of cooling. The sandy 
 deserts. 
 
 I. WHY A SOIL SHOULD BE ANALYSED. 
 
 1. THE benefits to be derived from the chemical exa- 
 mination and analysis of a soil are by many misunder- 
 stood. Some have represented it as the only sure guide to 
 successful cultivation ; while others have not scrupled to 
 pronounce the analysis of soils to be entirely useless, and 
 unfitted to lead to any profitable practical result. Both, 
 of these extreme parties are in error. For while it is often 
 very difficult, from an analysis alone, to explain either the 
 
PHYSICAL PROPERTIES OF THE SOIL. 
 
 past agricultural history, the present money value, or 
 how best to remedy the known defects of a soil, yet there 
 are many practical points on which analysis does throw 
 light, and modes of practical treatment which it serves at 
 once either to discourage or to recommend. 
 
 2. Thus, on m any accounts, it is desirable to know how 
 much lime a soil contains. Soils rich in lime generally 
 produce a sweet herbage, sound and nutritious green crops, 
 and grain of a full ear and strong straw. To secure these 
 advantages, the farmer is willing to apply lime ; but the 
 land may contain enough already, and to apply more 
 might only be a waste ; or it may contain little or none, 
 and he may be about to apply too little. A simple 
 analysis settles difficulties of this kind, determines the 
 per-centage of lime, and points out what in the circum- 
 stances is best to be done. 
 
 3. Again, the proportion of organic or combustible 
 matter in a soil regulates, in some degree, the dose of 
 lime it is proper to ad'l the kind of mineral, vegetable, 
 or other manure it may be proper to use upon it and in 
 the case of moorish or peaty soils, how far clay or sand 
 would be likely to improve it. Hence it is desirable to 
 know what per-centage of organic matter a soil contains. 
 
 4. Again, a poor soil has sometimes much resemblance 
 to clay, and yet, on chemical examination, proves to con- 
 sist mainly of a very fine sand. To ascertain this, is to 
 determine at once how the soil may be improved. Or a 
 soil may be found, upon analysis, to be too largely im- 
 pregnated with oxide of iron, or to contain peculiarly 
 noxious combinations of iron, or to be too rich in common 
 salt; and each of these results of analysis indicates to the 
 
PHYSICAL PROPERTIES OF THE SOIL. 9 
 
 skilful man the steps which will most quickly or econo- 
 mically bring the several soils into a fertile condition. 
 
 5. These are some of the plainer cases in which useful 
 information may be derived from comparatively simple 
 analyses of soils. When the skill of the analyst is suffi- 
 ciently refined to enable him to detect or determine the 
 phosphoric acid, the potash, the ammonia, or the nitric 
 acid which a soil contains, other conclusions may be 
 drawn which are not without their practical value. It is 
 the pretended application of such determinations made 
 hastily and without sufficient care or knowledge, either 
 chemical or agricultural which have led many to deny as 
 hastily, that any good at all is to be derived from the 
 analysis of a soil. (See Chap. VII.) 
 
 II. HOW TO SELECT SPECIMENS OF SOILS FOR ANALYSIS. 
 
 6. In the same field, different varieties of soil often 
 occur ; and some recommend that, in collecting a specimen 
 for analysis, portions should be taken from different parts 
 of the field and mixed together, by which an average 
 quality of soil would be obtained. But this is bal ad- 
 vice, when the soils in different parts of the field are 
 really unlike. Suppose one part of a field to be clay, and 
 another sandy as is often the case in most countries and 
 that an average mixture of the two varieties of soil is sub- 
 mitted to analysis, the result obtained will apply neither 
 to the one part of the field nor to the other ; that is, it 
 will be of little or no practical value. In selecting a spe- 
 cimen of soil, therefore, one or two pounds should be taken 
 from each of four or five parts of the fields where the soil 
 
10 PHYSICAL PROPERTIES OF THE SOIL. 
 
 appears nearly alike. These should be well mixed together, 
 and dried in the open air, or before the fire. Two sepa- 
 rate pounds should then be taken from the whole, for the 
 purpose of analysis ; or, if it is to be sent to a distance, 
 should be tied up in clean strong paper ; or, what is much 
 better, should be enclosed in clean, well-corked bottles. 
 
 III. TO DETERMINE THE PHYSICAL PROPERTIES OF 
 
 THE SOIL. 
 
 7. Determination of the density of the soil, or its weight 
 compared with that of water. In order to determine the 
 density of the soil or its specific gravity, as it is also 
 called a portion of it must be dried at the temperature 
 of boiling water (212 Fahr.),till it ceases to lose weight: 
 or upon a piece of white paper, in an oven, at a heat not 
 great enough to render the paper brown. A common 
 phial or other small bottle, perfectly clean and dry, may 
 then be taken and filled with distilled or pure rain-water, 
 up to a mark made with a file on the neck, and then care- 
 fully weighed. Part of the water may then be poured 
 out of the bottle, and 1000 grains of the dry soil intro- 
 duced in its stead. The bottle must then be well shaken, 
 to allow the air to escape from the pores of the soil ; filled 
 up again with water to the mark on the neck, and again 
 weighed. The temperature of the water should all the 
 while be kept as near to 60 Fahr. as possible. The 
 weight of the soil divided by the difference between the 
 weight of the bottle when it contains the soil and water, 
 and the sum of the weights of the soil and of the bottle 
 of water added together gives the specific gravity. 
 
PrtYSICAL PROPERTIES OF TriE SOlL. ll 
 
 Thus, let the bottle with water weigh 2000 grains, and 
 with water and soil 2600, then 
 
 Grains. 
 
 The weight of the bottle with water alone . .x . 2000 
 
 The weight of the dry soil, . . , . ) . ... loOO 
 
 Sum being the weight which the bottle with the soil ) 
 and water would have had, could the soil haye been / . . 3000 
 
 introduced without displacing any of the water, 
 
 But the weight of the bottle fith soil and water was . . 2600 
 
 Difference being the weight of water taken out t< i 
 
 admit 1000 grains of dry soil, ... > 400 
 
 Therefore 1000 grains of soil have the same bulk as 400 
 grains of water ; or the soil is 2 times heavier than water, 
 since YoV 2.5 its specific gravity. 
 
 8. Determination of the absolute weight. The absolute 
 weight of a cubic foot of solid rock is obtained in 
 pounds by multiplying its density or specific gravity by 
 63 the weight in pounds of a cubic foot of water. But 
 soils are porous, and contain more or less air in their 
 interstices, according as their particles are more or less 
 fine, or as they contain more or less sand or vegetable 
 matter. They are not so heavy, therefore, as the solid 
 rocks from which the are formed. Fine sands are the 
 heaviest, clays the next in order, and peaty soils the lightest. 
 The simplest mode of determining the absolute weight of 
 a soil is to weigh an exact imperial half-pint of the soil in 
 any state of dryness, when this weight, multiplied by 1 50, 
 will give very nearly the weight of a cubic foot of the soil 
 in that state. 
 
 9. Determination of the relative proportions of gravel, 
 sand, and clay. Five hundred grains of the dry soil may 
 be boiled in a flask, or in a small enamelled iron pan, half 
 full of water, till the particles are thoroughly separated 
 
12 PHYSICAL PROPERTIES OF THE SOIL. 
 
 from each other. Being allowed to stand for a couple of 
 minutes, the water, with the fine matter floating in it may 
 be poured off into another vessel. This may be repeated 
 several times, till it appears that nothing but sand or 
 gravel remains. This sand and gravel is then to be washed 
 completely out of the flask or pan, dried, and weighed . 
 Suppose the weight to be 300 grains, then 60 per cent * 
 of the soil is sand and gravel. The sand and gravel are 
 now to be sifted through a gauze sieve more or less fine, 
 when the gravel and coarse sand are separated, and may 
 be weighed and their several proportions estimated. 
 
 These separate portions of gravel and sand should now 
 be moistened with water and examined parefully with the 
 aid of a microscope, with the view of ascertaining if they 
 are wholly silicious, or if they contain also fragments of 
 different kinds of rock sand-stones, slates, granites, traps, 
 lime-stones, or iron-stones. A few drops of strong muri- 
 atic acid (spirit of salt) should also be added. The pre- 
 sence of lime-stone is then shown more distinctly by an 
 effervescence, which can be readily perceived by the aid 
 of the glass of peroxide of iron, by the brown colour 
 which the acid speedily assumes and of black oxide of 
 manganese, by a distinct smell of chlorine, which is easily 
 recognised. In the subsequent description of the soil, 
 these points should be carefully noted. 
 
 Suppose the sand and gravel to contain half its weight 
 
 of fine sand, then our soil would consist of coarse sand 
 
 mall stones 30 per cent, fine sand 30 per cent, clay 
 
 and other lighter matters 40 per cent. When the sand is 
 
 * As 500: 300: : 100 to 60, 
 
PHYSICAL PROPERTIES OF THE SOIL. 13 
 
 very fine, care must be taken that none of it is washed off 
 and reckoned as clay. 
 
 10. Absorbing power of the soil. A thousand grains of 
 the soil, made perfectly dry, as described in 7, should be 
 crushed to powder, spread over a sheet of paper, exposed 
 in the open air in ordinary dry weather, shaded from the 
 sun for twelve or twenty-four hours, and then weighed. 
 The increase of weight shows its power of absorbing mois- 
 ture from the air. If it amount to 1 5 or 20 grains, it is 
 so far an indication of great agricultural capabilities. 
 
 11. Its power of holding or retaining water. This same 
 portion of soil may next be put in a funnel upon a 
 double* filter, and cold water poured upon it, drop by 
 drop, till the whole is wet and the water begins to trickle 
 down the neck of the filter. It may now be covered with 
 a piece of glass, and allowed to stand for a few hours, occa- 
 sionally adding a few drops of water, until there remains 
 no doubt of the whole soil being perfectly soaked. The 
 two filters and the soil are then to be removed from the 
 funnel, and the filters opened and spread for a few minutes 
 upon a linen cloth, to remove the drops of water wuich 
 adhere to the paper. The wet soil and inner filter being 
 now put into one scale, and the outer filter into the other, 
 and the whole carefully balanced, the true weight of the 
 wet soil is obtained. Suppose the original thousand 
 grains now to weigh 1400, then the soil is capable of 
 holding 40 per cent of water, f 
 
 12. Rapidity with which the soil dries.- The wet soil 
 
 * That is one filter within another. 
 
 f 1000 : 400 the increase of weight as 100 : 40. 
 
14 PHYSICAL PROPERTIES OF THE SOIL. 
 
 with its filter may now be spread out upon a plate, and 
 exposed to the air, in what may be considered the ordinary 
 circumstances of temperature and moisture of the place, 
 for four, twelve, or twenty-four hours, and the loss of 
 weight then ascertained. This will indicate the compara- 
 tive rapidity with which such a soil would dry, and the 
 consequent urgent demand for draining, or the contrary. 
 As great a proportion of the water is said to evaporate 
 from a given weight of silicious sand saturated with water, 
 in four hours, as from an equal weight of pure clay in 
 eleven, and of peat in seventeen hours when these several 
 soils are all placed in the same circumstances. 
 
 In making this experiment, a portion of pure quartz 
 sand or of pipe-clay may be employed for the purpose 
 of obtaining a comparative result as to the rapidity of 
 drying. 
 
 13. Power of absorbing heat from the sun. The same 
 method may be adopted in regard to the power of the soil 
 to become warm under the influence of the sun's rays. 
 Two small wooden boxes, containing each a layer, two or 
 three inches in depth, of one of the kinds of soil which 
 are to be compared, may be exposed to the same sunshine 
 for the same length of time, and the heat they severally 
 acquire determined by a thermometer, the bulb of which 
 is buried a full quarter of an inch beneath the surface. 
 Soils are not found to differ so much in the actual tem- 
 perature or degree of warmth they are capable of attain- 
 ing under such circumstances most soils, when dry, be- 
 coming 20 or 30 warmer than the surrounding air in 
 the time of summer as in the relative degree of rapidity 
 with which they acquire this maximum temperature. 
 
PHYSICAL PROPERTIES OF THE SOU.. 15 
 
 This rapidity depends very much upon the darkness of. 
 the colour of the soil. When the proportion of organic 
 matter is great, the soil is generally very dark in colour, 
 and the absorption of heat from the sun most rapid. 
 
 But the mineral constituents of the soil also influence 
 this quality. Of all the known constituents of soils, dry 
 quartz sand absorbs heat most rapidly. It reaches the 
 maximum temperature, on a sunny day, neai-ly five times 
 sooner (as 90 to 19 TiNDALL)lhan a similar surface of dry 
 gypsum. To this circumstance is to be ascribed both 
 the pleasant warmth of the sand-hills along our sea 
 coasts on a summer day, and the scorching heats which 
 distinguish both air and soil in regions of sandy desert. 
 
 14. Rapidity of cooling. The above property derives 
 another practical interest from its being connected with a 
 corresponding rapidity of cooling. Dark soils cool most 
 rapidly, and mists and fogs settle over them, and dews 
 fall and moisten them. So, also, naked sandy soils and 
 plains part with their heat as rapidly as they take it in. 
 Hence the chill nights which succeed the fiery noondays 
 of the African Sahara and hence the alternate heats and 
 chills which burn up thin sandy pastures, and make dark, 
 moorish, or peaty lands unpropitious to our cultivated 
 crops. 
 
CHAPTER II. 
 
 ORGANIC MATTER OF THE SOIL. 
 
 Determination of the organic matter of the soil; the proportion or per-centage. 
 The humic and ulmic acids. The insoluble vegetable matter, or humu?. 
 Other organic substances in the soil ; how determined. 
 
 15. Determination of the per-centage of organic matter, 
 The soil must be thoroughly dried in an over or other- 
 wise in a little sand-bath for example, over a lamp or 
 charcoal fire at a temperature not higher than from 
 250 to 300 Fahr. The humic and ulmic acids of soils* 
 will bear the latter temperature without change. An 
 accurately weighed portion (100 to 200 grains) must 
 then be burned in the open air, till all the blackness 
 disappears. This is best done in a small platinum capsule, 
 over an argand, spirit, or gas lamp. The loss indicates 
 the total weight of organic matter present. It is scarcely 
 ever possible, however, to render soils absolutely dry, 
 without raising them to a temperature so high as to 
 char the organic matter present. Hence the weight of 
 the organic matter, as determined from the loss, will 
 always somewhat exceed the truth ; the water which still 
 
 See the author's Lerlures on Agricultural Chemislry and Geology, 2d edition k 
 p. 71 ; or his Elements, 6th edition, p. 21. 
 
ORGANIC MATTER OF THE SOIL. 17 
 
 I 
 
 remains in the soil being driven off along with the organic 
 matter, when the soil is heated to redness. This excess, 
 also, will in general be greater in proportion to the quan- 
 tity of clay in the soil, since this is the ingredient of most 
 soils from which the water is expelled with the greatest 
 difficulty. (See under 18 c.) 
 
 16. Determination of the humicand ulmic acids. These 
 acids, whether merely mixed with the soil, or combined with 
 some of the lime and alumina it contains, are extracted 
 by boiling with a solution of the common crystalised 
 soda of the shops. Into about two ounces by measure 
 of a saturated solution of this soda, contained in a flask, 
 200 or 300 grains of soil, previously reduced to coarse 
 powder, are introduced, an equal bulk of water added, 
 and the whole boiled or digested on the sand-bath, with 
 occasional shaking for an hour or two. The flask is then 
 removed from the fire, filled up with water, well shaken, 
 again boiled, and the particles of soil afterwards allowed 
 to subside. The clear liquid is then poured off. If it has a 
 brown colour, it has taken up some humic or ulmic acid. 
 In this case, the process must be repeated once or twice 
 with fresh portions of the soda solution, till the soluble 
 organic matter appears, by the pale colour of the last 
 solution to be altogether taken up. These coloured 
 solutions are then to be mixed and filtered. This filter- 
 ing generally occupies considerable time, the humic and 
 ulmic acids clogging up the pores of the filter in a 
 remarkable manner, and permitting the liquid to pass 
 through sometimes with extreme slowness. 
 
 When filtered, muriatic acid is to be slowly added to 
 the coloured liquid which should be kept in motion by 
 2 
 
18 ORGANIC MATTER OP THE SOIL. 
 
 a glass rod till effervescence ceases, and the whole has 
 become distinctly sour. On being set aside, the mixed 
 ulmic and humic acids fall in brown flocks. A filter is 
 now to be dried and carefully weighed,* the liquid fil- 
 tered through it, and the acids thus collected. They 
 must be washed on the filter with pure water rendered 
 very slightly sour by muriatic acidf till all the soda is 
 separated. The filter with its contents is then to be 
 dried at 250 Fahr., till it ceases to lose weight. The 
 final weight, when the known weight of the filter is 
 deducted from it, gives the quantity of humic and ulmic 
 acids contained in the portion of soil submitted to exa- 
 mination. As it is rarely possible to wash these acids 
 perfectly upon the filter, rigorous accuracy requires that 
 the filter and acids should be burned after being weighed, 
 and the weight of ash left, minus the known weight of 
 ash left by the filter, deducted from that of the acids 
 
 This is best effected by putting the filter into a small covered porcelain cruci- 
 ble of known weight, and heating it for ten minutes over a lamp or otherwise, 
 at a temperature which just does not discolour the paper, allowing then the 
 crucible to cool under cover, and when cold weighing it. The increase above the 
 known weight of the crucible is that of the filter, which, besides being recorded 
 in the experiment-book, should also be marked in several places on the edge of 
 the filter with a black-lead pencil. 
 
 -; This is to prevent the humic acid from passing through the filter, which it in 
 rery apt to do, when the saline matter is neatly washed out of it. 
 
 \ This is ascertained by collecting a few drops of what is passing through 
 upon a slip of clean glass or of platinum foil, and drying them over the lamp, 
 when, if a perceptible stain or spot is left, the subst&nce it not sufficiently washed. 
 
 | The ash left by the paper employed for filters should always be known. This 
 is ascertained, once for all, by drying a quantity of it in the way described in the 
 previous note, weighing it in this dry state, burning it, and again weighing the 
 ash that is left. In good filtering paper, the ash ought not to exceed one percent. 
 
ORGANIC MATTER OF THE SOIL. 19 
 
 as previously determined. It is to be observed here that 
 by this, which is really the only available method we 
 possess of estimating the humic and ulmic acids, a certain 
 amount of loss arises from their not being wholly insoluble, 
 the acid liquid which passes through the filter being 
 always more or less of a brown colour.* 
 
 The two acids thus estimated occur in soils mixed 
 together in various undetermined proportions. It is not 
 easy to separate them from each other, and no known 
 practical good would result from a rigorous determination 
 of the proportions of each. 
 
 17. Determination of the insoluble vegetable matter or 
 humus. Many soils, after this treatment with carbonate 
 of soda, are still more or less of a brown colour, evidently 
 due to the presence of other organic matter. To separate 
 this, it is recommended to boil the soil, which has been 
 treated with carbonate of soda, and which we suppose 
 still to remain in the flask, with a solution of caustic 
 potash, repeated, if necessary, as in the case of the soda 
 solution. By this boiling, the vegetable matter, which 
 was insoluble in the carbonate of soda is changed in 
 chemical constitution, and dissolves in the caustic potash, 
 giving a brown solution. From this it may be separated 
 in brown flocks by the addition of muriatic acid, and then 
 collected and weighed as above described. 
 
 In some soils, also, distinct portions of scarcely altered 
 
 The portion which thus remains in solution may be precipitated by adding a 
 imall quantity of a solution of alum, and afterwards pouring in ammonia in 
 excess. The alumina falls coloured by the organic matter, and after being col- 
 lected on a filter, washed and dried, the weight of organic matter in the precipi- 
 tate may be determined approximately as described under 15*. 
 
20 ORGANIC MATTER OF THE SOIL. 
 
 vegetable fibre such as portions of roots, &c. are pre- 
 sent, and may be separated, mechanically dried, and 
 weighed. 
 
 1 8. Of other organic substances present in the *oi/. The 
 sum of the weights of the above substances, deducted from 
 the whole weight of organic matter, as determined by 
 burning, gives that of the other organic substances present 
 in the soil. The quantity of these is in general compara- 
 tively small ; and unless they are soluble in water, there 
 is no easy method of separating them and determining 
 their weight. The following two methods, however, may 
 be resorted to : 
 
 a. Half a pound or more of the moist soil may be 
 boiled with two separate pints of distilled water, the 
 liquid filtered and evaporated to a small bulk. From 
 clay soils, when thus boiled with water, the fine particles 
 do not readily subside. Sometimes, after standing for 
 several days, the water is still muddy, and passes 
 muddy through the filter ; but after being evaporated, as 
 above recommended, to a small bulk, most of the fine 
 clayey matter remains on the paper when it is again fil- 
 tered. As soon as it has thus passed through clear, the 
 liquid may be evaporated to perfect dryness at 250 Fahr. 
 and weighed. Being now treated with water a portion 
 will be dissolved this must be poured off, and the in- 
 soluble remainder again perfectly dried at 250 Fahr., 
 and weighed. If this remainder be now heated to red- 
 
 o 
 
 ness in the air, any organic matter it contains will be 
 burned off, and the weight of this organic matter will 
 be indicated by the loss on again weighing. This loss 
 may be considered as humic, ulmic, or some other acid 
 
ORGANIC MATTER OP THE SOIL. 21 
 
 rendered insoluble by the drying at 250.* It does 
 not require to be added to the weight of humic acid 
 already determined (16) because in that experiment 
 a portion of soil was employed which had not been 
 boiled in water, and from which, therefore, the carbo- 
 nate of soda would not at once extract all the humic and 
 other acids. The present experiment need only be made 
 when it is desirable to ascertain what weight of acid 
 organic matter a soil contains in a state in which it is 
 soluble in water. Where carbonate of ammonia, of potash, 
 or of soda is present in the soil, this quantity may be 
 very considerable, and may exercise an important influ- 
 ence upon vegetation. 
 
 b. That which was taken up by water from the dried resi- 
 duum is again to be evaporated to dryness dried at 212, 
 weighed, and burned at a low red heat. The loss is organic 
 matter, and may have been crenic or apocrenic, or some 
 other of the organic acids which are formed in soils, and 
 the compounds of which, with lime, alumina, and protoxide 
 of iron, are soluble in water. If any little sparkling or 
 burning, like match-paper, be observed during this heating 
 to redness, it may be considered as an indication of the 
 presence of nitric acid in the form of nitrate of potash, 
 soda, or lime. In this case the loss by burning will slightly 
 exceed the true amount of organic matter present, owing 
 to the decomposition and escape of the nitric acid also. 
 
 It may, for example, consist in part ofgeic or spocrenic acids (see Lectures or 
 Eltmentt) especially if there be iron in the ash which remains.. Where gypsum 
 is present in the insoluble portion, which is not unfrequently the case, the loss 
 will be partly water since gypsum, after being dried at 250", loses gtill about 21 
 per cent of water when heated to redness. 
 
22 ORGANIC MATTER OF THE SOIL. 
 
 The mode of estimating the quantity of this acid, when it 
 is present in any sensible proportion, will be hereafter 
 described. 
 
 c. The caustic potash employed to dissolve the insol- 
 uble humus (17) takes up also any alumina which may 
 have been in combination with the humic or ulmic acids, 
 or may stilll remain united to the geic, crenic, mudesous, 
 or other organic acids. When the solution is filtered, and 
 the humic and ulmic acids are separated from it by the 
 addition of muriatic acid till the liquid has a distinctly 
 sour taste, this alumina, and the acids with which it is 
 in combination, still remain in solution. After the brown 
 flocks of humic acid, however, are collected on the filter, 
 the alumina may be thrown down from the filtered solu- 
 tion by adding caustic ammonia to the sour liquid, until 
 it has a distinctly ammoniacal smell. The light precipi- 
 tate which falls must be collected on a filter, and washed 
 with hot water till the potash is as completely separated 
 from it as possible. It is then to be dried at 300 F. , 
 heated for some time in a close crucible over the lamp, at 
 a temperature which begins to discolour it, and weighed. 
 Being now burned in the air till it is quite white, and 
 again weighed, the last loss may be considered as mude- 
 sous, or some similar organic acid. 
 
 The reason why this second method of drying over the 
 lamp is here recommended, is that alumina and nearly all 
 its compounds part with their water with great difficulty ; 
 and even with the precautions above prescribed, it is very 
 likely that a larger per-centage of organic matter may be 
 indicated by this experiment than in reality exists in 
 the alumina collected and dried. The check which 
 
ORGANIC MAfTER OP THE SOIL. 23 
 
 the accurate experimenter has upon all these deter- 
 minations is this, that the sum of the several weights of 
 the humic and ulmic acids, the insoluble humus, the vege- 
 table fibre and of the crenic and mudesous acids, if pre- 
 sent should be somewhat less than that of the whole 
 combustible organic mater, as determined by burning the 
 dry soil in the open air (15). This quantity we have 
 seen to be in most cases greater than the truth, because 
 any remaining water, or any nitric acid the soil may con- 
 tain, is at the same time driven off. 
 
 I may further remark upon this subject, that the quan- 
 tity of alumina thus dissolved by the caustic potash, is in 
 most soils very small, and the quantity of organic matter 
 by which it is accompanied in many cases so minute, that 
 the determination of it may be considered as a matter of 
 curiosity, rather than one of practical importance. 
 

 CHAPTER III. 
 
 SALINE MATTER OF THE SOIL. 
 
 Qualitative determination of the matters soluble in water. To test for sulphuric 
 acid, for chlorine, for alumina, magnesia, and the oxides of iron and manga- 
 nese, for lime, for potash and soda, for ammonia and for phosphoric acid, by 
 different methods. 
 
 19. WITH a view to determine the nature of the soluble 
 saline matter in the soil, a preliminary experiment must 
 be made. An unweighed portion must be introduced 
 into five or six ounces of boiling distilled water* in a 
 flask and kept at a boiling temperature, with occasional 
 shaking for a quarter of an hour. It-may then be allowed 
 to subside, after which the liquid is to be filtered till it 
 passes through clear. This is to be repeated once or 
 twice, and the several liquids mixed. The solution is then 
 to be tested in the following manner : 
 
 Small separate portions are to be put into so many 
 clean wine-glasses or test-tubes, and the effect produced 
 upon these by different chemical substances carefully 
 noted. If with a few drops of 
 
 20. Nitrate of baryta, it gives a white powdery preci- 
 pitate, which does not disappear on the addition of nitric 
 
 In all analytical operation* in which the uee of water is spoken of, it must 
 bo understood that pure distilled water is meant. 
 
SALINE MATTER OF THE SOIL. 25 
 
 or muriatic acid, the solution contains sulphuric acid. If 
 the precipitate does disappear on adding the acid, it con- 
 tains carbonic acid. In this latter case, the liquid if 
 concentrated to a small bulk will also effervesce on the 
 addition of either of the acids above mentioned.* 
 
 21 . If with nitrate of silver it gives a white curdy pre- 
 cipitate, insoluble in pure nitric acid, and speedily be- 
 coming purple in the sun, it may be presumed to contain 
 chlorine. 
 
 22. If with caustic ammonia it gives a pure white 
 gelatinous precipitate, it contains either alumina, or mag- 
 nesia, or both. In this case, muriatic acid must be added 
 till the precipitate disappears, and the solution is dis- 
 tinctly acid. If on the addition of ammonia again, and 
 in excess, the precipitate reappears undiminished in 
 quantity, it contains alumina only. If it be distinctly 
 less in quantity, we may infer the presence of both mag- 
 nesia and alumina ; and if no precipitate now appears, 
 that it contains magnesia only. If a large quantity of 
 magnesia be present, it may be necessary to re-dissolve 
 the precipitate thrown down by ammonia, and to make 
 the solution acid a second time before on the re-addition 
 of ammonia the precipitate will entirely disappear. 
 
 23. If the precipitate, by ammonia, have more or less 
 of a brown colour, the presence of iron, and perhaps man~ 
 ganese, may be inferred. If, after re-dissolving and adding 
 ammonia a second time, the colour of the precipitate has 
 
 * The leained reader will understand why, for the sake of simplicity, I take no 
 notice of substances not likely to be present In the soil as, for example, baryta, 
 which would here be thrown down along witk the lime, or of oxalic acid, which, 
 equally with the sulphuric or carbonic acid, would give a white precipitate with 
 nitrate of baryta. 
 
26 SALINE MATTER OF THE SOIL. 
 
 disappeared, it has been due to manganese only; if it still 
 continue brown, it is owing chiefly or altogether to the 
 presence of oxide of iron. If the colour of the precipitate 
 by ammonia, be very dark, it consists almost entirely of 
 oxide of iron, and may contain little or no alumina ; when 
 it is only more or less brown, the presence of both alumina 
 and oxide of iron may with certainty be inferred. 
 
 24. a. If, after the first addition of ammonia, the solu- 
 tion be filtered to separate the alumina, the oxides of iron 
 and manganese, and the magnesia that may be thrown 
 down if then, with oxalate of ammonia, it gives either 
 immediately.or after a time,a white cloud,which gradually 
 falls to the bottom in the form of a white powder, it con- 
 tains lime. The greater and the more speedy the milki- 
 ness, the larger the quantity of lime may be presumed to 
 be. Of course, if ammonia produces no change in the 
 liquid, the oxalate of ammonia may be added at once, 
 without the previous filtration, which is required to sepa- 
 rate oxide of iron, alumina, or magnesia. 
 
 b. If oxalate of ammonia be thus added till all the lime 
 falls, and the liquid be again filtered, evaporated to dry- 
 ness, and then heated to incipient redness in the air, till 
 the excess of oxalate of ammonia is destroyed and driven 
 off and if a soluble residue then remain,* it is probable 
 that potash or soda, or both, are present. 
 
 c. If, on dissolving this residue in a little water, the 
 addition of a few drops of a solution of tartaric acid to 
 it produce a deposit of small colourless crystals (of 
 cream of tartar), or if a drop of a solution of bi-chloride 
 
 Xot prectp'.tated from its solution by ammonia, for if so precipitated, it if 
 partly at least chloride of magnesium. 
 
SALINE MATTER OF THE SOIL. 
 
 of platinum produce in a short time a yellow powdery 
 precipitate, it contains potash. If no precipitate is pro- 
 duced by either of these-r-re-agents, as they are called 
 the presence of soda may be inferred. If a yellow pre- 
 cipitate, containing potash and platinum, be formed, it 
 is to be separated by a filter, and the filtered solution, 
 after being treated with sulphuretted hydrogen and again 
 filtered, to separate the excess of bi-chloride of platinum, 
 is to be evaporated to dryness. If, then, a soluble saline 
 residue still remain, the solution contains soda as well as 
 potash. 
 
 It is to be observed, that some magnesia, if present, 
 may accompany the potash and soda through these several 
 processes. After the separation of the potash, a little 
 caustic ammonia will detect the presence of magnesia ; but 
 it will rarely be found so far to interfere with this preli- 
 minary examination as to prevent the experimenter from 
 arriving at correct results. (See 37), 
 
 25. If the addition of bi-chloride of platinum to the 
 solution filtered from the soil and evaporated to a small 
 bulk give a yellow precipitate, it contains either potash 
 or ammonia. If, when collected on the filter, dried, and 
 heated to bright redness in the air, white fumes are given 
 off by this yellow precipitate, and only a spongy mass of 
 metallic platinum remains behind, the solution contains 
 ammonia only. If, along with the platinum, there remains 
 after the heating, a portion of a substance which is soluble 
 in water, has a taste like that of common salt, and gives 
 again a yellow precipitate with bi-chloride of platinum, it 
 contains potash, and if the spongy platinum contained in 
 the burned'mass, after prolonged heating, amount to more 
 
28 SALINE MATTER OF THE SOIL. 
 
 than 57 per cent of the weight of the yellow precipitate 
 collected, or if it be to the matter soluble in water in a 
 higher proportion than that of 4 to 3, the solution con- 
 tains both potash and ammonia. 
 
 26. The presence of ammonia among the substances 
 extracted by water from the soil may also be detected by 
 evaporating the liquid to a small bulk, or to perfect dry- 
 ness on the water-bath, and then adding a few drops of a 
 solution of caustic potash. The smell of ammonia, if pre- 
 sent, becomes immediately perceptible ; or if in too small 
 quantity to be detected by the smell, it will, if present, 
 restore the blue colour to reddened litmus paper. This 
 experiment is best made in a small tube. 
 
 27. If, when the solution, obtained directly from the 
 soil, is evaporated to dryness, and the residue heated to 
 redness in the air, a deflagration or burning like match - 
 paper be observed, nitric acid is present. Or, if the dry 
 mass, when put into a test-tube with a little muriatic 
 acid, evolves distinct red fumes on being heated, or enables 
 the muriatic acid to dissolve gold-dust, and form a yellow 
 solution ; or, if to a colourless solution of green vitriol 
 (sulphate of iron), introduced into the tube along with the 
 muriatic acid, it imparts more or less of a brown colour 
 in any of these cases the presence of nitric acid may with 
 certainty be inferred. It will be only on rare occasions, 
 however, that salts, so soluble as the nitrates, will be 
 found in sensible quantity in the small portion of a soil 
 likely to be employed in these preliminary experiments. 
 (See 69.) 
 
 28 a. If ammonia throw down nothing from the solu- 
 tion, and if nothing fall when a few drops of a solution 
 
. 
 
 SALINE MATTER OF THE SOIL. 29 
 
 of chloride of calcium is added, no phosphoric acid is 
 present. 
 
 b. Or, if nothing be thrown down by ammonia, the solu- 
 tion may be evaporated to a very small bulk, rendered 
 acid by the addition of nitric acid, and then dropped into 
 a solution of molybdate of ammonia, prepared as de- 
 scribed in 40 a. If any trace of a yellow precipitate now 
 fall, phosphoric acid is present. 
 
 c. But if ammonia cause a precipitate (see 22), and 
 after this is separated by the filter nothing farther falls 
 on adding the chloride of calcium as above described (a), 
 the phosphoric acid, if any is present, is contained in the 
 precipitate thrown down by ammonia. Let this, after 
 being well washed on a filter with distilled water, be dis- 
 solved off with a little diluted nitric acid. This solution, 
 reduced if necessary to a small bulk, is to be dropped into 
 a solution of molybdate of ammonia, as above described 
 (I), and thus tested for phosphoric acid. 
 
 d. Or, if the precipitate thrown down by ammonia be 
 wholly or in part insoluble in pure acetic acid in the cold, 
 that which is undissolved probably contains phosphoric 
 acid in combination with peroxide of iron, or alumina, or 
 both, and may be farther tested, if thought necessary, with 
 molybdate of ammonia. But if cold acetic acid dissolve 
 the whole, it may be inferred that no phosphoric acid is 
 present in the precipitate thrown down by ammonia.* 
 
 I have been thus particular in describing the methods 
 
 * This latter sentence is true only in the case of a precipitate obtained by 
 means of ammonia from a solution which, like that of a soil, always contains 
 iron and alumina. If a solution of phosphate of lime (bone earth), or of phos- 
 phate of magnesia in muriatic acid, for example, be treated with ammonia in ex- 
 cess, a white precipitate will fall which does contain phosphoric acid, and yet 
 
30 SALINE MATTER OF THE SOIL. 
 
 of detecting phosphoric acid in the soil, both because it has 
 always been one of the most difficult substances to detect 
 when present only in minute quantity, and because it is 
 also- one of the most important ingredients of a soil. 
 
 29. If, when the solution is evaporated to dryness on 
 the water-bath, the dry residue moistened with muriatic 
 acid and treated with water if then a light flocky matter 
 be separated, which, when collected and heated to red- 
 ness, only burns white and does not disappear, it contains 
 silica.' 
 
 These preliminary trials being made, notes should be 
 kept of all the appearances presented. The arranging 
 of the method and order to be adopted for separating 
 from one another, and for estimating the weight of each of 
 the substances, will depend upon the number and nature 
 of those which the solution has been found actually to 
 contain. 
 
 It is to be observed that the methods above described, 
 as suited for the examination of the saline solutions ob- 
 tained from a soil, are equally applicable to the examina- 
 tion of any other saline solution, whether natural or arti- 
 ficial. 
 
 dissolves readily in acetic acid. Bat if, before adding ammonia to the muriatic 
 acid solution of the phosphate, a few drops of a solution of sulphate of peroxide 
 of iron be poured into it, then ammonia throws down a precipitate of a brownish 
 colour, which is not wholly dissolved by acetic acid. The peroxide of iron which 
 was added has united with phosphoric acid, and formed a combination which is 
 insoluble in ace^icAcid. 
 
CHAPTER IV. 
 
 ESTIMATION OF THE SALINE MATTERS. 
 
 Quantitative determination of the several substances dissolved out by water. Esti- 
 mation of the sulphuric acid, of the chlorine, of the lime, of the oxide of 
 iron, of the alumina, and of the manganese. Different methods of estimating 
 the magnesia. Estimation of the potash, soda, and ammonia. Difficulties 
 attending the estimation of the phosphoric acid. Method by molybdate of 
 ammonia. Examination of natural waters. 
 
 30. The quantity of soluble saline matter extracted 
 from a moderate quantity of any of our soils is rarely so 
 great as to admit of a rigorous analysis being made, and 
 the preceding determination of the kind of substances 
 it contains will be in most cases sufficient. Cases may 
 occur, however, in which much saline matter may be 
 obtained by treating the soil with water. (See 69.) It 
 will be proper, therefore, briefly to state the methods by 
 which the respective quantities of each constituent may 
 be accurately determined. 
 
 31. Estimation of the sulphuric acid. The solution 
 being gently warmed, a few drops of nitric acid are to be 
 added until it becomes slightly sour, and any carbonic 
 acid that may be present is expelled. Nitrate of baryta 
 is then to be added to the solution as long as anything 
 falls. The white precipitate, which is sulphate of 
 
32 ESTIMATION OF THE SALINE MATTERS. 
 
 baryta, is then to be collected on a weighed filter, well 
 washed with distilled water, dried over boiling water, cr 
 at 212Fahr., as long as it loses weight, and then weighed. 
 The weight of the filter being deducted,* every 100 grains 
 of the dry powder are equal to 34.31 grains of sulphuric 
 acid. 
 
 32. Estimation of the chlorine. The solution of nitrate 
 of silver must be added as long as any precipitate falls, 
 the precipitate then washed, dried at 212 Fahr., and 
 weighed as before. Every 100 grains of chloride of silver 
 indicate 24.72 grains of chlorine, or 40.56 grains of com- 
 mon salt. 
 
 33. Estimation of the lime. A little diluted muriatic 
 acid being now added to throw down the excess of silver, 
 and a little sulphuric acid to separate the excess of 
 baryta added in the former operations, and the precipi- 
 tates caused by these acids separated by filtration, 
 caustic ammonia is to be poured in, till the solution is 
 distinctly alkaline. If no precipitate fall, oxalate of 
 ammonia is to be added as long as any white powder 
 appears to Be produced. The solution must then be left 
 to stand over-night, that the whole of the lime may 
 separate ; the white powder afterwards collected on a 
 filter, washed, dried, and burned with the filter at a low 
 red heat. The grey powder obtained is carbonate of 
 lime, every 100 grains of which the ash of the filter 
 being deducted contain 44 grains of lime. 
 
 To be quite sure that the whole of the lime is thrown 
 
 Or the whole may be heated to redness in the air, and the filter burned 
 wy. In this case, the weight of aah left by the paper must be ascertained by 
 previous trials, and the due proportion deducted from the weight of the sulphate 
 (p. 18, nte.) 
 
ESTIMATION OF THE SALINE MATTEKS. 33 
 
 down, it is proper to add a few additional drops of 
 oxalate of ammonia to the clear solution before filtering 
 it. If no milkiness is produced after half an hour or an 
 hour, the lime has all fallen. 
 
 34 . Estimation of the peroxide of iron. But if a precipi- 
 tate fall on the addition of ammonia, as above prescribed, 
 the solution may contain magnesia, alumina, and the 
 oxides of iron and manganese. In this case the precipi- 
 tate is to be re-dissolved by the addition of muriatic acid 
 to the solution till it is distinctly acid, and ammonia 
 again added in slight excess. If any precipitate now 
 fall, it will consist only of alumina and oxide of iron, 
 unless magnesia and oxide of manganese be present in 
 large proportion, when a minute quantity of each may 
 fall at the same time. 
 
 The precipitate is to be collected on the filter as 
 quickly as possible the funnel being at the same time 
 covered with a plate of glass, to prevent the access of the 
 air washed with hot distilled water, and then re-dissolved 
 in muriatic acid. This is best effected by spreading out 
 the filter in a small porcelain dish, adding dilute acid till 
 all is dissolved, and then washing the paper well with dis- 
 tilled water. A few drops of nitric acid are then to be 
 added, and the solution heated, to convert the whole of 
 the iron into peroxide. A solution of caustic potash added 
 in excess will at first throw down both the oxide of iron and 
 the alumina, but will afterwards re-dissolve the alumina, 
 and leave only the oxide of iron. A gentle heat will assist 
 this process. The oxide of iron is to be collected on a 
 filter, washed, dried, heated to redness,and weighed. Every 
 JOO grains of this peroxide are equal to 90 grains of 
 3 
 
34 ESTIMATION OF THE SALINE MATTERS. 
 
 protoxide, in which state the iron had most probably 
 existed in the original watery solution from the soil. 
 
 35. Estimation of the alumina. To the potash solution 
 muriatic acid is added till the alkali is saturated, or till 
 the solution reddens litmus paper,* when the addition of 
 ammonia precipitates the alumina ; or a solution of sal- 
 ammoniac may be added to the potash solution till the 
 alumina falls. As it is difficult to wash this precipitate 
 perfectly free from potash, it is better, after collecting it 
 on the filter, to dissolve it off again by means of dilute 
 muriatic acid, and to re-precipitate it by caustic ammonia. 
 When well washed, dried, and weighed, this precipitate 
 gives the true quantity of alumina present in the solution, 
 or in the portion of saline matter submitted to analysis. 
 
 36. Estimation of the oxide of manganese. To the 
 ammoniacal solutions from which the oxalate of lime has 
 been precipitated (33), a solution of hydro-sulphuret of 
 ammonia is to be added. The manganese will fall in the 
 form of a flesh-red sulphuret. When this precipitate has 
 fully subsided, it must be collected on the filter and 
 washed with water containing a very little hydro- 
 sulphuret of ammonia. The filter is then put into a 
 glass or porcelain basin, the precipitate dissolved off by 
 dilute muriatic acid, and the solution warmed and filter- 
 ed, if necessary. A solution of carbonate of soda then 
 throws down carbonate of manganese, which is collected, 
 
 * Litmus paper is paper stained by dipping it in a solution of litmus, a vege- 
 table blue colour, prepared and old for the purpose of detecting the presence of 
 free acids, by which it is reddened; or of free alkalies, by which, after being 
 reddened by an acid, the blue colour is restored. 
 
ESTIMATION OF THE SALINE MATTERS. 35 
 
 dried, and heated strongly to redness in the air. Of the 
 brown powder obtained, every 100 grains indicate the 
 presence of 93.03 grains of protoxide of manganese in the 
 salt or solution under examination. 
 
 It will only be in rare cases that alumina, or the oxides 
 of iron or manganese, will be found in sensible quan- 
 tity in the watery extract of a soil. Sulphate of iron 
 and sulphate of alumina do sometimes occur, however, in 
 the soil, and to these unfrequent cases the processes above 
 described are intended to apply. Of course they instruct 
 the reader also how to separate iron, alumina, and man- 
 ganese from mineral waters or any other sah'ne solutions. 
 
 37. Estimation of the magnesia. a. If no potash or soda 
 be present in the residual solution after separating the 
 manganese, the determination' of the magnesia is easy. 
 A few drops of muriatic acid are added, and the whole 
 gently heated, and afterwards filtered, to separate the 
 sulphur of the excess of hydro-sulphuret of ammonia pre- 
 viously added. The solution is then evaporated to dry- 
 ness, and the dry mass heated slowly to dull redness, to 
 drive off all the ammoniacal salts. A few drops of diluted 
 sulphuric acid are added to what remains, to change the 
 whole of the magnesia into sulphate, the mass again 
 heated to redness, and weighed. One hundred grains of 
 this sulphate indicate the presence of 33.33 grains of pure 
 magnesia. 
 
 6. Or after filtration, as above, to separate the sulphur 
 ammonia is again added in excess, and then a solution of 
 phosphate of soda. Ammoniacal phosphate of magnesia 
 falls which is collected on the filter, washed with water 
 
36 ESTIMATION OF THE SALINE MATTERS. 
 
 containing a little ammonia, dried and heated to redness, 
 and weighed. Every 100 grains contain 35.94 of 
 magnesia. 
 
 This is the converse of the process described in 40 c. 
 
 c. But if potash or soda be present the weight of 
 which it is desirable also to determine the mode of sepa- 
 rating the magnesia will vary according as the solution 
 contains or is free from sulphuric acid. 
 
 If it contain no sulphuric acid, the dry mass, after 
 heating to dull redness, is treated with a little water 
 which dissolves it all except a little magnesia, which need 
 not be separated. A quantity of red oxide of mercury 
 previously reduced to an exceedingly fine powder, by rub- 
 bing in a mortar with water is then to be added, well 
 mixed the mixture evaporated to dry ness, and then 
 heated to redness. Water now dissolves out the potash 
 and soda only, and leaves the magnesia. This is to be 
 collected on a filter, washed not with too much water 
 heated to redness, and weighed. 
 
 d. Or another way is, to prepare carbonate of silver, 
 by precipitating nitrate of silver with carbonate of am- 
 monia and washing then to boil the solution of the 
 mixed chlorides with this carbonate of silver till the solu- 
 tion becomes strongly alkaline. When filtered hot, only 
 magnesia and chloride or carbonate of silver remain on 
 the filter. A little dilute muriatic acid poured upon the 
 washed filter dissolves out the whole of the magnesia. 
 The solution evaporated nearly to dryness, treated with a 
 few drops of sulphuric acid, then again evaporated to 
 dryness and heated to redness, gives the magnesia in the 
 
ESTIMATION OF THE SALINE MATTERS. 37 
 
 state of sulphate, of which every 100 grains contain 33.33 
 grains of magnesia. 
 
 c. But if sulphuric acid be present along with the mag- 
 nesia, potash, and soda, we dissolve the dry mass in water, 
 adding a little muriatic acid, if necessary, to dissolve the 
 magnesia, which may have become insoluble in water. 
 Ammonia is now poured in, in excess, and, if this cause a 
 railkiness, a little more acid, till the addition of ammonia, 
 again in excess, leaves the solution clear. Arseniate of 
 ammonia now throws down the magnesia, which, after 
 twelve hours, may be collected on a filter, washed with cold 
 water which contains and smells of ammonia, and then 
 dried at 212 Fahr. Every 100 grains of the precipitate 
 thus dried contain 21 grains (20.97) of magnesia. This 
 method separates the magnesia, but not the sxilphuric 
 acid, from the solution. 
 
 f. Or, when sulphuric acid is present, baryta water may 
 be added to the solution, which will precipitate the siil- 
 phuric acid as sulphate of baryta, and the magnesia at the 
 same time as caustic magnesia. It is quickly filtered and 
 washed. Dilute sulphuric acid then dissolves the mag- 
 nesia from the filter, leaving the sulphate of baryta. The 
 solution of magnesia is evaporated, and the sulphate of 
 magnesia determined as in a. 
 
 38. ^estimation of the potash and soda. a. If no sul- 
 phuric acid has been present, the solution containing the 
 potash and soda, as left by process 37 c, is to be eva- 
 porated to dryness, and heated to dull redness. The 
 weight of the mass, which consists of a mixture of 
 chloride of potassium with chloride of sodium (common 
 
38 ESTIMATION OF THE SALINE MATTERS. 
 
 salt), is accurately determined ; it is then dissolved in a 
 small quantity of water, and a solution of bi-chloride of 
 platinum added to it in sufficient quantity. Being eva- 
 porated by a very gentle heat nearly to dryness, weak 
 alcohol is added which dissolves the chloride of sodium 
 and any excess of salt of platinum which may be present . 
 The yellow powder is collected on a weighed filter, washed 
 well with alcohol, dried by a gentle heat, and weighed on 
 the filter. Every 100 grains indicate the presence of 
 19.31 potash, of potash, or 30.56 grains of chloride of 
 potassium. 
 
 The quantity of chloride of sodium is estimated from 
 the loss. The weight of the chloride of potassium above 
 found is deducted from that of the mixed chlorides previ- 
 ously ascertained : the remainder is the weight of the 
 chloride of sodium. Every 100 grains of chloride of 
 sodium (common salt) are equivalent to 53.17 of soda. 
 
 b. When the magnesia has been separated by means 
 of silver, the solution, before being evaporated, is to be 
 made slightly sour with muriatic acid, that the chloride of 
 silver maybe thrown down, collected on a filter, and washed. 
 The filtered solution is then evaporated and treated as in a. 
 
 c. When the magnesia has been separated by means of 
 arseniate of ammonia, the solution containing the alkalies 
 is to be evaporated to dryness, and heated to redness in 
 a porcelain crucible, till fumes cease to be given off. When 
 cold, add a little sal-ammoniac, and heat again. By this 
 operation the excess of arsenic acid is wholly driven off, 
 and, as the fumes of this arsenic acid are poisonous, care 
 must be taken that they are not inhaled. The mixed 
 chlorides of potassium and sodium remain as in the 
 
ESTIMATION OP THE SALINE MATTERS. 39 
 
 method a, and are to be treated in the same way, if no 
 sulphuric acid is present. But if sulphuric acid is pre- 
 sent, the mixed salts are dissolved in water, and the acid 
 precipitated by baryta water, and separated by filtration, 
 as in 37 /. 
 
 d. After the precipitation by baryta, according to this 
 method (37/) ammonia and carbonate of ammonia are 
 added to the filtered solutions which are heated to boiling. 
 In this way the excess of baryta is separated. The filtered 
 solution is then evaporated to drive off the ammonia, 
 muriatic acid added to convert the alkalies into chlorides, 
 and then these mixed chlorides separated as described 
 under a. 
 
 39. Estimation of the ammonia. a. If ammonia be pre- 
 sent in the solution along with potash and other substances, 
 the method by which it can be most easily estimated is to 
 introduce a separate portion of the solution into a large 
 tubulated retort, to add water until it amounts to nearly 
 an English pint then to introduce a quantity of caustic 
 potash or caustic baryta, and to distil by a gentle heat 
 into a close receiver, containing a little dilute muriatic 
 acid, until fully one-half has passed over. Bi-chloride of 
 platinum is then to be added to the solution which has 
 come over, previously rendered slightly acid by muriatic 
 acid, and the whole is evaporated nearly to dryness by a 
 very gentle heat. Dilute alcohol is then added to wash 
 out the excess of the salt of platinum, and the yellow 
 powder is collected on a filter, washed with spirit, dried 
 by a very gentle heat and weighed. One hundred grains 
 indicate the presence of 7.61 grains of ammonia. 
 
40 ESTIMATION OF THE SALINE MATTERS. 
 
 b. Or the yellow powder, without being so carefully 
 dried, may be heated to redness, when only metallic pla- 
 tinum will remain. One hundred grains of this metallic- 
 platinum indicate the presence of 17.21 grains of am- 
 monia. 
 
 c. Or the acid liquor in the receiver may be eva- 
 porated to dryness in a glass beaker over the water-bath 
 till it ceases to lose weight. The salt obtained is sal- 
 ammoniac, of which every 100 grains represent 31.8 
 grains of ammonia. But this method is not so accurate 
 as the preceding. 
 
 40. Estimation of the 2>hospkoric acid. The presence 
 of phosphoric acid in the solution being already ascertain- 
 ed (28), its quantity may be most easily estimated as 
 follows : 
 
 a. Dissolve molybdic acid in ammonia, and to the 
 solution add pure nitric acid till the precipitate at first 
 formed again dissolves. This acid solution of molybdate 
 of ammonia is the most delicate test for phosphoric acid 
 yet known. The substance to be examined by it for phos- 
 phoric acid may be dissolved in muriatic acid, but nitric 
 acid is to be preferred. Or, if the substance be already 
 in solution, as in the watery extract of a soil, the solution, 
 as I have already directed (28), should be made acid by 
 means of nitric acid. 
 
 b. Evaporate the solution to be tested to a small bulk, 
 and add to it a large excess of the solution of molybdate 
 of ammonia. This is necessary, because the yellow preci- 
 pitate which falls contains nearly 30 times as much molyb- 
 dic acid as it does of phosphoric acid. It is known that 
 enough of the molybdic has been used when, before col- 
 
ESTIMATION OF THE SALINE MATTERS. 41 
 
 lecting the precipitate on a filter, a drop of the super- 
 natant liquid gives, with sulphuretted hydrogen water, a 
 brown precipitate of sulphuret of molybdenum . 
 
 Digest the solution with the yellow precipitate which 
 has fallen, for several hours, at a gentle heat ; collect the 
 precipitate on a filter, and wash it with a fresh portion of 
 the same solution of the molybdate as was employed to 
 throw it down. This precipitate on the filter contains all 
 the phosphoric acid. But to be sure of this, the filtered 
 solution (filtrate) should be set aside for some time in a 
 warm place, to see if any farther precipitate falls. 
 
 c. The yellow precipitate upon the filter is now to be 
 dissolved, while still moist, in solution of caustic ammonia, 
 and washed well from the filter. To this new solution add 
 one of ammoniacal sulphate of magnesia as long as a pre- 
 cipitate is seen to fall. Set aside for twelve hours in the 
 cold. The ammoniacal phosphate of magnesia which has 
 fallen is in the state of minute shining crystals, which can 
 be well distinguished by the aid of a pocket microscope. 
 It is to be collected on a filter, washed with water, with 
 which a third or fourth part of solution of ammonia has 
 been mixed, dried, heated to redness, the filter burned 
 separately, and its ashes added to the rest. Deducting 
 the ashes of the filter (p. 18, note), every hundred grains 
 of the phosphate of magnesia thus obtained contain 64.06 
 grains of phosphoric acid (note, p. 74). 
 
 d. The ammoniacal sulphate of magnesia required in 
 this operation is easiest prepared by dissolving sulphate 
 of magnesia in water, adding ammonia to throw down mag- 
 nesia, then muriatic acid to dissolve it ; again ammonia 
 followed by muriatic acid, sufficient, on shaking, to make 
 
42 ESTIMATION OF THE SALINE MATTERS. 
 
 it clear again and so on, till the addition of ammonia in 
 excess no longer makes the solution milky. The prepara- 
 tion may be made more quickly by adding at once a 
 solution of sal-ammoniac* sufficient to prevent ammonia 
 from throwing down the magnesia ; but in this way the 
 young manipulator is more likely to add an excess of 
 sal-ammoniac, which is to be avoided. 
 
 The process above described is excellent for determin- 
 ing small quantities of phosphoric acid, such as occur in a 
 soil. The quantity of molybdic acid required, in propor- 
 tion to the phosphoric acid, is so great, however, that when 
 larger quantities of phosphoric acid are to be determined, 
 it is usual to employ other methods, which need not be 
 here described. 
 
 Note on the examination- of waters. It may be of use to 
 some of my younger readers, if I here remark that natu- 
 ral waters are examined in the same way as the watery 
 solution of a soil. The methods described in the two pre- 
 ceding chapters for the qualitative and quantitative 
 examination and analysis of an artificially prepared solu- 
 tion, will enable the young experimenter to arrive at 
 satisfactory results in regard to all but a few of the more 
 rare natural solutions which form our springs. The ochrey 
 or calcareous deposits which sometimes fall from them, 
 either when exposed to the air, or when they are boiled, 
 must be treated like the earthy matter of the soil, as 
 described in the succeeding chapter. 
 
 * The reader understands that the ammonia and muriatic acid, successively 
 added, form sal-ammoniac in the solution itself. 
 
CHAPTER V. 
 
 EA.RTHY MATTERS OF THE SOIL. 
 
 Matter insoluble in water. Treatment with muriatic acid ; testing of thig solu- 
 tion. Estimation of the soluble silica, the sulphuric acid, the iron as per- 
 oxide, the alumina, lime, magnesia, oxide of manganese, phosphoric acid, 
 potash and soda. How to estimate the protoxide of iron and the carbonic 
 acid in a soil. Treatment of substances insoluble in muriatic acid. Heating 
 with sulphuric acid Fusion with alkaline carbonates. Summary of the pre- 
 ceding methods. Note on tile and fire clays. 
 
 I. ESTIMATION OF THE SUBSTANCES SOLUBLE IN 
 MURIATIC ACID. 
 
 41. AN un weighed portion of the soil in its natural 
 state has been used for the preparation of the watery 
 extract already examined, as described in Chapter III. 
 A part of this same soil, after being so extracted with 
 water, is to be treated with muriatic acid diluted with 
 one or two waters. If bubbles of gas are seen to escape 
 from the soil when the acid is first added, the presence of 
 carbonate of lime, and in some cases of carbonate of 
 magnesia, may be inferred. The quantity of carbo- 
 nate may be judged of by the rapidity and length of 
 time during which these bubbles of gas continue to be 
 given off. 
 
44 EAKTHY MATTERS OF THE SOIL. 
 
 42. The soil and acid thus mixed are to be disgested 
 on a sand or water bath for some hours, diluted with 
 water and the solution filtered. It is then to be ex- 
 amined qualitatively, as described in Chapter III. Gene- 
 rally it will be found to contain silica, alumina, oxide of 
 iron, oxide of manganese, lime, magnesia, potash and soda, 
 with sulphuric and phosphoric acids. But some of these 
 may be absent ; and this it is necessary to ascertain, as 
 it will then be unnecessary in the subsequent analysis 
 to take any steps for determining their quantity. The 
 silica may be sought for as described in 45. 
 
 43. a. This preliminary examination being made, a 
 weighed portion of the soil, dried at 250 Fahr., and 
 weighed, is first repeatedly boiled in distilled water, as 
 described in 19, and then covered over with diluted 
 muriatic acid, and gently heated on a water or sand 
 bath, with occasional stirring for twelve hours. Water is 
 now added, the whole well shaken or stirred together, al- 
 lowed to settle,and the solution poured off through a filter. 
 
 b. Over the still undissolved portion of the soil strong 
 muriatic acid may now be poured so as just to cover it, 
 and the whole disgested again, with the aid of heat, for 
 several hours. Water is added, the whole thrown upon 
 the filter already employed (a), and the insoluble matter 
 washed till water ceases to remove anything, and dried at 
 250 Fahr., till it ceases to lose weight. This weight, 
 deducted from that of the dry soil employed, indicates 
 the proportion of the washed soil which is soluble in acids. 
 
 From 100 to 400 grains of the dry soil may be taken 
 for this treatment with acid, according as it naturally 
 contains more or less sand and srravel. 
 
EARTH1" MATTERS OF THE SOIL. 45 
 
 44. The dry insoluble matter being now heated to 
 redness, the organic matter burns away, and there re- 
 mains only the insoluble mineral matter of the soil. This 
 is to be weighed, and kept for subsequent treatment and 
 analysis The loss, which is organic matter insoluble 
 in water or acid, may probably serve as a check upon 
 some of the determinations already made, when examin- 
 ing the soil in reference to its organic matter only, as 
 described in Chapter II. 
 
 45. To the mixed acid solutions, 43 a and I, which will 
 probably be of a reddish-brown colour, from the presence 
 of peroxide of iron, a little nitric acid is to be added, after 
 which they are to be evaporated to dryness on the water- 
 bath, moistened with muriatic acid, and, after standing 
 some time, treated with water. The silica remains insol- 
 uble, and may be collected on a lilter, washed, dried, 
 heated to redness, and weighed. The weight indicates 
 the proportion of silica existing in the soil in a state to 
 be readily dissolved by acids. 
 
 In less careful analysis of soils, this separation of the 
 silica soluble in acids, which is rarely large in amount, 
 may be neglected. 
 
 46. The solution filtered from the silica contains all the 
 ingredients of the soil which are soluble in muriatic acid, 
 and the nature and names of which have been already 
 determined (42). These ingredients may be separated 
 from each other, and their several weights estimated 
 most readily, as follows. If all the substances named in 
 42 have been found in it, divide the solution into four 
 equal parts by measure. 
 
 47. In i^G first, estimate the sulphuric acid if any be 
 
46 EARTHY MATTERS OF THE SOIL. 
 
 present by adding to it a solution of nitrate of baryta or 
 of chloride of barium, and treating the precipitate as de- 
 scribed in 31. If no sulphuric acid be present, the solu- 
 tion need only be divided into three parts. 
 
 48. In the second, determine the phosphoric acid by 
 means of molybdate of ammonia, as described in 40. 
 With this view, it may be advantageously evaporated to 
 dryness, and treated with concentrated nitric acid aided 
 by heat, till the smell of chlorine passes off. It may then 
 be dissolved in a little diluted nitric acid and added to 
 the solution of molybdic acid. Or the peroxide of iron and 
 alumina may be at once precipitated from the solution, 
 collected on a filter, dissolved while moist in dilute 
 nitric acid, and added to the molybdate of ammonia. As 
 I have already said, the whole of the phosphoric acid con- 
 tained in a soil almost invariably falls along with the per' 
 oxide of iron and the alumina. 
 
 49. From the third solution may be determined 
 
 a. The lime and magnesia, as described in 33 and 
 37. 
 
 b. The peroxide of iron, as described in 34. 
 
 c. The alumina, as described in 35. The alumina ob- 
 tained in this way will contain also the phosphoric acid. 
 But the weight of the latter has already been determined 
 in the second portion of liquid (48), and this, deducted 
 from the weight of the alumina here found, will give the 
 true weight of the alumina. 
 
 In some cases a portion of the phosphoric acid may 
 remain in the oxide of iron which has been separated 
 from the alumina, but the proportion of phosphoric acid 
 in a soil is generally so small that, in an analysis of this 
 
KARTHY MATTERS OF THE SOIL. 47 
 
 kind, it is rarely necessary to have recourse to further re- 
 fined manipulations for the sake of a theoretical accuracy 
 which can lead to no practical result. 
 
 But it may happen also that the soil will contain so 
 much phosphoric acid, that, when ammonia is added to 
 the acid solution, a quantity of phosphate of lime or phos- 
 phate of magnesia, or both, may fall along with the iron 
 and alumina. This may be tested as follows : 
 
 Dissolve the precipitate in sulphuric acid, add an equal 
 quantity of sulphate of ammonia, making a clear solution 
 with the smallest possible quantity of water. Into this 
 solution pour alcohol in large quantity, shake well to- 
 gether, and leave the whole to settle. Add now a little 
 ether, and if this troubles the solution, let it stand again 
 for twelve hours, then filter and wash the precipitate with 
 a mixture of alcohol and ether. Distil off the alcohol 
 and ether, and test the remaining solution for phosphoric 
 acid by means of ammoniacal sulphate of magnesia, as 
 described in 40 c. 
 
 The precipitate on the filter will dissolve in water, 
 from which ammonia will throw down oxide of iron and 
 alumina oxalate of ammonia, lime, and phosphate of 
 soda, magnesia, if any of these are present. 
 
 If by this testing the presence of lime and magnesia in 
 the precipitate from the acid solution of the soil by 
 ammonia, be ascertained the phosphoric acid may be 
 separated from it (the precipitate), and estimated as 
 phosphate of magnesia in the way here described the 
 iron and alumina as described in 34 and 35 and the 
 lime and magnesia as described in 33 and 37. 
 
 d. The oxide of manganese may be determined as de 
 
48 KARTHY MATTERS OF THE SOIL. 
 
 scribed in 36, though in ordinary soil analysis the special 
 separation of this oxide may be neglected, as it is usually 
 present only in small quantity 
 
 e. Potash and soda, also, will only be present in very 
 minute quantity in this acid solution, and in most soil 
 analysis may be neglected. In this case the magnesia is 
 thrown down at once by phosphate of soda (37 5.) If it 
 be desired accurately to estimate them, however, either 
 together or singly, it may be done by the methods de- 
 scribed under 38. 
 
 50. From the fourth solution, the total quantity of iron 
 may again be determined by the measure method here- 
 after described under 65. Or if this trial, which is very 
 brief and simple, be thought unnecessary, the acid solu- 
 tion may only be divided into three portions (46). There 
 is an advantage, however, in such a double determination 
 by independent methods, as the one result serves to con- 
 trol and test the other. 
 
 51. Estimation of the protoxide of iron in the soil. It is 
 known that there are two oxides of iron. 
 
 Iron. Oxygen, 
 
 The first or protoxide, consisting of 6 16 
 
 The second or peroxide, or sesquioxide 56 -j j 
 
 The first of these, by exposure to the air, soon changes 
 into the second. Nevertheless, it frequently occurs in 
 the soil, and sometimes materially affects its agricultural 
 qualities. It is necessary, therefore, in many cases, that 
 the quantity of this protoxide contained in a soil should 
 be accurately estimated. By the process described in 34, 
 or by the measure method 65, the whole of the iron has 
 been already obtained in the state of peroxide. The fol - 
 
EARTHY MATTERS OF THE SOIL. 49 
 
 lowing method enables us to determine how much of this 
 existed in the soil in the state of protoxide : 
 
 A little powdered chalk or common soda is introduced 
 into a flask with a Ujngish neck, diluted muriatic acid 
 poured upon it, and allowed to stand till it has all dis- 
 solved, and the flask has become filled with carbonic acid 
 gas. A weighed portion of the dry soil is then to be intro- 
 duced into the flask, diluted muriatic acid poured over it 
 not in too large excess the flask lightly corked, and the 
 whole digested till the oxides of iron are all dissolved. 
 Powdered carbonate of baryta is now to be introduced in 
 excess, and the whole digested with the aid of occasional 
 shaking. By the action of the baryta, the' whole of the per- 
 oxide of iron and alumina will be gradually separated from 
 the solution, while the protoxide of iron will remain dis- 
 solved. The full production of this effect will be indicated 
 by the solution becoming nearly colourless, or only of a 
 pale green. The flask is now to be filled with hot boiled 
 distilled water, corked carefully, and the whole allowed 
 to settle. The solution is then decanted, or, if necessary, 
 filtered, and the insoluble matters collected on the filter 
 and washed. The solution contains all the iron which 
 existed in the soil in the state of protoxide. It is boiled 
 with a little nitric acid to convert it into peroxide, preci- 
 pitated by ammonia, and separated from alumina, if any 
 be still present, by the method already described in 34. 
 When dried and weighed, every 100 grains of this perox- 
 ide represent 90 grains of protoxide in the soil. 
 
 The weight of the peroxide thus obtained, deducted from 
 that of the whole peroxide of iron already determined, 49b, 
 gives the weight of peroxide actually existing in the soil. 
 4 
 
50 EARTHY MATTERS OF THE SOIL. 
 
 In this process the flask is filled with carbonic acid, 
 only to prevent the protoxide from absorbing oxygen. 
 Where carbonate of baryta cannot be obtained, carbonate 
 of lime or chalk may be used in its stead. 
 
 52. Estimation of the carbonic acid in the soil. When 
 lime and magnesia are present in a soil, they are usually 
 combined for the most part with carbonic acid. A 
 smaller portion is in combination with humic and hulmic 
 acids, and a portion probably also with silica. When the 
 soil is treated with muriatic acid, these carbonates of lime- 
 and magnesia are decomposed, and their acid escapes in 
 the form of carbonic acid gas. 
 
 It is not usual, in the analysis of a soil, to estimate 
 directly the weight of this carbonic acid. The lime and 
 magnesia obtained in an analysis are commonly con- 
 sidered to have been altogether in the state of carbonates 
 in the soil except what is known to have been in the 
 states of sulphate or phosphate and the carbonic acid 
 required to convert them into carbonates is calculated 
 and adopted as the/ true proportion of this acid contained 
 in the soil. This is not strictly correct, however ; and 
 where rigid accuracy is required, it is necessary to 
 estimate the weight of the carbonic acid directly. This 
 may be done by the following method : 
 
 a. One or two hundred grains of the soil, carefully dried 
 at 212 to 250 Fahr., are to be introduced into a small 
 weighed flask or bottle, and then just covered with a 
 weighed quantity of cold diluted muriatic acid. The 
 carbonates in the soil will be gradually dissolved, and the 
 carbonic acid will be set free in the form of gas. After 
 twelve hours, or when the action has entirely ceased, a 
 
EARTHY MATTERS OF THE SOIL. 51 
 
 small tube is to be introduced through the mouth of the 
 flask nearly to the surface of the solution, and air sucked 
 through it till the whole of the carbonic acid is drawn out 
 of the flask. The flask with its contents is now weighed, 
 and the loss of weight indicates the amount of carbonic 
 ucid very nearly. Every 100 grains of carbonate of 
 lime in the soil will lose in this way 44 grains of car- 
 bonic acid or every 100 grains of carbonic acid indi- 
 cate the presence of 227.27 grains of carbonate of lime, 
 or of 127.27 grains of lime in the state of carbonate. 
 
 b. This method is not rigorously accurate, since, on the 
 one hand, a small loss of weight may occur from the 
 escape of watery vapour carried off by the gas or sucked 
 out by the tube ; and, on the other, a small gain, by the 
 retention of a small quantity of carbonic acid in the solu- 
 tion itself. It is made rigorous by passing the suction or 
 escape tube through a well-fitting cork, putting it into 
 the flask before the commencement of the operation, and 
 weighing them together. The cork is removed to intro- 
 duce the materials, and immediately replaced. A weighed 
 tube, filled with chloride of calcicum,* is then attached, by 
 an India-rubber joining,f to the escape tube, so that the gas 
 passes through it and escapes dry. By heating the solution 
 
 * Chloride of calcicum is prepared by dissolving lime in muriatic acid, evapo- 
 rating to dryness, heating in a crucible till it melts, pouriag it out upon a 
 cold flag or iron plate, breaking into pieces, and, while still hot, putting it into a 
 well-stoppered bottle. It absorbs moisture with great rapidity, so that if moist 
 air be made to enter one end of a tube 6 or 8 inches long filled with broken 
 pioci's of the chloride, it will escape at the other end quite dry. 
 
 f Caoutchouc tubes of various si/.es are prepared and Hold for the purpose of 
 connecting pieces of apparatus together. They are recommended by their soft- 
 ness (when gently warmed), by their elasticity, and by their power of resisting 
 the action of acids and alkalies. 
 
52 EARTHY MATTERS OF THE SOIL. 
 
 at the close of the operation, any gas retained by the liquid 
 is also expelled ; and, by slightly loosening the cork, air 
 may be sucked through the united tubes till all the gas 
 is drawn out of the flask. The chloride-of-calcicum tube 
 is now detached and weighed separately. The increase of 
 its weight, if any, is to be added to that of the flask and 
 suction-tube weighed together.* 
 
 II. ESTIMATION OF THE SUBSTANCES INSOLUBLE IN 
 
 MURIATIC ACID. 
 
 53. The part of the soil which remains insoluble in 
 muriatic acid consists chiefly of quartz sand, of fragments 
 of rock, and of undecomposed clay and other silictates. 
 
 If there be much pure sand and fragments of undecom- 
 posed rock, these had better be washed or picked out and 
 weighed separately. The fine part or the whole if 
 thought advisable after being reduced to fine powder, 
 first in a steel and then in an agate mortar, may then be 
 treated in one or other of two ways. 
 
 54. First. It may be drenched with concentrated sul- 
 phuric acid, and heated for a considerable time in a 
 slightly-covered platinum crucible over a lamp, till the 
 sulphuric acid is nearly all driven off. When cold, it is 
 treated with water, which, after being allowed to settle, is 
 filtered. If, on the addition of ammonia in excess to this 
 solution, a precipitate of alumina or of oxide of iron 
 
 * Various modifications of this apparatus are in use, some more and some less 
 complicated. The passage of another tube through the cork, nearly to the bot- 
 tom of the flask by which the acid may be poured in at the beginning, and the 
 air enter at the close of the operation is an improvement, but what I have de- 
 scribed in the text will, in careful hands, give very good results. 
 
EARTHY MATTERS OF THE SOIL. 53 
 
 appears, the treatment with sulphuric acid is to be 
 repeated a second, and if necessary, a third time, till 
 everything soluble is taken up by the sulphuric acid. 
 
 By this treatment the insoluble silictates are decomposed, 
 and only pure silica remains in the crucible undissolved. 
 This may be collected on the filter, washed, dried, heated 
 to redness, and weighed. Its weight represents the pro- 
 portion of insoluble silicious matter in the soil. 
 
 The solution in sulphuric acid may contain alumina, 
 oxide of iron, lime, and magnesia. These are to be sepa- 
 rated, and their several weights determined by the pro- 
 cesses already described. Only in rare cases will this 
 solution contain potash or soda, or phosphoric acid ; but 
 if the presence of these substances be suspected, they also 
 can be sought for and separated as described in the pre- 
 ceding section. 
 
 55. Second. a. Or the portion of soil on which hot 
 muriatic acid refuses to act may be mixed with three 
 times its weight of a mixture of carbonate of potash with 
 carbonate of soda, in equal equivalents,* and heated to 
 fusion in a platinum crucible. Place the crucible while 
 still hot on a cold plate, the fused mass will then readily 
 separate from the sides of the crucible as it cools, and can 
 be easily taken out. The fused mass, along with the cru- 
 cible, is then put into a beaker glass, covered with water 
 
 * That is, in the proportion of 69 of dry carbonate of potash to 53 of dry carbo- 
 nate of soda, since these two salts consist respectively of 
 
 Carbonate of Potash. Carbonate of SoUa. 
 
 Carbonic acid, 22.0 Carbonic acid, 22.0 
 
 Potaah, . . 47.2 . Soda, . . .31.2 
 
 69.2 53.2 
 
 See note, p. 82. 
 
54 EARTHY MATTERS OF THE SOIL. 
 
 and slowly treated with diluted muriatic acid, aided by a 
 gentle heat, as long as anything is dissolved. A tolerably 
 large vessel should be employed, that nothing may escape 
 during the effervescence that takes place. The residue is 
 silica, which is to be collected on a filter, washed, dried, 
 and weighed. 
 
 b. The solution in muriatic acid may contain silica, 
 alumina, oxide of iron, lime, and magnesia. A little nitric 
 acid being added, it is to be evaporated to dry ness on the 
 water-bath. As it approaches to dryness, it should be 
 constantly stirred, that it may be obtained in the form 
 of a dry powder. It is then moistened with muriatic 
 acid, after a little treated with water, and the silica which 
 remains undissolved collected on a filter, washed, heated 
 to redness, and weighed. This weight is to be added to 
 that of the silica already obtained (a.) 
 
 From the acid solution the alumina, oxide of iron, lime, 
 and magnesia or such of them as are present are to be sep- 
 arated by the processes described in the preceding section . 
 
 56. a. Potash and soda will rarely be extracted from the 
 insoluble part of the soil by this process. But if it is 
 desired to seek for, or to estimate the amount of, these 
 substances in the portion of the soil left undissolved by 
 muriatic acid, it must be reduced to very fine powder and 
 intimately mixed with four or five times its weight of 
 hydrate of baryta, and heated to incipient fusion over a 
 lamp in a silver crucible. Platinum is slightly attacked 
 by caustic baryta. When cold, the fused mass is treated 
 with diluted muriatic acid, as ia 56 a. 
 
 b. The silica, soluble and insoluble, is then separated 
 as after the fusion with potash and soda (55 b), and the 
 
EARTHY MATTERS OF THE SOIL. 55 
 
 alumina and oxide of iron thrown down by ammonia. 
 Sulphuric acid is then added, so as exactly to precipitate 
 the whole of the baryta held in solution, after which the 
 lime is thrown down as usual by ammonia and oxalate of 
 ammonia. Magnesia, potash, and soda, if all present, are 
 now in the solution in the state of chlorides, and may be 
 separated by the methods already described. 
 
 c. But if, in separating the byrata, an excess of sul- 
 phuric acid has been added, the solution containing the 
 magnesia and the alkalies is to be evaporated to dryness, 
 and heated to redness, to drive off the ammoniacal salts. 
 Dissolved in water, with the aid of a few drops of muriatic 
 acid, if necessary, a solution of caustic baryta is to be 
 added, by which the sulphuric acid and the magnesia are 
 both thrown down, and may be collected on a filter and 
 washed. Sulphuric acid dissolves out the magnesia, which 
 may be evaporated and estimated in the state of sulphate 
 of magnesia, as already described under 37/. 
 
 d. From the solution containing the alkalies the excess 
 of baryta is to be thrown down as carbonate, by adding 
 carbonate of ammonia, and boiling (38 d.) Filtered 
 from this, evaporated to dryness, and heated a few drops of 
 muriatic acid being added, if necessary, to insure their be- 
 ing in the state of chlorides the alkalies are obtained 
 alone, and may be weighed. The potash is then estimated 
 by means of bi-chloride of platinum, as already described 
 under 38, and the soda from the loss. 
 
 This process I have thought it necessary to describe ; 
 but, as I have already stated, it will very rarely be neces- 
 sary to test for, much less to estimate quantitatively, the 
 
56 EARTHY MATTERS OF THE SOIL. 
 
 alkaline matters contained in the portion of a soil upon 
 which muriatic acid ceases to act. 
 
 The accuracy and care with which the successive pro- 
 cesses have been conducted, is tested by adding together 
 the weights of the several substances that have been sepa- 
 rately obtained. If this sum does not differ more than 
 one per cent from the weight of the soil employed, the 
 results may be considered to be deserving of confidence. 
 One of the points in which a beginner is most liable to 
 err is in the washing of the several precipitates he collects 
 upon his filters. As this is a tedious operation, he is very 
 likely to wash them at first only imperfectly, and thus to 
 have an excess of weight when his quantifies are added 
 together whereas a small loss, in a correct analysis, is 
 almost unavoidable. The precipitates should always be 
 washed with distilled water, and till a drop of what 
 passes through leaves no stain, when dried, upon a bit of 
 glass or of bright platinum foil. 
 
 III. SUMMARY OF THE PRECEDING METHODS. 
 
 57. The following scheme may be useful as giving a brief 
 view of the successive steps which are to be taken in order 
 to separate the several substances from the solutions in 
 muriatic acid by the methods above described. 
 
 A. Digest the soil in distilled water, dry at 250 Fahr., 
 weigh, digest with dilute muriatic acid for twelve hours, 
 and then with concentrated muriatic acid. Dilute, filter, 
 and mix the solutions. 
 
 B. Add a little nitric acid, evaporate to dry ness, 
 
EARTHY MATTERS OP THE SOIL. 
 
 moisten with muriatic acid, treat with water, filter, and 
 then collect, wash, heat to redness, and weigh the silica. 
 C. Divide the solution into three equal portions. 
 a. In the first, estimate the sulphuric acid by means 
 
 of chloride of barium (31). 
 If. In the second, estimate the phosphoric acid by 
 
 molybdate of ammonia. (40 b). 
 c. Treat the third as follows-: It may contain 
 alumina, oxide of iron, oxide of manganese, lime, 
 magnesia, potash, and soda, as well as the sul- 
 phuric and phosphoric acids already estimated 
 in the other portions of the solution. 
 
 a. Add caustic ammonia. The 
 precipitate contains alumina, 
 oxide of iron, phosphoric acid, 
 and perhaps some phosphate of 
 lime and phosphate of magnesia. 
 Collect on the filter, and wash. 
 
 6. Dissolve the precipitate in a 
 small quantity of sulphuric acid, 
 add a little sulphate of ammonia, 
 and then pour the solution into a 
 large quantity of alcohol. Add 
 a little ether, filter, and wash the 
 precipitate with mixed alcohol 
 and ether. 
 
 c. From the solution distil off 
 the alcohol, dilute the water, 
 and precipitate the phosphoric 
 acid by ammoniacal sulphate of 
 magnesia (40 Q c). Compare the 
 weight of this phosphoric acid 
 with that obtained already by 
 molybdate of ammonia C b). It 
 ought to be a little less, as by the 
 present process the whole of the 
 phosphoric acid is not rigorously 
 separated. 
 
 d. Dissolve in water what re- 
 mains on the filter (b) ; add cans- 
 tic potash in excess, and heat 
 The alumina and oxide of iron 
 with lime and magnesia, if pre- 
 sent, are precipitated, but the 
 alumina is re-dissolved. Filter, 
 wash the precipitate, dry, heat to 
 redness, and weigh. 
 
 e. Dissolve this precipitate in 
 muriatic acid, throw down the 
 oxide of iron by ammonia, filter, 
 wash, dry, heat to redness, and 
 weigh the oxide of iron again. 
 If it weighs less than the whole 
 precipitate did, the filtered solu- 
 tion contains lime or magnesia. 
 Add it to the solution from a. 
 
 /. To the potash solution rf add 
 sal-ammoniac, and boil to precipi- 
 tate the alumina. Collect on a 
 filter, wash, heat to redness, and 
 weigh. 
 
 Note. If no phosphoric acid be 
 present, or if much oxide of iron 
 be present along with it, the pre- 
 
EARTHY MATTERS OF THE SOIL. 
 
 cipitate from a by ammonia con- 
 tains no lime or magnesia, and 
 the steps b, c, and e become un- 
 necessary. 
 
 g. To the ammoniacal solution 
 from a (mixed, if necessary, with 
 that from c), add oxalate of am- 
 monia. Collect, wash, heat to red- 
 ness, and weigh the carbonate of 
 lime (35). 
 
 /. Add hydrosulphuret of am- 
 monia to throw down the manga- 
 nese as sulphuret. Collect, dis- 
 solve in muriatic acid, precipi- 
 tate by carbonate of soda, collect 
 again, wash, dry, heat to redness, 
 and weigh the oxide of manga- 
 nese (36). 
 
 i. If no potash and soda are 
 present, precipitate the magne- 
 sia by phosphate of soda (from 
 the filtered solntion 7i), collect, 
 wash, dry, and weigh (37 b). Or 
 evaporate to dryness, add a few 
 drops of sulphuric acid, heat to 
 redness, and weigh the sulphate 
 of magnesia (37 a). 
 
 k. Or if the alkalies are present, 
 .and no sulphuric acid, evaporate 
 to dryness, and drive off all the 
 ammoniacal salts by heat. Dis- 
 solve them in a little water, add 
 linely-divided red oxide of mer- 
 cury, evaporate to dryness, and 
 heat to redness. Water then dis- 
 solves the alkalies, and leaves the 
 
 magnesia, which is collected and 
 weighed (37 W c). 
 
 I. The solution contains the 
 chlorides of potassium and so- 
 dium. Evaporate to dryness, hunt 
 to dull redness, and weigh. Re- 
 dissolve in water, separate the 
 chloride of potassium by bi-chlo- 
 ride of platinum, collect, dry, and 
 weigh (38 o). The chloride of n' 
 dium is estimated by the h><. 
 
 m. But if sulphuric acid 1>e pre- 
 sent, precipitate by caustic baryta, 
 filter, and wash. Dissolve the prct :i- 
 pitated magnesia from the filter by 
 means of sulphuric acid, evaporate 
 to dryness, and estimate either as 
 sulphate or as phosphate, (37 /i. 
 
 . To the solution filtered from 
 the baryta and magnesia, add 
 carbonate of ammonia, and boil. 
 Collect the carbonate of baryta on 
 the filter, evaporate the solution 
 to dryness, heat to drive oft' tin- 
 ammoniacal salts, add a few 
 drops of muriatic acid, and heat 
 again (38 d). 
 
 Weigh now the mixed chlorides, 
 and proceed as under /. 
 
 o. Finally, from the solution of 
 a separate portion of the soil in 
 muriatic acid, precipitate the 
 peroxide of iron by means of car- 
 bonate of baryta, and then esti- 
 mate the protoxide as described 
 under ,">! '". 
 
 Ifute on tile anil Jire clays. 1 simply add here, in reference to clays of every 
 kind, that they are examined and analysed exactly in the same -way ss the in- 
 soluble matter of a soil. 
 
CHAPTER VI. 
 
 ANALYSIS BY MEASURE ORES OF IRON. 
 
 Estimation of substances by measure; principle on which the method is based. 
 Estimation of chlorine in this way. Estimation of silver. Estimation of 
 the oxides of iron by measure. Standard solution of per-manganate of pot- 
 ash; its effect on the protoxide of iron ; mode of using it. Estimation of the 
 protoxide of iron in a soil. Estimation of the whole quantity of iron. 
 Analysis of the ores of iron. Estimation of the iron only, very brief aud 
 easy. Estimation of the other ingredients longer and more difficult. 
 
 I. ESTIMATION OF SUBSTANCES BY MEASURE. 
 
 58. BESIDES the methods already described, by which 
 the ingredients of a soil are severally separated, collected, 
 and directly weighed, another general method of analysis 
 exists by which the separation and weighing of each is 
 dispensed with, and their several quantities estimated by 
 measure. This method, being more speedy, involving less 
 labour, and rendering the use of the balance less frequent, 
 has recently come much into favour, and is daily becoming 
 more improved and more widely applicable. 
 
 This method is simply an extension of the processes of 
 testing or qualitative examination already described in 
 Chapter III., and is based upon the two principles 
 
 1. That the presence of one known body, A, may be 
 detected in a solution by the visible change or reaction 
 
60 ANALYSIS BY MEASURE ORES OF IRON. 
 
 produced in the liquid by the addition of a solution of 
 another known body, B. 
 
 2. That the quantity or weight of the body A may be 
 calculated from the known quantity of the body B, which it 
 is necessary to add to the solution before the visible change 
 or re-action ceases to be produced by new additions. 
 
 59. And the way in which these principles are applied 
 to quantitative analysis is to prepare a standard solution 
 of the body B, every cubic inch or other measure of which 
 contains a known weight of B. If of this solution it be found 
 necessary to add a known measure to the solution A before 
 visible change ceases, then the weight of B being known 
 from the measure, the weight of A, which is equivalent to 
 it, can be calculated. 
 
 60. Thus a solution of common salt forms a white 
 visible curdy precipitate when added to a solution of 
 nitrate of silver. The curdy precipitate is chloride of 
 silver. If the solution of common salt be added drop by 
 drop, shaking, and allowing the whole to settle after each 
 addition, we shall arrive at length at a point when a fur- 
 ther drop of the salt solution will produce no further pre- 
 cipitate. 
 
 Now, 58.46 grains of common salt (chloride of sodium), 
 containing 35.46 of chlorine, throw down exactly 143.46 
 grains of chloride of silver, containing also 35.46 grains 
 of chlorine united to 10P- grains of silver.* Or 100 grains 
 
 These two substances consist respectively of 
 
 Common Salt. Per cent. Chloride of silver. Per cent. 
 
 Chlorine, 35.46 > of C 60.663 Chlorine, 35.46 > Qr C 24.724 
 
 Sodium, 23.00 > (39.337 Silrer, 108.00 > J 75.276 
 
 58.46 100.00 143.46 100.00 
 
ANALYSIS BY MEASURE ORES OF IRON. 61 
 
 of common salt throw down 245.34 grains of chloride of 
 silver, containing 184.68 of silver and 60.66 of chlorine. 
 If, therefore, we dissolve 100 grains of pure common salt 
 in distilled water, and then add water till the solution fills 
 exactly 100 measures in our graduated tube, every mea- 
 sure will represent 1 grain of common salt. Suppose now 
 we add this solution (A) to that which contains silver (B), 
 till it ceases to throw down anything, and that on looking 
 at our graduated tube we find that 10 measures of the 
 common salt (A) have been required. These ten measures 
 contain 10 grains of common salt, and represent 14.346 
 grains of chloride of silver, or 10.797 grains of silver, 
 which, without weighing, is the quantity of silver con- 
 tained in the solution B. 
 
 61. Or the process may be reversed. The standard 
 solution (A) may in every hundred measures contain 100 
 grains of pure nitrate of silver, and this may be employed 
 exactly in the same say to estimate the quantity of chlorine 
 in a solution B. Every 100 grains of nitrate of silver 
 throw down 84.38 grains of chloride of silver containing 
 25.8 grains of chlorine ;* so that if exactly 10 measures 
 of the silver solution A. be added to the chlorine or com- 
 mon salt solution B, before precipitation ceases, then the 
 quantity of chlorine contained in the solution was exactly 
 one-tenth of 25.8, or 2.58 grains. 
 
 This method may be employed, if thought desirable, in 
 
 Nitrate of silver consists of 
 
 Per cent. 
 
 1 Nitrogen, 14. j ( 8.23 
 
 28.24 
 
 t i iMirogen, i*. \ 
 " \ or \ 6 Oxygen, 48. [ 
 UG. J ( , Silve ,. 108 . ) 
 
 Nitric acid. 
 
 Oxide of silver, 116.3 i 1 Silver, ' 108.5 I 63.63 
 
 170. 170. 100. 
 
62 ANALYSIS BY MEASURE ORES OF IRON. 
 
 estimating the quantity of chlorine in the watery solution 
 of a soil, or in any other solution, instead of the more 
 tedious one of collecting and weighing as described in 32. 
 
 II. ESTIMATION OF THE OXIDES OP IRON BY MEASURE. 
 
 62. The oxides of iron, and especially the protoxide of 
 iron, may be very conveniently estimated by measure, 
 
 a. The first step is to prepare a standard solution of 
 pcr-manganate of potash. For this purpose a portion of 
 the per-manganate is dissolved in water in a stoppered 
 bottle, is allowed to settle till quite clear, and is then de- 
 canted carefully, or is at once filtered through asbestos 
 into another bottle which is kept well closed. The solu- 
 tion is of a beautiful violet colour. This solution has the 
 property of imparting oxygen to the protoxide of iron, 
 converting it into the peroxide, and at the same time be- 
 coming itself colourless. By adding a solution of known 
 strength, therefore, to one containing protoxide of iron 
 very carefully, and with constant stirring as long as the 
 colour disappears, the quantity of the protoxide can br 
 calculated. 
 
 63. The next step, therefore, is to ascertain the strength 
 of the solution of per-manganate of potash. For this pur- 
 pose 10 grains of fine pianoforte wire are dissolved, by the 
 aid of heat, in pure muriatic acid slightly diluted, then 
 boiled, and distilled water added to raise the bulk of the 
 solution to 100 measures of our graduated vessel. Every 
 10 measures now contain 1 grain of iron equal to 1.285 
 grains of protoxide, or 1.428 of peroxide of iron. 
 
 To 10 measures of this solution, containing one grain 
 
ANALYSIS Br MEASURE ORES OP IBON. 63 
 
 of iron (or a larger quantity may be taken), add the solu- 
 tion of the per-manganate till the mixture begins to 
 exhibit a pale red tint, which does not disappear on stir- 
 ring, and mark exactly how many measures of the per- 
 manganate have been employed. Suppose 20 measures 
 have been required, then we conclude that 20 measures 
 of the solution are capable of per-oxiding one grain of 
 iron in the state of protoxide, and therefore indicate the 
 presence of 1.285 grains of protoxide. 
 
 This testing should be repeated two or three times, that 
 the strength of the solution may be accurately ascertained ; 
 and it should again be repeated at intervals when, after a 
 time, it is again to be employed, as the dissolved per- 
 manganate gradually decomposes, and the solution conse- 
 quently becomes weaker. 
 
 64. To estimate the quantity of protoxide in a soil, by 
 this method, is now easy. To the solution of a weighed 
 quantity of the soil, prepared in an atmosphere of carbonic- 
 acid, as described in 51, and diluted with Avater, add that 
 of the per-manganate, till the faintest red tint is visible. 
 The number of measures required for this purpose the 
 strength of the per-manganate being known indicates 
 exactly the quantity of protoxide of iron which the solu- 
 tion contains. 
 
 65. To estimate the peroxide of iron in the solution i.s 
 nearly as easy. It involves, however, two operations. 
 
 . To the acid solution from the soil which may or 
 may not be prepared in an atmosphere of carbonic acid- 
 add a few small pieces of sheet zinc, cork the flask loosely, 
 and heat to boiling. The zinc dissolves, and the hydrogen 
 given off reduces the peroxide of iron in the solution to 
 
64 ANALYSIS BY MEASURE ORES OF IRON. 
 
 the state of protoxide. If the solution be quite colourless 
 when all the zinc is dissolved, or only of a pale green, the 
 de-oxidation is complete. If it is still brownish, a little 
 more zinc is added, and the solution again heated to boil- 
 ing. No zinc must be left undissolved. The whole of tin- 
 iron is now in the state of protoxide. 
 
 b. To this solution add that of the per-manganate as 
 before, till the pale red tint becomes visible. From the 
 measure employed, the whole quantity of iron in the soil 
 is easily calculated. And if from this whole quantity we 
 deduct that which is in the state of protoxide as already 
 found (64), we have the quantity which is present in 
 the state of peroxide. 
 
 In making these determinations, greater accuracy is 
 attained by taking a bulk of pure distilled water equal to 
 that of the mixed solutions employed, and ascertaining 
 by experiment how much of the per-manganate solution 
 is necessary to impart to the water a visible red tint. 
 This quantity must be deducted from that which was 
 added to the iron solution, as it was expended in colour- 
 ing the liquid, and in not per-oxidising the iron. 
 
 These methods are much more simple and expeditious 
 than those described in the preceding chapters (34 and 
 51), but they are susceptible of great accuracy. In the 
 analysis of a soil, however, we can only employ them 
 as auxiliary processes, and to test our other methods. 
 We cannot add the per-manganate to the acid solutions 
 from- which all the other constituents of the soil are to be 
 separated, and therefore, in making a somewhat full and 
 complete analysis of a soil, we must still separate and esti- 
 mate' the iron by the methods previously described. 
 
ANALYSIS BY MEASURE ORES OF IROK. 65 
 
 g III. ANALYSIS OF IRON ORES. 
 
 66. It is chiefly in the analysis of substances which 
 contain the oxides of iron only, or in which we desire to 
 estimate the quantities and proportions of the two oxides 
 of iron only, that this method becomes of immediate 
 practical value. 
 
 a. We prepare our standard solution of per-manganate, 
 or test it anew for the occasion. 
 
 b. We dissolve our iron ore say 100 grains in muri- 
 atic acid by the aid of heat ; dilute, filter, and divide 
 into two equal portions. 
 
 c. Into the one we pour the solution of per-manganate 
 till the visible lint appears, and from the measure used 
 we calculate the quantity of protoxide of iron. 
 
 d. Into the other, contained in a flask, we introduce a 
 few pieces of zinc, dissolve completely by the aid of heat 
 satisfying ourselves, by the disappearance of colour, that 
 the whole of the iron has been changed into protoxide. 
 We then add per-manganate of potash again, and deter- 
 mine the whole iron which the quantity of ore employed 
 (100 grains) contains. 
 
 The larger weight (from d) indicates the total per- 
 centage of iron which is contained in the ore ; the smaller 
 number (from c), the per-centage in the state of protoxide; 
 and the smaller, deducted from the larger, gives the per- 
 centage in the state of peroxide. 
 
 In iron ores the protoxide of iron very frequently exists 
 in the state of carbonate. It is so, for the most part, in 
 the clay iron ores, in the oolite ironstone beds, and in many 
 5 
 
66 ANALYSIS BY MEASURE ORES OF IRON. 
 
 others. In such ores, every 100 grains of iron in the state 
 of protoxide are equal to 126 grains of carbonate of iron.* 
 
 67. Where it is not desired to determine the propor- 
 tions of the other ingredients of a clay or other mixed 
 iron ore, the above method is easy, ready, and, in the 
 hands of a good and careful manipulator, very accurate. 
 It is sometimes desirable, however, for economical pur- 
 poses, to ascertain the proportions both of lime and of 
 clay which an iron ore contains, and even the proportion 
 of phosphoric acid. In such cases the ore must be dis- 
 solved in muriatic acid with the aid of heat, and the 
 solution treated in the same way as if it were the acid 
 solution yielded by a soil. And if the insoluble matter 
 of the iron ore is also to be analysed, it must be heated 
 with concentrated sulphuric acid, or fused with the mixed 
 carbonates of potash and soda, as if it were the insoluble 
 matter of a soil, and subsequently treated exactly in the 
 same way (41 to 56). 
 
 Such an examination of course involves both time and 
 labour. 
 
 * Thus, of pure metallic iron 
 
 100 grains are equal to 128.63 of protoxide of iron. 
 100 ... ... 142.79 of peroxide of iron. 
 
 100 ... ... 102.85 of carbonate of iron; and 
 
 100 ... of protoxide to 126.70 of carbonate of iron. 
 
CHAPTER VII. 
 
 GENERAL REMARKS ON THE ANALYSIS OF SOILS. 
 
 Tbc organic matter, what it practically suggests. Soluble saline matters ; quau tit T 
 of, in fertile soils. In what cases it is necessary minutely to examine them. 
 Examples of Indian soils. Soil from the plains of Attica. How saline mat- 
 ter is to be removed from a soil. Matters soluble in muriatic acid ; which of 
 them may be neglected. Insoluble matter not always necessary to be ana- 
 lysed. How to interpret the results of an analysis. 
 
 68. The Organic Matter. The estimation of the total 
 quantity of organic matter in a soil throws light on the 
 two practical questions hew much lime would it be safe 
 to add to it ? and in what condition ought we to add it ? 
 Where the proportion of organic matter is large, large 
 doses of lime may be applied, and it may be in the caustic 
 state. Where the proportion is small, only small doses of 
 caustic lime are usually admissible, though of unburned 
 lime, chalk, or rich calcareous marl, large applications may 
 be made. 
 
 Then, in regard to the organic acids, they are generally 
 the cause of what is called the sourness of a soil. This 
 sourness is remoyed by quicklime and by wood ashes, 
 so that the use of these is indicated when solutions of car- 
 bonate of soda extract much humic and ulmic acids from 
 the soil. Quicklime applied before rain soonest sweetens 
 
68 GENERAL REMARKS ON THE ANALYSIS OF SOILS. 
 
 the land, though chalk, or chalk marl, or shell sand, per- 
 form the same office somewhat more slowly. 
 
 69. The soluble saline matter in the soil is rarely verv 
 considerable in quantity, and in most cases it will be suf- 
 ficient to examine qiialitatively the watery solution of a 
 soil. Cases do occur, however especially in low flat plains 
 which lie near mountain ranges, or the soil of which is 
 rich in lime where much saline matter exists in the soil, 
 and is extracted from it by water. Such are some of the 
 soils in India, which, by washing, yield from 1 to 7 per 
 cent of saline matter. Thus in several Indian soils exa- 
 mined by the late Mr. Fleming of Barochan, there were 
 
 contained in 100 parts 
 
 1 2- :;- 4 J 3 
 
 Carbonate of lime, . . Ih 5 4.J 4 2 
 
 Carbonate of magnesia, . 3$ 2 1 
 
 Saline matter (chlorides, sulphates, 
 
 and nitrates,; . . . 1 1J 3J 3 7 
 
 No. 1 was near Gya in South Behar. Never lies fal- 
 low, is covered with water during part of the rainy season 
 produces from 30 to 50 bushels of wheat per acre. 
 
 No. 2. Same district. Not inundated by the rains 
 produces wheat, pease, cotton, or poppy in the dry, and 
 Indian corn and millet in the wet season. Sometimes 
 manured with wood ashes and cow-dung. 
 
 No. 3. From North Behar, Tirhoot. Deep loam, 
 yielding two crops yearly. Not flooded 25 to 30 bushels 
 of wheat per acre. 
 
 No. 4. Tirhoot. Light-coloured soil, not so produc- 
 tive as No. 3. Saline efflorescence in patches. 
 
 No. 5. Tirhoot. Still less productive ; nearly sterile 
 in places from saline efflorescence, except in the rainy 
 season, when it produces good crops of Indian corn. 
 
GENERAL REMARKS OX THE ANALYSIS OF SOILS. 69 
 
 From these examples we see that from 3 to 4 per cent 
 of saline matter may exist in a soil in certain circum- 
 stances, without rendering it unproductive. More than 
 this, however, few soils can contain, and vet continue 
 productive. Where such large quanties occur, the saline 
 matter ought to be washed out and carefully analysed. 
 A large proportion, where the soil continues fruitful, will 
 usually prove to consist of the nitrates of potash, soda or 
 lime. In this country as little as 1 per cent of common 
 salt has been found to prevent crops from growing healthily 
 upon them. The fertile alluvium of the delta of Egypt, 
 contains, in many places, upwards of one per cent of 
 soluble saline matter, but it is not all common salt. 
 
 The nature of the saline effloresence which forms upon 
 a soil is always more or less influenced by the nature 
 of the adjoining rocks. Around Durham, where we 
 are in the neighborhood of magnesian limestone rocks, 
 sulphate of magnesia is the prevailing incrustation which 
 forms on the soil in hot dry seasons. In some red sand- 
 stone countries, gypsum is a frequent incrustation, and 
 common salt in others ; while at the foot of granitic and 
 similar rocks, alkaline salts of various kinds chiefly 
 appear. 
 
 The practical cure for soils made barren by excess of 
 saline matter, is the establishment of a thorough drainage. 
 In showery countries these drains will carry away the 
 excess of saline matter which the rains will dissolve and 
 convey to them. In arid countries, the drain must be 
 aided either by artificial irrigation or by yearly natural 
 inundations, such as those to which the salty soils of 
 Tirhoot owe their half-yearly fertility. 
 
70 GKNKR.VL REMARKS OX THE AXALTCId OK SOILS. 
 
 70. I once received a sample of soil from the plains of 
 Atlica, with the information that wheat sown at the close 
 of the rainy season ripened and yielded well, but that 
 saline matter rose to the surface in such abundance as 
 gradually to destroy, or entirely burn up the more ten- 
 der grass ; and I was asked to say how grass might be 
 made to grow. 
 
 The soil, on analysis, was found to consist of 
 
 Carbonate of lime, ..... 33.0H 
 
 Carbonate of Magnesia, . ... . 0.7."> 
 
 Sulphate of lime, (gypsum,) . . . 0.18 
 
 Phosphate of lime, ..... 0,03.; 
 
 Oxide of iron, . ' . . . 2.91 
 
 Alumina soluble in muriatic acid, . . 2.:;r> 
 
 Organic matter, ..... 5.75 
 
 Salts soluble in water (common salt and sulphate ) A ., 
 of soda,) ..... 5 " 
 
 Insoluble silicious matter (not further analysed,) 50.33 
 
 100.563 
 
 This soil was peculiarly rich in lime, but did not over- 
 abound in saline matter. It contained all the elements 
 of a fertile soil, and its history evidently showed that it 
 was the saline matter rising with the water from beneath, 
 and left on the surface as the sun of the dry season licked 
 the water up, which was the cause of the agricultural evil. 
 The remedy was easy. " Open drains, that the water 
 which comes from the mountains in the rainy season may 
 carry the saline matter to the sea, instead of lodging in 
 and soaking the soil of the plains, ready to parch the 
 sprouting grass as the dry season progresses." And a 
 similar remedy will cure all similar cases. 
 
 71. Matters soluble in muriatic acid. From open, 
 oamy, or sandy soils, it will seldom happen that, after 
 
OKSERAL RKMARK4 ON THE ANALYSIS OF SOILS. 71 
 
 boiling in water, any appreciable quantity of potash or 
 soda will be extracted by muriatic acid. The analysis of 
 the acid solution of these soils may therefore be simpli- 
 fied by neglecting the estimation of the trace of alkaline 
 matter they may contain. 
 
 Stiff clays, however, are more rich in potash and soda, 
 in states of combination which render them insoluble in 
 water. In the analysis of clay soils, therefore, it will 
 always be proper to examine qualitatively a portion of 
 the acid solution, and thus to ascertain if an appreciable 
 quantity of alkali be present, before deciding upon the 
 exact steps to be taken in conducting the quantitative 
 analysis. 
 
 72. As to the matter insohtble in muriatic acid, an 
 ultimate analysis of it is only necessary in very parti- 
 cular instances. 
 
 . That which water takes up represents the actually 
 soluble matter of the soil which is ready at the time to 
 minister to the growth of plants. 
 
 b. That which is taken up by muriatic acid contains 
 those constituents of the soil which are likely to become 
 available to the plant next in order, as the carbonic and 
 other acids formed naturally in the soil continue to act 
 upon them. 
 
 c. That which the muriatic acid leaves undissolved may 
 contain substances vahiable to plants, but they are in 
 such a state of combination as only after a long time or 
 after some energetic chemical treatment, such as the 
 application of quicklime or sulphuric acid to become 
 available to their use. 
 
 In most cases, therefore, the immediately and practi- 
 
72 GENERAL REMARKS ON THE ANALYSIS Of SOILS. 
 
 cally valuable constituents of the soil may be judged of 
 by a quantitative examination of the soluble parts of the 
 soil only. 
 
 73. Lastly, I would remark that it is only by bringing- 
 a very considerable familiarity with practical agriculture to 
 bear upon the results of the chemical analysis of a soil, 
 that correct and practically useful deductions can be drawn 
 from them. In every case, therefore, before finally inter- 
 preting these results, we ought to ascertain 
 
 first, The condition of the land as to drainage. 
 
 Second, The kind of cropping and manuring to which 
 it has been subjected during the preceeding ten years. 
 
 Third, The peculiarities of climate, if any, to which 
 the soil or locality is exposed. 
 
 With the aid of these practical elements, if he under- 
 stand their practical bearing, good economical suggestions 
 may often be drawn by the agricultural chemist from an 
 accurate determination of the chemical composition of a 
 soil. 
 
CHAPTER VIII. 
 
 ANALYSIS OF LIMESTONES AND MARLS. 
 
 Kstiination of the carbonate of liine, and of the carbonate of magnesia. Com- 
 plete analysis of a limestone. Analysis of calcareous mar'.s. 
 
 I. ANALYSIS OF LIMKSTONES. 
 
 74. Estimation of the carbonate of lime. In many 
 eases it is sufficient for all economical purposes to deter- 
 mine the proportion of carbonate of lime which a limestone 
 contains. This is very easily done. 
 
 a. The limestone is dissolved in dilute muriatic acid, 
 hastened, if necessary, by a gentle heat. The insoluble 
 matter is collected on a filter, washed, heated to redness, 
 and weighed. The weight indicates the proportion of 
 insoluble earthy matter which the limestone contains, and 
 thus at once shows whether it is worthy of any further 
 examination. If so 
 
 b. To the filtered solution caustic ammonia is added, 
 and the precipitate collected and weighed as in a. This 
 gives the proportion of soluble alumina, oxide of iron, and 
 phosphoric acid, if any, which the limestone contains. 
 
 c. To the filtered ammoniacal solution oxalate of am- 
 monia is added ; the oxalate of lime collected, washed, 
 
74 ANALTSM OIT LIMESTONES A>*n MARLS. 
 
 burned, and weighed, as directed as in 33. The weight 
 represents that of the carbonate of lime contained in tin- 
 portion of limestone employed. 
 
 If the three weights obtained from these three opera- 
 tions, when added together, make up very nearly that of 
 the limestone employed, it may be inferred that little else 
 is contained in it, and the quality of the limestone judged 
 of accordingly. 
 
 75. Estimation of the carbonate of magnesia. But the 
 deficiency may be considerable, or the limestone may be 
 suspected to contain magnesia, the proportion of which it 
 is desirable to ascertain. In this case 
 
 To the solution filtered from the oxalate of lime we add 
 phosphate of soda as long as a precipitate falls, and collect 
 it as described in 37 b. Of the phosphate of magnesia 
 obtained, every hundred grains represent seventy-nine 
 grains of carbonate of magnesia in the limstone.* 
 
 76. Complete analysis of a limestone. For most lime- 
 stones the above examination is sufficient. But it is some- 
 times desirable to ascertain the quantity of alkaline mat- 
 ter it contains the phosphoric acid, if any the soluble 
 silica and for hydraulic purposes, the composition of the 
 matters insoluble in muriatic acid. With a view to such 
 a complete analysis the following are the steps : 
 
 a. Dissolve in dilute muriatic, acid, and collect the 
 insoluble matter. 
 
 * The phosphate of magnesia obtained- l>y this process, and the 
 carbonate, are composed respectively of 
 
 Carbonate. Per cent. Phosphate. Per cent 
 
 Magnesia, 20 .|7.fi2 Magnesia, -10 o5.84 
 
 Carbonic acid, 2 '2 .~>2.3.s Phosphoric acid, 71.4 C4.0<: 
 
 42 100 111.4 100 
 
ANALYSIS OF LIMESTONES AND MARLS. 75 
 
 b. Boil this insoluble matter in a solution of carbonate 
 of soda, collect on a filter, wash well, and heat to redness. 
 
 c. Treat this insoluble matter as if it were the insoluble- 
 matter of a soil. Heat it with sulphuric acid, or fuse it 
 with the mixed carbonates of potash and soda, and pro- 
 ceed to separate its constituents as described in 53 to 57. 
 
 d. Add muriatic acid to the soda solution b till it is 
 distinctly acid. Evaporate to dryness on the water-bath, 
 stirring towards the end of the process. Drench with 
 muriatic acid, treat with water, and filter. What remains 
 on the filter is silica, soluble in carbonate of soda. It is 
 washed, dried, heated to redness, and weighed. 
 
 e. The muriatic acid solution a is evaporated to dry- 
 ness and treated as in d. What remains on the filter in 
 this case is silica, soluble in muriatic acid. 
 
 f. The acid solution from e is treated with ammonia in 
 excess, and the precipitate, if any, is collected and 
 weighed. It contains alumina, oxide of iron, and phos- 
 phoric acid, if present, with perhaps a little lime and 
 magnesia. 
 
 g. If the precipitate, while still moist, dissolves wholly 
 in acetic acid, it contains no appreciable quantity of 
 phosphoric acid. The iron and alumina are therefore 
 separated by caustic potash in the usual way (34, 35). 
 
 h. If it is not wholly dissolved by acetic acid, or if, for 
 other reasons, a further research is thought necessary, a 
 separate portion of 600 grains of the limestone is dissolved 
 in muriatic acid, and the solution treated with ammonia in 
 excess. A larger precipitate is thus obtained, containing 
 a more appreciable quantity of phosphoric acid. This 
 precipitate is dissolved in nitric acid, and the phosphoric 
 
76 ANALYSIS OF LIMESTONES AND MAKLS. 
 
 acid separated by molybdate of ammonia, and estimated 
 as described in 28 and 40. Every 100 of phosphoric 
 acid obtained indicate the presence of 217.6 grains of 
 phosphate of lime in the limestone.* 
 
 i. The ammoniacal solution from f is treated first with 
 oxalate of ammonia to separate the lime, and then with 
 phosphate of soda to separate the magnesia, as already 
 described (37 5). 
 
 k. Potash and soda will sometimes be found in a lime- 
 stone ; but it will very rarely, indeed, be advisable to 
 seek for it in the residual solution i. By reducing a por- 
 tion of the limestone to exceedingly fine powder, and boil- 
 ing with distilled water, any common salt, or other soluble 
 saline matter which it may contain, will be extracted. By 
 evaporating the solution to dryness, the weight of this 
 may be estimated, and it may, if necessary, be afterwards 
 qualitatively examined, like the watery extract of a soil 
 (19 to 29). 
 
 II. ANALYSIS OF MARLS. 
 
 77. By a marl, or a calcareous marl, is generally 
 understood a clay or sand, which contains intermixed with 
 it a variable proportion of the carbonates of lime and 
 magnesia, and often a trace of phosphate of lime. The 
 mode of examining them is nearly the same as in the case 
 of an impure limestone. 
 
 * The phosphate of lime consists of 
 
 Per cent. 
 
 Lime, . . . 84.0 54.05 
 
 Phosphoric acid, . . 71.4 45.95 
 
 1/55.4 100. 
 
ANALYSIS OF LIMESTONES AND MARLS. 
 
 77 
 
 a. If, on adding muriatic acid, bubbles of gas are given 
 off, it may be inferred that carbonate of lime is present. 
 A weighed quantity is therefore treated with dilute mu- 
 riatic acid, the insoluble matter collected on the filter, 
 washed, heated to redness, and weighed. 
 
 b. To the acid solution ammonia is added, the precipi- 
 tate collected, washed, and subsequently examined for 
 phosphoric acid, if thought necessary, as in the case of 
 a limestone (767i). 
 
 c. From the ammoniacal solution the lime is thrown 
 down by oxalate of ammonia, and the magnesia by phos- 
 phate of soda, as already described. 
 
 d. If it is thought necessary to examine further the 
 matter insoluble in muriatic acid (a), it is treated in the 
 same way as if it were the insoluble matter of a soil 
 (3 to 57). 
 
CHAPTER IX. 
 
 ANALYSIS OF SALINE MANURES. 
 
 Saline manures. Common salt ; how it is adulterated and examined. Nitrate of 
 soda. Numerous adulterations ; how to detect them. Sulphate of soda ; 
 how to test it. Sulphate of lime, or gypsum. Sulphate of ammonia and 
 sal-ammoniac; mode of examining them. 
 
 78. THE use of portable manures, either natural or 
 artificial, has now become so very extended that a simple 
 popular method of testing them has become very necessary 
 both to the dealer and to the purchaser. Such simple 
 means I shall endeavor to supply in the present chapter. 
 
 The portable manures at present in use consist chiefly 
 of unmixed saline manures, of preparations of bones, and 
 of natural and artificial guanos. I shall consider each of 
 these classes in their order. 
 
 The saline manures which are applied to the land in 
 this country in an unmixed state are common salt, nitrate 
 of soda, sulphate of soda, gypsum, and the sulphate and 
 muriate of ammonia (sal-ammoniac.) 
 
 I. EXAMINATION OF COMMON SALT. 
 
 79. Common salt is too low in price to admit of being 
 profitably adulterated with any other saline substance ex- 
 
ANALYSIS OF SALINE MANURES. 75) 
 
 cept gypsum. But it may be mixed with sand, or it may 
 contain, as natural impurities, traces of chloride of calcium 
 or chloride of magnesium. To detect and estimate these 
 
 a. It should be put into a hot oven in a covered vessel, 
 or dried in some other way, at a heat of 300 Fahr., and 
 the loss of weight noted. This determines the proportion of 
 water it contains, which in moist samples is sometimes 
 considerable. 
 
 b. When thus dried, it should be treated with water, 
 and the insoluble matter collected, dried, weighed, and 
 examined. This shows how much earthy or other in- 
 soluble impurity it contains, and a slight examination will 
 often be sufficient to show what the impurity consists 
 of. Most of the gypsum, if any is present, will remain 
 in this insoluble matter. 
 
 c. Into a pint of boiling water put an unweighed 
 (quantity of the salt ; stir and add salt till the water i.s 
 
 fully saturated, and a portion remains undissolved. Let 
 it stand to settle, and then upon a weighed pound of the 
 dried salt, reduced to fine powder, pour the clear saturated 
 solution ; stir and shake well. Set aside to become clear, 
 and then pour the solution entirely off again. Dry the 
 salt, and weigh it. The loss shows the proportion of the 
 chlorides of calcium and magnesium which the salt con- 
 tains. This operation is founded on the fact that, after 
 water has been fully saturated with common salt, it is still 
 capable of dissolving these two chlorides, and therefore of 
 extracting them from the common salt with which they 
 may be mixed. 
 
 d. If a more minute chemical examination be wished 
 for, the operator will estimate 
 
80 ANALYSIS OF SALINE MANURES. 
 
 The lime by oxalate of ammonia (33). Every 100 
 grains of the carbonate of lime obtained represent 111 
 grains of chloride of calcium, or 136 grains of dry sulphate 
 of lime, or 172 grains of common gypsum in the salt. 
 
 The magnesia by phosphate of soda (37 6). Every 
 100 of the phosphate of magnesia obtained represent 85.3 
 grains of chloride of magnesium in the salt. 
 
 The sulphuric acid by chloride of barium (31). If the 
 same solution be employed for this purpose which has 
 been already used for separating the lime and magnesia, 
 it must be made distinctly sour with pure muriatic acid 
 before the chloride of barium is added. 
 
 Every 1 00 grains of sulphuric acid represent 1 70 grains 
 of anhydrous or dried gypsum in the salt. From the 
 weight of the lime, as estimated by the previous operation, 
 as much is to be taken as is required to unite with this 
 sulphuric acid to form gypsum. The remainder only of 
 the lime is to be reckoned as chloride of calcium.* 
 
 II. EXAMINATION OF NITRATE OF SODA. 
 
 . Nitrate of soda is often very moist. A weighed 
 quantity, therefore, should be thoroughly dried in an 
 oven or otherwise at about 300 Fahr., and the loss of 
 weight ascertained. This gives the proportion of water 
 it contains. 
 
 b. The dry salt may now be treated with water, and 
 
 * Chloride of calcium consists of 
 
 Calcium, ....... 20. 
 
 Chlorine, ....... 35.46 
 
 55.46 
 
ANALVSIS OF SALINE MAMJKKS 
 
 the insoluble matter, if any, collected, dried, and weighed. 
 This gives the proportion of earthy or other insoluble 
 matter which it may naturally contain, or with which it 
 may have been artificially adulterated. If the earthy 
 matter effervesces when acid is added, it consists in part 
 at least of chalk. 
 
 c. Of soluble salts the nitrate may contain, naturallv, 
 sulphate of soda, sulphate of magnesia, sulphate of lime, 
 (gypsum), and common salt. These impurities often 
 occur mixed with it in the native nitre-beds, but they 
 may be added also by way of adulteration. For the 
 latter purpose, crystallised carbonate of soda, which is 
 cheaper than the nitrate, may also be added. 
 
 d. When common salt is thrown upon red-hot coals, it 
 sparkles or flies about with a crackling noise (decrepitates). 
 Nitrate of soda, and the other salts above named, do not 
 behave in this way. If a decrepitation take place, there- 
 fore, when the nitrate of soda is thrown upon red coals, 
 the presence of common salt may be inferred. Its quan- 
 tity, at least, whether it is great or small, may also be 
 guessed at by the quantity of this decrepitation. 
 
 To estimate the exact amount of common salt in the 
 nitrate, however, a weighed quantity must be dissolved 
 in distilled water, and precipitated by nitrate of silver, as 
 described in 32. 
 
 <?. If the addition of nifrie or muriatic acid, or of vine- 
 gar, to a saturated solution of the nitrate, causes bubbles 
 of carbonic acid gas to appear, then it is adulterated with 
 carbonate of soda. The simplest way of determining how 
 much carbonate is present, is to put a solution of a 
 
 weighed quantity of the nitrate into a stoppered bottle 
 6 
 
82 ANALYSIS OF SALINE MANURES. 
 
 to add clear lime water as long as a precipitate of car- 
 bonate of lime falls ; to cork well up, shake, and allow 
 the white powder to subside. The clear solution is then to 
 be poured off, the bottle filled with boiled distilled water, 
 and allowed again to subside. The clear liquor is again 
 poured off, and the precipitate collected quickly on a filter, 
 dried, heated to dull redness, and weighed. Every 100 
 grains of this carbonate of lime represent 133 grains of 
 dry, or 358 grains of crystallised carbonate of soda.* 
 
 /. To ascertain if it is adulterated with sulphate of 
 soda or sulphate of magnesia, a hot solution of the nitrate 
 is to be made slightly acid with nitric acid, to decompose 
 any carbonate which may be present. If, on the addition 
 of nitrate of baryta, no milkiness appears, it contains 
 no sulphate ; but if it become milky, sulphuric acid is 
 present. 
 
 If, on the addition of lime-water, a white gelatinous 
 precipitate appear, it contains sulphate of magnesia, if 
 not sulphate of soda; and perhaps a little sulphate of 
 lime may also be present. 
 
 To determine the quantities of these ingredients;, a 
 weighed portion of the salt is dissolved, and the solution 
 divided into two equal parts. 
 
 From the first, sulphuric acid is thrown down by nitrate 
 
 of baryta (31). 
 
 > 
 
 * Common crystallised carbonate of soda contain- IM ! -s th;<u <'. 
 per cent of water, its composition being 
 
 Soda, L'l.s 
 
 Carbonic acid, .... l."..t 
 Water, . . . . . . ( ,:'.s 
 
 JOO 
 See note, p. >'' 
 
ANALYSIS OF SALINE MANURES. 33 
 
 From the second, lime, if present, by oxalate of am- 
 monia (33), and afterwards magnesia by phosphate of 
 soda (375). 
 
 III. EXAMINATION OF CARBONATE OF SODA. 
 
 80. Crystallised carbonate of soda is rarely adulterated 
 in the English market. It may be more or less purely 
 prepared, however, containing- traces of common salt and 
 sulphate of soda. If a crystal, when heated to perfect 
 dryness in an oven, loses 62 per cent of water, it may be 
 considered as nearly pure. 
 
 It is the dry powdery sodas of the shops which arc 
 most subject to adulteration. Dry sulphate of soda and 
 finely-powdered common salt are the mixtures it usually 
 contains. To detect them, a hot concentrated solution of 
 the soda is treated with nitric acid, till all escape of car- 
 bonic acid gas ceases. If much sulphate of soda be pre- 
 sent, a strong solution of chloride of calcium (prepared 
 by saturating muriatic acid with chalk) will make it milky, 
 or even thick with precipitated sulphate of lime (gypsum) . 
 The presence of common salt may be detected by the 
 taste of the dry carbonate, and by its crackling in the 
 tire. 
 
 The proportion of sulphate may be determined by ni- 
 trate of baryta (31). Every 100 grains of sulphuric 
 acid indicate 178 grains of diy, or 403 grains of crys- 
 tallised sulphate of soda. 
 
 The proportion of common salt is estimated by means 
 of nitrate of silver (32). 
 
ANALYSIS OF SALINE MAM RK- 
 
 IV. K.YAMI.XATIOX OF SI Ll'HATE OF bolt A 
 
 81. Crystallised sulphate of soda is rarely adulterated 
 because of its cheapness. It consists of 
 
 Per cent. 
 
 Soda :;i.-.! ]y.p>.") 
 
 Sulphuric ad<l. . . -10 1'l.vj 
 
 Water, .... :MI .,:>.:; 
 
 161. 'J 100. 
 
 so that, if a crystal, when thoroughly dried, loses about 
 />6 per cent of water, it maybe looked upon as practically 
 pure. 
 
 The dry powdery sulphate of the shops usually contain- 
 common salt (which is still cheaper), and some times ;_:\ p 
 sum. By dissolving in the smallest possible quantity <>f 
 water, the greater part of the gypsum will remain behind 
 in the state of a white powder, and may be collected. If 
 much common salt be present, it miy be detected by th' 
 taste. Its exact quantity can only be determined by rncan^ 
 of nitrate of silver (32). 
 
 V. EXAMINATION OF (.\l'-\ M . 
 
 82. Gypsum is sold either in the unburned or burned 
 state. The uuburnecl, crushed or ground gypsum is 
 rarely adulterated. By washing with water, it is easy to 
 ascertain if there are any earthy uncrystalline substances 
 among it. When heated to redness, thi> crystallised gyp- 
 sum loses 21 per cent of water ; and by this test its free- 
 dom from admixture may also be judged of. 
 
ANALYSIS .OV SALINE MANURES. 85 
 
 (rypsum in the unburned and burned states consists 
 of 
 
 Unburned or Burned 
 
 crystallised. or dry. 
 
 Lime, -Vj}fc*i.*, ,-J'M.i' 28 28 
 
 Sulphuric; acid, .,r-v, - J () l(l 
 
 Water, ' .' .''"'.'' 1* 
 
 8<i CS 
 
 Burned gypsum crushes easily,. and forms a fine white 
 powder. The only adulterations its price admits of art- 
 slaked lime, chalk and pipe-clay. If it give off no bubbles 
 of gas when first moistened, and then treated with an acid 
 it contains no chalk. If, when mixed and shaken up with 
 water, it give a clear solution which is not rendered milky 
 by blowing air through it from the lungs for a length of 
 time, it contains no quicklime. And if, when heated with 
 sulphuric acid, and then treated with water, it give a so- 
 lution from which' ammonia throws down no alumina, it 
 is not adulterated with clay (see 54) 
 
 .'j ."lifljaosjiffci-.* i"i hlyo* t -'Ai/!muuuj I* <t.& ..<*. 
 
 VI. EXAMINATION OP SAL-AMMONIAC AND StJLtHATE OF 
 AMMONIA. 
 
 83. These salts, when pure, are colourless dissolve 
 easily and without residue in cold water when mixed 
 with slaked lime, give off a strong smell of ammonia 
 and when heated over the lamp, entirely volatilise. They 
 should therefore 
 
 First, be mixed with slaked lime, to ascertain if they 
 really contain ammonia. 
 
 Second, be treated with water, and the proportion of 
 insoluble matter, if any, estimated. 
 
 Third, heated to incipient redness, till all vapours 
 
86 ANALYSIS OF SALINE MANURES. 
 
 and smell cease, and the residue, if any, then weighed 
 and examined. 
 
 If the salt begin to rise in vapours when heated to 300 
 or 350 Fahr., and gradually disappear without melting, 
 it is sal-ammoniac ; but if it melt below 300 Fahr. (284), 
 and do not begin to rise in vapour below 536 Fahr., it is 
 sulphate of ammonia. 
 
 By these tests the two salts of ammonia can readily be 
 distinguished. If anything remains unsiiblimed on heat- 
 ing to dull redness, it will be sulphate of soda, common 
 salt, or gypsum. The nature of this residue can readily 
 be recognised by the rules already given. 
 
 The two salts of ammonia consist respectively of 
 
 Sal- Ammoniac. Percent. Sulphate of Ammonia. Percent. 
 
 Ammonia, 17.0 or 31.8 Ammonia, 17 or 25.7G 
 
 Muriatic acid, 3G.4 " 68.2 Sulphuric acid, 40 " 60.61 
 
 Water, . n " 13.C3 
 
 >3.l 100 
 
 C(> 100 
 
 So that sal-ammoniac, weight for weight, contains one-fifth 
 more ammonia than the sulphate of ammonia does. 
 
CHAPTER X. 
 
 EXAMINATION OF BONE MANURES, GUANOS AND 
 OIL-CAKES. 
 
 Crushed bones. Dissolved bones ; how to test tbem. Superphosphate of lime ; 
 different varieties of, how examined. Natural guanos ; mode of examining 
 Artificial guanos and mixed manures ; analysis of. Examination of oil-cake* 
 used as manures. 
 
 I. EXAINATION OP BONES, CRUSHED AND DISSOLVED. 
 
 P-4. Crushed bones, or bone dust, are occasionally 
 adulterated with earthy admixtures. The presence of 
 such adulterations may be detected 
 
 First, By mixing with water, when the lighter bone 
 May be washed off, leaving the heavier sand and earthy 
 matter at the bottom. 
 
 Second, By burning a weighed portion in the air at a 
 red heat, and weighing the ash or residue. If the ash 
 exceed half the weight of the bones, earthy or other matter 
 has been added to them. 
 
 85. Dissolved bones, By mixing crushed bones with 
 one-third to one-half their weight of commercial sulphuric 
 acid, they are reduced after a time into a pulpy state. 
 When dried ly admixture with more lone dust, and laid 
 
.'P. EXAMINATION OF BONE MANURES AND GUANOS. 
 
 in a heap for some time, they form an excellent prepara- 
 tion, which is sold under the name of dissolved bones. 
 
 The above mode of preparation gives pure dissolved 
 bones ; but when manufactured for sale it is usual to dry 
 the wet mass by mixing it with gypsum, with saw-dust, 
 charcoal powder, dried peat, ground chalk even, and 
 many other comparatively worthless, if not actually inju- 
 rious, substances. 
 
 Dissolved bones ought to be sour to the taste, and water 
 mixed with and allowed to stand upon them should become 
 distinctly sour. When stirred with water, and the lighter 
 parts poured off, they ought to leave no sand or other heavy 
 earthy matter behind. The presence of saw dust, charcoal, 
 peat, and other vegetable matters, may be ascertained by 
 examining the lighter portions which are washed off. 
 
 86. For a more minute examination the following steps 
 may be taken : 
 
 a. Heat a weighed portion to 350 Falir. as long as it 
 loses weight. The loss is water. Heat now to redness 
 in the air till everything combustible is burned away, and 
 weigh again. The second loss consists of vegetable mat- 
 ter, if any is present, of the gelatine of the bones, and of 
 the excess of sulphuric acid. 
 
 b. Digest the burned residue in dilute muriatic acid to 
 dissolve the phosphates ; filter, wash, heat to redness, and 
 weigh the undissolved portion. It consists of gypsum and 
 other earthy impurities which the manure may contain. 
 
 c. Boil this insoluble matter in a solution of carbonate 
 of soda, collect on the filter again, and treat witli dilute 
 muriatic acid. If it entirely dissolves with effen '< <}}>>. 
 the insoluble matter from I has been tfvp>um unlv. The 
 
EXAMINATION OS BONE MANURES AND GUANOS. 39 
 
 boiling with carbonate of soda has converted it into car- 
 bonate of lime. If it does not dissolve in dilute muriatic 
 acid with effervesence, it consists of clay or other earthy 
 impurities which have been added to the manure. 
 
 d. To the acid solution from b add ammonia in excess. 
 Collect the precipitate, wash, dry, heat to redness, and 
 weigh. It consists of phosphate of lime,, with a little 
 phosphate of magnesia. Every 100 grains of this precip- 
 itate indicate the presence of aboiit.200 grains of bones 
 or bone-dust in the manure. This is the really valuable 
 ingredient in the manure ; and if it has been prepared 
 from bones at all, its worth may be calculated from the 
 quantity of bones indicated by the weight of the mixed 
 phosphates thus obtained. 
 
 87. The weight pf sulphuric acid added to the bones 
 by the manufacturer is not usually quite enough entirely 
 to decompose and render them soluble. But as the imme- 
 diate efficacy of prepared bones as a manure is very much 
 determined by the proportion of them which is so ren- 
 dered soluble, it is desirable to ascertain how far this 
 effect has been produced in the sample we are examining. 
 For this purpose 
 
 a. A weighed quantity is to be digested with the aid of 
 heat in a large bulk of water say 500 grains in a pint 
 of water frequently stirred, allowed to cool, <fec., and 
 finally filtered. 
 
 b. Ammonia is added in excess, the phosphate of lime 
 which is thrown down collected on a filter, washed, heated 
 to redness, and weighed. Every 100 grains indicate 200 
 of bones contained in the manure in a soluble state. ; '. : 
 
 <, To the filtered solution, ammoniacal sulphate of 
 
90 EXAMINATION OF BONK MANURES AND GUANOS. 
 
 magnesia is added as long as a precipitate falls (40c). 
 The precipitate, after twelve hours, is collected, dried, 
 heated to redness, and weighed. Every 100 grains of 
 the phosphate of magnesia obtained indicate the presence of 
 about 300 grains of bones in the manure in a soluble state. 
 The two weights of bones indicated by b and < are 
 added together, and the sum subtracted from that of the 
 whole weight of bones in the manure (87rf). The re- 
 mainder is the proportion of bone-dust in the manure which 
 is not in a soluble or immediately available state. 
 
 II. EXAMINATION OF SUPER-PHOSPHATE OF LIMK. 
 
 88. By super-phosphate of lime was meant at first 
 simply burned bones rendered soluble by means of sul- 
 phuric acid. This is easily examined. 
 
 a. A weighed portion is boiled in water for some time, 
 thrown on a filter, and washed. The solution contains 
 the soluble phosphates, which may be separated and esti- 
 mated, as in 86, d. 
 
 b. The insoluble matter on the filter is now boiled for 
 tin hour in a solution of carbonate of soda. The sulphate 
 of lime, by this process, is changed into carbonate of lime. 
 This is collected on a filter, washed, heated to redness, 
 and weighed. If pure, or unmixed with sulphate and 
 phosphate, this carbonate of lime will dissolve with effer- 
 vescence in dilute muriatic acid, and will not be precipitated 
 again by caustic ammonia in excess. Every 100 grains 
 are equal to, or contain the same quantity of lime as, 
 about 200 grains of ordinary bone dust,* or as 1 15 grains 
 of bone-ash. 
 
 * Or M alwut 170 grains of cletin, perfectly dry bones. 
 
EXAMINATION OF BONE MANURES AND GUANOS. 91 
 
 c. But if ammonia throws down a precipitate from the 
 solution of this carbonate in muriatic acid, it is phosphate 
 of lime, which remained insoluble in water a. It is to be 
 thrown down and collected, as in 86 d. 
 
 The soluble phosphate from a, added to the insoluble 
 phosphate from b, gives the whole quantity of phosphate 
 contained in the portion of manure examined. 
 
 89. But by way of improving this variety of super- 
 phosphate, bones themselves instead of bone-ash were after- 
 wards dissolved by means of sulphuric acid, and this 
 preparation was and is still sold by many under the name 
 of super-phosphate. The mode of examining this variety 
 lias been explained in the preceding section. 
 
 90. 3S"ow, however, the commercial super-phosphates 
 are manufactured by dissolving bones or bone-ash with a 
 variable proportion of powdered mineral phosphate of 
 lime, and mixing the whole intimately together. This 
 variety is not so valuable as either of the others above 
 mentioned, chiefly because the mineral phosphates em- 
 ployed contain always a large quantity of carbonate of 
 lime and of insoluble earthy matter. Upon this lime much 
 of the sulphuric acid is wasted in converting it into gyp- 
 sum, and the manure is contaminated with an uncertain 
 proportion of comparatively useless ingredients. The 
 samples brought into the market, however, differ very 
 much in value, and it may often be desirable to test and 
 compare them. 
 
 A tolerable approximation to the value of a sample may 
 be made by boiling a weighed quantity, as described 
 under 88, and calculating the proportion of dry bone-earth 
 the chief valuable ingredient which the manure contains. 
 
92 JvXAMINATIOX OF r.oXK MA NITRES AND OTAN' 
 
 For a more detailed examination, the method given for 
 examining dissolved bones (86) may be employed. 
 
 III. EXAMINATION OK NATURAL 
 
 91. Of simple tests which can readily be applied to a 
 natural guano, the three following are within the reach <>t' 
 every one : 
 
 a. Dry a weighed quantity at 212 Fahr. The loss of 
 weight is water, and shows whether it has been unduly 
 moist. This operation can be performed by placing a 
 thin basin upon a pan of boiling water, spreading the 
 guano on the bottom of the basin, and covering it with a 
 paper till it has become dry. 
 
 b. Mix the guano with slaked lime. If a Mmnu; smell 
 of ammonia is given off, it may be presume d t<> he rich 
 in this valuable ingredient. 
 
 c. Mix a quantity of the guano with water, and stir 
 well ; allow it to settle for a few minutes, and pour oil' 
 the lighter matters which still float on the water. Repeat 
 this till all the lighter part is washed away. It will now 
 be seen if the guano is mixed with much sand or gravel. 
 And if a weighed portion of guano has been tlms washed 
 the sandy matter which remains can be dried and weighed, 
 and its proportion determined. 
 
 92. A more thorough analysis of the gufin< is t<> ! 
 performed as follows : 
 
 a. It is to be dried at 212 Fahr., and the water deti-r- 
 mined as before. From strong-smelling guanos a little 
 ammonia is driven off by this drying, but it rarely amounts 
 19 1 per cent, and can In- allowed for if necessary. 
 
EXAMINATION OF BONE MANURES AND GUANOS. 93 
 
 b. The dried guano is to be heated to redness in the 
 air, till everything combustible disappears. The loss 
 consists of organic matters and ammoniacal salts. 
 
 c. The burned residue is to be treated with dilute 
 muriatic acid, till everything soluble is taken up. The 
 insoluble matter collected on the filter, washed, heated to 
 redness, and weighed, gives the proportion of useless gravel, 
 sand, silica, or other matters which the guano contains. 
 
 Or this burned residue may be washed first with dis- 
 tilled water, to dissolve out the saline matter (//), and 
 then treated with acid as here described. 
 
 d. Among these other matters, gypsum, added as an 
 adulteration, may be one. If this be suspected, the 
 insoluble matter is boiled in a solution of carbonate of 
 soda, again collected on a filter, and washed. If it now 
 dissolves with effervescence in muriatic acid, it has been 
 gypsum ; if only part of it dissolves, the insoluble part 
 can be washed, dried, and weighed, and the gypsum 
 estimated from the loss. 
 
 Or, if greater accuracy be desired, ammonia may br 
 added to this solution (?) in muriatic acid, and the limo 
 afterwards precipitated by oxalate of ammonia, collected, 
 and heated to redness (33). Every 100 grains of the 
 carbonate of lime obtained indicate 136 grains of burned 
 gypsum in the insoluble matter from c, or 172, grains of 
 common gypsum in the manure.* This method is nioro 
 accurate, because the carbonate of soda may have dissolved 
 some silica from the insoluble matter, which would propor- 
 
 * In the niauuic the gypsum will exist as common gjp&um, uontuintii" 21 per 
 pent of water; but as obtained from r. it is burned gypsum, havingbecn heated to 
 redness. 
 
94 EXAMINATION OF BONE MANURES AND GUANOS. 
 
 tionately increase the apparent proportion of gypsum if 
 calculated from the loss. 
 
 e. To the acid solution from c, ammonia is added in 
 excess. The phosphate of lime of the guano, generally 
 mixed with a little phosphate of magnesia, falls. This 
 is collected on a filter, washed, heated to redness, and 
 weighed. 
 
 /. If carbonate of lime or chalk have been present in 
 the guano, it is contained in the filtered solution from e. 
 It is estimated by adding oxalate of ammonia, and col- 
 lecting and heating to redness the oxalate of lime in the 
 usual manner, (33). 
 
 g. By now evaporating the filtered solution from/, and 
 heating to dull redness to drive off the ammoniacal salts, 
 the saline or alkaline matter contained in the guano is 
 obtained. Or it may be extracted at once by washing 
 the burned residue from I with distilled water, and eva- 
 porating the solution to diyness. 
 
 It will rarely be necessary to analyse this saline matter 
 further. It generally consists of sulphate of soda and 
 common salt, with a trace of sulphate of potash. But 
 if it be desired to determine the proportions of each, the 
 solution is divided into three equal parts the sulphuric 
 acid is thrown down from one by chloride of barium(31), 
 the chlorine from another by nitrate of silver, and the 
 third is treated with caustic baryta, as described in tho 
 summary, p. 58, letters m and n. 
 
 h. If it be desired to determine the per-centage of am- 
 monia which the guano contains, a weighed portion is 
 put in a small retort, and covered with a dilute solution 
 of caustic potash. The retort is adapted to a receiver 
 
EXAMINATION OF BONK MANURES AND GUANOS. 95 
 
 containing a little dilute muriatic acid, and then, by the 
 aid of heat, the matter in the retort is distilled to dryness. 
 The ammonia which passes over combines with the muri- 
 atic acid in the receiver, and by evaporating the whole of 
 the liquid to dryness in the water-bath it is obtained in 
 the state of sal-ammoniac. Every 100 grains of this sal- 
 ammoniac indicate the presence of 31 .8 grains of ammonia 
 in the guano. (See also 39 a.) 
 
 IV. EXAMINATION OF ARTIFICIAL GUANOS AND MIXED 
 MANURES. 
 
 93. Artificial guanos have generally dissolved bones 
 or some variety of the so-called super-phosphates for their 
 basis. To this are added variable quantities of common 
 salt, sulphate of soda, sulphate of magnesia, sulphate of 
 ammonia, and, more rarely, nitrate of soda. Useless 
 additions of gypsum, burned clay, ground bricks, ochre, 
 tfcc., to give the mixture a color, and to lower its price, 
 are also made by many manufacturers of artificial manures. 
 
 . An artificial guano should be subjected to the same 
 general treatment as a natural guano. It may be first 
 tested roughly for water, ammonia, and sandy or earthy 
 admixtures, as described under 91. If a further exami- 
 nation or analysis be thought necessary, then the water, 
 the organic matter, the sand, clay, and gypsum, the 
 phosphates and the lime, are to be estimated as in the 
 preceding section (92, a to g). 
 
 b. If the soluble salts obtained by the procesess g have 
 been found, by a preliminary testing, to contain magnesia, 
 this earth may be separated by caustic baryta, as described 
 
96 EXAMINATION OF BONE MANURES AND GUANOS. 
 
 in 37 c, and the alkalies afterwards estimated cither sep- 
 arately or together, as described in 38.* 
 
 c. The ammoniacal salts are also determined as in a 
 natural guano (92 h). 
 
 d. The nitrates, if present, would be destroyed by heat- 
 ing the artificial guano to redness. They must, therefore, 
 be extracted with water from the guano, or mixed manure 
 as it comes to market. The filtered watery solution must 
 then be tested for nitric acid, as described in 27 a . Then 
 i f nitric acid be present, and the quantity of chlorine and 
 sulphuric acid has already been determined, the weight of 
 this acid is calculated from the loss. 
 
 V. EXAMINATION OF OIL-CAKES, 
 
 The cake obtained from many varieties of oily si n!> 
 when crushed in the mill, is used in England, and in many 
 other countries, as a manure. It is chiefly rape-cake, 
 hemp-cake, mustard-cake, cotton-cake, and some others. 
 not much relished by cattle, which are so employed. 
 
 Linseed, poppy, nut, and other sweet oily cakes, which 
 are relished by cattle, and bring a high price in the 
 market, are frequently adulterated with less costly mate- 
 rials. Those which are used as manures are said to be so 
 adulterated also. Where such admixtures of cheaper sub- 
 stances are suspected, the following steps may he taken: 
 
 1 . Reduce the cake to powder, and burn a weighed por- 
 tion of it in the open air, till everything combustible bums 
 away. The ash should be nearly Avhile, and should not 
 exceed seven or eight per cent of the weight of the cake. 
 
 * See also Hie summary in ii;,'e 5**, uinlcr Uttn> 1, in. :unl . 
 
EXAMINATION OP BONE MANURES AND GUANOS. 97 
 
 2. Treat the ash with diluted muriatic acid. It 
 should nearly all dissolve, leaving no material quantity 
 of sand behind. 
 
 3. To the filtered solution add ammonia in excess, 
 when phosphate of lime will fall. Collected, dried, and 
 heated to redness, the weight of this phosphate should be 
 equal to three -fifths of the whole weight of the ash. If 
 it is much less, some admixture may be suspected. 
 
 4. Reduced to powder, and treated with ether, a gen- 
 uine oil-cake will yield from ten to twelve per cent of oil. 
 This may be obtained in a separate state by pouring off 
 the ether into a small open glass vessel, when the ether 
 will evaporate, and leave the oil behind. 
 
 5. By breaking the cake into small pieces, treating with 
 repeated portions of boiling water, and then squeezing the 
 insoluble remainder in a thin linen cloth, the husk of the 
 original seed will be obtained in a separate state. An 
 examination of this residue will show whether any 
 foreign seeds have been mixed with the cake, what they 
 are, and to what extent the adulteration has been carried. 
 It is easy in this way, for example, to detect the husks of 
 the small and lighter coloured seeds of brown, or, as it is 
 commonly called, black mustard. 
 
 6. When mustard-seed is crushed and mixed with cold 
 water, it emits the strong pungent smell for which pure 
 mustard is distinguished. Rape-seed, so crushed and 
 mixed with cold water, exhibits also a sensible pungency 
 of smell, greater sometimes than that of mustard-seed, but 
 which varies in strength with the sample of rape -seed 
 examined. In taste, however, the mustard-seed is much 
 the stronger. 
 
 7 
 
98 EXAMINATION OF BONE MANURES AND QUANOS. 
 
 Mustard-cake and rape-cake, prepared by cold crushing, 
 exhibit the same properties as the seeds they are made 
 from. If we suspect an adulteration of rape with mustard 
 cake, therefore, we reduce the suspected mixture to a fine 
 powder and mix it with cold water. We reduce to powder 
 also a sample of pure rape-cake, and mix it with water, 
 by way of comparison. The smell of the pure rape will 
 probably be quite equal in pungency to that of the sample 
 adulterated with mustard ; but the taste will be more 
 pungent in proportion to the quantity of mustard-cake 
 present. 
 
 In this experiment boiling water must not be used, as 
 that at once destroys, not the pungent smell, but the 
 pungent taste, both of rape and of mustard, in the form 
 either of seed or of cake. 
 
 The above method of testing applies to cakus prepared 
 by cold crushing ; but if, during crushing, either mustard 
 or rape seed be heated above 176 Fah., it no longer 
 gives the characteristic pungent smell, when afterwards 
 powdered and mixed with cold water. Most of the rape- 
 cake brought to market has been prepared by hot crush I ny 
 the seeds, at a temperature often as high as 300 Fah. 
 This variety of cake emits very little of the pungent smell, 
 when crushed and mixed with water. Samples occasion- 
 ally come into the market, however, which have been 
 crushed in the cold ; and as these emit a powerful odour, 
 they have sometimes been unjustly called adulterated, and 
 been said to contain quantities of black mustard. Great 
 caution, therefore, must be exercised in coming- to such 
 conclusions. 
 
INDEX. 
 
 Absorbing power of the soil, 13, 14. 
 
 Acid, sulphuric, to test for and estimate, 
 24, 31 its action on the earthy part of 
 a soil, 52. 
 
 phosphoric, how detected, 29. 
 
 phosphoric, how estimated, 40. 
 
 acetic, as a teat, 29. 
 
 free, detected oy litmus. 34. 
 
 molybdlc, as a test and re- agent, 
 
 40,46. 
 
 muriatic, its use in the analysis of 
 
 soils, 43. 
 
 carbonic, estimation of, in the soil, 
 
 50. 
 
 summary of methods of analysis 
 of, 57. 
 
 Acids, humic and ulmic, how to separate 
 from the soil, 17. 
 
 crenic, apocrenic, jrcif, and nitric, 
 
 in the soil, 21. 
 
 Air, how to dry, 01. 
 
 Alcohol, employment of, S9. 
 
 Alkaline matter in a limestone, 76. 
 
 Alumina, to detect and separate, 25, 34. 
 to separate phosphoric acid from,47. 
 
 Ammonia in the toil, to detect and esti- 
 mate, 27. 28, 39 salt* of. how to test 
 and analyse, 85 arseniate of, as a 
 test, 37 hydrosulphnret of, as a test, 
 34 molybdate of, as arc-agent, 40. 
 
 Ammoniacal phosphate of magnesia, 41. 
 
 sulphate of magnesia as a re-agent, 
 
 Alalysis of soils, uses of, 8 how to se- 
 lect specimens for, 9 summary of the 
 methods, 57 how Its results should 
 he aided and interpreted, 72 of clays, 
 >>8 by measure or volume, principles 
 of, 59 of limestones, 73 marls, 76. 
 
 Arseniate of ammonia, as a test, 37. 
 
 Arsenic acid, its poisonous fumes. 38. 
 
 Ash of filters, how determined, IS. 
 
 Barium, chloride of, ns a test nnd re- 
 agent, 40. 
 
 Baryta, caustic, use of for fusions, 54 
 water to separate sulphuric acid, 37 
 carbonate of, as a re-agent, 49 nitrate 
 of, as a test, 24. 
 
 Bi-chloride of platinum as a test, 27. 
 
 Bones, crushed and dissolved, how to 
 test and analyse. 87. 
 
 Burned gypsum, its properties, 85. 
 
 Caoutchouc tubes, use of, 51. 
 
 Carbonate of ammonia as a re-agent, 39 
 of baryta as a re-agent, 49 of iron, 
 its composition, 66 of lime, how de- 
 tected in a soil, 43 how to estimate 
 it, 73 of magnesia, to estimate in a 
 limestone, 74 its composition, ib 
 of potash, its composition, 53 of 
 soda, dry_, its composition, ib, crys- 
 taliscd, its composition, 82 how to 
 detect it in nitrate of soda, 31 of sil- 
 ver, how prepared, 36 as a test, ib. 
 
 Carbonic acid in a soil, how to estimate, 
 50. 
 
 Chalk, o& a re-agent, 49. 
 
 Chloride of barium as a re-agent, 46 of 
 calcium, as a test and re-agent, 28, 83 
 its composition, 80 how prepared, 
 61 used for drying gases, ib in 
 common salt, 80 of magnesium in 
 common salt, ib. of sodium in a so - 
 1 11 1 ion, how estimated, 38 to estimate 
 it by measure, CO its composition, ib. 
 of silver, composition of. ib. 
 
 Chlorine, to test for and estimate, 25, 3? 
 to estimate by measure, 61. 
 
 Clay and oolite iron ores analysed, 65. 
 
 Clays, tile and fire, how to analyse, 
 58. 
 
 Common salt in a solution, how estima- 
 ted, 38 to estimate by measure, 60 
 composition of, ib. its effect on the 
 fertility of a soil, 69 how to tet and 
 analyse, 78 how to purify, 79 to 
 estimate the earthy chlorides in, 80 
 sulphuric acid in, ib. , 
 
100 
 
 IXDEX. 
 
 Constituents of a soil, their relation to 
 
 the feeding of plants, 71. 
 Cooling of a soil, rapidity of, 15. 
 Crushed bones, how to test and anal vse, 
 
 87. 
 
 Density of soils, to determine, 10. 
 Dissolved bones, bow to test and an- 
 alyse, 88. 
 Drying power of the soil, 13. 
 
 Ether, use of, 47. 
 
 Feeding of plants, relation of the scve- 
 eral constituents of a soil to the, 71. 
 
 Filter, how to dry and weigh, 18 -ash 
 of, how determined, ib. 
 
 Fire and tile clays, how to analyse, 58. 
 
 Fusion of soil with potash and sotto, 53. 
 with hydrate of baryta, 54. 
 
 Gold dust as a test, 23. 
 
 Grave) and sand in a soil, 12. 
 
 Green vitrol, as a test, 28. 
 
 Guanos, natural, to test and analyse, 02 
 
 adulteration in, 93 alkaline matter 
 
 of, 94 ammonia in, 95 artificial, to 
 
 test and analyse, iti. 
 Gypsum, how to test and analyse, 84 
 
 composition of, burned and nnbtirned 
 
 85. 
 
 Heat absorbed and retained by a soil, 14. 
 Humic and ulmic acids of the soil, to 
 
 estimate, 17. 
 
 Hutnus of the soil, 19,21. 
 Hydrate of baryta, use of for f u&iou, 54. 
 Hvdrosulphate of ammonia a.s :i t--t 
 
 34. 
 
 India-rubber tubes, 51. 
 
 Indian soils, saline matter in, Or. 
 
 Insoluble matters of a soil, 45, 52. 
 
 Iron, peroxide of, in a soil, to estimate, 
 33, 43, 63 to separate it from alumi- 
 na, 33 oxide of, to separate phos- 
 phoric acid from, 47 protoxide of, in 
 a soil to estimate, 43, 63 oxides and 
 carbonate of, their composition, 48, 6G 
 oxides of, to estimate by measure, 
 63 -ores of, to analyse by measure, 65 
 carbonate of, in iron ores, it. 
 
 Lime, to detect and separate, 26, 32 
 carbonate of, how to estimate, 73 
 superphosphate of, 12 to test for and 
 analyse, 90. 
 
 Limestones, how to analyse, 75 alka- 
 line matter in, to estimate, 76, 
 
 Litmus paper, how prepared, 34. 
 
 Magnesia, to detect and separate, 25, 35 
 to separate from potash and soda, 3d 
 to separate phosphoric acid from, 
 47 sulphate of, its composition, 35 
 
 carbonate of, its composition, 74 
 phosphate of, its composition, tb. 
 
 Manganese, oxide of, to detect and esti- 
 mate, 34. 
 
 Manure cakes, to examine, 97. 
 
 Manures, mixed, to test and analyse, 95 
 saline, to test and analyse, 78. 
 
 Marls, how to analyse, 77. 
 
 Measure analysis, principles of, 59. 
 
 Mixed manures, to test and analyse, 9,">. 
 
 Molybdate of ammonia as a re-agent, 
 40, 46. 
 
 Muriatic acid, its use in the analyses of 
 soils, 43. 
 
 Mustard ssed and cake, to examine, 97. 
 
 Natural waters, how to test and analyse, 
 42. 
 
 NMtrate of baryta as a test, 24- of silver 
 as a test, 25 its composition, 61 
 standaid solution of it, ib. of soda, 
 how to test and analyse, 81 to detect 
 common salt in it, tft. adulterations 
 of it, it. to detect carbonate of soda 
 in it, ib. 
 
 Nitrates, how detected in the soil, 23 
 how detected in mixed manures, 96. 
 
 Nitric acid in the soil, how to detect it, 
 21,2*. * 
 
 Oil cakes to test and examine, 97. 
 Oolite and clay iron ores, how analy -!, 
 
 65. 
 
 Ores of iron, how analysed, 65. 
 Organic matter of a soil, to determine, 
 
 16 -what it practically suggests, 63. 
 Oxalate of ammonia as a test, 26. 3-.'. 
 Oxides of iron, to detect and estimate, 
 
 33, 48, 63 composition of, 60. 
 
 Per-manganate of potash as a re- agent, 
 62 standard solution of, ib. 
 
 Phosphate of soda as a test, 35 of mag- 
 nesia, its composition, 36, '4. 
 
 Phosphoric acid, to detect and estimate, 
 29, 40 to separate it from allumina, 
 magnesia, and oxide of iron, 47. 
 
 Plants, feeding of, relation to the several 
 constituents of a soil to the, 71. 
 
 Platinum, bi-ch\ori<!e of, as a te^:, 27, 
 38. 
 
 Totash, carbonate of, ils composition, 
 53 and 6"da in a soil, to detect and 
 estimate 26, 37. 
 
 Precipitates, to ascertain if they an- 
 completely washed, IS. 
 
 Bape and mustard cakes, to examine, 
 117. 
 
 Pal-ammoniac as a re-agent, 34, 3S. 42 
 its composition, 86 how to test and 
 analyse, 85 its relation to heat, 86. 
 
 Saline manures, to te*t and analv=e, 
 78. 
 
INDEX. 
 
 101 
 
 Saline matter of the soil, 24 ia Indian 
 Boils, 68 in soils near Durham, 69 
 on the plains of Athens, 70 in allu- 
 vium of Egypt, 69. 
 
 Sand and gravel in a soil, 12. 
 
 Silica soluble in the soil, 30, 45 in a 
 soil, how determined, 53. 
 
 Silver, to estimate by measure, 61 car- 
 bonate 11 f, as a test, i!G nitrate of, us 
 a test, 25. 
 
 Slaked lime, its use as a re-agent, 85. 
 
 Soda in a soil, 7, 38 carbonates of, 
 their composition, 53, Si! nitrate of, 
 to test and analyse, 80- carbonate of, 
 to test and analyse, S3 sulphate of, 
 to test and analyse, 84 its composi- 
 tion, Of. 
 
 Soils, why they should be analysed. 7 
 proportions of lime and organic mat- 
 ter in, what they suggest, 8 fine sand 
 in, often resembles clay, ib. oxide of 
 iron in, ib. benefits of a more reGned 
 analysis of, 9 how to select speci- 
 men!! for analysis, ib. physical prop- 
 erties of, how determined, 10 density 
 of, to determine, ib. absolute weight 
 of, 11 proportions of gravel, sand and 
 clay in, ib. power of absorbing and 
 retaining water, 13 rapidity of dry- 
 ing, zft. and of cooling, 15 power of 
 absorbing heat from the sun, 14 or- 
 ganic matter, how determined, 16 
 hurnic and ulmic acids of, 17 insolu- 
 ble vegetable matter of, 19 use of 
 alum in determining their organic 
 matters, ib. soluble organic acids in, 
 21 nitric acid in, how to detect, ib , 
 28 saline matter of, 24 sulphuric 
 acid of, ib., 31 chlorine of, 25, 38 
 alumina of, 25, 34, 55 magnesia of, 
 25, 35 peroxide ot iron in, 26, 33, 63 
 protoxide of iron in, 48, 63 lime 
 of, 26, 32 potash and soda in, 26, 37, 
 ammonia in, to detect, 27 phosphoric 
 
 acid in, to detect and estimate, 29, 40 
 soluble silica i a, 30, 45 -treatment 
 of, with muriatic acid, 43 earthy 
 natters of, how examined, ib. to de- 
 tect carbonate of lime in, ib estima- 
 tion of carbonic acid in, SO insoluble 
 part, how to fuse in potash and soda, 
 53 with caustic baryta, 54- silica in, 
 how determined, 53 -organic matter 
 of, what it practically suggests, 68 
 Indian, soluble saline matter in, ib. 
 near Durham, saline efflorescence in, 
 09 from plains of Athens, composi- 
 tion and qualities of, 70 of Egypt, 
 fi9 relation of their several constit- 
 uents to the feeding of plants, 71 
 how the results of an analysis should 
 be interpreted, 72. 
 
 Sulphate of ammonia as a re-agent, 47 
 its composition, 86 how to test and 
 analyse it, 85 its relations to heat, 
 86. 
 
 Sulphate of iron in soils, 35 of alumina 
 in soils, ib, of lime or gypsum, how 
 to tost and analyse, 85 of magnesia, 
 its composition, 35 its use as a re- 
 agent, 41. 
 
 Sulphuric acid, to test for and estimate, 
 24, 31 to separate from potash, 37. 
 
 Superphosphate of lime, to test and ana- 
 lyse, 90. 
 
 Testing, preliminary, of a soil, 24, 44. 
 Tile and fire clays, how to analyse, 58. 
 
 Ulmic acid of the soil, 17. 
 
 Vegetable matter of the soil, 19. 
 Volumetrical analysis, Principles of, 59. 
 
 Water absorbed and retained by a soil, 
 
 13. 
 
 Waters, natural, how to examine, 42. 
 Weight, absolute, of soils, 11. 
 
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