i QD f ,•<%> .■^' THE art II. CHEMISTRY— GENERAL DEFINITIONS. Thbes Chabactebistics of Chemical Affinity . . 123-125 INORGANIC CHEMISTRY. Elements . . . 125-126 Nomenclature — Symbols — Atomic Weights 126-127 Binaries , . , . 127-128 Acids — Bases — Neutrals , , 128-130 Tebnabies . , 130 Nomenclature of Oxygen and Sulphur Salts 130 Metalloids . . . 131-177 Oxygen — Ozone and Antozone . 131-138 Hydrogen and its Compounds , . 138-143 Nitrogen 143-144 Air — Hygrometers , . 144-146 Compounds of Nitrogen 146-151 Chlorine and its Compounds , . 151-155 Bromine .... 155 Iodine , 156 Fluorine 156-157 Carbon — Its Three Modifications , . 158-159 Compounds of Carbon 160-165 Boron . 165-166 Silicon— Silica . 166-168 CONTENTS. VU Sulphur ....•• . 168-169 Sulphurous, Sulphuric and Hydrosulphuric Acid . 169-173 Selenium . . 174 Phosphorus . . . 174-177 METALS. Physical and Chemical Propertibs of Metals . . 177-179 Salts ....... 179-180 GROUP I. Potassium ...... . 181-185 Sodium ...... 186-189 Lithium . . . . . 189 Ammonium ...... 190-191 GROUP II. Barium ..... 192-193 Strontium ..... 193 Calcium ...... 193-196 Magnesium ..... . 196-198 GROUP IIL Aluminum, etc. . . . 198-201 Metals lately Discovered by Spectral Analysis 202 GROUP IV. Manganese ..... 202-204 Iron . . . . . . 205-209 Cobalt ...... 209 Nickel ...... 210 Chromium ..... 211-212 Zinc ...... . 212-213 Cadmium— Copper .... 214 Lead . ..... . 215-217 Bismuth . 217-218 Uranium ...... 218 GROUP V. Tungsten— Vanadium— Molybdenum 219 Tellurium— Arsenic .... 220-222 Titanium— Tin ..... 222 Antimony ..... 223-224 Tantalum— Columbium .... 224 GROUP VL Mkrcury . . . 224-225 Silver ...... 225 Gold — Platinum .... 226-227 Palladium ..... 227 Iridium— Osmium— Ruthenium— Rhodium . 228 ORGANIC CHEMISTRY. Classification of Organic Bodies . . 228-230 I. Saccharine and Amylacbous Bodies 230 \. Starch ..... . 280-231 vm CONTENTS. Saccharine and Amylaceous Bodies continued. 2. Gum ..... 3. Lignine . . " . Creosote — Paraffine — Coal-Tar — Naphthalin 4. Sugar ..... Fermentation .... Alcohols ..... Ether ..... Products of Oxidation of Alcohol Action of Chlorine and Sulphur on Alcohol Formic Acid .... n. Ethtl — Methyl, Etc. Kakodyl Propyl — Butyl — Amyl Benzoyl — Cinnamyl — Salacyl Vegetable Acids . . Oxalic — Tartaric Citric Malic — Tannic — Gallic . Obganic Basks . I. Organic Alkalies, oe Alkaloids II. Artificial Alkaloids III. Artificial Alkaloids IV. Artificial Alkaloids POUND Radicals V. Oils («) Homologous with Aniline Containing several Com- Fixed Oils, or Fats .... Saponification .... Soap-Making — Candle-Making . (6) Essential or Volatile Oils (a) Hydrocarbon Essential Oils . (b) Oxyhydrocarbon Essential Oils Camphors — Resins and Balsams (c) Essential Oils Containing Sulphur VI. Cyanogen and its Compounds VII. Organic Coloring Principles . . « . Litmus — Madder — Safflower — Brazil-wood — Log' wood — Quercitron — Fustic-wood — Saffron- Turmeric — Cochineal — Chloropbyle VIII. Albuminous Bodies .... Protein — Albumen — Casein — Gelatin — Kreatin — Blood, Etc. .... Appendix ...... Index ...... NOTES ON CHEMISTRY, PART I. CHEMICAL PHYSICS. In consequence of the close relation existing between various physical forces, and the sciences which discuss them, it is necessary in treating one subject, to use some terms belonging strictly to other affiliated departments. Thus in our present abstract of Chemistry, many terms of Mechanics, Electricity, Heat, Light, etc., must be occasionally employed, and we therefore place in this Introduction, such definitions and brief explanations, as may render such terms, when afterwards employed, suf- ficiently intelligible. GENERAL PROPERTIES OF MATTER. Impenetrability. — The power of occupying space exclu- sively, or so that another portion of matter cannot at the same time exist in the same place. Extension, Bulk or Volume. — The amount of space occu- pied by any substance, expressed in some unit, arbitrarily established. See Appendix, page 283. (9) 10 MECHANICAL FORCES. Figure. — The outline or boundary of any body, or por- tion of matter. This is generally expressed by certain Geometrical terms, such as Sphere, Cube, Pyramid, Prism, Octohedron, etc. Matter is Indestructible. — By this term, we express the fact, that no force exists in nature, capable of annihilating an atom of matter ; and that, amid all the changes goiog on in bodies, by the operation of natural causes and the artificial conditions of our experiments, no particle per- ishes or ceases to exist, but that which was once in exist- ence, may always be found, however changed in its form, by a suflBciently thorough search. Example. — Gun-cotton ignited, explodes and disap- pears, being converted into gas; but if the explosion is conducted in an exhausted glass flask, while the cotton disappears, the whole apparatus will weigh as much as before the explosion : proving that no loss of matter has occurred. MECHANICAL FORCES. Gravitation. Gravitation is the force of attraction which exists be- tween every atom in the universe and every other atom, drawing bodies together with a force, which varies, directly with the products of their masses, and inversely with the squares of their distances. Gravity.— This term is used to express that part of the universal gravitation, which exists between the earth and bodies near its surface. Weight is the numerical expression of the Gravity of any body (i. e. the attraction between it and the Earth) reduced to some arbitrary unit, as the pound, ton, ounce grain, etc. See Appendix, page 287. Mass. — By this word we indicate the quantity of matter in a body. This is always expressed, relatively, by the GRAVITATION. ]1 weight. Thus we believe that a body weighing 2 lbs., has twice 3 3 much matter in it as a body weighing 1 lb. Specific Gravity, or Density. — By this we indicate the relative weight of equal volumes or bulks, of different sub- stances. Thus, as a cubic inch of iron weighs t times as much as a cubic inch of water, we say that their densities are as 1 to 1. In practice the density of water at a temperature of 60^, is assumed as the unit of density for all solids and liquids, and air at 60° with the barometer at 30 ins. is the unit for gases. When, therefore, we say that the density of iron is 1, of mercury 13^, of gold 19, of alcohol .t92, of chlo- rine 2.5, and of hydrogen .069, we mean that the first four of these bodies are respectively 1,13^, 19 and .192 times as heavy as equal bulks of water ; and that the two j^jg^ j^ last are respectively 2.5 and .069, or l-14th as heavy as equal bulks of air. The methods for determining these densities, it would be out of place to explain here in full. But we may remark briefly, that the density op SOLIDS is determined, by finding their loss of weight when immersed in water, as is shown in the figure, and then dividing the whole weight by this loss, which gives the density. Thus, 56 grains of iron will lose in water 8 grains, then 66 -^ 8 = T which is the density of iron. The Density of Liquids is found directly by providing a vessel which will hold a known weight (say 1000 grains) of water, filling this with the liquid to be examined, and weighing. Thus, a 1000 gr. bottle (see figure) j-jg, g. being filled with mercury, weighs 13,500 grs. the density of mercury is therefore 13*; the same bottle filled with alcohol would have weighed 192 grs., its density therefore is .792. 12 COHESION. The density of liquids is also in practice frequently deter- mined by the Hydrometer. Here the liquid to be tested is poured into a tall jar (see figure 3) and a little tube with a di- vided scale, etc. (see figure 4) is floated in it. The lighter the liquid the lower the tube will sink, before it displaces enough fluid to support its weight, and thus by observing the degree on the stem to which it sinks, and, referring to a table carefully prepared, which al- ways accompanies the instru- ment, the density of the liquid may at once be read ofif. Hydrometers are sometimes used as a rough means of deter- mining the amount of some salt, etc. in a solution, by its effect on the density. In these cases, the tables are often prepared to indicate this fact, and make no reference to the density. This, for exam- ple, is the case in the Lactometer, the Yinometer, the Saccharometer, etc. The Density of Guses is determined likewise by weighing them in a closed vessel of known capacity, with very careful attention to the temperature and height of the barometer. Cohesion. Coliesioil is that force of attraction which exists between adjacent particles of matter. E. g. The force which holds together the particles of gold, in a sheet of gold leaf, or of lead in a bullet, and which will cause various ^ig. 4. COHESION. 13 parts of gold leaf firmly pressed Fig- 5. together, or two halves of a bullet lately cut, to cling with notable te- nacity; as may be seen by the ex- periment figured in the drawing, where two plates of lead, cleaned and pressed together, will support a large weight, by their cohesion. This force varies greatly with dif- ferent materials, as may be seen by their various strength, tenacity, or resistance to rupture. See Appen- dix, page 290. Adhesion is a term applied to this force, for convenience, when it acts between different substances. E. g. Solder and Gold, Silver, etc. ; Wood and Glue, and the like. This is, however, a name for a class of actions, not for a new or different force. Capillary Attraction again is the name given to that class of cohesive actions, where this force is exerted between a solid of a tubular, laraillar, or porous structure, and a liquid, and causes a change of level in the liquid, where it comes within reach of the attraction of the solid. Ex. The rising of oil in a lamp-wick, of sap in trees, of water in the earth, etc. The height varies with the diameter of the tube and the liquid used, as may readily be shown by the apparatus. Fig. 6. 2 Fig. 6. 14 COHESION. Fig. 7. Diffusion of Liquids or Gases is the action by which liquids or gases of different densities will mix with or dis- solve in each other, even against gravity. It seems a direct result of " capillary cohesion," the porous nature of liquids and gases being taken into account. E. g. Fill a glass half full of oil of vitriol, sugar syrup or the like heavy liquid ; pour upon it gently a layer of water ; ^Sjpw^^^ after a time they will become completely mixed. So if the vessels a e connected by a fine tube are filled, {a with light hydrogen, e with heavy carbonic acid), they will soon be found to have completely mingled their contents. Osmose, indicates a similar interchange in liquids, when it takes place through a porous membrane, as moist bladder, parchment paper, etc. In this case the rate of transfer varies greatly in different substances, and thus may be made a means of analysis. This subject has been extensively studied by Gra- ham, and under the title ''Dialysis," is fully discussed in several papers. See Franklin Institute, Jour- nal, Yol. 44, pp. 181 and 253. Transpiration of G-ases indicates the same action in the case of aeriform bodies, a most striking example of which is fur- *- nished by the following experiment. The porous cup or battery cell A, is cemented, bottom upward with plaster of Paris, in the long glass funnel B. The bell jar C filled with hydrogen being then placed over A, this gas will transpire into the interior of A and B, so rapidly as to force ^wvuWaiHIIlllli'lii out the air in a series of bubbles, through REPULSION. 15 water placed in the little vessel D, into which dips the end of B. The bell jar being then removed, the hydrogen which has passed into A, will transpire again into the outer air, with such energy, as to raise the water from D, to a great height in the funnel tube. The wonderful power which some porous bodies, such as charcoal, coke, platinum black, etc., possess, of con- densing gases, seems closely allied to the above actions, and to result like them from cohesive attraction. Repulsion. Repulsioil is that force of mutual recession, which exists between adjacent particles of matter, opposing cohesion, and greatly affecting its action in many cases. This force is most largely exhibited in gases, and gives to these bodies their almost unlimited powers of expansion. Thus, if a flask, containing a bubble of air, but otherwise filled with water and inverted in a vessel of the same, is placed under 16 HEAT. the receiver of an air-pump, as the atmospheric pressure is removed, the bubble will expand, until it fills the whole flask. It is this force of " repulsion" which gives to all matter its elasticity of volume. It is closely related to heat, being, perhaps, another consequence of the same cause, i. e. the motion of all material atoms. See page IT. Polarity. Polarity is that directive force which causes adjacent particles of matter to assume definite relative positions. Its fullest exhibition is found in the phenomena of crys- tallization, but it is the origin of all rigidity of form to be found in solid bodies. The subject of Crystallography is too extensive to be here discussed, and we must confine ourselves to a few references and general statements. By reason of polarity, the particles of solids (and those of liquids and gases, when about to assume the solid form) strive to aiTange themselves in definite directions as regards each other, thus forming lines, parallel or inclined ; plates, and solids of geometric forms, as cubes, prisms, octohedrons, and the like. Examples of this action are furnished in the snow crys- tals, frost markings on window-panes, and the action of a slowly evaporating solution of common salt, etc. In many cases this polarity opposes cohesion, and thus produces a strain in the crystallized body, which gives it a power of affecting light in a remarkable way. See page 69. HEAT. Heat is the name by which we indicate the cause of a sensation experienced when we approach a fire ; and of certain effects, expansion, fusion, etc., commonly observed to be connected with the same. This cause, we have now every reason to believe, is simply a motion, greater or less, among the particles of bodies. In other words, the par- HEAT. 17 tides of a hot body are moving more rapidly than those of a cold one, and from this more rapid motion, come all the properties by which hot substances are distinguished from cold ones. These rapid vibrations, communicated by contact to the hand, affect the nerves of touch with the "tingling" sensation called "heat." When this motion of particles becomes more rapid, it causes them to pass through greater distances, to push each other apart, and to strike with greater force against the sides of a contain- ing vessel ; hence arise the phenomena of expansion. This rapid motion in solid particles, increasing, may at last throw them beyond the range of the polar force ; so making the solid, liquid ; hence fusion. Again, this same motion, yet more increasing, and thus causing a still wider separation between particles, may drive them apart beyond the reach of Cohesion ; so changing the solid or liquid into a gas or vapor ; hence vaporization, as in boiling, etc. Sources of Heat. — 1st. The Sun, where it is possibly maintained by the impact of solid bodies, scattered through space, which from time to time must fall in upon the sun. The heat from this source, shows certain properties of intensity, which indicate a very high temperature in the orb from which it proceeds. 2nd. Mechanical action, Friction, percussion, etc. It has been proved by Joule and others, that a given amount of mechanical action or motion is capable of producing a given amount of heat, however the motion be applied. Thus, the force or motion implied in the fall of one pound weight, through 1*72 feet, is capable of evolving heat enough to raise the temperature of one pound of water one degree. This is known as " the equivalent of heat." 3rd. Electricity, when passing through a resisting me- dium. E. g. Lightning, Electric sparks, Electric light, Pla- tinum wire, ignited by a current, etc. 2* 18 HEAT. 4th. Chemical combination, including ordinary combus- tion. Examples of this are countless ; thus the mixing of water with oil of vitriol, or with quicklime, or anhydrous sulphate of copper, develops great heat. So all cases of combustion. The cause of the heat motions in all these cases is plain. In the 1st and 2nd, the great mechanical motion is converted directly into a series of small reciprocating motions or vibrations, i. e, " heat." In the 3rd, the resisted force, as it passes through, causes the resisting matter to vibrate, besides, in some cases, tearing off particles from the solid points between which it moves, so giving them also vibratory motion. In the 4th, the different particles rushing together to unite, in like manner establish vibrations, by a similar mechanical action. The ANIMAL HEAT generated in the bodies of living creatures, is simply one case of the 4th source, as it is pro- duced by union of the oxygen absorbed by the blood in the lungs, with the effete matter, exhausted tissue, etc., found throughout the body. It is simply slow combustion, which, together with similar actions, such as the decay of wood in the air, has received the name of Eremakatjsis. Fig. 10. O Measurement of Heat. Thermometers. — Instruments for measuring heat. The air thermometer invented by Sanc- torio, in 1626, consists of a glass tube and bulb, partly filled with air, dipping into a vessel of water. When heated, the air expands and the surface of the water falls in the tube ; when cooled, the air contracts and the water rises. This instrument is delicate, but difficult of ad- justment for comparison of results. HEAT. 19 The spirit thermometer, invented by a member of the Florentine Academy, consists of a capillary glass tube, with a bulb, partly filled with alcohol, otherwise vacuous, and hermetically sealed, and having a scale attached, divided into degrees, as will be presently described. This instrument is much used for very low tempera- tures, but is useless above 150° F., as alcohol boils about 1730 F. The mercurial thermometer invented by Reaumur. This is exactly like the last, mercury being substituted for alco- hol. In order that various instruments may be made to accord, two fixed points have been settled upon, the melt- ing point of ice, and the boiling point of water. The height of the mercury corresponding to these being ascer- tained, the space between may then be divided into de- grees, according to one of three scales now in use, the Fahrenheit, the Centigrade, the Reaumur. The first, F., divides the space into 180°, numbering the first 32° and the last therefore 212° (32 -f 180 = 212.) The second, C, divides it into 100°, numbering the first 0° and last 100°. The third, R., divides it into 80°, numbering the first 0° and last 80°. To convert degrees of one of these scales into those of another, the following formula may be used. Cent. = |R. = 6 (F.— 32) A table showing at a glance the coi-responding degrees, will be found in the Appendix, p. 291. Reau.= 4 c. = 4 (F. — 32) Fahr. = I C. +32 = I R. 4- 32 Above and below the fixed points, the degrees are marked off by simple measurement, and comparison with those between. Degrees below the 0° of each scale are numbered progressively downwards, and are distinguished by the sign minus ; thus the freezing point of mercury is — 40° F. 20 HEAT. Specific Heat. — We might suppose that the same amount of heat being applied to different bodies would raise them all to the same temperature ; but this is not so. From the different arrangement of particles in various bodies, some require more force than others to develop a given velocity of movement. This difference of capacity for becoming heated, we call Specific Heat. In expressing it relatively, we assume water (which has the greatest of all rtodies), as the unit. Specific Heat of Solids and Liquids. Water 1.0000 Alcohol, sp. gr. =0.81 0.7000 Nitric Acid, sp. gr. =1.29895 0.6613 Wood, in the average 0.4800 Sulphuric Acid, sp. gr. 1.605 0.3346 Sweet Oil 0.3096 Lime 0.2169 Sulphur 0.2085 Glass 0.1929 Cobalt 0.1498 Iron 0.1098 Nickel 0.1035 Copper 0.0940 Tellurium , 0.0912 Antimony 0.0507 Zinc 0.0927 Tin 0.0475 Platinum 0.0344 Bismuth 0.0298 Mercury 0.0290 Gold 0.0288 I^ead 0.0281 The high specific heat of water is of great value in moderating the extremes of temperature and equalizing climate in the neighborhood of large masses of water. The excess of heat is there absorbed without rendering the water proportionately hot, and again emitted, without corresponding fall of temperature. HEAT. 21 Specific heat of Gases and Vapors as compared with equal weight of Water. Water 1.00000 Air 0.23741 Oxygen 0.21751 Hydrogen 3.40900 Nitf-ogen 0.24380 Chlorine 0.12099 Bromine 0.05552 Carbonic Acid 0.20246 Carbonic Oxide 0.24.500 Nitrous Oxide 0.24470 Nitric Oxide 0.23173 Marsh Gas 0.59295 Ether Vapor 0.47966 Alcohol Vapor 0.45341 Olefiant Gas 0.40400 Sulphurous Acid 0.15531 Hydrochloric Acid 0.18521 Sulphuretted Hydrogen 24218 Ammonia 0.50836 Turpentine Vapor 0.50610 Bisulphide of Carbon... 0.15696 A curious connection between the specific heat of bodies and their atomic weights was first announced by Dulong and Petit, and has been confirmed by Regnault, namely, that the specific heats of elements are inversely as their atomic weights ; or that the products of these two quanti- ties are constant. According to the experiments of Keg- nault, however, this " constant " may vary between 2.95 and 3.41. We should, from this law, conclude that the same amount of heat is needed to raise an atom of any element through a given number of degrees. In compound bodies the same law holds good, except that the constant varies with different classes of bodies. Thus, for the protoxides it is 5.64, for the sesquioxides 13.6, for the sulphides 4.92, for the carbonates 10.15, etc. Effects of Heat. I. Expansion. — All bodies, with cer- tain exceptions to be presently noticed, expand with an increase of temperature, and contract with a loss of heat. This expansion is, however, very various in diflferent bodies, as will appear from the following table : HEAT. Linear Expansion of Solids between 32° and 212° F. for each degree. Copper 0.00001092 Bronze 0.00001009 Brass, Cast 0.00001043 White Glass 0.00000478 Platinum 0.00000491 Untempered Steel... 0.00000600 Cast Iron 0.00000618 Wrought Iron 0.00000656 Tempered Steel 0.00000689 Gold 0.00000815 Silver 0.00001060 Tin 0.00001207 Lead 0.00001850 Zinc 0.00001633 Cubic Expansion of Liquids between 32° and 212° for each degree F Mercury 000085 Water 000258 Sulphuric Acid 000330 Oil of Turpentine or Ether 000380 Common Oil 000444 Alcohol or Nitric Acid 000633 Cubic Expansion of Gases oetween 32° and 212° for each degree F. Air 0.00203111 Hydrogen 0.00203766 Nitrogen 0.00203788 Sulphurous Acid 0.00203866 Hydrochloric Acid... 0.00204511 Cyanogen 0.00204561 Carbonic Acid 0.00204977 From this it appears that the expansion of various gases is practically the same. At temperatures above and below those mentioned in the foregoing tables, the rate of expansion varies slightly with different substances, increasing with the rise in tem- perature, and decreasing with the reverse; but these changes are not of sufficient importance to be here dwelt upon. A great variation is also found at those temperatures where the body changes its form, as from liquid to solid ; and, in the case of water, this amounts to a reversal of the rule. Between the melting point, 32° and 40°, water contracts as it grows hotter, so that its maximum density is at that point, 1. e. 40° ; growing less by change of tem> perature either way. HEAT. 23 The tables above given hold good both ways ; bodies contracting when lowered in temperature, just as they expand when raised. The close equality in expansion of glass and platinum is of great value, enabling us in constructing apparatus to directly weld or join these substances without risk of fracture through change of temperature. Applications of expansion and contraction are countless. Shrinking tires on wheels, iron wheels on axles, etc. ; draw- ing up the falling wall of the Conservatoire des Arts et Me- tiers ; compensating pendulums and balance- wheels; ther- mometers of all kinds ; testing strength of steam boilers easily and safely, by filling full with water, closing all valves, attaching pressure guage, and warming ; air en- gines, etc. Effects of Heat. n. Fusion. — Solid bodies heated to a certain point, begin to change their form, and to become liquid, excepting, of course, such compounds as suffer decomposition before this fusing point is reached. The temperature at which this change takes place differs greatly with different bodies, but is unchangeable for each, except as it is slightly affected by great changes of pres- sure. Thus, under pressure of 100 atmospheres, the melting point of paraflQne is raised 6'3°, and of spermaceti 3. go Y rpjjg melting point of ice, however, is lowered by pressure, so that it may become liquid under pressure, and solidify on the relief of the same. This explains the phenomena of "regelation," and the motion of glaciers. Sec Tyndall on Heat as a Mode of Motion, page 208. The fusing point of different substances will be given hereafter, where their various properties are described under the head of Chemistry. Latent Heat of Liquids. — We observe by experiment that a large amount of heat is required to convert a solid into a liquid, without producing any effect in changing its 24 HEAT. temperature. Thus, if a pound of ice at 32° is mixed with a pound of water at 116°, the ice will be melted, and we shall have two pounds of water at 32° ; all the additional heat in the water (144°) having been absorbed by the ice, without, however, any increase to its tempera- ture, but with simply a change in its state. Heat so absorbed we call "latent heat." This phenomenon should be expected from our theory. A certain amount of force, in the shape of heat-motions, or vibrations, must be expended in overcoming the polar force between the particles, and thus changing the state of the body. This latent heat varies with different bodies, as will be seen from the following table, in which the number shows how many degrees, the heat absorbed in fusing the given substance, would raise the same after liquefaction. Bismuth 22.75 Sulphur 16.86 Lead 9.66 Phosphorus 9.05 Fusible metal* 8.10 Mercury 4.93 This latent or absorbed heat, is absolutely necessary to the change of form from solid to liquid ; hence if in any way this change is effected without giving this required heat, the body will, or must, lose a corresponding amount of its own heat or heat motion, having in this case performed this work of change, by and at the expense of its own inter- nal motive power or heat vibrations, and it must therefore fall in temperature. This is the theory of " freezing mix- tures." Certain bodies if mingled become liquid, by rea- son of certain attractions among their particles, they con- sequently absorb heat motions in effecting this change, and fall in temperature. Some of these bodies, and the descents * 1 Lead, 1 tin, and 4 bismuih. Water 142.65 Nitrate of Soda 112.98 Zinc 50.63 Silver 37. 92 Tin 25.65 Cadmium 24.58 HEAT. 25 accomplished bj rapidly mixing them, are given in the following table. Sulphate of Soda 8] ^^„ ^ _ XT J u, • A -J . ^ +50° to + 2. Hydrochloric Acid 5 j Pounded ice or snow 2] ncyo i n Common salt IJ Sulphate of Soda 3} ^^ T^•l ^ ^T-. • A • ] o f + ^^° to —2. Dilute Nitric Acid 2j Sulphate of Soda 6 Nitrate of Ammonia ^ Y + 50° to — 14. Dilute Nitric Acid 4 Phosphate of Soda 9] Dilute Nitric Acid 4 | + 50° to -20. Such preparations as the above are often used ; in chem- ical operations, where a very low temperature is required, as in preparing liquid sulphurous acid, in surgery, and in culinary processes, as in the preparation of ice-cream. In all cases the more finely the ingredients are pulverized, and the more thoroughly they are mixed, the lower the temperature reached. It must also be remembered that the fluid obtained, is far colder than the solids employed, and is indeed the efficient source of refrigeration and must not therefore be drained oflF or allowed to escape, until it has done its work. Freezing. Congelation. — As we might naturally expect, when the action last discussed is reversed, and heat is abstracted from a liquid, it will at a certain point, begin to change its form and become solid. We might also sup- pose that the point at which this change took place, in any substance, was the same either way. This is indeed so as a rule, but not under all conditions. Thus, if water, de- prived of air, is kept absolutely at rest, it may be cooled to 11° without freezing; then, the least shock or jar, will cause it to freeze in an instant. So a concentrated hot 26 HEAT. solution of sulphate of soda, cooled at rest and out of con- tact with air, remains liquid indefinitely, until shaken or exposed to the atmosphere. In becoming solid, the liquid develops as much heat as it abstracted in becoming liquid ; this is shown in the case of the water by the immediate rise in temperature of the whole material to 32°, on the freezing of part, and in the ease of the sulphate of soda, by a notable heating. In all ordinary cases, moreover, we find that while we are freezing or solidifying any liquid, its temperature does not fall, during the whole process, though heat is being abstracted from it at a rapid rate. Expansion in Freezing. — At the moment of passing from the liquid to the solid state, most substances expand. This is very notable in water, which increases to 1.0Y5 times its bulk at 40° ; hence ice floats on water. This expan- sion takes place with such force as to burst even strong iron vessels, and, under very heavy pressure restraining this expansion, according to M. Mousson, water will not entirely solidify. Like water, cast-iron, antimony and bismuth, expand in solidifying ; mercury, phosphorus, stearine, etc., contract. Effects of Heat. III. Vaporization. — Liquids when heated to a certain point, begin to change their state, and to pass into the condition of gases. The temperature at which this change takes place, differs greatly with differ- ent substances, though it is the same for the same body, under the same conditions ; but it is largely affected by changes of pressure, the nature of the containing vessel, etc. The phenomenon alluded to, is commonly called boil- ing, and the temperature at which this action begins, is called the ''boiling point." The boiling points of various bodies will be stated hereafter, in connection with their other properties. HEAT. 27 The effect of a change in pressure, on the boiling point of water, will be seen from the following table. Water, boiling in the open air, is under a pressure of about 15 lbs. per sq. inch (or such as would be given by a column of mercury 30 inches high), due to the weight of the atmosphere. Under this condition its boiling point is 212° F. Its boiling point is 0. 098 lbs. pr. sq. in. = 0. 006 atmospheres 32° = 0.017 " 60° = 0.033 " 80° = 0.062 ** 100° = 0.247 " 150° == 0.505 " 180O = 1.000 " 2120 = 2. ** 251.6° = 3. ** 276.4° = 4. " 295.6° = 5. " 311.2° = 6. " 324.3° == 7. «' 335.8° = 8. «' 345.8° == 9. " 355.0° =10. " 363.4° =12. " 378.4° =20. «♦ 420,3° =40. " 487.0° =66.6 " 548.0= From this table^ various conclusions may be drawn. The boiling point varies less and less with the pressure, as it ascends. Thus, the change of less than one atmos- phere makes a difference of 180° in the boiling point between 32° and 212°, while it makes a change of but 39° between 212° and 251°, and of but 25° between 251° and 216°, etc. These points of pressure and temperature being inseparable, one may serve as a measure of the other. Under pressure of 0. 200 ins. of mercury = 0.098 0.524 = 0.257 1.000 = 0.490 1.860 = 0.911 .7420 = 3.636 15.150 = 7.420 80.000 = 14.700 61.200 = 30. 91.800 = 45. 122.400 = 60. 153 000 = 75. 183.600 = 90. 214.200 = 105. 244.8 = 120. 275.4 = 135. 306.0 = 150. 387.2 = 180. 612.0 = 300. 1223.0 = 600. 203S. = 1000. f' HEAT. Fig. 11. A liqaid inclosed in a tight vessel, will generate a pres- sure corresponding to its temperature. If in any way this pressure is relieved, the liquid will boil violently, because heated above its boiling point for this lesser pres- sure. This is well illustrated by the Culinary Paradox. Here a glass, containing water in the act of boiling, is corked and in- verted. If now cold water is poured yCC \i{^^ •'•i''''i I <^^®^ t^® flask, the vapor or steam ('^^kJlr^^^^^^ contained will be condensed, the pressure thus relieved, and the water made to boil violently. The same thing is proved by various experi- ments in freezing by evaporation, to be presently described. This fact is again usefully applied in the manu- facture of sugar. The pressure of the atmosphere varies at different heights ; this ef- fects the boiling point of water, and thus' we may, with a thermometer, measure the height of various locations. A change in boiling point of 1° indicates a change in height of 600 feet. On Mt. Blanc water boils at 183°, and at Quito at 194°. For tension of various vapors at different temperatures, see Regnault's Tables, Fr. Inst. Jour., Vol. XY., pp. 136, 207, 278, 356, and 437 ; Vol. XYL, pp. 48, 115, 186, 257, 328, and 388; Yol. XYIL, p. 50, 114, and 190 ; Yol. XL., p. 241. The change in volume which accompanies the change of a liquid to the gaseous form, is very great, varying, however, with the pressure; the volume of- steam," like that of any other gas, varying inversely with the pressure applied. At the ordinary atmospheric pressure, however, water expands 1694 times in becoming steam. In round HEAT. 29 numbers, a cubic inch of water makes a cubic foot of steam. The nature of the vessel containing the liquid, has a marked effect upon its boiling. A vessel oflfering strong adhesion to the liquid, and no points from which bubbles of steam can be readily disengaged, raises the boiling point, and renders that action violent and spasmodic. Thus, water in a smooth and clean glass flask, may be raised to 222° before it boils. A few scraps of metal, or even angular bits of glass, will lower the boiling point to its normal state, and mode- rate the violence of the action. Water deprived of air, boils also with difficulty and vio- lence. In fact. Grove, from many experiments, concludes that if water could be entirely deprived of all gas (a re- sult never yet attained), it would not boil till heated hot enough to cause its decomposition. See Proceedings of the Royal Institution, 1864, p. 166. Latent Heat of Gases. — As in the conversion of solids into liquids, so also in the conversion of liquids into gases, we observe that a large amount of heat is ex- pended in effecting this change, without any influence upon the temperature of the body in question. This fact likewise accords with our theory, as before. The lost or latent heat is but so much heat-motion expended in over- coming the cohesive force, which kept the body in its liquid form. The latent heat of different gases or vapors, varies greatly, that of water or steam being the highest. Thus, the heat required to convert one pound of water into steam, would raise a pound of water otherwise through 912 degrees. With other bodies it is as in the table. Water 972. Alcohol 374, Acetic Acid 183. 3* Ether 162. •Turpentine 133. 30 HEAT, Where differences of pressure are introduced, the latent heat varies, decreasing with the increase of pressure, and consequent rise of the boiling point. As we have already noticed with the latent heat of liquids, so with gases, if the change of state is accom- plished without a supply of extraneous heat, heat must be supplied and lost by the changing body itself. We may regard the liquid particles as possessing motions or heat vibrations, tending to throw them beyond the range of cohesion, but not yet sufficiently powerful to overcome that force. Hence, they vibrate within their boundaries like a pendulum, restrained, but without loss of motion, thus preserving their temperature. If now a little addi- tional force is given them, just enough (with what they possessed) to overcome cohesion, they break their bounds, but, in doing so, have spent their force, and (like a pen- dulum which has just been able to break from its sup- port) fall motionless, or nearly so, into their new state. In other words, lose much of their heat motion and be- come "cold." All cooling or freezing by evaporation is of this kind. A striking instance is as follows : If a little water in a small dish is supported over a larger one containing oil of vitriol, both being under the exhausted receiver of an air-pump ; the boiling point of the water will be so low, under the diminished pressure, that this action will go on at the ordinary temperature, and (the va- por formed being absorbed by the oil of vitriol) will continue. But the water, passing into vapor, destroys or renders latent much heat motion, it therefore becomes cold, and cools the water from which it rises, until finally the latter is frozen by its own evaporation. We may thus Fig. 12. HEAT. 31 have the strange anomaly, of water, at once boiling and fr-eezing, practically realized. On the same principle operates the Cryopherous of Wollaston, consisting of two connected bulbs containing some water, and exhausted of air. All the water being turned into one bulb, and the other placed in a freezing mixture ; the vapor within is thus condensed as fast as it forms, and the water from which it rises is quickly frozen, as before, by its own evaporation. A more practical application of the same general prin- ciple, is furnished in the freezing apparatus of Carr^. Fig. 13. This consists of two strong wrought-iron vessels, A and B,* connected by a tube C, the whole exhausted, and closed air-tight. A contains strong aqua ammonia, and is placed in a furnace, where it is heated until a thermom- eter, set in an oil tube D, indicates a temperature of 270° F., B, in the meantime, being immersed in water at the ordinary temperature. By this means the ammonia is driven out of the water in A, and is condensed under a pressure of 65 atmospheres into a liquid form in B. A * B. is shown in section. 32 HEAT. is then removed from the furnace and plunged into the water which before surrounded B, while the vessel con- taining the substance to be frozen is placed in the opening in B, a little alcohol being poured into the space between to prevent it from freezing fast. The pressure being relieved by the cooling of A, the condensed ammonia in B boils, and its vapor being rapidly absorbed in the now cold water in A, this action is kept up, causing a rapid loss of heat in B. With the small apparatus sold in Paris for 100 francs, the heating occupies about 30 minutes, after w^hich, with care, two cans full of water (about 2 quarts) may be frozen into solid ice. This apparatus may be applied to domestic uses. On the large scale it has been so constructed as to be continuous in its action, and has been reported upon favorably by the French Academy. See Journal of the Franklin Institute of Pennsylvania, Yol. 48, page 109. Evaporation is the term by which we designate the gradual vaporization of a liquid at its surface, which may take place at any temperature. Example, Drying of a wet cloth. This action, like vaporization, implies a great absorption of latent heat. Thus masses of water are but little affected by the heat of summer, and the body in like manner by the evaporation of perspiration from its surface is saved from an injurious elevation of its tempera- ture, even when exposed to intense heat. Thus Dr. Fordice, Sir Joseph Banks, and others, sat for half an hour in an oven with a joint of meat which was cooked during the time. Condensation. —When the action described in vapori- zation is reversed, and the temperature of a gas is lowered, a point may at last be reached, at which it will change its state, and become liquid. This change of a gas into a liquid by loss of heat is called Condensation : when assisted by pressure, it is termed Liquefaction HEAT. 33 The temperature at which this change takes place is identical with that at which the reverse change happens, in each substance ; in fact its boiling point, and as might be expected, the latent heat expended in the reverse change is redeveloped in this. Thus a pound of steam, at 212^, would give out in passing into the state of water, at the same temperature, as much heat as would raise a pound of water through 9*72°, or 912 pounds of water through 1°. Distillation. — By combining the two processes of vapo- rization and condensation, we may effect the separation of substances having different boiling points, when these are mixed. This operation is called distillation. We place the mixture in a closed vessel called a retort or still, and there heat it, until the more volatile body is vaporized; the vapor formed is carried directly into a condenser, receiver, worm, or the like, where it is cooled, and so rendered liquid. The more volatile body is thus separated from that which is less so, and which remains in the retort or still, not being heated to its boiling point. It must be remembered, however, that the less volatile body will, in these conditions, evaporate, and that thus portions will pass over with the other. A complete separation cannot, therefore, be thus obtained. Alcohol will, for example, carry over with it at least fifteen per cent, of water, and mercury a notable quantity of gold, even, as well as other metals. Sublimation is the term applied to a like action, when the substance treated is a solid, which passes into the gaseous state, directly or after fusion, and likewise back into the solid form. Example, purifying sulphur, iodine, etc. Transfer of Heat. — Heat may pass from place to place, and body to body, in one or other of three ways, i. e., by Conduction, Convection, or Radiation. Conduction is the transfer of heat by means of particlos 34 HEAT. in contact. E. g. The end of a poker being put in the fire, the handle will, in time, become heated, by conduc- tion, through the iron itself. This power of conduction belongs chiefly to solids, and varies greatly in different substances, as will appear from the following table : Table of conducting powers of Solids. Gold 1,000 Silver 973 Copper 898 Iron 374 Zinc 363 Tin 303.9 Lead 179.6 Marble 23.6 Porcelain 14.2 Clay 11.4 Fig. 14. From this it follows, that whenever we wish to pro- mote the transfer of heat, we should use good conductors, as in culinary vessels, steam boilers, and the like ; while for the prevention of this transfer, bad conductors should be employed, as in ice-houses, winter clothing, handles of tea-kettles, etc. Condnction takes place with great dif- ficulty IN LIQUIDS. Thus, if an air ther- mometer is placed in a liquid, as in the drawing, and this is strongly heated at the surface, by a hot iron, very little effect will be produced upon the ther- mometer, at a short distance below. The conducting power of gases is pro- bably even less than that of liquids, though owing to their great mobility and diathermancy, this is hard to demonstrate directly. The efficiency of double sashes, double walls, in iron furnaces, and the like, however practically indicates this, as does also the following phenomenon. The spheroidal state. — By this term we indicate the condition of a liquid, when thrown upon a solid body, heated considerably above the boiling point of the former; HEAT. 35 when it is lifted out of contact with the solid, by vapor first formed, and then remains floating upon this cushion of steam, which is supplied as it escapes, by evaporation at the lower surface, and protects the liquid from any great accession of heat, so that this is never raised to its boiling point. This is well shown by dropping water over an inverted red-hot platinum dish, properly focussed in a magic lantern, and watching the image on a screen. If liquid sulphurous acid is employed, water may be frozen in a red-hot crucible ; or with solid carbonic acid and ether, mercury even can be frozen in the same situation. The non-con- ducting state of the vapor is clearly necessary to the above condition. By reason of this same action, the hand is pro- tected if placed for a moment in a stream of molten iron, gold, or the like ; the skin being shielded by a non-conducting layer of vapor from the burn- ing fluid. This fact explains some conjurers feats, and many of the famous ordeals. For the production of this spheroidal state, a certain temperature is required ; hence the value of the test ap- plied by the laundress to her flat-irons. If the water runs ofl^ in drops without boiling, the iron is hot enough. Convection. — This term describes the transfer of heat by particles in motion — as thus: Heat being applied to the bottom of a vessel of water, the lower particles of the fluid become hot, are consequently dilated, and giving place to cold, and therefore denser particles rise, carrying their heat into other parts of the vessel. This mode of transfer can only exist in liquids and gases, ^ hose particles are mobile, and is in fact the means by which masses of such bodies become heated through- out. The currents thus established are easilv shown 36 HEAT. in water, by a little powdered amber mixed in the liquid, and in air by smoke or dust. Fig. 16. In all cases of heating such sub- stances on the large scale, as in steam boilers, house furnaces, etc., it is very important that the tendencies of these currents should be studied, and their maintenance and regularity carefully provided for. To such cur- rents we owe the draught of chimneys, the ventilation of buildings, the trade, and other winds, many great ocean currents, etc. Radiation. — By this term we indi- cate the transfer of heat, by motions of the nature of undulations, or vibrations, in a certain mobile fluid, pervading all space, called the luminiferous aether. This impalpable fluid or gas is incapable of any direct physical test, but is believed (for the very strongest indirect reasons) to exist, and to be not only the vehicle of heat, but that also of light, whence its name lumi- niferous, or "light bearing." A hot and cold body placed at a distance in a vacuum, will rapidly become equalized in temperature ; the one gaining, the other losing heat. We suppose, in this case, that the motions of the hot body have communicated vibrations to the aether, which this has in turn conveyed to the colder. Heat propagated by this means is reflected, refracted, absorbed, polarized, etc., exactly as is light, and may, in fact, be regarded simply as slowly moving (in the sense of vibrating) light. This, however, will be more fully discussed. Radiant heat is best reflected by planished surfaces of metal, and best absorbed by dull, rough surfaces, such as lampblack. It is also absorbed in very difi"erent degrees, LIGHT. 3t by gases and vapors, and by certain solids and liquids. This absorption varies, however, with the character of the radiant heat, as regards its intensity, heat from hot iron at 500° passing where that from water at 200° would not. Rock salt is the most " diathermanous^^ solid known, and offers equally little resistance to heat of all intensities. It is by radiation that the sun's heat reaches us, or that of a fire, before which we stand, etc. LIGHT. By tlie word Light we indicate the cause of that sen- sation, affecting the eye, when it is turned upon the sun, stars, a burning body, or the like. This cause, we have every reason to believe, is identical in its nature with heat ; that is, we believe it to be simply a very rapid vibratory movement among the particles of ordinary matter, and the luminiferous aether already men- tioned, which pervades all space, and most bodies (and which, though too rare and fine to admit of any direct measurement or physical testing) is yet abundantly capable of producing those phenomena which we attribute to its agency. In fact, the conclusions which these phe- nomena themselves lead us to draw, respecting its light- ness and mobility, forbid us to expect that, with the rough means at our disposal, we should be able in any direct way to test or examine it. The difference between heat and light consists simply in the rapidity of the motions or vibrations producing them. If these number between 450 billions and 780 billions per second, they constitute light: if less than the first, they are heat: if more than the last, they are actinism. See page 54. Sources of Light. — As might be expected from our theory, 4 38 LIGHT. all sources of heat are, or may become, if intensified, sources of light. Thus we have, 1st, the Sun. 2nd. Me- chanical action. E. g. Flint struck in a vacuum, Perkins^ iron wheel revolving 6000 times a minute, and touched with a steel file, Fig. 17. 3rd. Electricity. E. g. Sparks, lightninsr, aurora, elec- Fig. 17. trie light, glowing wire, etc. 4th. In- tense chemical action. E. g. Combination of iron and sulphur, phos- phorus and iodine, ordinary combustion, etc. 5th. Phosphores- cence. E. g. Glow- worms, fire-flies, etc. In all these cases the "light vibrations " are developed exactly as those of heat — by the same actions. Propagation of Light. — Light emanates from all luminous bodies in straight lines, radiating from every luminous point. It passes without loss or change through free space, but is variously acted upon, and changed in its direction and character when traversing different bodies. These changes we shall study in their order presently. The Velocity of Light in free space is 190,000 miles per second. This Roemer proved by observation of the eclipses of Jupiter's first satellite, in 1675, and Foucault demonstrated experimentally with a very ingenious apparatus, by which he was able to prove that the velocity of light was less in water and dense media, than in air and other rare ones. Since light is projected in Fig. 18. LIGHT. 39 straight lines, an opaque body, placed before a source of light, will cut off its rays from a certain space. This space, so deprived of light, we call the shadow. Thus, A, Fig. 18, being a source of light, and B C an opaque body, the indefinite space, B C E D, is its shadow. If the source ^^^' ^^' of light is a point, or at a vast distance from B C, this shadow will be definitely bounded by B D and C E ; but if the source of light con- sists of many points, or an extended surface, A B, Fig. 19, then there will be a full shadow, C D E F, where no light enters, and around this as penumbra, or gradually decreasing shade, G C E, and F D H, from which is excluded the light of some only, among the luminous points in A B. Interference. Though, as a general rule, rays of light, like sounds, may cross each other in all directions, without any inter- ference or mutual disturbance, yet in certain cases inter- ferences may occur. Thus, if two rays are brought together in such a way that the rising phase in the vibrations or waves of one, corresponds with the sinking phase of the other, their opposite motions will be mutually destructive; the light motion will cease, and the light will disappear. Two rays of light may thus unite to produce darkness. If, however, the two waves of light coincide in phase of motion, a double brightness is the result. This action has the most exact parallel in sound, and in undulations of liquids, etc. Thus, an opening like figure 20 being made between two rooms, a sound produced in one of them will not be heard in the other, unless one of the two openings, cd, is closed ; because the sound waves 40 LIGHT. coming through the two passages, and meeting in different phases, effect a mutual destruction.'*' We shall have fre- quent cause to refer to this subject of interference. But at present we shall confine ourselves to one case. Two adjacent cones of light, proceeding, for example, from two pinholes near together in a card, produce on a screen, at a short distance, a series of dark and light bands in homogeneous and colored fringes in mixed or white light. Diffraction. — By this term we indicate the effect pro- duced on light, in passing across the edge of an opaque body. In this case a new system of undulations is developed in the aether, having the solid edge as their centre. These, by their interference with the original rays, produce fringes of light and darkness (or color with mixed light) within and without the geometric shadow of the solid edge. Wires, gratings, etc., act in the sa^me way. * The two rooms are at a and b. LIGHT. 41 Fig. 21. Reflection. — When a ray of light falls upon a polisLed surface, it is thrown off again at an angle the same as that of its incidence. This may be well shown as follows : The mirror, M, being so adjusted that a ray of light from any source is thrown down through a diaphragm, N, upon a pol- ished horizontal surface, n; this ray will be reflected up- ward, and will fall upon the little movable screen, P, when this is so adjusted, as to make the angle A n P equal to the angle A n N. From this it follows, that parallel rays, fall- ing on a plane polished surface, are reflected in parallel lines (see Fig. 22), and that diverging rays are reflected with Fig. 22. Fig. 23. the same divergence as before, the only change being, that they now seem to diverge from a point as far below the reflecting surface as their actual source is above it. (See Fig. 23). If, therefore, we are not aware of the reflecting surface, we may suppose the light to come, not from its true source, but from this supposed or equivalent source, behind the reflecting surface. This principle has been applied in Dr. Pepper's theatri- 4* 42 LIGHT. cal arrangement for "the ghost." A large sheet of plate glass, A B, without silvering, is fixed near the front of the stage. The "ghost," brightly illuminated by a lime- light, is placed at C D, and the rays of light passing from this figure through the trap door, C B, and reflected from A B, enter the eyes of the audience at 0, just as if they came from a similar figure standing on the stage at E T. The mirror may also be placed at an angle across the stage, and the " ghost " reflected from behind one of the wings. If the reflecting surface is curved, parallel rays falling upon it at different places, will make with it difi'erent angles, and, hence, will be reflected in dif- ferent directions. If the reflecting surface is of parabolic form, then parallel rays falling on it will be reflected to one point, called its focus, and reciprocally a source of light being placed in this focus, its rays are all thrown out in parallel lines. The reflecting power of different bodies is very various, and changes with the angle of the inci- dent light. Transparent bodies, such as glass, at certain angles, allow part of the light to be transmitted, and part Fig. 25. LIGHT. 43 to be reflected. This last increases with the obliquity un til a certain point is reached, called the angle of total re- flection, when all is reflected, and the body is, as it were, absolutely opaque. The following table illustrates the relative reflecting power of a few substances at different angles. The incident light making angles with the surface of 60° to 90» Water Glass (Ist surface) Black Marble, polished Mercury as on Mirrors 5° 15° 30° 72 21 6.5 54 30 11.2 60 15.6 5.1 70 15.6 5.1 1.8 2.5 2.a 60. Unpolished surfaces, by reason of their minute, invisi- ble, but countless irregularities, reflect the light they receive in all directions ; or, in other words, disperse it, thus becoming, in this respect, similar to luminous bodies. Part of the light received is of course, however, absorbed, even if the body is white ; and if it is colored, it must absorb all those colors which it does not give back. Thus, a red body absorbs all the colors but red, a green one aU but green. When the reflecting surface is corrugated very finely, as is the case with mother of pearl, fine rulings on glass, etc., the reflected rays from adjacent ridges (being very little separated), will interfere and produce (in mixed or white light), colored fringes, or, as it is called, "m- descencey All visible, non-luminous objects also reflect light, but from extreme irregularity of surface, presenting all angles to the incident ray, they throw it off in all dire'^'tions, like luminous bodies. Reflection will not only take place at the surface of a dense medium, but also of a rare one. Thus, an object may be seen reflected from below a surface of water, where we may regard the air as the reflecting surface i4 LIGHT. (see Fig. 26), or from the rear surface of a plate of glass, where the same is true. So, also, a ray of light, passing Fig. 26. ■iiiiiiiiiiiiiiiiiiii!miiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii»^^ out with a vein of flowing water, will be reflected back and forth from the interior surface of the water, thus fol- lowing the stream and illuminating it, and seeming to bubble up where the stream breaks. By an extensive application of this principle, the beau- tiful experiment of the illuminated fountain is arranged, the jets being lit up by two powerful lime or electric lan- terns, one immediately below, and the other directly above them. If light falls obliquely on a very thin plate, as in a soap bubble, film of oil on water, etc., the rays reflected from the first and second sur- faces, may interfere, being very little apart (see Fig. 27), and thus produce, with mixed or white light, colors depend- ent upon the thickness of the film, as will be explained further on. The rays which pass through will also sufi'er interference from those twice reflected within the plate, so giving us the same effect by transmit- ted, as by reflected light. The film may be of a rare substance, as air inclosed be- Fig. 27. Fio-. 28. LIGHT. 45 tween two plates of glass. If this air film varies in thickness regularly around a centre, as when it is pro duced by placing a lens upon a plate of glass it will de- velop, with white light, concentric rings of color. These are known as Newton's rings. The apparatus for produc- ing them is shown at Fig. 28. Refraction. — A ray of light, coming obliquely upon the surface of a body more or less dense than that through which it was before passing, is bent from its course, and. passes on in a new direction. This bending is called refraction. Where the ray passes from a rare to a dense body, it is bent inward towards the latter; in passing from dense to rare this is re- versed. In other words, the path of the ray would be the same whichever way it went ; or if it passes through a dense or rare body with parallel faces, it will simply be displaced, not changed in its direction. (See Fig. 29.) If the opposite sides of the body were not parallel, however, ^. ^^ its direction would be changed (see Fig- 30). ^^ ^ The amount of this bending differs with different bodies, and also with the angles of the incident rays. The relative refracting powers of differ- ent substances, are indicated by certain numbers, called "INDICES OP REFRACTION." Thcsc are determined by experiment. See Table. Table of Indices of Refraction. — Solids. Fig 29. 4 X)\ \c Chromate of Lead... 2.50 to 2.97 Diamond 2.47 to 2,75 rhosphorus 2.224 Glass of Antimony. 2.216 Native Sulphur 2.115 Zircon 1.95 Borate of Lead 1.866 Carbonate of Lead.. 1.81 to 2.08 Ruby 1.779 Felspar 1.7G4 46 LIGHT. Tmrmaline 1.668 Topaz, colorless .... 1.610 Beryl 1.598 Emerald 1.585 Flint-glass 1.57 to 1.58 Quartz 1.547 Rock Salt 1.545 Rosin 1.543 Sugar 1.535 Phosphoric Acid ... 1.544 Sulphate of Copper 1.53 to 1.55 Citric Acid 1.527 Nitre 1.514 Spermaceti 1.503 Crown Glass 1.500 Sulphate of Potash 1.509 Sulphate of Iron 1.494 Tallow, Wax 1.492 Sulphate of Magnesia 1.488 Iceland Spar 1.654 Obsidian 1.488 Gum Arabic 1.476 Borax 1.475 Alum 1.465 Fluor-spar 1.436 Ice 1.310 Liquids. Bisulphide of Carbon 1.678 Oil of Cassia 1.631 Oil of Bitter Almonds 1.603 Canada Balsam 1.528 " Linseed 1.485 ** Naphtha, rapeseed 1.475 Olive 1.470 '* Turpentine 1.470 *' Almond 1.469 ♦' Lavender 1.467 Sulphuric Acid, 1-7 1.429 Nitric Acid, 1-48 .... 1.410 Sol. Caustic Potash, 1.41. . 1.405 Hydrochloric Acid... . 1.410 Sol. of Common Salt 1.575 Alcohol, rectified 1.372 Sulphuric Ether 1.358 Sol. of Alum 1 356 Blood 1 354 Albumen, White of Egg... 1.351 Distilled Vinegar 1.372 Water 1.336 Gases. Air 1.000294 Oxygen 1.000272 Hydrogen 1.000138 Nitrogen 1.000300 Chlorine 1.000772 Nitrous Oxide 1.000503 Nitric Oxide 1.000303 Ammonia 1.000385 Sulphuretted Hydrogen 1.000644 Hydrochloric Acid 1.000449 Carbonic Oxide 1.000340 Carbonic Acid 1.000449 Cyanogen 1.000834 defiant Gas 1.000678 Marsh Gas 1.000443 Hydrochloric Ether 1.001095 Sulphuric Ether 1.900153 Sulphide of Carbon 1.000150 LIGHT. 4T Fig. 31. Fis. .32. To obtain the actual refraction for a given ray by a given substance, we have this rule. The sine of the angle of the ray after refraction, equals the sine of the angle of the in- cident ray divided by the refrac- tive index of the body in ques- tion. Thus, suppose an inci- dent ray, A B, whose sine is C D, then the sine, G 0, of the angle, E B G, which the ray makes after entering the dense body, X Y, is equal to C D divided by the index of refraction of X Y. Thus, if X Y is flint-glass, 0G=CD--1.6 thisbeingthe index of refraction of this substance. We have already seen, that if the opposite surfaces of a refracting medium are not parallel, the direction of a ray passing through will be changed. (Fig. 29.) It is moreover evident that if these surfaces, one or both, are curved, the rays falling upon them will be more or less converged towards a point, or diverged and scattered, according as the curve or curves are convex or concave. See figures 32, 33 and 34. If now all these curves should be elliptical, the following re- sults would be accurately attained. Parallel rays falling upon a convex •lens would all be converged and collected at a certain point 0, Fig. 35, which is called Fig. 34. the " FOCUS." The distance C O is called the " focal DISTANCE." This is fixed for the same lens, but dif- fers with the material and 33. 48 LIGHT. Fig. 35. curvature of different lenses. We can roughly determine this for any lens, by holding it up at some distance from a window, and finding how far from it a sheet of paper must be held, to receive a sharp image of the same. This will be the focal distance. If instead of parallel we have divergent rays coming upon the lens, say from C, outside of the focus 0', they can- not, of course, be collected Fig- 36. at so near a point as 0, but yet will be centered at some more distant one C. If C comes nearer to 0', Q' will be further off from 0. These points C and C are called -'conjugate foci," and of course admit of an infinite variety of values in the same lens, though always having a fixed inverse relation to each other. If corresponded with O', the rays would emerge from the lens parallel, and thus have no focus. If C were inside of 0', the emerging rays would diverge. A con- cave lens reverses all the actions of a convex one. formation of Images by Lenses. — Again, if rays from Fig. 37. points not in the line C C, such as P and come upon the lens A B, they will be focussed at certain points P' LIGHT. 49 and 0', bearing the same relation to P and that C does to C. We shall thus have an image formed at 0' P' of luminous or illuminated object, differing in size, as the conjugate foci differ in distance from the lens. So that a small object, brought near to the lens, will make a large image at a distance, while a large body at a dis- tance will make a small image close to the lens. E. g. For the first, the solar or gas microscope and magic lantern ; for the last, the camera obscura. The image, as we see, will be inverted. This image may be again magnified by another lens placed beyond 0' P', Fig. 37. Spherical Aberration. — All that we have said would be strictly true of lenses whose curves are elliptical or hyper- bolic ; but in practice such lenses cannot be constructed ; their curves must be spherical. Now with spherical lenses the rays passing through the edges are more refracted than those traversing the central portion, and are therefore fo- cussed at a nearer point. Hence, the clear image, C D, made by the central rays would be obscured by the scattered light, P, from the edges, and likewise with Fig. 38. the image of the border rays. With a single spherical lens we cannot ob- tain a perfectly sharp image, owing to this, which is called ''spherical aberration." By the combination, however, of two or more lenses of different curvature, this difficulty is over- come. For details, see Brew- ster's optics. We have the fol- lowing forms of lenses in common use: A, Piano convex; B, Piano 5 50 LIGHT. concave; C, Double convex; D, Double concave; E, Meniscus. Double Refraction. — When a transparent solid is sub- jected to pressure or strain in one direction, it splits or sepa- rates an incident raj into two, one of these being refracted according to the laws already expressed, the other in a dif- ferent direction and degree. The first is called the " ordi' nary ;^^ the second the ''extraordinary ray^ Many crystalline and other bodies possess the same properties, owing to the molecular strain generated in them by the crystalline force. Among these the most remarkable is Iceland Spar, carbonate of lime crystallized in oblique rhombohedric prisms. These crystals have two obtuse and six acute solid angles, a line joining the obtuse angles is called the AXIS of the crystal. In this direction alone it has no double refraction, any plane parallel to this axis is called a "PRINCIPAL SECTION," as A X B Y. In every other it separates the rays in a most complete manner, so that a line seen through a moderate thickness of this substance appears double. We shall return to this property under the head of "polarized light." Though Iceland Spar alone possesses the property of double refraction in so great a degree as to be at once evident to mere casual observation, a multitude of other bodies have the same power in much lower degree. Thus quartz may be made to show a double image, if formed into a prism, as will be presently explained. So also with glass under pressure ; by combining many prisms, a double image may be obtained. Except, in- deed, for the mechanical difficulties, similar treatment would develop like results in nearly all crystalline bodies, except those of the "monometric" system, i.e., cubes, octohedrons, and their deriv-atives, in most animal and LIGHT 51 vegetable fibres, shells, scales, granules, etc., and even in some liquids. By certain effects, however, resulting from this double refraction, hereafter to be described, its exist- ence in all these bodies is easily, though indirectly de- monstrated. To develop double refraction strongly in quartz, we cut two prisms from a crystal in such a way that in A B C E D the axis of the crystal is in the direction A B, and in B C F G D E parallel to G F, and cement their oblique faces together. A ray then entering the surface A D E I at right angles, suffers no change until it reaches the surface D E C B at X, when it is separated by double refraction, aided by the obliquity of the prism, into two rays, X P and X Q. This appa- ratus is called the Prism of Rochon. A similar prism may be made of Iceland Spar, or we may use simply a single prism of that substance, correcting its chromatic aberration, by a compensating prism of glass. Such a " double image prism," as it is called, will give an enormous separation to the two rays, or images. See Appendix, page 294 To show the double image with compressed glass, a system of prisms is arranged, as in the drawing, so that A B C D project and suffer compression from plates of metal forced against their ends. The intermediate prisms, R M N, etc., not pressed, serve to correct in the ray passed from R to T, all deviation, dispersion, etc., except that double refraction produced by the pressure. Compositionof White Light— We have heretofore spoken of light as if it were all of one kind ; a simple motion of a definite sort. Every thing we have said would indot^d 52 LIGHT. Fig. 43. be strictly true, say of pure yellow light, such as is pro- duced by burning alcohol and salt; but would require certain limitations if applied to white light, which is what we generally understand by the unlimited noun "light." This light is far from being simple ; and we will now pro- ceed to study its nature. If a ray of light, passing through a narrow opening or slit, is al- lowed to fall upon a refracting prism whose axis is parallel to this opening, it will of course be refracted or bent from its course ; but instead of producing a single line of light upon a screen placed in its path, it will develop a broad band, in which all the colors of the rainbow will be found beautifully blended. It would thus appear that, in the ray of white light were all these colors. This decomposition of white light may be strikingly shown Fig. 44. LIGHT. 53 as follows. (See Fg. 44.) We place Fig. 45. as an object, in an ordinary magic- lantern, B, arranged for the lime- light, a plate of brass having an opening in it i of an inch wide, shaped like a rainbow, with 3 inches span. This being properly *'focussed" on a screen, say at a distance of 50 feet, the lantern should be tilted up, as shown in the drawing, and a prism held as indicated by the figure, in front of its object lens. The arch of light will then be depressed by refrac- tion to the proper place on the screen, and broken by dispersion into all the prismatic or rainbow hues. The prism for this experiment should be made by grinding a glass bottle into the shape shown, figure 45, cementing plates of glass on the open sides with the mixture of molasses and glue used by printers to make their *'inking-rollers," and filling it with bisulphide of carbon. We know on general mathematical principles, that the more rapid the vibrations in a ray, the more it ought to be refracted ; and we therefore conclude that white light consists of not one only, but many kinds of motions ; the slowest of which, separated from the others as at R, is recognized as red light, while the most rapid is seen as violet atY; and all others arrange themselves in gradual progression as indicated in the plate facing page 123. Nor does our experiment stop here. By the use of deli- cate thermometric apparatus, (see page 121) we find that be- low R, Fig. 43, intense heat is present, gradually fading off as we descend ; while a sensitive photographic plate or fluoresent screen will inform us, that above V, (for a distance 54 LIGHT. more than five times as great as R Y, if an electric light and lenses and prisms of quartz are used,) there is spread an influence which, though invisible, acts most powerfully in effecting photo-chemical decomposition, and may even become perceptible to the eye through the influence of fluoresent action, this we call actinism. The variegated band or ribbon of light thus obtained is called a "spectrum." If sunlight is used in this experi- ment, and the spectrum, in place of being projected upon a screen, is examined through a telescope into which it is thrown, countless fine black lines will be seen crossing the band, which from their discoverer are called Fraun- hofer's lines. Passing over their cause, to be hereafter discussed, we at present notice only that they are abso- lutely fixed with reference to the colors of the spectrum, and their relative places in its length ; and being sharp and well defined, are of the greatest use with regard to all purposes of measurement. (See plate.) The most prominent of these are marked upon the plate, and desig- nated by the letters which have always been used to describe them. If by another inverted prism or lens, or otherwise, these colors are united, they produce w^hite light again. It is customary to speak of the colors con- tained in white light and constituting the spectrum, as seven in number: Ked, Orange, Yellow, Green, Blue, Indigo, andYiolet; or as 3 primary colors: Red, Yellow, and Blue, with the various tints which would be developed by their combination ; as Green composed of Yellow and Blue, Yiolet of Red and Blue, and Orange of Red and Yellow. In this case, regarding the spectrum as being made of three graduated spectra, one of red, one of yel- low, and one of blue light, which, variously overlying each other, produce all the blended tints. Complementary colors are such a pair as would, united, make white. One of these at least must therefore be a LIGHT. 55 compound color. Thus, red and green, yellow and violet, blue and orange, are complementary colors. We ought, however, to remember that the above ideas are adopted merely for convenience ; and that every tint is as truly a distinct thing, as each note in a musical scale. Tliat each tint of color represents simply so many vibrations per second. Lengths of Undulations and Numbers per Second. Lengths in parts of an inch. Number in an inch. Number per second. Line B Line C .00002708 .00002583 .00002441 .00002319 .00002295 .00002172 .00002072 .00002016 .00001909 .00001870 .00001768 .00001G89 .00001665 .00001547 86.918 38.719 40.949 48.123 43.567 46034 48.286 49.609 52.479 53.472 56.569 59.205 60.044 64.631 451,000,000,000,000 473,000,000,000,000 500,000,000,000,000 527,000,000,000,000 632,000,000,000,000 562,000,000,000,000 590.000,000,000,000 606,000,000,000,000 611.000,000 000 000 Middle Red Line D Middle Orange... Yellow... Line E Middle green Line F Middle blue ** indigo Line G 65.^,000,000,000,000 691,000.000,000,000 723,000.000 000.000 Middle violet Line H 733.000.000,000,000 789.000,000,000,000 Spectrum Analysis. We find that certain bodies, when vaporized in a flame, communicate to it definite colors; as sodium, yellow; stron- tium, red ; barium, green, etc. ; and we naturally conclude that the particles of these bodies are capable of vibrating at certain rates, corresponding to these colors, and at no others. This supposition is most completely confirmed. If we look at the spectrum produced by a flame otherwise non-luminous (as of alcohol, a Bunsen burner, etc.\ in which sodium is introduced, we shall see, in place of the rich band of various colors, simply a single sharpl}^ defined yellow line (see plate facing page 123, Na.) ; showing that OD LIGHT. all the vibrations here present, are of exactly one velocity. Strontium, in like conditions giving a purplish red light will show us some red lines and one bright blue (see plate facing 123, Sr. ;) so with other bodies, especially the metals. The amount of the material needed to produce these effects, is extremely small ; and we at once see that we have here a most useful and wonderful means of chemical analysis for some bodies. We provide ourselves with a Spectroscope, which con- sists essentially of a narrow slit or opening, a prism, and telescope to examine the spectrum, and a Bunsen burner with a stand supporting a loop of platinum wire. We then fasten the substance to be examined in the platinum wire, support it in the flame of the burner, and examine the spectrum of this flame with the spectroscope. The lines we then see, tell us at once of the presence of certain substances, and the lines we miss, of the absence of others ; due allowance being made for certain effects of combina- tion, which we have not here space to discuss. Absorption Bands To produce the bright lines above mentioned, the heated body must be in the state of vapor ; a highly heated solid, gives out rays of all velocities, and hence produces a con- tinuous spectrum. But if this mixed or white light — this harmony of various notes — passes through such a vapor, capable of but one or two rates of motion, the rays of -the white light which correspond with these, communicate all their motion to the vapor particles, and so lose the power of further onward propagation. Thus, a ray of white light, which has traversed such a vapor, will have lost just those motions which the vapor itself would pro- duce ; and if resolved into a spectrum, will show blank spaces, that is in fact dark lines, where these rays should have been. LIGHT. 57 This may be proved experimentally ia a most direct and striking manner (see Tyndall, on Heat, p. 42t) ; and furnishes us at once with a means of accounting for the Frauenhofer lines. (This was first pointed out by Bunsen and Kirehhoff). An. de Chem. et Phy. T. 68. p. 5. The sun's light proceeds from within his atmosphere. This atmosphere consists of incandescent vapors. Each substance in this vapor abstracts certain vibrations, and produces certain blank spaces, or dark lines., in the spec- trum. By comparing these dark lines with the bright lines of vaporized bodies, we may determine what ma- terials are found in the solar atmosphere ; and thus reach the grand idea of analyzing an orb 95 millions of miles distant. We conclude, in fact, that the principal solar lines indicate, as above, certain bodies in his atmosphere, as follows: B indicates Potassium. C " Hydrogen. D (( Sodium. E (( Iron. b ** Iron and Magnesium. P (( ^Strontium (?), Iron, and Hydrogen. G (( Iron. H (( Calcium. We also recognize chromium, nickel, and possibly, zinc, cobalt, and manganese ; but find no indications of lithium, copper, or silver. This process has been also applied to many fixed stars and nebulae, and has shown us that some of these last (even those which have been resolved; as the dumb-bell, that in sword-handle of Orion, etc.,) are not star clusters, but gaseous bodies ; since they give three bright lines, and not continuous spectra. (See Journal of the Franklin Institute, Vol. 49, p. 422). Vaporized bodies, however, do not alone possess this power of absorption. Many, or all gases, at ordinary 58 LIGHT temperatures, liquids, and solids, act in a similar manner; and the study of these absorption bands has opened a new field to chemical research. (See Journal of Chemical Society, 1864, Yol. 2., pp. 59, 304.) Reference will be made from time to time to these matters, under the heads of the various substances which have special relation thereto. Fluorescence. — When light vibrations of very great rapidity, such as belong to actinism rather than to light, fall upon certain bodies, they cause them to vibrate, but with less velocity, so that visible rays are thrown off from them in place of the actinic ones which they have received. Thus, if the spectrum, made with lenses and prisms of quartz from the electric light, is caused to fall on a sheet of paper coated with a solution of sulphate of quinine in water containing tartaric acid, a long band, above the part generally luminous, will be seen to glow with pearly blue light. This light contains dark bands analagous to the Frauenhofer lines. A great number of substances possess this power ; canary-colored glass, extract of sun- flower, of horse-chestnut bark, of chlorophyl, of turmeric, nitrate of uranium, and the natural phosphate of the same, as also a phosphate prepared in a peculiar manner to resemble the native phosphate. But none act in so striking a manner as quinine and canary glass. The light best fitted to develop these effects, is that obtained by the electric discharge in a vacuum, and no experiment in physics can exceed in beauty that which is seen when the discharge of a Ruhrakorff coil is caused to flow from the tinfoil lining of a canary goblet, over its edge to the pump plate, under an exhausted ^jljlil bell-jar. We then have u goblet of lu- Fig. 46. LIGHT. 59 miaous emerald, filled with fire, from which pink, purple, and blue streams pour over on every side, and drip at every part. A very beautiful effect is also produced by passing the Fig. 47. discharge through an exhausted electric egg of this same glass, and figures, painted on a screen with quinine, entirely invisible by ordinary light, become luminous in the dark by the light of the "aurora tube" (Fig. 79). Phosphorescence. When these reverberations or secondary vibrations of light are very persistent, and last for some moments after the cause of them has ceased to act (resem- bling the resounding of a sonorous body, as a bell after it has been struck) ; we call the phenomenon Phosphorescence, not, however, using this term in the same sense as when it is employed in connec- tion with the body Phosphorus, which, in this sense, is not phos- phorescent. Sulphides of calcium and stron- tium, exhibit this action in the most prominent manner. Such bodies, exposed to a strong light, and then removed to a dark place, continue to glow visibly for some time. The same effect is also very beautifully shown in some Geisslor tubes, which continue to emit light after the discharge in them has ceased. 60 LIGHT. This is noticed in the form shown at A B, in Fig. 80. Dispersive Power is the term applied to that property of unequally refracting the different colors, by which the prismatic spectrum, and other similar effects, are pro- duced. This power varies with different bodies, as may be seen from the followinor table : Table of Oil of Cassia 0.139 Sulphur after Fusion 0.130 Phosphorus 0.128 Sulphuret of Carbon 0.115 Balsam of Tolu 0.103 Balsam of Peru 0.093 Oil of Bitter iMmonds 0.079 Oil of Aniseed 0.077 Acetate of Lead, fused 0.069 Guaiacum 0.066 Oil of Cumin 0.064 Oil of Tobacco 0.064 Gum Ammoniac 0.0G3 Oil of Cloves 0.062 Oil of Sassafras 0.060 Rosin 0.057 Oil of Spearmint 0,054 Kock Salt 0.053 Caoutchouc 0.052 Flint-Glass, 1st sample .... 052 Oil of Thyme 0.050 Oil of Caraway Seeds 0.049 Oil of Juniper... 0.047 Flint-Glass, 2d sample 0.047 Nitric Acid 0.045 Canada Balsam 0.045 Oil of Rhodium 0.044 Oil of Poppy 0.044 Muriatic Acid 0.043 Gum Copal 0.043 Nut Oil 0.043 Dispersive Powers. Turpentine 0.042 Felspar 0.042 Balsam Capivi 0.041 Amber 0.041 Calcareous Spar. 0.040 Oil of Rape-seed 0.040 Diamond 0.038 Olive-oil 0.038 Gum Mastic 0.038 Beryl 0.037 ^ther 0.037 Seleinte 0.037 Alum 0.036 Castor-oil 0.036 Crown-Glass, Green 0.036 Water , 0.035 Citric Acid 0.035 Glass of Borax 0.034 Crown-Glass 0.033 Plate-Glass 0.032 Sulphuric Acid 0.081 Tartaric Acid 0.030 Nitre, least refr 0.030 Borax.: 0.030 Alcohol 0.029 Sulphate of Baryta 029 Rock Crystal 0.026 Borax Glass (B 1, Quartz 2) 0.026 Sulphate of Strontia 0.024 Fluor Spar 0.022 Cryolite 022 LIGHT. 61 Chromatic Aberration.— Its Correction. From this difference in dispersive power come some important results. We readily see that our former statements about lenses must be modified with regard to this ; namely, that beside other irregularities in the focussing of rays where white light is used, the violet rays would come to a focus much nearer to the lens than the red, and the other colors at va- rious intermediate points ; so that from this cause we would have an ill defined image fringed with color which would change with the relative position of the screen object and lens. Thus at Y the im- age would have a border '^g- • of unfocussed red and other rays, and at R of violet and other ones. This would be a most fatal error, but fortunate- ly it may be corrected, thus : A concave lens would of course reverse all the effects of the convex one A, B, and would disperse the colors in an opposite direction. Such a lens, if of equal curvature, would therefore exactly neutralize the disper- sion of A, B ; but then it would also neutraliz(^ the refrac- tion, and thus make the lens as useless as a flat plate of glass. But if the concave lens were made of a substance having a much greater dispersive power than A B.then it would neutralize the dispersion, even though of less cur- vature, and thus would (Hminish, it is true, but not dati^oy the refractive action of A B. In short, it would make it a lens of longer focus, and " achromatic," that is without color. The substance commonly used for this purpose is (lint- glass. Combining thus a double convex lens of crown- 6 LIGHT. Fipr. 50. glass, with a plauo concave, or with a meniscus lens of flint (there being here two refracting curves for the crown, and one for the flint, see A B), or by uniting two double convex lenses of crown, with one double concave of flint, see C D, we obtain what are called " achro- matic," or " CORRECTED LENSES," which are almost free from irregularity of re- fraction. It is, however, impossible to find any two bodies, whose refractive and dispersive powers so exactly correspond as to make an absolute correction. Polarized Light. — We have yet another point to con- sider about the nature of light. Not only is a ray of light composite, in the ways already mentioned, but also as regards the plane in which its vibrations are moving. Thus, a ray of ordinary light may be looked upon as consisting of vari- ous series of undulations, moving in every possible plane containing its line of direc- tion. The cross section of such a ray would be represented by Figure 50, the radial lines indicating the planes in which the particles were vibrating. By various means we may so modify and " sift out" these vibrations, as to obtain a ray in which all are in parallel planes, so that its section would be represented by figure 51, the parallel straight lines representing the planes in which the particles are vibrating. Plane Polarized Light is that in which all the vibrations are in parallel planes, at right angles to the direction of the ray. This plane polarized light (the word plane is often LIGHT. 63 Fig. 52. omitted for brevity) may be obtained from ordinary light, in one of the three ways following : 1st. By reflection and transmission. If a ray of light falls upon a transparent reflecting body, such as water or glass, at a certain angle, differing with the substance, it will be partly reflected, and partly transmitted ; both parts will be polarized more or less entirely, the one transmitted, in a plane perpendicular to the surface of the reflector, and the reflected one at right angles to this. The figure will give a good idea of this action. We here assume only two planes of motion in the ordinary ray, for convenience. In practice, of the other vibrations, those nearest one plane go to it, and those nearest the other to it ; or escaping, give that mixture of ordinary light to our polarized ray, from which it is never entirely free. The polarizing angle for Glass is 56° 45'; for Water, 52° 45' ; for Quartz, 57° 32'; for Diamond, 68° ; and for Obsidian, 56° 30'. 2nd. By absorption. If a ray of light passes through a slice of the mineral tourmaline, which is cut parallel to the axis, all its vibrations, except those in one plane, are absorbed and destroyed within the crystal, so that the emerging ray is polarized. The iodo-sulphate of quinine in crystals possesses this same property. 3rd. By double refraction. Whenever a ray suffers double refraction, it is also polarized, each of the emergent rays being polarized in a plane at right an- gles to the other. Nicoi.'s i*i{i.sM i se»' ])age 50). i.^ciaad Spar is the substance used in preparing polarized Fis:. 53. 64 LIGHT. light in this way, and since in practice it is desirable to get rid of one of the two rays, the crystal is cut in a plane passing through its obtuse angles, and again cemented together with Canada balsam. By this means the extra- ordinary ray, A B, suffers total reflection at the surface of the balsam, and is thrown out at the side. This is called a Js^icol's Prism. Fig. 53. Properties of Plane Polarized LigM. — These may be most easily understood and remembered by means of a simple physical illustration, which is extremely useful as a means of briefly expressing the facts of the case, though in no respect to be regarded as an explanation of their final cause. Suppose that light rays are so many flat rulers, and that polarizing bodies are gratings, whose bars are par- allel to the planes in which they transmit polarized light. Then an ordinary ray, having its rulers in all positions, coming upon one of these gratings, all the rulers are "reflected," "absorbed," or " refracted, out of the way," except those which are parallel to the bars of the grating, and which therefore get through. If now a second grating is set beyond, parallel to the first, all the rulers which have passed the first will pass it also ; but if this second grating is set at right angles to the first, the rulers will all be stopped by the two ; for those that passed the first are just those which cannot pass the second. Thus it is in fact with light. If we place two polarizing bodies in the path of a ray, it will pass, if both are par- allel, but will be entirely cut ofi" if they are "crossed." When two polarizing bodies are used, the one nearest the light is called the polarizer, and the other the analyzer. Thus Fig. 54 represents an apparatus for developing the effects of polarized light. Light falls upon the mirror A B from the left. The reflected, polarized ray, which is thrown upward, then passes through the tube H H, which LIGHT. 6b contains an analyzer, ^jg* 54. such as a bundle of glass plates placed obliquely in the tube. If these tast are paral- lel to the mirror A B, the polarized ray will be reflected, and will not be seen through H H ; but by turning this tube H H hori- zontally through 90° in the socket G G, on which it rests, the light will be no longer reflected, but will be transmitted by the analyzer, and may be seen through H H. A rotation, however, of 90° more, or 180° from the starting point, will again bring the analyzer into a position to reflect all the polarized light from A B and show none of it through liiiii H H. Objects to be ex- amined by polarized light, may be placed in the ring F F,, and viewed through the analyzer in 11 II. Plates of doubly refracting sub- stances, display splendid colors, and sections of crystals, the beautiful iris rings to be presently described. 6-^- Fig. 55. LIGHT. A plate of doubly-refracting substance may be regarded as a grating, with two systems of openings (Fig. 55) at right angles, leading off, however, in different directions. Colored Effects of Plane Polarized Light. — Suppose a ray of ordinary light. A, to fall upon a Nichol's prism, and 1 „ 6. to yield a plane polarized ray, O. If this ray now passes through a very thin plate of some doubly refracting body, C, placed as represented, the ray will be split into two, p' and s'; one of which will be retarded behind the other, by the distance of part of a vibration (this depending on the nature and thickness of the film) ; but these, being in different planes, cannot interfere with each other, though they will be so little apart in position as still to be prac- tically together. If now these adjacent yet separate rays fall on another Nichol's prism, each will again be split, and a half of each will be refracted to p' s', while the other halves will be thrown out at p" s". Now p' and s' will be in the same plane, and capable of interfering. If then, white light has been used, and the retardation of one ray behind the other amounts to half a red vibration, the red vibrations in p' and s' will interfere and destroy the red light ; if, however, the retardation was half a red vibration, it would be more than half a yellow or blue one; LIGHT. 6t Fig. 57. hence these waves would not interfere, and we should have green light at p' s' by the removal of the rea. If the plate C were thinner, or of some other material, the retardation would have been less; it then would not have destroyed the red, but some other color, and we should therefore have something else than green at p' s'. If the principal section of the plate C was parallel or perpendic- ular to the plane of polarization of the light O, it would pass through unchanged, and be transmitted or not by D, according as B and C coincided or not. If instead of the thin plate C we place a slice, made at right angles to the axis, of a double refracting body, in the same position, with a diverging beam of polarized light, we will have projected on a screen a black or white cross, intersecting a system of consecutive rainbow-colored rings. (See figure 51.) The cause of this may be stated as follows : The slice of crystal may be regarded as having its doubly re- fracting properties arranged about its centre ; or, to give it a physical repre- sentation, as having openings for the passage of rays, in radial and circum- ferential directions, as in the figure 58. Suppose now the polarized light to be vibrating in a vertical plane, its vibra- tions will pass through in the line M N, and the other radial lines near ^'[i this, without change ; so also through the parts of the circles near X' Y, which are also vertical ; and this light ^ will then either be stopped or transmitted by the analyzer D, according as that corresponds or is opposite to the polarizer B. This will then give the black or white cross. A vertical polarized ray, striking at R. will, however, find .^vni ^ 68 LIGHT. Fig. 59. Fig. 60, no direct passage, but will be split, part going through the radial, part by the circular passage. These divided rays will be united, and will produce color, as in the case of the thin plate before described. Moreover, the divergent rays, coming on this plate, will have to traverse greater thicknesses the further they come from the centre (see figure 59) ; thence will produce different colors, and as these differences will vary con- centrically about the axis X, the colors will be disposed in rings, intersected by the crosses. The best specimen for this experiment is a plate of Ice- land spar, about one-twentieth of an inch thick, well pol- ished. Such an one, placed as indicated by the drawing Fig. 56, in a good gas microscope, with a screen about 20 feet off, gives a most charming figure, which may be further en- hanced by adding to it a plate of quartz, similarly cut and about one-tenth of an inch thick. Some bodies, such as nitre, have two axes of no double refraction near to- gether. Similar slices from these give double systems of rings, crossed by dark or light " brushes," produced by union of two crosses. (See Fig. 60). Other crystals of two axes, such as sugar, aragonite, etc., have these so far apart that only one system of rings and brush can be seen at a time. (See Fig. 61.) These actions of polarized light are used in a variety of ways in chemical investigations. The change of color pro- duced by polarized light in many bodies, crystalline and organic, help us to recognize them; and Fi?. 61. LIGHT. 69 the presence of these crosses or colored rings are simi- larly useful, besides helping us to study the condition of crystalline bodies, in relation to their condition of me- chanical strain. Blocks of glass, gelatin, etc., strained by pressure or sudden heating or cooling, exhibit colored figures, having Fig. 62. remarkable analogy to those of crystals. These, when used in the gas microscope, must have an object-glass in front of them, between them and the analyzer. Rotation of the Polarized Ray.— If in place of the slice of Iceland spar, in the experiment just described, we put a similar plate of quartz, cut from a crystal at right angles to its axis, we shall have a system of colored rings as before, but instead of the cross, black or white, the central space will be filled with colored light, which will change, as the analyzer D is rotated, through all the colors of the spectrum. The reason of this is as follows: This sub- stance, though like others it does not produce double re- fraction along its axis, etc., does twist the plane of the polarized ray, giving its edge, as we may say, the shape of a screw-thread. The amount of this twist is. however, dififerent for each color. Hence in each position of the TO - LIGHT. analyzer some colored rays will pass, while others will be stopped; thus the colors are produced. Some specimens twist the ray in one direction, others ib the opposite. Those which so turn it that the colors change upward, from red through yellow, green, etc. to violet, when the analyzer is rotated over the crystal in the direc- tion that watch-hands move over its face, are said to have right-hand polarization, or to be dextrogyre ; those that change oppositely from violet, through green, etc., to red, by the same motion, or similarly to the first by an oppo- site motion, are said to have left-hand rotation, or to be Isevogyre. The amount of this polar rotation varies with different bodies, and in the same body with its thickness. This power of rotation belongs to other solid bodies besides quartz ; to others, as Faraday's heavy glass, it may be communicated by magnetic action ; and it also exists in some liquids and solutions, as that of cane and grape sugar. Saccharimeter. — With regard to these substances this property is used as a commercial test of value. By means of an appropriate apparatus, a given depth of solution, containing a known quantity of the sample in question, is examined by polarized light, and the amount of rotation suffered by a given color being ascertained, we may from this estimate the quantity of the corresponding substance contained in the solution. Cane sugar has right, and grape sugar left-hand rotation. If these are mixed they in part neutralize each other's effect; we must, then, after our first determination, convert the whole into grape sugar by hydrochloric acid, and then, having made a new determi- nation, settle by a calculation the original proportion of each. This process may be applied to many other sub- stances. ELECTRICITY. 1 Fig. 64. Circularly Polarized Light is that in which the vibra- tions are in two planes, at right angles to each other, but differing also in phase by an odd number of quarter-wave lengths. It may be produced by passing a ray of plane polarized light, through a Fresnel's rhomb (Fig. 63), when suffering two total reflec- tions at an angle of about 54°, it will issue w^ith the properties required for circular po- larization. Circularly polarized light may also be obtained by Airy's method, if ordinary light is made to fall vertically on a film of mica or selenite, of such a thickness, that the ordinary ray shall be retarded more than the extraordinary by the required amount. With circularly polarized light the images produced by slices of crystals are changed, the black cross disappearing, and the alternate segments of the rings being dislocated. Thus, for Iceland spar, we have the Figure 64. Elliptically Polarized Light is that in which the vibra- tions are in two planes, perpendicular to each other, but differing by some quantity, not an exact multiple of quar- ter-wave lengths. This is obtained from a Fresnel's rhomb if the incident and refracted rays have any other angle than 45° between their planes; also if common light is reflected from a metallic surface. ELECTRICITY. We indicate by this term the cause of a certain class of phenomena, such as the attraction which amber, etc., pos- sesses for light bodies after being rubbed, the lightning flash, the decomposition of bodies by a' galvanic apparatus, the polar position of a magnet, etc. Y2 ELECTRICITY. Theory of tlie Double Fluid. — In giving a physical explanation of electric phenomena, and connecting them in a way convenient for study and reference, we must begin by making certain assumptions, which, however, it must be remembered, have no other proof than that they strvc t( connect and explain the phenomena in question. We assume that all space and all mattei* is pervaded by two impalpable fluids, alike in general character, but having, in certain respects, exactly opposite properties; that, for this reason, when mingled in equivalent quanti- ties, they entirely neutralize each other, as regards these opposing properties, and show no signs of their existence (these fluids, together or separately, may perhaps constitute that ssther, to which we have before alluded, as serving to transfer the vibratory motions, which we recognize as light andheat). These opposite electric fluids we designate as positive (+), and negative ( — ), and their assumed pro- perties may be very briefly stated. The particles of each fluid are mutually repellant, but attract those of the opposite fluid, and of matter generally. They are capable of rapid motion or transfer through some bodies, as metals, moist air, etc., but are almost precluded from traversing others, as glass, shellac, dry air, etc. They may be, 1st, separated and confined in or upon certain bodies ; or, 2nd, set in rapid motion in opposite directions ; or, 3rd, Caused to form series of currents in the individual particles of certain substances. These three conditions give rise to three divisions of our subject, Statical Elec- tricity, Galvanism, and Magnetism. STATICAL ELECTRICITY. By this term we indicate that condition of the electric fluids in which they are separated more or less completely, and confined for a greater or less time, to certain bodies. The methods by which this separation may be effected ELECTRICITY. 73 are numerous, but the simplest and most characteristic is by friction. If two different substances are rubbed upon each other, their electric fluids will be more or less separated; an excess of the positive fluid collecting in one, and of the negative in the other. Experiment : Rub a glass rod with a silk handkerchief; bring the rod near a pith-ball suspended by a silk thread, the ball will be attracted ; so also will ii be by the silk (each fluid in turn attracts the matter of the ball). Now touch the ball with the rod, then ball and rod will have the same fluid ; hence the ball will now be re- pelled by the rod, but will be more powerfully attracted by the silk than before (these two have now opposite fluids which attract). In this case the glass collects the positive fluid, the silk the negative. The power of collecting one or the other fluid is not positive in certain substances, but simply relative ; the body which takes positive and loses negative fluid by friction with one substance, will, with another, take negative and yield positive. Arranging all substances in their order of positive or negative attraction we would have a table like the following, in which any substance, rubbed with one below it, will take positive fluid, but rubbed with any above it will take negative fluid. This is what we mean by calling a body electrically positive or negative. The bodies at the beginning are, in a general sense, posi- tive ; those at the end negative ; but any substance is positive to any one below it, and negative to any one above. Table of some Substances in their Electrical Relations, Fur. Paper. Smooth glass. Silk. Woollen clothe Lac. Feathers. Rough glass. Wood. Sulphur. Gun-cotton and like bodies. 74 ELECTRICITY. Conductors and Insulators. Bodies through which the fluids easily pass are called Conductors, those which resist their motion, Non-conduc- tors or Insulators. These properties are relative, as we may see by the following table, which begins with the best conductors, and ends with the worst, which is, there- fore, the best insulator. In the following list the bodies are arranged in their order of conducting power, according to the present state of knowledge on the subject, and though probably not absolutely correct, it will serve to show how insensibly conductors and non-conductors merge into each other: — Table showing the Relative Condacting Power of Certain Substances for Electricity. Metal, best conductor. Well-burnt charcoal. Plumbago. Concentrated acids. Powdered charcoal. Dilute acids. Saline solutions. Metallic ores. Animal jfluids. Sea water. Spring water. Rain water. Ice above 13° Fahr. Snow. Living vegetables. Living animals. Flame smoke. Steam. Salts, soluble in water. Rarefied air. Vapor of alcohol. Vapor of ether. Moist earth and stones. Powdered glass. Flowers of sulphur. Dry metallic oxides. Oils, the heaviest the best. Ashes of vegetable bodies. Ashes of animal bodies. Many transparent crystals, drj Ice below 13° Fahr. Phosphorus. Lime. Dry chalk. Native carbonate of bary'es. Lycopodium. Caoutchouc. Camphor. Some siliceous and argillaceoua stones. Dry marble. Porcelain. Dry vegetable bodies Baked wood. Dry gases and air. Leather. ELECTRICITY. Parchment. Mica. Dry paper. All vitrifications. Feathers. Glass. Hair. Jet. Wool. Wax. Dyed silk. Sulphur. Bleached silk. Resins. Raw silk. Amber. Transparent gems. Shellac. Diamoad. Gutta percha, worst conductor. Y5 The Electrical Machine. To eflfect this separation of the fluids with ease, we employ an "electrical machine," which consists of a glass disk. A, mounted on an axle, and turned by a handle, of a " rubber," B, made of leather spread, with mosaic gold (bisulphide of tin), and supported on a glass column ; of a silk apron, E, of collecting points, F, and of a round ended cylinder of metal, G, called the *' prime conductor," supported on a glass column. The positive electricity, developed in the glass, by fric- tion on the rubber, when the former is turned, is car- Fig. 65. ried round to the points, being protected from escape by the apron. At the points it is drawn oflf into the T6 ELECrr.TCITY. prime conductor, where it collects. The negative elec- tricity accumulates in the rubber. To get much positive electricity, we must connect the rubber with the earth, by some good conductor ; to get much negative, we must in like manner connect the prime conductor, insulating of course the rubber. With this apparatus, many ingenious experiments, illus- trating the attractive and repulsive powers of unlike and like fluids, may be performed, such as the dancing images, the sportsman and birds, the dancing pith balls, the in- dustrious spider, the electric flyer, and orrery, etc. Hydro-Electric Machine. A similar separation of the electric fluids may be effected by the friction of steam, containing particles of water in suspension, on the sides of peculiarly shaped orifices. (See Fig. 66.) In this case Fig. 66. the orifices become negative, the issuing steam positive. Points placed opposite the escaping steam will collect the posi- tive fluid. Again, by the dry pile to be described hereafter, see page 101, this same separation is effected ; and again, also, by the Ruhmkorfif coil, which will be described, when the necessary pre- liminary matters have been discussed. (See page lit.) Electrical Attraction and Repulsion. The first effect of electricity actual!}^ observed, and that most likely to excite attention, is the attraction and subsequent repulsion of light bodies. The connection of these actions with our theory of electricity has been already explained, page 72, but the phenomena them- selves may be strikingly exhibited by the following pieces ELECTRICITY. Tt of apparatus and instruments for measurement of electric force : The chime of bells (Fig. 67) consists of a brass rod, Fig. 67. A. B, supported by a stand, and connected by a chain or wire with an electrical machine. From each end of this rod hangs by a chain a metallic bell, wliich thus receives electricity from the machine. Near each bell hangs by a silk thread a little brass ball or clapper, which is attracted by the bell, until it strikes it, when, receiving a charge of fluid, it is repelled in turn, but attracted then by a centre bell which is suspended by a silk cord fVom the rod, A B, and is connected with the ground by a chain. Each clapper, as it strikes this bell, therefore gives up its elec- 7* Y8 ELECTRICITY. tricity, aud is then again attracted to the outer bell, so that a constant motion and chiming is thus maintained. The dancing pith-balls (Fig. 68) exhibit a like action. The balls are in this case first attracted by the upper plate, touch it, become charged, are repelled; strike the. lower plate, so lose their charge, are again attracted, and so on. Fig. 69. The electrical umbrella (Fig. 69) consists of many strips of colored paper connected with a brass rod, which may be supported on the prime conductor of an electrical ma- chine. These strips, being all similarly excited, repel each other, and so stand out like an open umbrella, when the machine is in operation. On a similar principle is constructed the quadrant elec- troscope. In this the brass rod fits into the prime con- ductor, and has attached to it a light rod with a pith-ball. This being charged similarly to the rod, is repelled from it, ELECTRICITY. T9 the amount of its repulsion, measured on a small quadrant, indicating the intensity of the charge. This is, of course, but a rough instrument ; one far more delicate is furnished in the gold-leaf electroscope, Fig. TO. Here two strips of gold-leaf (Dutch gold is best) are sus- pended from a brass plate, in a glass vessel ; any electric fluid passed into them causes them to repel each other, and so diverge. Fig. 70. Fig.. 71. A more delicate instrument, of like nature, is seen in Coulomb's electrometer. Fig. Yl. In this case a light rod of gum shellac carries at one end a pith-ball, and is sup- ported by a (ibre of silk, the whole being inclosed in a glass vessel ; a small brass ball terminates a wire which enters 80 ELECTRICITY. * this vessel. If this wire, and consequently the brass ball is excited, it first attracts the pith-ball, but then, after con- tact, repels it, so twisting the silk fibre. The distance to which the pith-ball is repelled in this, as in a former case, indicating the intensity of the electrical excitement in question. Distribution of Electricity. The electric fluids, when separated as above, always reside on the surfaces of bodies. Thus, in non-conductors, they cannot penetrate the substance, and being collected at the surfaces must remain there; and in conductors, by reason of the mutual repulsion of like particles, they are forced outward to the surface. Opposite fluids, put in the same conductor, would, of course, mingle and neutralize each other. By reason of this repulsion, the fluids readily collect on and escape from projections and points ; and similarly enter a conductor by such points from a sur- rounding surcharged medium. Thus we terminate all instruments, intended to retain electricity, with rounded surfaces, balls, and the like ; but use points where we desire to introduce the fluids, as in the collecting points, F, Fig. 65, of the electrical machine (these points are attached to the brass rods, one of which is shown in the drawing, along their iuner sides, and are directed towards the glass plate). So, again, with lightning rods; these should have sharp points, for, if thus provided, and in good connection with the ground, they attract and gradually withdraw from the approaching thunder-clouds their charges of electricity, and thus often prevent a '^flash,^^ as well as divert to a safe channel those not to be so obviated. That electricity occupies alone the outer surfaces of bodies, may again be shown if we provide a hollow metallic sphere, with an insulating support and an opening by ELECTRICITY. 81 which its iDterior surface may be reached. Then, when the sphere has been charged, electricity may easily be obtained from its outer surface by touching it with a ''test plane," i. e. a little button or wafer of brass mounted on a glass handle ; while none can be obtained by this means from the inner surface. The " test-plane," after touching the sphere, should be brought in contact with the plate of the electroscope. Fig. *rO, when the gold-leaves will diverge, if any electricity has been received by the planes. Indlictioil of Electricity. — This phenomenon, like the last, is the direct, necessary consequence of those general properties of the electric fluids, stated at the commence- ment of this subject. Thus, suppose a conductor charged with positive elec- tricity, to approach an insulated conductor in the natural state, without touching it. Then the positive fluid in the charged conductor will drive the positive fluid in the insulated conductor to its further side, and draw the negative fluid to the nearer. The fluids would in this way be separated in this insulated conductor, so long as the charged one remained near it. This mode of sepa- rating the fluids we call "induction." It develops some curious consequences. The Electrophorus. — Suppose we have a shallow pan, filled with solid shellac, and excite this negatively by friction ; that we then place upon it a plate of brass, varnished with shellac, and having a glass handle. The lower face of this will become Fig. 72. positive, and the upper negative, for the reasons just stated. If now we connect this with the ground for a moment, by touch- ing it with the finger, the repel- led negative fluid will escape, and jj^ some positive will enter to fill 82 ELECTRICITY. the space of that drawn towards the shellac. If this plate is now lifted away from the shellac, by its glass handle, it will clearly have in it an excess of positive fluid, which, being no longer held to one place by an attraction, can pass all over it and escape. This action can be repeated without loss of electricity to the shellac, and thus furnishes a supply of that agent, which admits of many ingenious applications, among others the light- ing of gas burners, as in the many forms of apparatus for that purpose, invented by Robert Cornelius, Esq., of Philadelphia. The Leyden Jar. — We have already noticed, that the electric fluids, by reason of repulsion, reside on the sur- faces of conductors, and tend to escape therefrom. Such bodies are thus unfit to serve as reservoirs of this agent, but by an application of this fertile action of "induction," the difi&culty is surmounted. We coat a glass jar inside and out, nearly to the top, with tinfoil. We close the mouth with a cork or cover of wood, through which passes a rod, connected metalli- cally with the inner coating. Holding the jar by its outer coating in the hand, or otherwise connecting it with the ground, we then pass electricity into the inner coating, by the rod. As this spreads over the inner coating, it drives away a corresponding amount of the same fluid from the outer coating, and draws into it an equiva- ^^^ • lent amount of the opposite, so that the two coat- ings become oppositely charged, and these fluids, attracting each other, do not tend to escape. This apparatus is called the Leyden Jar. A number of these having their outer coatings united by strips of tinfoil pasted in a box which contains them, and their inner coatings united by brass rods, form a "battery of Leyden Jars." To use tb*^ electricity thus stored, we make such a connectioQ ELECTRICITY. 83 Fig. 74. that it may pass from one to the other coating, through the object or apparatus we wish it to traverse. Transfer of Electricity. — Elec- tricity may pass from one body to another, by three different methods; by conduction, by con- vection, and by discharge. Conduction is the transfer through particles in contact. This takes place with different facility, in different bodies, as has been already mentioned, see page Y4, and also varies with the temperature of the same body, diminishing with an increase of heat. Where the size of the conductor is sufficient for the quantity of the current to be conveyed, no change is produced ; but when the conductor is insuf- ficient, and resists the passage of the fluid, heat is developed. Thus a large battery being discharged through a strip of gold-leaf, placed between two plates of glass, melts and vaporizes the gold ; driving it into the glass, so as to produce a purplish stain. So w^ith a fine wire of iron, or platinum, etc. When passing freely through a good conductor, elec tricity moves with a velocity of 288,000 miles per second. This was measured by Wheatstone, in 1834. (See Philo- sophical Transactions for that year, page 589.) Convection is the transfer of electricity by motion in particles of an interposed fluid, such as air. Thus, the air particles touch- mg a charged conductor, get the same fluid, and are repelled, move off to some neutral or oppositely charged body and allow others to take their piace. These in turn follow the same course, a current is established, and Fig. 75. 84 ELECTRICITY. the electricitj is thus transferred. This may be well shown by attaching a pointed wire to the prime-con- ductor of a machine, and holding a burning candle or lamp near it. The flame will then be blown aside, if not extinguished, by the draft of air. Discharge is the simultaneous transfer of electricity developed by induction in the particles of an interposed non-conductor. Thus, particles ABC etc., in a given line' being excited by mutual induction, make a discharge when A gives its fluid to B, at the same time that B gives its own to G,.and so on. This transfer may be more or less resisted, and its character thus modified, by the inter- posed substance. We accordingly have two classes of discharge, the disruptive discharge, flash, or spark, where the fluids pass through a highly resisting medium, and the diffused or flame discharge, where the medium ofi'ers but slight resistance. Between these there may be every possible gradation ; but we may include all cases in one or other of these classes, without further division. The Disruptive Discharge is seen when the fluids pass through the air, as in the ordinary spark from the machine, from the Leyden jar, from the induction coil, and in the lightning. In all cases it is accompanied by a light and sound, both varying in intensity with the amount of elec- tricity which is passing. The color of the light varies with the points between which, and the medium through which, it passes. In all our experiments the spark is ac- companied by a transfer of the material of which the points are made, and it is only reasonable to conclude that the light owes its existence to the vibrations pro- duced in these particles, as they are torn ofi* from one point and thrown towards the other. The sound is caused by the rapid heating and cooling of the air in the path of the flash, thus producing in it such a vibration as will affect our ears. ELECTRICITY. 85 Viewed through the spectroscope, the light of this dis- charge gives only bright lines, varying with the sub- stances, showing that they are in a gaseous state when developing this light. (Pro. of Roy. Inst., 1863, p. 47.) Many pretty experiments may be made with this dis- charge — as the lightning-jar, the lightning-plate, the spark-plate, the letter-plate, the luminous profile, the lightning-house, etc. This spark is capable of igniting many compounds, — as gun-cotton, ether, explosive mixture, burning gas, etc. ; but will not fire gunpowder, unless it is retarded, as by passing through a wet string.* It will also effect many chemical changes of combination and decomposition. For igniting most of these bodies we place them upon the table of the universal discharger, Fig. 76, and then pass Fig. 76. ll!iilll!llililllillll!illllliiill!!il!'iiPiillllliil!li^^ • In this experiment the wet string must be between the powder and the negative coating 8 86 ELECTRICITY. the spark through by means of the adjustable rods c d f g, supported on the glass columns h h. Liquids like ether we place in a spoon, and take a spark into it by a wire hung from the prime conductor of a ma- Fig. 77. chine; and for explosive gases, such as a mixture of oxygen and hydrogen, we use a little brass cannon (Fig. 78), having a small brass rod passing through a gla.ss tube Fig. 78. into it, so that a spark entering this may spring acro»» to the body of the cannon inside, so firing the contaipcd gases, and driving out a cork placed in the muzzle. If an egg be placed upon the table of the universal dis- charger. Fig. 76, and the spark from a Leyden jar, or the Ruhmkorff coil, be passed through, it will be illuminated in a remarkable manner, so as to have the appearance of being red-hot. Its vitality is of course destroyed, but it is otherwise uninjured by this treatment. ELECTRICITY. 8T 79. The Glow Discharge. — This takes place when the inter- posed medium offers little resistance to the passage or the fluids. This is well seen where the discharge traverses rarefied air, gas, or vapor, as in the aurora tube (Fig. 7^), where the tall glass tube is exhausted by the air-pump, and then has its caps con- nected with the poles of a Ruhmkorff coil. The color of the discharge in this case is chiefly effected by the rarity and nature of the interposed medium. This is well illustrated in the Geissler tubes (Figs. 80 and 81), which are filled with various gases, and then exhausted, by means of a mercurial air-pump, to a Torricel- lian vacuum, or nearly so, and sealed. If now the platinum wires, passing through their ends, are connected with the poles of a Ruhmkorff coil, streams of beautifully variegated light will fill them, crossed by obscure bands. With hydrogen this light is chiefly pale purple; with nitrogen pink, with a violet-blue glow, filling the negative end of the tube, where the wire, entering the bulb, will be coated as it were with a layer of orange-colored light. Bulbs of Canary glass placed within these tubes, as in C D, Fig. 80, Fig. 80. 88 ELECTRICITY. glow like so many emeralds amid the purplish and pink light of the discharge. In some cases the exhausted tubes, bent into complex forms, are surrounded by other tubes, which may be filled with various fluorescent or even simply colored solutions. Thus in Fig. 81 we fill A C with a solution of quinine and B D with nitrate of uranium. We then have the negative ball, say F, full of blue light, the part T) C brilliant rose-color, F purplish- pink, and the portions within the solutions are bordered from A to C with a magnificent blue, and from B to D with a rich green color. The single tube G H (Fig. 81) is arranged on the same plan. Simple colored solutions, such as bichromate of potash and sulphate of copper, may be used in place of the fluorescent ones, with equally MAGNETISM. 89 Fi-. 82. beautiful effect. There are few things, if any, within the range of philosophical experiments to be compared for beauty with these just de- scribed. If a double barometer (Fig 82) has its two mercury columns connected with the poles of a "coil," a stream of light will pass through the arched vacuum above. This light will be white, on account of the vapor of mercury present. An absolute VACUUM (obtained by placing caustic pot- ash in a vessel filled with carbonic acid and then exhausted, and allowing the pot- ash to absorb the last trace of this gas) is totally impervious to the electric dis- charge. If, however, the potash is heated the discharge will be renewed, the slight vapor produced seeming to furnish matter sufficient for this action. This same effect was observed with the intense water-bat- tery of 3520 cells used by Gassiot as well as with the coil. (Philosophical Trans- actions, 1859, p. 148. MAGNETISM. Magnetism is that department of electricity which treats of the properties of magnets. A magnet is a body which has the power of attracting iron and some other metals, and of setting itself in a definite position with reference to the earth's axis, so that one end points toward the north pole. According to our theory, a magnet owes these, and its other peculiar properties, to the fact that the electric fluids 8* 90 MAGNETISM. Fig. 83. Fig. 84. in its various particles are not at rest, but are flowing in opposite directions, malcing a series of closed circuits in each particle. Regarding for simplicity the positive flnid alone, Fig. 83 would indicate the condition of a magnet. The small spheres representing particles, and the arrows showing the direc- tions of the currents of positive fluid in each. The negative fluid we suppose to be forming similar currents in the opposite direction. With the direction for the positive current indicated in the figure, the front end (to the right) would be the South, the other end the North pole. These directions being reversed, the poles would be reversed also. The aggregate effect of all these currents would evidently be nearly identical with a close spiral around the surface, as in Fig. 84. Of magnets, we have — natural magnets or loadstones, artificial magnets, and electro-magnets. The end of any magnet, which turns towards the north, we call its north pole, the other the south pole. Loadstone. — This is a peculiar ore of iron, being a mix- ture of the proto and sesquioxide of iron (FeO-f Fe^Og), found abundantly in nature, and possessed of the magnetic properties already mentioned. Artificial Magnet. — This is a bar or rod of steel, which has received magnetic properties by being rubbed with another magnet, or placed within a spiral galvanic current. Such a magnet will possess all the peculiar properties of the natural loadstone, generally in intenser degree. These magnets are sometimes made in the shape of straight bars, sometimes they are bent into the shape of a MAGNETISM. 91 horse-shoe or of the letter U. These are called " horse- shoe or U MAGNETS." They gradually lose their mag- netic properties unless a bar of soft iron is kept across their poles as S N, Fig. 85. This bit of iron is called an "arm- ature." A magnetic bar made light, and delicately Fig. 85. MAGNETISM. balanced, so as to tarn horizontany about a point, is called "a magnetic needle.'''' Two such needles, fastened one over the other with re- versed poles, form an as- Fig. 86. tatic needle, which will stand east and west, and be deflected by a very fee- ble force, see Fig. 86. In practice astatic systems are so constructed as to have one needle more powerful than the other; they therefore point north and south, but can be de- flected by very feeble forces. With all magnets, like poles repel, opposite poles attract. Besides iron, in its va- rious forms, magnets attract feebly nickel, cobalt, and chromium ; and very powerful mag- nets have also a pecu- liar effect on all other bodies, causing some to arrange themselves Iq the line of their poles, and others at right an- gles to this, see Fig. 87. The first are called Magnetic, the second Diamagnetic bodies. Among the magnetic substances are salts of iron^ even in solution, as also those of chromium and manga- nese ; among the diamagnetic are bismuth, antimony, phosphorus, most gases, and organic bodies. Electro-magnet. — This is a bar of soft iron, around which a spiral galvanic current is made to pass, as, for example, MAGNETISM. 93 in a bobbin of insulated wire. Such a body has all the properties of a mag- net so long as the current continues, but loses them the moment this cur- rent ceases. In electro-magnets the wire is gene- rally wound entirely outside of the iron bar ; so that the current produces its Fig. 88. Fig. 89. effect only inwards. A very ingenious modification has been made, however, by Mr. Ebon Jayne, in which the Fig. 91. GALVANISM. u'hole influeDce of the current is utilized. In this, the coil is wound on a bar of iron which forms one pole, while a cylinder of iron, slipped over the coil and joined to the bar at one end by an iron cap forms the other. See Fig. 90. Magnetism by Induction. — Whenever a magnet is brought near a bar of iron or steel, it con- fers upon it, all magnetic properties. The poles of the induced magnet are opposite to those of the inducing one. Thus, if the horse-shoe magnet, N S, have two iron keys brought near it, as in the drawing, the keys will be magnetized by induction, with poles, as shown in the figure ; and nails, in turn brought near to these, w^ould be likewise affected. If the body once magnetized in this or any other way is of steel, it retains its magnetic properties, but if it is of wrought iron, it loses them, as soon as the magnetizing agency is withdrawn. GALVANISM. Gralvanism is that department of electrical science which treats of the phenomena first pointed out by Galvani and Volta, as the result of certain connections of two metals and a liquid, and of other actions having a close relation to these in cause and character. According to our theory, we believe that when two metals are immersed in a liquid capable of acting chemically upon one of them, and are connected by a good conductor, as the chemical decompo- sition of the liquid, which ensues, progresses, the electric fluids are separated, and caused to pass in opposite currents GALVANISM. 95 through the circuit of the materials employed ; the positive fluid, going to the metal least acted upon, thence through the conductor to the other metal, and so through the liquid to the starting-point again ; the negative fluid following, mean- while, the same path in the opposite direction. Such a combination of parts is called a galvanic " couple;" many of these connected form a " BATTERY ;" couplcs of Cer- tain forms are called "cells." The two metals or their equivalents (for non-metallic bodies may in some cases be used) are called " elements ;" the one most acted upon being always the positive sub- stance (see page 73) ; the other the negative. The posi- tive fluid will, however, always come out from the nega- tive element. The fluid used is commonly called the " EXCITING LIQUID." In the following table each substance is negative with all above, and positive with all below it, when placed in galvanic relation. This order is in some cases, however, effected by the nature of the fluid employed. See Phil. Transactions, 1840, p. 113. Diluted sulphuric acid is the exciting liquid assumed in the table here given : — Electro-chemical Order of the Principal Elements. Electro-negative. Iodine. Oxygen. Phosphorus. Sulphur. Arsenicum. Selenium Chromium. Nitrogen. Vanadium. Fluorine. Molybdenum. Chlorine. Tungsten. Bromine. Boron. 96 aALVANISM. Carbon. Cobalt. Antimony. Nickel. Tellurium. Iron. Titanium Zinc. Silicon. Manganese. Hydrogen. Uranium. Gold. Aluminum. Platinum. Magnesium. Palladium. Calcium. Mercury. Strontium. Silver. Barium. Copper. Lithium. Bismuth, Sodium. Tin. Potassium. Lead. Electro-positive. Cadmium. The terminal points of the series, where the connection outside of the liquid is not completed, are called the posi- tive and negative " poles" or " electrodes," according as the positive or negative fluid comes from them. Galvanic Batteries. Omitting those forms of galvanic batteries which, how- ever interesting in an historical connection, are not prac- tically useful, and have therefore been abandoned, we will describe the forms now generally employed. Hare's Calorimeter. This consists of two very large spirals of sheet zinc and copper, wound together, in close proximity, without con- tact. This is accomplished by interposing strips of card- board while hammering into shape, these being afterwards removed, and the strips sustained and kept in place by wooden bars, as indicated in the Figures 93, 94, 95. This pair of plates is then immersed in a tub, bucket, or large jar of diluted acid, and for a short time will act with won« derful energy. The hydrogen, liberated by the decompo- sition of the water (whose oxygen goes to the zinc form- GALVANISM. Fig. 93. 9t Fig. 94. ing oxide of zinc, which is then taken up by the acid), at once attaches itself to the copper-plate in countless bubbles, which not only interfere with the con- ducting power of the series, but present a positive surface in place of the negative copper, thus causing the battery rapidly to "run down," or lose strength. Smee's Battery. — Tn this each cell consists of a glass jar, containing diluted sulphuric acid, in which hang from a cross-bar of wood three plates, the middle one of pla- tinum, coated with a deposit of the same metal tinely 9 98 GALVANISM. divided, to which hydrogen bubbles will not adhere. At each side of this hangs an amalgamated zinc plate. These two zinc elements are united, so that they act as one. In connecting several of these, the zincs of one cup are joined by a wire to the platinum of the next, and so on. In place of platinum plates leaden ones, coated first with silver, and then with platinum black, may be em- ployed. This battery is feeble but steady, and may be charged and left for a long time without deterioration, if the connection is not made between its poles Daniel's Battery. — In this each cell consists of a copper vessel, containing a solution of sulphate of copper ; within this a porous cell or cup of unglazed earthenware, con- taining diluted sulphuric acid, in which is immersed a cylinder of zinc. The hydrogen liberated in this case passes into the sulphate of copper, decomposing it and throwing down metallic copper, by combining with the oxygen of the oxide of copper in the salt, so forming water. This battery, therefore, gives off no gas at all, and (some crystals of sulphate of copper being placed on a shelf in the outer vessel to restore the solution as it be- comes impoverished) is very constant. It is, however, feeble, as compared with the following forms. , GALVANISM. 99 Fi-. 97 Grrove's Battery. — Tn this each cell consists of an outer jar, containing diluted sulphuric acid, in which is set a hollow cylinder of zinc ; within this is a porous cup, filled with strong nitric acid, in which hangs a slip of platinum foil. The hydrogen liberated in this case, passing into the nitric acid, takes some of its oxy- gen from it to form water, leaving it as nitric oxide, which at first dissolves in the acid, and when that is saturated escapes in fumes. The decomposition of the nitric acid developes an in- crease of force, which ren- ders this the most powerful form of constant battery yet invented. Illllllilllllllllllllllllllllllllllllllllllllllillllllllllllllllll Fi*'. OS. Bunsen's Battery. — This battery differs from the last only in the substitution of solid bars or cylinders of " gas-carbon " for the platinum foil. This is dictated by economy. The best form of this battery for rapid , handling is that manufactured by Delcuil, of Paris. The cokes are hollow cylinders, very porous, and connection is made by copper plugs, which can be forced into the ends of these, and are joined to copper strips riveted to the zincs Connections can be made and broken by this me&ns with greater ease, certainty, and dispatch than L.cfC. 100 GALVANISM. with the best form of binding screws ; and this, in the management of a large battery, is of great importance. For telegraphic purposes, however, the battery made by Chester & Co., of New York, is better than this. Modified Forms of the Bimsen Battery. — Chester & Co., of New York, manufacture a Bunsen battery, which an- swers very well for medical applications, in which the gas-coke is made into a cup in which the zinc is supported, the exciting fluid being a solution of sulphate of mercury. This gives off no fume and uses no seriously corrosive liquid. Its energy and constancy are increased by addi- tion of a little table-salt. An ordinary Bunsen cell will act in a similar manner, for a short time, if the porous cell is removed, and a solution of glauber salt (NaO,S03) is em- ployed as the only exciting liquid. (See Journal of the Franklin Institute of Pennsylvania, Yol. 50, p. 68, 1865.) Chester & Co. also manufacture another form of the same battery, under the title of "electropoion battery." The important feature in this is the substitution of a mix- ture of sulphuric acid and solution of bichromate of pot- ash for the nitric acid. This removes the difficulty of acid fumes, and relieves a great expense, the cost of this mix- ture being about one-tenth that of nitric acid. A good recipe for this mixture is this : in a gallon of water dissolve one lb. of bichromate of potash ; to this add two pints of oil of vitriol. (See Journal of Franklin Institute, Yol, 50 page 68.) This battery works very well with the Kuhmkorff coil and also for the electric light. The Iron or Maynooth Battery. — In this, each cell con sists of an iron cup, containing a mixture of equal parts of nitric and sulphuric acids, within this is a porous cup filled with dilute sulphuric acid, and containing a plate of amalgamated zinc. Tiie best form of this battery is that manufactured by Bullock and Crenshaw, of Philadelnhia, GALVANISM. 101 iu which the iron cups are rectangular, and the zincs of rolled metal. This is the cheapest form of battery, and equal, if not superior, to any other of equal surface, in effect. We must, however, in this connection remark that the mixture of strong nitric and sulphuric acids here used gives off a most acrid and irritating fume less during the action than during the charging and emptying of the battery. Arrangements should, therefore, be made for a strong draft or current of air to carry these fumes away from the operator during this process. The best plan is to conduct it in the open air. The electro-motive forces of some of the preceding bat- teries have been estimated as follows : Bunsen element 839 Grove 829 Daniel 470 Smee Hare 210 208 Besides those already mentioned, very many other com- binations of solids and liquids have been suggested for galvanic batteries, but none others have proved in prac- tice successful. Thus, we have copper and carbon with the mixture of bichromate of potash and sulphuric acid already mentioned. Copper and zinc with SO3 and flowers of sulphur. The Bunsen solids with sesquichloride of iron, etc. The Dry Pile, invented by Zamboni, consists of many thousands of alternate disks of zinc and silver paper ; or of silver paper, with a paste of black oxide of manganese and gum, spread on the wrong side, without the zinc; arranged in a glass tube or other insulating support. (See Fig. 99.) CJX- 102 GALVANISM. Fi^. 100. The natural moisture of the paper here serves the office of au exciting fluid, and very intense, though feeble effects are pro- duced. Thus, the ex- tremities will attract light bodies, and even give minute sparks ; exhibit- ing in fact rather the effects of statical, than of dynamical electricity. This results from the great number of ele ments, and bad conduct ing power of the pile, which favors a separation of the fluids, but not the establishment of a cur- rent. One of the piles, thoroughly dried, ceases, to act ; but recovers on exposure to moist air. A double column of this sort arranged as in (Fig. 100) will keep the light ball, a, vibrating between its poles for years. Gas Battery.— See page 109. Management of Gralvanic Batteries. — Where a number of cells are to be used together, they should be united in different ways, according to the effects which we desire to obtain. If great resistances are to be overcome, as in the electric light, the heating of fine wire, etc., they should be placed in a series, as indicated by (Fig. 101), whoiT a Bunsen battery is shown in ground plan, the ii 1 11 1 1 1 111 1 GALVANISM. 103 carbon of each cell being connected with the zinc of its right hand neigh- Fig. 101. bor. This gives us a current of intensity, great in proportion to the number of the cells (within certain limits), and of quantity, pro- portional to the size of a single cell. If the resistance to be overcome is very small, as when the current has only to pass through a short and good ^^°' ^^^• conductor, the cells should be united, as shown in (Fig. 102), all the zincs being joined together at one side, and the carbons at the other ; then, con- necting Z and C, we obtain a current, whose intensity is only that of a single cell, but whose quantity is pro- portional to the number of cells employed. Usually we require in electrical apparatus, some in- tensity, with as much quantity as we can get. A good Fiff. 104. practical arrangement for ordinary apparatus is shown (Fig. 103), and for a Ruhmkortf of 9 inch spark, or under, 104 GALVANISM. in Fig. 104. For larger coils the series should be in- creased in quantity, but not in intensity, until we come to the large coils of 16 to 20 inches, when 15 cells should be used, in three rows, giving intensity of three, and quantity of five. In setting up a nitric acid battery, it is most conveni- ent to mix the dilute acid in the cells beforehand, then to put in all other parts, and make the connections ; and lastly, to pour in the nitric acid. This prevents the dulling of the connections by fumes, and saves nitric acid ; as the cells get soaked with the diluted sulphuric acid beforehand. The mixed liquids to be used should always be mixed beforehand, and allowed to cool entirely. In all large batteries the connections should have as much contact surface, and be as large in section, as pos- sible. After use, the battery should be taken apart, as soon as possible. More injury will occur to a battery, while standing disconnected, than when it is in active use; as the local currents have at this time full play. The zinc elements should be well washed, drained, and kept (apart from the other portions of the battery) in as dry a place as possible. The porous cells and carbons should be kept in water, if to be used soon again, and soaked for at least a week (in water frequently changed), before being dried and put away. To put away porous cells, etc. (which have been simply washed after use), in contact with the zinc elements, is to insure great injury, and perhaps even destruction, to the battery. Carbons used with such batteries as that described, page 100, should be soaked in diluted nitric acid, when they become coated with a white deposit of oxide of zinc, or the like. Amalgamation. — Zinc is the active element employed GALVANISM. 105 in all batteries, and on account of certain impurities which cannot be removed, but by very expensive treat- ment, is subject to " local action ;" that is, a little speck of some foreign substance will form, with the zinc im- mediately around it, a little galvanic pair, which will cause a rapid corrosion of the zinc, formation of hydrogen bubbles, interference with, and opposition to the general current of the battery, and other evils. To remedy this difficulty, we resort to amalgamation ; that is, coating the surface of the zinc with mercury, which unites with it, and practically excludes all such local action as we have described, preventing, in fact, to a great degree, any chemical action between the liquid and metal, until the entire galvanic circuit is closed, and the true chemico- electric action begins. Batteries in use should be thoroughly amalgamated. This is best done some days before they are to be set up, as zincs freshly amalgamated, sometimes heat, and suffer local action, in an unaccountable manner. Effects of the Galvanic Currents. Heating and Lnminous. — We have already noticed that a wire is heated by a current, which it is unable to conduct, and that the discharge of a battery of Ley- den jars will thus fuse and vaporize gold, iron, plati- num, etc. (page 83). Similar effects are produced by a galvanic current. Thus, the current from 40 Bunsen cells, 8 inches high, will keep 6 feet of platinum wire, No. 2Y, at a bright red heat, 3 feet at a white heat, and will fuse a sliortcr piece. By cooling part of the wire, as with a wet cloth, we make the rest hotter; because more electricity can pass by the cool wire, heat diminishing the conducting power. The surrounding medium has a certain effect on this experiment, for a draft of air will cool the wire ; as 10(5 GALVANISM. Fig. 105.' also will £;uch a gas as hydrogen, on account of the mo- bility of its particles. Luminous Effects. — When a very powerful series, of 30 or 40 elements, is terminated by points of dense carbon, and these, being first in contact, are separated a little, a most dazzling light is produced. In this case particles of the carbon are driven across from the positive to the nega- tive pole, causing such vibrations as produce intense light to take place in both the points, and to some extent in the flying particles. This may be admirably shown where the points, regulated as they burn away by Duboscq's Electric Lamp, are placed in a lantern, and, through a diaphragm, throw an enlarged inverted image of themselves on the screen. If the lower or positive point in the lamp is replaced by a cup of carbon, holding a fragment of silver, and the discharge is taken from this, the light given off is green, the length of the discharge is increased 5 times, and the negative point becomes beaded with drops of liquid silver, car- ried over by the current. On the screen we see the image shown at Fig. 105. The flame, emerald green, and like a tongue licking the point, now on one side, now on another: the points red, tipped with white, and the silver drops, like so many beads of dew. This discharge, called the electric light, when produced from a single series of 48 Bunsen elements, is equal to 572 candles. By increasing the number of elements in series above this, the gain in intensity of light is small, though the arch of flame may be made longer; thus 46 elements give an intensity of 235, and 80 elements of 238. But by increasing the quantity, as by using three parallel series GALVANISM. 107 of 36 elements, the intensity rises to 385 ; that of sunlight being 1000. We have reason to believe, from certain spectral lines and fluorescent effects, that the intensity of heat and light in the electric discharge is greater than in the sun. See Paper by Wm. A. Miller, in Proceedings of Royal Insti- tute, 1863, p. 47. Chemical Effects of the Galvanic Current. If the poles of a galvanic battery are placed in any com- pound fluid they tend to separate it into its constituents, the positive being attracted to and collecting around the negative pole, and the negative about the positive pole Thus, if we have a U tube, with a solution of sulphate of soda colored by tincture of cabbage, and plunge two plati- num strips, forming the terminals of a battery, in the ends, the acid or negative element of the salt will collect about the positive pole, turning the cabbage-purple red in that limb, while the alkali, or positive constituent, will collect about the negative pole, and turn the purple of that limb to a rich green. Again, if the fluid contains but two ''ele- ments,'*' as water (consisting of oxygen and hydrogen). 108 GALVANISM. these will likewise be separated and eliminated. Thus the glass vessel, Fig. 107, containing water, and having two platinum strips let into it below, connected with the battery, the oxygen will be given off at the positive pole, and the hydrogen at the nega- tive, and these, rising in bubbles, may be collected in tubes ar- ranged for the pur- pose. This action, called Electrolysis, is in- deed our most potent means of effecting the decomposition of chemical bodies. So- dium, potassium, etc., were discovered by this means ; by this means also we mea- sure the quantity of a galvanic current, the amount of water decomposed, and of gas evolved, being in proportion to the quantity of the current passing, we therefore have an apparatus, arranged like the preceding, except that both gases are collected together and measured, the amount collected in a given time, indicating the quantity of the current. Figs. 108 and 109 show two forms of this apparatus. The first is the most complete and efficient, but the second is the simplest and most easy of construction. The cork and wires must be well coated with sealing wax. GALVANISM. Fig. 108. 109 The great industrial ap- Fig- 109. plication of this same action, in electro-plating and gild- ing and electrotyping, must not be forgotten. Here, the matrix or mould being made of, or covered with a con- ducting material, is suspend- ed in a solution of the metal to be deposited, and made the negative pole of a gal- vanic series. The positive metal is then deposited on this in so solid a state as to form a complete plating, or admit of being itself removed and used for printing, etc., as the case may be. Gas Battery and Secondary Piles. After the apparatus. Fig. 107, has been used for a few mo- ments, if it is disconnected from the battery and connected W'ith a delicate galvanometer, a current will be shovni, op- 10 110 GALVANISM. posito to that of the original battery. This is produced by films of oxygen and hydrogen attached to the platinum plates. On this principle Grove constructed his gas bat- tery. So also powerful "secondary piles" may be pro- duced by immersing two or more plates of lead in a solu- tion of Glauber salt, connecting the end plates with a bat- tery, and after a time disconnecting. Properties of Currents Moving Freely in Wires. Magnetizing Effects. — We have already noticed that a current passing around a bar of iron renders it a magnet, permanently if the bar is of steel, temporarily if the bar is of soft iron (page 92). This action is well shown in many pieces of apparatus, such as the divided ring, the armature engine, &c. Fig. 110. The most remarkable application of this action is, how ever, found in the first telegraph practically applied, i. e. that of Morse (Fig. 110). In this an intermittent current (whose breaks and flows are controlled by an operator at GALVANISM. Ill one end of a long circuit), causes, at the other end, an ar- mature or bar of soft iron, attached to a lever, to be re- peatedly attracted by an electro-magnet set beneath it, and thus makes a pencil at the other end of this lever produce upon a moving band of paper, dots by a short and strokes by a more continued pressure. An alphabet of these marks being pre-arranged between two operators, communication may be thus made through great distances with indefinite velocity. By ingenious and elaborate arrangements of mechanism, the message sent is automatically printed by the apparatus, as in the instrument of House or of Hughes, and is even in that of Bain reproduced in an autographic copy. Velocity of Galvanic Currents in Good Conductors. This, according to experiments of the U. S. Coast Sur- vey, is about 18.100 miles per second in land lines, but through submerged cables the velocity is much less. Magnetic Properties of Coils or Solenoids. As might be antici- Fig. ill. pated from the theory of magnets, a coil or solen- oid (Fig. Ill) through which a current is pass- ing, has all the proper- ties of a magnet. It will attract iron, repel with its poles the like and attract the unlike poles of magnets, ar- range itself north and south, and, in fact, comport itself in all respects like a magnetic bar. 112 GALVANISM. Pig. 112. Again, Slich a Coil will tend to draw into itself a bar of iron whose end is brought within its reach. This is well illustrated by the ex- periment of the suspended bar (Fig. 112), and by Page's coil engine, in which bars attached to cranks and alternately drawn into coils, are caused to operate machinery. Again, snch a Coil will cause a magnetic needle to stand at right angles to the planes of its circular currents. This principle is applied Fi^. 113. GALVANISM. 113 in the apparatus used for measuring the intensity of cur- rents ; for the amount of deflection will vary in a known ratio to the intensity of the current. For currents of small quantity the Galvanometer (Fig. 113) is used. This consists of a heavy flattened coil of wire, within and over which an astatic pair of needles is suspended. The deviation of these is noted on a circular graduated scale, when a current is passed through the coil by means of the binding screws. For currents of great quantity we employ the Tangent Compass (Fig. 114), which consists of a band of copper, bent nearly into a ring, supported on a stand, with a binding screw attached to each end, and with a small compass-needle supported at the centre. With this in- strument the intensity of the current is proportional to the tangent of deflection of the needle. A Solenoid will be acted upon by a current in this, as in other respects, exactly like a magnetic needle. By reason of this " tangential force," also, a wire carrying a current tends to revolve about a magnet parallel, or nearly par- allel to it. Again, a Magnet will likewise rotate around a current — as may be proved in a similar mannerrr— and also around a current, passed through half its own length. Many effects similar to the foregoing may be developed by the magnetic action of the earth, and may be readily explained, on the principles already stated, by regarding the earth as a great magnet, with its north pole (in a magnetic sense) at the south, and the south pole at the north extremity of its axis. Wires carrying currents in the same direction attract each other. Wires carrying opposite currents repel each other. A conductor carrying a current between the poles of a 10* 114 GALVANISM. Fig. 114 U magnet, at right angles to the line joining them, is re- pelled. Galvanic Induction. By Currents and Magnets. — If two wires are placed parallel to each other, and an intermit- tent current is passed through one of them, at every in- terruption of the flow an instantaneous "induced or GALVANTSa^. 115 SECONDARY CURRENT," coincident in direction with the first or " PRIMARY CURRENT," will be developed in the other wire. At every renewal of the primary, on the other hand, a momentary induced current will be devel- oped in the other or "secondary wire," opposite in direc- tion to the "primary." These induced currents may be best shown by using coils or helixes of wire, wound on spools or bobbins. Thus we have a large bobbin of fine wire, A, for the Fig. 115. t secondjary, and a smaller one, B, of thick wire, fitting into the fomier, for the primary current. These beinc: put in place, and an intermittent current passed through B, the secondary, developed in A, may be demonstrated by connecting its ends with a galvanom- 116 GALVANISM. eter, or by holding them in the hands, when a shock or series of shocks will be perceived. A like effect would be produced if, in place of interrupt- ing the current in B, we left it continuous, and then rap- idly moved B out of and into A. A magnet may be similarly used, as a substitute for B, being thrust into, and withdrawn from A, with the same Fig. 116. iiftct ; or we may place a bar of soft iron in A, and then ause it to receive and lose magnetism by the approach nd withdrawal of a permanent magnet. This will of oour^ie be precisely equivalent to inserting and withdrawing it. This is the principle of action in the magneto-electric machine, Fig. 116, and others of like nature. By such means, many magnets being employed, currents are oo- GALVANISM, in Fi-. 117, tained capable of electro-plating on the large scale, of illu- minating light-houses with the electric light, etc. Lastly, we may put B in its place, insert a soft iron bar in the centre of it, and then pass a discontinuous current through B ; we shall then have the combined inductive effect of the coil and magnet. This is realized in the or- dinary medical induction coil (Fig. IIT). A bar of iron may have excited on its surface an induced current, which interferes with its in- fluence on the secondary coil. For this reason a bundle of needles is more effective than a bar. If these needles are surrounded by a con- ducting envelope, such as a tube, their efficiency is again reduced, unless this tube has a longitudinal opening to interrupt its conducting power. A secondary helix, like that just described, if made of very great size, constitutes the apparatus known as the Ruhmkorff coil, which yields a secondary current of so great intensity as to possess all the properties of statical Fix. 118. JL m 118 GALVANISM. electricity. This coil, as originally constructed by Ruhm- korff, is shown (Fig. 118) as improved by E. S. Ritchie, Esq., of Boston, in Pig. 119. (See Franklin Institute Journal, vol. 40, p. 64.) Fig. 119. To both these coils, when a great resistance is to be overcome, as when the spark is to be passed in air, the "condenser-'' of Fizeau is an addition of great importance. This consists of two sheets of tinfoil of great extent, 40 to 100 square feet, separated by oil or gummed silk, folded away in compact form (in general, packed in the base on which the rest of the apparatus is supported), and con- nected with the primary circuit, at each side of the point where it is interrupted. This condenser delays the action of the extra-current (to be presently described), and so enables the electricity to collect and overcome a resist- ance before this interfering action can take efifect. Where the resistance is small, as in discharges in a vacuum, or through good conductors, the condenser is not required. The largest coils of this sort contain 30 miles of wire Jn the outer helix, and give sparks of 20 inches in length GALVANISM. 119 This coil is at once the most convenient and powerful means of producing statical electricity within our reach. With 6 to 10 Bunsen cells, one of Ritchie's 6 to 15 inch coils will produce a continuous stream of sparks 6 to 15 inches in length ; will charge a large Leyden jar, so that it will be discharged with a report like a torpedo many times in a second; and will operate all electrical vacuum experi- ments with a splendor and volume of light entirely unap- proached by any other electrical apparatus. It is not, however, fit to perform experiments of attraction and re- pulsion, because the fluids are developed in it, not steadily, but in a series of instantaneous flashes. The Extra-Currents. — This is the name given to induced currents, similar to those above described, which are developed in a primary wire at the moment of making and breaking connection. The inverse extra-current, de- veloped at making connection, is of course overcome by the opposing primary then started ; but the " direct " extra- current produced at breaking circuit, shows itself very fully. It occasions the bright spark seen at breaking con- nection, where the circuit passes by a long wire, espe- cially if this is coiled, and may be made to give a shock, fuse platinum wire, etc., exactly as the ordinary induced current would. It is often used in medical batteries, and is then gener- ally called "the primary induced or Henry current." Currents are also induced by magnets in moving con- ductors. Thus, a copper disk being '^^ rotated under a compass needle, will have currents developed in it, which, by their ac- tion on the needle, will cause it to revolve about its point of support. 120 GALVANISM. Again, a disk of copper rotated between the poles of a powerful magnet becomes very hot by reason of the cur- rents developed in it ; in fact, Tyndall using a brass tube in this way has melted fusible metal in it in 1^ minutes. Thermo-Electricity. If tw^o different metals, such as Bismuth and Antimony, united at one point, be heated at this junction, a current of electricity will be established between them in one direction; if they are cooled in the same place the current will be reversed. If, therefore, many such '^' ^-^^ bars be joined alternately, as in Fig. 120, W)]^'B heated at one side, A B, and cooled at the other, C D, a sort of battery will be pro- duced, and a strong current obtained. The flow thus developed is called Thermo Elec- tricity, but is in all respects identical with the galvanic current of the battery. In the following table many substances are arranged in order, from, the most positive Bismuth to the most negative Tellurium. Any one of these will be positive to any below, and nega- tive to any above it; that is, when heated with one below the positive fluid w^ould pass to that other metal by the junction, and so on. Here, as in the battery, how^ever, the positive pole will be connected with the negative ter- minal element Bismuth, Nickel, Cobalt, German Silver, Brass, Lead, Tin, Copper, Platinum, Silver, Zinc, Iron, Antimony, Tellurium. According to Bunsen and Becquerel (see Jour, of Fr. GALVANISM. J21 fnst., Yol. 49, p. 422), the most powerful series of any may be made of copper, pyrites, or sulphide of copper, and me- tallic copper. This development of electricity by heat may be well shown by the thermo-elec- tric revolving arch, Fig. 122, where the lamp, heating the junction of the brass ring with the iron arch, causes a current which rotates the frame, so as to bring the other junction into the lamp, when the same thing is repeated, and a rota- tory movement is thus kept up. This action, by which heat develops a galvanic current, is of great use in the measurement of very delicate variations of temperature; for by connecting a small thermo-electric combination or pile, as Fig. 123, with a delicate galvanometer, changes of temperature may be noted which would otherwise escape all observation. Such an arrangement is called a Thermo- MULTiPLiER, and is of inestimable value in most branches of physical research. Animal Electricity. Some fish, such as the Raia torpedo, and the gymnotus or electrical eel, by reason of a peculiar anatomical struc- ture within their bodies, in some sort resembling a gal- vanic pile, develop notable quantities of electricity, so that they give a very severe shock if touched, and may be caused to magnetize a bar of iron, fuse gold-leaf, etc. Though this intense and special manifestation of electric 11 122 GALVANISM. disturbance is confined to a few creatures, provided with a peculiar set of organs, electrical action goes on in some degree in all living animals, and is closely connected with their vital actions. Thus electric currents can be proved to exist in the muscles when these are in action, and a sort of galvanic battery can even be produced by connecting in order, many portions of muscular substance. The subject of animal electricity, in its relation to phy- siology, is one of great interest ; but it is as yet too much mixed with doubtful theory, and too extended in its scope for discussion in this place. Spectra A BT P Rb K G K Bb PS Du.vd.l i^- SonLith .Phila.d^ PART II. CHEMISTRY. General Definitions. Clieinistry is that science which treats of the distin- guishing properties of bodies and of their actions under the influence of Chemical Affinity. Distinguishing Properties are those possessed by certain substances exclusively, and by which they may, therefore, be recognized. Ex. Gold has a specific gravity of 19.26, a yellow color, and melts at 2016° F. ; these properties make it distinguishable from other substances. Chemical Affinity is that force of attraction which exists between the particles of substances of a different nature, causing them to unite so as to form compounds, having properties unlike those of the constituents. 1st. It acts between particles, i. e. only at insensible distances, thus requiring an intimate mixture or approach «f particles to bring them within its range. Thus sulpluir and chlorate of potash mingled in lumps effect no combi- nation, but if ground together in a mortar a violent com- bination takes place (a few grains onl}^ should be used for this experiment). From this fact arises tlie utility oi' pulverization, fusion, and solution in conducting chemical actions. (123) 124 CHEMISTRY. 2nd. It acts between substances of a different nature. Thus acids will combine with alkalies, and vice versa, but not acid with acid, or alkali with alkali. As a general rule, the more different the properties of the substances, especially in an electrical sense, the greater their force of combination. 3rd. It causes the iormatiou of compounds with prop- erties different from those of their constituents. These differences are chiefly in (a) Color, (5) State, (i. e. solid liquid or gaseous), (c) or in Temperature. (ft) To illustrate changes in color. Prepare seven glasses containing solutions in water of the following substances : I. Ferrocyanide of potassium. II. Chromate of potas- sium. III. A mixture of the foregoing. lY. Sulpho- cyanide of potassium. V. Hydrosulphate of Ammonium. YI. Sulphuric Acid. YII. Ammonia. To each of these add a solution of nitrate of lead containing a little sesqui- nitrate of iron. The colors then, originally light yellow or white, will become as follows : I. Blue, II. Yellow, III. Green, lY. Red, Y. Black, YI. Milk-white, YII. Buff. Two blacks make a white. Make some ink in a glass by mixing in it tincture of galls and per-sulphate of iron. Drop into it some crystals of chlorate of potash. Make some common sulphuric acid black, by stirring it with a stick. Pour the black acid into the ink, and a clear solu- tion like water will result. (6) Changes in state. Two solids rnuke a liquid. Grind together in a mortar crystals of NaOjSOg* (6 parts) and NH^ 0,]Sr05 (5 parts). They will form a liquid. Mingle a saturated solution of CaCl. with a little oil of vitriol dilu- ted with half its bulk of water. These clear liquids will form an opaque solid. Two gases make a solid. Rinse one glass with a few drops of Ammonia and another with * NaO,S03 = Glauber salt, NH40,N05= Nitrate of Ammonia. CaCl =» Chloride of Calcium. INORGANIC CHEMISTRY. 125 Muriatic acid. Place their openings together; they will be filled with solid particles forming a dense cloud. (c) Differences in temperature. Pour oil of vitriol into water, introduce a test tube containing water, and stir it about. The water in this will boil. Pour water on an- hydrous CuOjSOs* or on Lime (CaO.); both will become intensely hot and give off steam. The laws which govern this force will be found on page 295. Substances are of two kinds: Inorganic or mineral, as metals, gases, rocks, &c., and Organic, or those connected with "life," as wood, flesh, &c. Organic bodies differ from inorganic in so many ways that they are best considered separately under the head of Organic Chemistry. Moreover this branch of the sub- ject can be developed more clearly after we have explained the laws which regulate the formation of the much sim- pler substances, in the domain of Inorganic Chemistry. INORGANIC CHEMISTRY. Inorganic bodies are either Elements, Binaries, Terna- ries or Quarternaries. 1st Elements are those bodies which have never been de- composed or separated into others. Their number is about G5, of which 52 are metals and 13 metalloids or non- metallic elements. The following table contains a list of these elements, with their symbols and atomic weights, combining proportions or equivalents. The names in brack- ets are those from which the symbols of certain bodies have been derived : 6 of these are metals known to the ancients and still retaining in this sense their Latin names, Sb Au Fe Pb Hg Sn. Two discovered in modern times follow their example, and one takes its name from a Ger- man mineral in which it was first found. * CuO,S08= Sulphate of Copper. 11* 126 INORGANIC CHEMISTRY. Table of the Elements. Names of Elements. Aluminum Antimony (Stibium).. Arsenic Barium Bismuth Boron Bromine Cadmium Caesium Calcium Carbon Cerium Chlorine Chromium Cobalt Copper Didymium Erbium Fluorine Glncinum .... Cold (Aurum) Hydrogen Iodine , Indium Iridium Iron (Ferrura) Lanthanum Lead (Plumbum) Lithium , Magnesium Manganese Mercury (Hydrargyrui Molybdenum... o 1 Al 1 13.7 Sb 120.3 , As 75 i Ba 68.5 Bi 208 , B 10,9 Br 80. Cd 56 ! Cs 133 1 Ca 20 I C 6 Ce 46 CI 35.5 1 Cr 26.7 Co 29.5 Cu 31.7 D 48 Er F 19 Gl 26.5 Au 197 H 1 I 127 In 37.07 Ir 99 Fe 28 Ln 47 Pb 108.7 Li 7 Mg Mn 12 27.6: Hg Mo 100 47.88 i Names of Elements. Nickel Niobium Nitrogen Osmium Oxygen Palladium Phosphorus Platinum Potassium (Kalium). Rhodixim Rubidium Ruthenium Selenium Silicon Silver (Argentum).... Sodium (Natronium) Strontium Sulphur Tnntalum Columbium 'I'ellurium Terbium Thallium Thorium Tin (Stannum) Titanium Tungsten (Wolfram). Uranium Vanadium Yttrium Zinc Zirconium Nomeiiclatiire of Elements. — Many elements bear in chemistry the same names as in common language. Ex. Zinc, Sulphur, Iron. Others are named from some striking peculiarity. Ex. Bromine derives its name from a Greek word meaning stench, in consequence of the disgusting odor it evolves Others from the place or substance in which they were discovered, Ex. Columbium, because INORGANIC CHEMISTRY. 127 it was found in an American mineral. Tantalum aerives its name from tantalite, the mineral wherein it was first found. All the newly-discovered metals are made to ter- minate in um or ium. Ex. Platinum, Caesium, Ruthe- nium. Symliols of Elements. — A symbol is a letter or combina- tion of two letters used to indicate one equivalent of the element for which it stands. We have therefore a symbol for each element, as O for Oxygen, H for Hydrogen, etc. The symbol is either the first letter or the first and char- acteristic following letter in the name of the element, as will be seen by reference to the above table. This second letter is added for distinction in those cases where the names of the two elements commence with the same letter. Thus, Carbon and Chlorine both commence with the letter C. In order to distinguish these two bodies, we must add the characteristic letter I in the name of the body last discovered, Chlorine, to its first letter C, so as to have a separate symbol, CI, for Chlorine. It will be noticed that the second letter is added in smaller char- acter; and, moreover, the definition of symbol, given above, makes it stand for only one equivalent of the ele- ment. 0, for example, does not represent the substance Oxygen in general, but merely 8 parts by weight of Oxy- gen. F should not call to mind Fluorine, but 19 parts relatively by weight of Fluorine. Since a symbol stands for one equivalent of the element, we must place figures if we wish to indicate several equivalents : thus the symbol Au stands for 1 equivalent of gold. To represent 5 equivalents of gold we write 5Au. In writing the for. mulae of compound bodies, however, the figure is placed after and a little below the symbol: thus the compound of Nitrogen, N, with 5 equivalents of Oxygen, 50, is not represented by N50, but by NO5, 2nd Binaries. — Binaries are compounds of two ele- 128 INORGANIC CHEMISTRY. ments, They are divided into three orders: I. Acids; II. Bases; and, III. Neutrals. An Acid is a body having a sour taste, reddening a so- lution of litmus, or of violets or red cabbage, and turning a solution of cochineal yellow, and combining with bases so as more or less to destroy their basic properties and to form with them salts. A Base is a body having a peculiar soapy taste, redden- ing a solution of turmeric, turning one of violets or cab- bage green, and one of cochineal purple ; and combining with acids to form salts, with mutual neutralization of properties. In both these definitions the last point only is universal in its application. Alkalies are strong bases which fulfil all the conditions above expressed. A Neutral Body is one so devoid of all active properties that it can scarcely be made to enter into combination. It occupies an intermediate position between acids and bases. I. Acids are again of three sorts, (a) Those contain- ing Oxygen or Sulphur in union with a metalloid or metal, as — Arseiiious acid = AsOg I Carbonic acid = COj Sulpharsenious acid =: AsSg | Sulphocarbonic acid = CSj (b) Those containing Sulphur, Selenium, or Tellurium, in union with Hydrogen, (c) Those containing Chlorine, Bromine, Iodine, Fluorine, or Cyanogen, in union with Hydrogen. (a) Acids of the first class, which contain Sulphur, are distinguished from those containing Oxygen, by prefixing sulph or sulpJio to the name of the corresponding oxygen acid ; thus AsSa corresponds to AsOg, Arsenic Acid, and accordingly we give to the first the name Sulpharsenic Acid. The name of the oxygen acids themselves are derived from the names of the metalloids or metals with which INORGANIC CHEMISTRY. 129 the Oxygen is combined. Ex. The acid body formed by the union of Chlorine with Oxygen tal^es its name from the metalloid, and is called Chloric Acid. When there are several compounds of Oxygen with the same element, the one which contains the most Oxygen is made to terminate in ic ; the one containing the least in ous. If another acid is afterwards discovered, containing more Oxygen than the acid which was made to terminate in ic, hyper (abbreviated per) is prefixed to the new acid, to distinguish it from the acid first discovered. Hypo denotes less Oxygen than the remainder of the name im- plies. The above rules are exemplified in the following series of acids : — Perchloric acid = CIO7 Chlorous acid = CIO3 Hypochloric acid = CIO4 Hypochlorous acid = CIO Chloric acid = CIO5 (b and c) The names of acids of the second and third class are formed by prefixing hydro to the name of the electro-negative element. (b) Hydrosulphuric acid =r HS Hydroselenic acid = HSe Hydrotelluric acid =:= HTe (c) Hydrochloric acid = HCl Hydrofluoric acid =:r HF Hydrocyanic acid = HCy And it will be noticed that the symbol likewise of the electro-negative element is written last in the above ex- amples. II. Bases are named from both elements which compose them, the more electro-negative being named first. Ex. Oxygen being negative to iron, these when united form Oxide of Iron. In writing the formulae of bases, however, the symbol of the electro-negative is placed last. Thus we express this same substance, Oxide of Iron, by FeO. If the compound contain one equivalent of the electro- negative element to each equivalent of the electro-positive 130 INORGANIC CHEMISTRY. one, prot or proto is prefixed to the name of the negative element; if 2 equivalents of the negative to each of the positive, deut, deiito, hi, or hin is prefixed ; if 3 negative to 2 positive, sesqui ; if 3 negative to each positive, trit, trito, or ter ; if 4 negative to each positive, quad or quadro ; if 5 negative to each positive, pent or penti. Ex. FeO, 1:1; Protoxide of Iron, FeOg, 1:2; Binoxide of Iron, Fe^Oa, 2:3; Sesquioxide of Iron, FeOs, 1:3; Ter- oxide of Iron. III. Neutral Bodies are of two kinds. 1st. Those formed by the union of a halogen* body with a metal ; they are marked by peculiar characteristics, and are known as Haloid Salts. 2nd. All other compounds of two elements which are neither acids nor bases. Both classes are named exactly like bases. Ex. NaCl, Chloride of Sodium. MnOj, Binoxide of Manganese. 3rd. Ternaries. — Consist of an acid and a base. The negative element, in both acid and base, must be the same. Ex. Arsenate of Potassa, K0,As05. Sulpharsenate of sulphide of potassium, KSjAsSg. Every such union of an acid with a base is called a Salt. If an oxygen acid is united with an oxygen base, we have an Oxygen Salt ; if a sulphur acid with a sulphur base, a Sulphur Salt. An oxygen salt is named by giving the name of the acid first, with its termination changed from ic to ate, and from ous to ite, and then adding the name of the positive element in the base, "oxide of" being understood. Ex. Sulphate of Iron, FeOjSOg. A sulphur salt is named in the same way, but "sulphide of" is expressed. If the acid be to the base in the ratio of 1 : 1, proto is prefixed to the name of the salt ; if as 2:1, bi ; if as 3 : 2, sesqui, etc. Salts are divided into three classes : 1st. Acid Salts. 2nd. Neutral Salts. 3rd. Basic Salts. See page 179. * Halogen, from a\6s, salt; yevvdo), I produce. They are Chlorine, Bro- mine, Iodine, Fluorine, and Cyanogen. OXYGEN. 131 Sym. 0. OXYGEN. Eq. 8. Oxygen was discovered, independently of each other, by Priestley and Scheele, in 1174. It was called by Priestley " dephlogisticated air," and by Scheele " Empyrean air." Its true nature was pointed out soon after by Lavoisier, to whom it owes its present name of oxygen, 6^vs acid, yevvdio, I produce. Because it was supposed to form all acid compounds. This idea is in a general way correct, but by no means universally true. Most acids contain 0, but many do not. Sources of 0. — Oxygen constitutes 46 per cent, by weight of all the principal rocks, granite, basalt, gneiss, sandstone, and limestone ; 30 per cent, of all the common metallic ores; one-fifth of the atmosphere, and eight- ninths of all water. Preparation of 0. — 1st. By heating Red Oxide of Mercury to 750° Fahr., HgO = Hg + 0. This process may best be exhibited by placing a little HgO in a test tube, supporting this in the retort holder, as in Fig. 124, and heating the oxide by means of a Bunsen burner, or powerful Argaud lamp, such as in Fig. 125. The decom- position soon begins. Metallic Mercury is deposited in the cooler portion of the tube, and the escaping gas will relight an extinguished match, with a coal yet on it, if plunged in the mouth of the tube. 2nd. By heating to redness Black Oxide of Manganese, 3Mn02 = MnO + Mn.Og -f 20. This requires an iron vessel and the heat of a good fire. 3rd. By heating Chlorate of Potash which gives off 39 per cent, of 0, KO^ClOj = KCl + GO. Half an ounce of K0,C105 yields 270 cubic inches, or nearly a gallon of 0. A pound yields about 30 gallons. 4th. When a little Black Oxide of iSlanganose is mixed with Chlorate of Potash, the Oxygen is disengaged at a 132 much lower temperature than otherwise. The Oxide of Manganese undergoes no change and seems to act solely by its presence. The operation may be well conducted on the small scale in a glass flask heated by a spirit lamp with an "Argand" or large hollow cylindrical wick, as is repre- sented in Fig. 125, the gas being collected as it forms, in a bell jar filled with water, and inverted over a pneumatic cistern. An India-rubber tube serves best to convey the gas from the flask to the cistern. In making large quan- tities of oxygen it is best to use a copper flask of one quart or more capacity, heated by a Bunsen burner which should be removed as soon as the gas begins to come over freely; the operation will then continue to the end without further heating. The gas may then be collected in a gas bag made of strong India-rubber cloth, after passing through lo a large washing bottle, or in such a receiver as is shown in Fig. 126, or Fig. 141. Fig. 126. To use the gas receiver, Fig. 126, we fill A with water ny pouring it into B, opening the stopcock a to admit it to 12 134 OXYGEN. A, and the cock e to allow the air to escape. Then both these cocks being closed, we remove the cork from d, and pass in, through this passage, the tube carrying the gas from the flask. As the gas enters it displaces the water, which then runs out around the entering tube at (i, cc are merely iron rods supporting B. If after A is full of gas d is closed, B filled with water, a bell-jar full of water placed in B, and the cocks a and h opened, water will flow through a into A and drive out gas through h into the bell jar. 5th. By strongly heating Red Lead, 2PbO,Pb02, or almost any deutoxide of a metal, the oxide will be reduced to a protoxide, yielding oxygen. 6th. By heating Nitrate of Potash (Nitre), K0,N05 = KO,N03+20. Tth. By heating a mixture of 2 parts strong Sulphuric acid (oil of vitriol), and 1 part black Oxide of Manganese, Mn02-fS03=MnO,S03+0. 8th. By heating 4 parts of Sulphuric acid with 3 parts of Bichromate of Potash, KO,2Cr03 + 4S03= KO,S03 4- Cr2033S03 -f- 30. One ounce of salt yields 200 cubic inches of 0. 9th. By heating Hydrated Protoxide of Barium in alter- nate currents of air and steam, when it will take from the air and yield it to the steam. 10th. By heating Nitrate of Soda and Protoxide of Zinc. 11th. By adding to Hypochlorite of Lime in solution (obtained by mixing commercial bleaching salt or chloride of lime with water, and decanting or filtering thnmgh a cloth) a few drops of nitrate of cobalt, and gently heating. In this case the oxide of cobalt which is formed, abstracts oxygen from the hypochlorous acid and lime (^leaving at last but chloride of calcium), and then in turn abandons this oxygen only to seize upon a fresh quantity. A pound of Chloride of Lime (commercial) treated with about a quart of water will yield in this way 2j gallons OXYGEN. 13a of oxygen. This process is a curious one, perfectly safe and easy to manage, but cumbrous where large quantities of gas are required, and no cheaper than the 4th. (See Journal of Franklin Institute, Yol. 50, p. 285.) 12th. By heating together Silica fsand) and Sulphate of Lime (plaster of Paris), Si03+CaO,S03=CaO,Si03 + S02 + 0. Silicate of lime is formed, and Oxygen with Sul- phurous acid passes off. The SO^ is removed by lique- faction or absorption in milk of lime, and the thus obtained pure. Of all these methods the 4th is at present the most available. Properties. — Oxygen is a gas, incapable of liquefaction by cold or pressure, and without color, taste, or smell. Its density is l.l05t; 100 cubic inches at 60°, and 29.988 inches barometric pressure, weigh 34.29 grains. It is slightly soluble in water, the latter dissolving at the ordi- nary temperature ^J^ of its volume of gas. It is the most magnetic of gases (see p. 92) ; in this respect the of the atmosphere is equivalent to a shell of iron enveloping the earth, and ^\q of an inch thick ; and by its changes of magnetism, due to those of temperature, produces the diurnal variations of the magnet. It is the great supporter of combustion. Almost every case of combustion consists in a union of the elements of the burning body with Oxy- gen. When bodies burn in the air the great excess of nitrogen present carries away much of the heat generated, but when oxygen alone is collected in a receiver, the heat developed by combustion can rise much higher, and the more ready supply of the "supporting body " will greatly intensify the action. This is well exhibited, as follows : We fill bell-jars, such as Fig. 127, with this gas over the pneumatic tank, by filling them first with water, and then allowing the gas to flow into them from a tube intro- 135 OZONE. duced under their immersed lower edge. (See Fig. 125.) We then attach to wires, or place in copper spoons, as their nature requires, pieces of charcoal, candle, sulphur, phosphorus, etc. (dry sand should be placed in the spoon, under the phosphorus), and ignit- ing, plunge them into the jars through their upper openings. These, bodies then burn with great splendor. To burn iron, or rather steel, we use an uncoiled watch-spring, which can be best ignited by the oxjhydrogen blowpipe, and then plunged in a jar of oxygen, or we may fuse a little sulphur fast to its end, light this, and then plunge it into the gas. Figure 121 represents phosphorus burning in oxygen; and Fig. 128 steel, in like case. Ere- macausis is the name applied to a very slow combination of bodies with oxy- gen, by which no light is evolved. This we see in decaying wood, and vegetable matter generally, in the res- piratory process of animals, etc. Oxy- gen drawn into the lungs is absorbed in the blood, and there combines with various dead matter, exhausted tissue, and the like, so producing heat needed for the support of animal life. Ozone and Ant-Ozone. — Besides its usual state. Oxygen has two other and dissimilar conditions designated by the above names. When dry air or oxygen is passed through a glass tube containing a number of fine wires coated with glass, which form the poles of a Ruhmkorflf Coil, the character Fig. 128. OZONE. 13t of the gas is changed. If it is passed through a strong solution of Iodide of Potassium (KI), part of it will be absorbed, setting free the Iodine. This is the Ozone. Another part will pass on unabsorbed, and may be col- lected with the gas which may have escaped action in a dry vessel. Its chief peculiarity is that in the presence of moisture or water, it forms with it a dense white cloud or fume, which subsides after half an hour or so, leaving the water and common oxygen. This substance so acting is called Ant-ozone. These were discovered by Schbnbein, and have been thoroughly studied by Meissner. (See Silliman's Journal, Yol. 3t, p. 325, 1864, for a review of Meissner's book.) Ozone is prepared, not only by the action of electricity on air, but also in the electric decomposition of water (page 108) ; by the action of phosphorus, partly covered with water, on air ; by the action of ether, turpentine, etc., on air ; by action of oil of vitriol on chameleon mineral (Silliman's Journal, 1863, Yol. 35, p. HI); and by plunging a red-hot glass rod into a glass having a few drops of ether in it. Its test is paper moistened with starch, containing a little KI (starch, 5 parts ; Iodide of Potassium, 1 part; to be boiled), which it turns purplish blue, or the juice of mushroom. Boletus luridus. Boletus cyanescenus, etc., or the alcoholic solution of the resin of Guaiacum, to which it communicates a blue color. The properties of ozone are like those of oxygen, but in all respects more intense. It has a peculiar smell, sug- gestive of scratched varnish, which may be easily per- ceived in the vicinity of a powerful Ruhmkorlf coil or elec- trical machine. It interferes with vegetation, formation of mould, etc. Antozone may be prepared, not only in the way above 12* 138 HYDROGEN. described, but by action of dilute Sulphuric acid (SO3) on Deutoxide of Barium (BaOa) diffused in water at a low temperature, and by passing Carbonic acid (COa") through BaOa diffused in water. In this case, however, the Anto- zone at once unites with water forming HOg. Antozone again seems to exist in Fluor Spar of Welsendorf, HO2, being formed by grinding this mineral with water. Test. — Antozone will develop the blue purple in starch containing KI, if very dilute solution of Sulphate of Iron (FeQSOa) be first added to that mixture. Ozone is often indicated by the symbol + 0, and Ant- ozone by — 0, and these are sometimes called positive and negative oxygen. Sym. H. HYDROGEN. Eq. 1. Hydrogen was discovered by Cavendish, in 1766. Its name is derived from rSwp, water ; and yfj^mw, I produce. It constitutes one-ninth of all water, and part of most animal and vegetable bodies. Preparation. — We always obtain H from water. Isi. By decomposing it with Sodium. Invert a test tube filled with water in a dish of the same, introduce a pellet of Sodium (Na) under it between the blades of Fig. 129. Fig. 130. scissors, the Na will soon escape and float on the water HYDROGEN 139 in the tube, setting free H, which will thus fill the latter. (Fig. 129.) 2nd. By passing steam over iron turnings placed in a tube and kept at a red heat by a furnace. 3rd. By decomposing water acidulated with sulphuric acid with zinc CH0,S03 + Zii = ZnO.SOg -f H.) This operation may be conducted in a "gas bottle," Fig. 130, the acid and water (mixed before and allowed to cool) being introduced by the long funnel, and the gas escaping by the bent tube. Or to make the process self- regulating, we may employ the apparatus represented in Fig. 131, where the gas, generated by the contact of the acid water with the zinc, h, if not allowed to escape, col- lects in the bell jar, displacing the acid solution from the zinc, and so stops the action until the gas is allowed to escape, admitting the liquid when the operation recom- mences. Such an apparatus, made of copper and of large size, is very convenient to work the oxyhydrogen blow- pipe, lime-light, etc. The bell in this case had better float loose in the outer jar or reservoir, and have a capa- city of 6 gallons. The charge should be a bucket of water and 6 lbs. of oil of vitriol, which will yield more than TO gallons of Hydrogen. Enough to run a powerful lime-light for two hours. 4th. By electrical decomposition of water (see page 108\ When prepared by this means, the hydrogen has its aftini- ties exalted so that it will decompose Sulphate of silver. (Smithsonian Reports. 1862, p. 397.) iMIIllll illlililllllllilllil'iilllllfl 140 HYDROGEN. Properties . — Hydrogen is a gas, colorless, transparent, tasteless, and inodorous ; it has a higher refractive power than any other gas; it is the lightest known substance, weigh- ing little more than yL as much as air. Density, 0.0692. One hundred cubic inches w^eigh 2.14 grains. On account of its lightness balloons have been filled with it, and soap bubbles so charged rise in the air. It may be collected by displacement (see Fig. 130), and poured upwards from one vessel into another. The extreme rarity of hydrogen was strikingly demon- strated in the attempts which were made to condense it to a liquid, by great pressure in iron receivers. The hy- drogen escaped through the pores of the iron. Ex. If a sheet of paper is placed at a little distance from the jet of a hydrogen generator, the current of gas will pass directly through the paper without altering its direction, and can be lighted upon the opposite side of the sheet. Hydrogen is combustible, burning with a bluish flame, giving little light but intense heat. If a long glass, or other tube, is placed around a small jet from which H. is burning, the supply of air being thus limited the burning will be reduced to a series of slight explosions, which will develop a musical sound. This arrangement has, there- fore, been called the Hydrogen Organ. The Oxy hydrogen Blowpipe, invented by Dr. Robert Hare, in 1802, consists of two concentric nozzles with other parts, by which a jet of oxygen is introduced into the centre of a jet of burning hydrogen. The most com- bustible body is thus supplied with the best supporter of combustion, and the heat evolved by their union is con- centrated in a small space. Its intensity is therefore very great. Silver, gold, platinum, etc., are fused and vapor- ized, iron, zinc, etc., burned with brilliant effect, and other results of a high temperature attained. The Lime-light — When the oxy hydrogen flame is di- HYDROGEN. 141 reeled upon a block of lime, this solid serves as a sounding- board to its intense vibrations ; and enables them thus to develop a light of great brilliancy. For the best effect, the pressure on the gases should not be less than f lb. per square inch, or 18 inches on a water gauge. If these two gases, and H, are mingled in atomic proportions (by volume, 1 to 2 ; by weight, 8 to 1) and ignited, they will explode with violent detonation, though relatively little force. This is well shown by blowing bubbles in soapy water with the mixed gases (from a bladder, gas- bag, or other receptacle), filling the hand with these and firing them. They will make a loud report, but will pro- duce no sensation to the hand. The detonation is caused by the instantaneous condensation of the vapor of water, which is produced by the combination of the two gases in contact with cold air. The water occupying, when con- densed, a volume HOO times smaller than when it was in the state of vapor, leaves a large vacuum. The rushing of the air from every quarter with great rapidity into this empty space, causes the detonation. Compounds of Hydrogen with Oxygen. I. Water.— Symbol, HO. Equivalent. 0. Sp. Gr. as Yapor, 0.622; as Liquid, 1.000; as Ice, 0.94. Properties, (a) Physical. — Clear, colorless, tasteless, in- odorous, transparent liquid. Below 32° it freezes into a variety of crystalline forms derived from the rhoiubohe- dron and six-sided prism. Evaporates at all temperatures, and under the usual pressure of the atmosphere boils at 212°. Reaches its maximum density at about 40°, and expands whether cooled below, or heated above, this point. In changing to ice, it becomes lighter and increases in volume ; and we therefore see why : 1st. Ice forms only on the top of streams. If water followed the same law as almost all other liquids, and 142 HYDROGEN. became heavier in freezing, oar rivers would be frozen aolid from bed to surface, the fish they contained destroyed, navigation would be interrupted for most of the year, and all the heat of a summer sun would scarcely suf&ce to make the streams liquid again. 2nd. A frost, by changing the water contained in the cellular tissue of fruit to ice, bursts the delicate cell struc- ture and destroys the fruit. 3rd. Water pitchers, fountains, water-pipes, drains, etc., burst in winter time, and frost-stones, or those very porous to water, crumble away. Its density at 60° is taken as 1.000 ; and with this standard the specific gravities of all liquids and solids are compared. One cubic inch of water at 62°, weighs 252.456 grains. A gallon (imperial) contains 10 lbs. Avoirdu- pois = YO.OOO grains, or 217.19 cubic inches of water. Air dissolved in Water. — The presence of air in water which has been exposed to the atmosphere, is readily shown by suffering some water to stand quiet for a time in a tumbler. Bubbles of gas collect on the inside of the glass; accurately, the amount of air is about 3.2 volumes to every 100 volumes of water. But this dissolved air is much richer in oxygen than atmospheric air, and con- tains 33 volumes of oxygen to 100, instead of the 21 volumes which are found in the atmosphere. This excess of oxygen is due to its being more soluble in water than nitrogen. Ex. Fishes, which breathe the air dissolved in water by means of their gills, die in distilled water. Spring waters derive their sparkling taste and invigorating quali- ties from the air which they hold in solution. Other bodies found in water. — Bain-wafer, in its pas- sage from the clouds, carries with it, in solution, all the substances which are found in the atmosphere ; such as oxygen, nitrogen, carbonic acid, traces of nitric acid, of carbonate and nitrate of ammonia. NITROGEN. 143 Spring and well water, which is rain-water drained from porous soils or rocks, contains, in addition to the above substances, various salts which it has dissolved out from the ground ; such as chlorides, sulphates, and carbonates of lime, magnesia, soda, potassa, and alumina. A small quantity of lime-salts is thought to render drinking-water more wholesome, and to aid in building up the bony struc- ture of the body. (6) Chemical. — Is the best solvent. Perfectly neutral ; uniting with most acids and bases. When combined with a powerful acid, it supplies the place of a base, and is called 6as2C water. In combination with a powerful base, it supplies the place of an acid, and is called acid water. Bodies combined with water are termed hydrates ; un- combined, anhydrous. If the water existing in a crys- tallized salt can be driven oif by heat without decompos- ing the salt, it is termed water of crystallization ; if it cannot, water of constitution. II. Binoxide of Hydrogen— HO, = 17. Sp. Gr. 1.453. Preparation. — Successive portions of Binoxide of Ba- rium are added to Hydrofluoric acid. Ba02+HF=BaF -f HO2. The insoluble Fluoride of Barium is removed by filtration, and the Binoxide of Hydrogen remaining in the liquid, concentrated by evaporation in vacuo. Properties. — A syrupy, colorless liquid, with an astring- ent and somewhat metallic taste ; bleaching litmus and other vegetable colors instantly. At 19° slowly decom- posed into oxygen and water; at 212°, with explosive haste. Many metals and metallic oxides instantly eftVct a like decomposition without themselves undergoing change. Sym. N. NITROGEN. Eq. 14. Discovered by Dr. Rutherford, in 17t2. Shown to form part of atmosphere by Lavoisier, in 1775. Called by the French azote (lifeless); from a, privative, and ^o*, life. Its 144 NITROGEN. name, nitrogen, is from virpov, nitre, and yswdio, I produce. Occurs as four-fifths of the atmosphere, and in minei-al and animal substances. Preparation. — 1st. By burning phosphorus in an in- closed portion of air over water. N and 5 -f P = N + PO5. 2d. By passing chlorine through aqua ammonia. NIfg + 3 CI = 3 HCl + N. 3rd. By heating solution of nitrite of ammonia ]S"H,0,N03 = 4 HO -f 2 N. 4th. By heating solution of nitrite of potassa with sal ammoniac. K0,N03 + :N^H,C1 = KCl + 4 HO -f 2 N. Properties. — These are all inert and negative. A gas without color, taste, smell, or capability of liquefaction, and solidification; density 0.912; does not support com- bustion, animal life, or enter, of its own accord, into com- bination. Mixture of Nitrogen with Oxygen. Atmosplieric Air. — Density at 60° taken as 1.000, and with this standard the specific gravities of all other gases are compared; 100 cubic inches weigh 31.0117 grains. Consists, by weight, of 23 parts oxygen, and 77 parts nitrogen; by measure, of 21 parts oxygen, to 79 parts nitrogen. There is also about one-thousandth part of carbonic acid gas, a trace of ammonia, and some vapor, varying greatly in quantity with the temperature. Regnault's Hygrometer. — The amount of moisture in the air, of course, aff"ects its power of taking more, or of promoting evaporation. The drver the air, the more rapid will be the evaporation taking place in it at equal temperatures. We can thus determine the amount of moisture in the air by means of this action, as follows. We have two thermometers {t t), supported near each other, one, however, plunged in a vessel of ether, A, through which air is drawn, by means of the aspirator, NITROGEN. 145 D. The dryer the air, the more the ether evaporates, and, therefore (see p. 32), the lower the temperature in A (indicated by one thermometer) falls below that of the air around indicated by the other. This difference in temperatures enables us to judge of the amount of mois- ture in the air. Fig. 132. ^a*^ The aspirator, D, is used in many cases where we wish to produce a steady flow of air through a piece of appa- ratus, as in some cases of analysis, the determination of the Carbonic acid in the air, etc. 13 146 NITROGEN. Fig. 133. The Dew Point is that temperature at which the mois- ture present in the air is enough to saturate it, and would begin to be deposited from it as dew. This is directly shown by Daniel's Hy- grometer. (Fig. 133.) This con- sists of a little cryopherous (see page 31), with a thermometer in one bulb, a, and a piece of cloth around the other, 6. By pouring ether over 6, we so promote evaporation in a, that its surface is cooled to the dew pointy and we see a misty deposit forming on a, which is coated with gold leaf, to show this the better. The temperature of the thermometer in a, at the time this happens, gives us the dew point. This temperature is *' high," or near that of the air, in damp weather; "low," or much below it, when the air is dry. Compounds with Oxyg^en. Nitrous Oxide, Protoxide of Nitrogen, Laughing Gas (NO ; Eq. 22). Sp. Gr. 1.525. Colorless, transparent, sweet-tasting gas; liquefiable at 45° under a pressure of 50 atmospheres; a candle or phosphorus burns fiercely, when plunged in this gas. Its solubility diminishes rapidly with increase of temperature ; 100 cubic inches of water, at 32°, dissolving 130 cubic inches of the gas; and at 15°, only 60 cubic inches. It intoxicates when inhaled, and produces insensibility to pain. Prepared by heating nitrate of ammonia, NH40,N05 = 4 HO + 2 NO. Nitric Oxide, Binoxide of Nitrogen, NO2. Obtained by acting upon copper, with dilute Nitric acid. 3 Cu 4- 4 NO;, = 3 (CuO,N05) + NO2 . Colorless ; in contact with NITROGEN. 141 air or oxygen is converted into a deep-red gas. whicn is the vapor of hyponitric acid, NO4 = NO2 -f- 20. Ex- tinguishes a candle, but causes phosphorus to burn brilliantly. Nitrous Acid — NO3. An orange-red vapor, obtained by mixing 4 volumes binoxide of nitrogen, with one volume oxygen. NO2 -|- = NO3 . In contact with water, de- composed into Nitric acid, and Binoxide of Nitrogen, 2HO + 6N02= 2(H0, NO5) + 4NO2. On account of a like action, it cannot be made to unite directly with metallic oxides ; the various nitrites are formed by heating corresponding nitrates ; thus, KOjNOs = KOjNOg -f 20, oxygen being evolved. Hyponitric Acid — NO4, A deep red vapor, at common temperatures, at 0°, an orange liquid ; obtained by heat- ing nitrate of lead. PbO, NO5 = PbO -f- + NO4. Nitric Acid — NO5. A crystalline solid, obtained by pass- ing dry Chlorine over well dried Nitrate of Silver, AgO,N05 + Cl=AgCl + 0-FN05. Hydrated Nitric Acid— H0,N05. The Hydrated acid is always meant when Nitric acid is spoken of, because An- hydrous Nitric acid is utterly devoid of acid properties. It is obtained by heating equal weights of Nitrate of Po- tassaandSulphuricacid,K0,N05+2(H0,S03)=K0,S03-f HO,S03-fHO,N05. Fig. 134. We place, for ex- ample, the above materials in a glass retort, Fig. 134, and apply heat by means of a spirit lamp ; then, as the Hydrated Nitric acid is liberated, it distils over into ^^^P 148 NITROGEN. the glass receiver, kept cool by a stream of water dis- tributed on its surface by means of linen or soft paper. Besides this compound, which has a specific gravity of 1.517, and which consists of 54 parts Anhydrous acid united with 9 parts water ; another definite compound of the Anhydrous acid with water exists, which has a spe- cific gravity of 1.424, and contains 54 parts of the former to 36 parts of the latter. Its formula would, therefore, be 4HO,N05. Properties. — The metals placed in contact with Nitric acid are oxidized at the expense of the acid, the latter easily yielding up a portion of its oxygen to them ; and owing to this free liberation of oxygen combustible bodies, such as red-hot charcoal in powder, and oil of turpentine when heated, burn vividly when Nitric acid is dropped upon them. Its chief use, indeed, is as an oxidizing agent. Strangely enough, when diluted till its specific gravity is 1.25, it oxidizes the metals more rapidly than when con- centrated. And the same is true with regard to its action upon animal and vegetable bodies, such as the skin, wool, feathers, and albuminous bodies, lignin, starch, and similar substances. Uses. — Owing to the rapidity with which Nitric acid oxidizes the metals, and the great solubility of the nitrates in water, Nitric acid is of invaluable use in the laboratory for dissolving minerals, metals, etc. Used to oxidize SO^ into SOain the manufacture of sulphuric acid ; when mixed with hydrochloric acid, as aqua regia, to dissolve gold, platinum, etc. ; to convert starch and sugar into oxalic acid; in dyeing ; in engraving on copper and steel — etch- ing; in the assay of money ; in polishing and cleaning rust from metals and alloys. It converts benzole into arti- ficial oil of hitter almonds; it is employed in forming ani- line colors, and to transform cotton fibre to gun-cotton. Tests. — Bleaches a solution of Indigo in Sulphuric acid when boiled with that liquid. Gives a brownish-red color AMMONIA. 149 in contact with a concentrated solution of Protosulphate of Iron. Compounds of Nitrogen and Hydrogen. Sym. NH3. AMMONIA (Volatile Alkali). Eq. 17. Sources. — When Nitrogen and Hydrogen come together in the nascent state, that is, at the moment when either one of them is liberated from some previous combination, they unite to form Ammonia. Thus, when lightning flashes through the air a small amount of vapor of water, HO, is decomposed into its two component elements, H and 0. The hydrogen and oxygen, at the moment of their libera- tion, unite with the nitrogen of the atmosphere ; the former to form Ammonia, NH3 ; the latter. Nitric acid, NO5. Or, when iron is exposed to the action of moist air, the iron decomposes the water, and unites with its oxygen, to form rust or Sesquioxide of iron (Fe^Og), while the Hydrogen set free, in the nascent state, combines with the nitrogen of the air to form Ammonia: 2Fe + 3HOH-N=Fe203+NH3. Ex. Disengagement of Ammonia from rust on mixing the latter with caustic potash. In the same manner, when Nitric acid acts upon zinc, tin, and iron ; thus, 8Zn + 8(HO,N05)=8(ZuO,N05) + 8H, the liberated hydrogen has the power, while in the nascent state, to decompose another portion of the Nitric acid, and form Ammonia: HO,N05-f-8H = GIIO+NH3. Lastly, when organic substances decompose — I. Spon- taneously — II. By heat alone — III. By heating with caustic potassa — the nitrogen and hydrogen combine, in the nascent state, to form Ammonia, and in this way is derived the fertiliziug property of manure, and the am- moniacal liquor of gas-works, which is the commercial source of Ammonia. Preparation. — I. Fill a matrass half full of equal weight 150 AMMONIA. of caustic potash and sal ammoniac, and heat the mixture gently ; collect over mercury, or by displacement upwards: Potassa. Chloride of Ammonium. Chloride of Potassium. Ammonia. Water. KO,HO+ NH.Cl = KCl + NH3 + 2H0 Fig. 135. II. A slight heat is sufficient to disengage all the Am- monia from its solution in water — the liquid Ammonia of commerce. Liquid Ammonia is prepared by receiving the ammo- niacal gas, first in a wash-bottle, filled with milk of lime, which is merely the hydrate of lime, CaO,HO, diffused through water, in order to absorb the Carbonic acid and im- purities accidentally present, and afterwards in a series of Woulf's bottles. Fig. 135, filled with distilled water. The gas enters by tube A, bubbles through the water, and passes by C into another similar bottle. The tube J) serves to prevent the liquid in one bottle from being drawn into another in case of a sud- den absorption, air instead then entering by this tube. Properties. — Ammonia is a colorless gas, which may be recognized: 1st, by its sharp, penetrating odor; 2nd, by its powerof browning turmeric paper, turning a solution of violets green, and cochineal, purple — whence its name of volatile alkali; 3rd, by the white fumes or cloud of Chlo- ride of Ammonium, NH4CI, which revolve about a glass rod previously moistened with Hydrochloric acid, HCl, Avhen brought near the slightest trace of free ammonia. It extinguishes a burning candle, but burns with a yellow flame when introduced in a fine jet into a bell-glass filled with oxygen ; it cannot be respired, and produces ophthal- mia among workmen exposed to ammoniacal fumes. Dropped on the skin, liquid ammonia produces a blister, CHLORINE. 151 and it is consequently employed to cauterize the bites of mad dogs. It is decomposed by heat and electricity into nitrogen and hydrogen ; by oxygen, with the aid of elec- tricity, into water and nitrogen ; a few bubbles of chlorine passed into a receiver filled with ammoniacal gas produce chloride of ammonium and nitrogen, accompanied by heat and light. Uses. — Equal amounts of cochineal, ammonia, and water boiled together furnish carmine. Many colors may be made, and still others, such as crimson and Prussian blue, may be modified by ammonia. It is largely employed by scourers to take out grease spots, and to restore colors changed by acids ; by the manufacturers of artificial pearls to prepare the Essence d^ Orient. This is obtained by hold- ing in suspension in liquid Ammonia the minute 'scales of the Blay-fish, and is used by injecting it into pearl-like glo- bules of glass. The scales attach themselves to the inside walls of the hollow glass drops, and sparkle like Indian pearls. In medicine, besides its internal and external application to the bites of serpents, stings of insects, etc., it is used in the treatment of hoven. This disease arises in sheep and cows from eating green apples and wet grass, which gene- rate so large a quantity of Carbonic acid in the intestines, as to cause death in a short time. The ammonia absorbs this gas, forming the salt, Carbonate of Ammonia. Sym. CI. CHLORINE. Eq. 35.5. Discovered by Scheele in 1144. Its true character pointed out by Gay Lussac and Thenard in 1809. Its nnme given by Sir H. Davy, from z'^^po^, yellowish-green, color of younir grass. Chief source in nature, common salt. rreparation. — 1st. Heating in a flask sUgJithj diluted hydrochloric acid with binoxide of manganese, 2IlCl-f- 162 CHLORINE. MnO.,= MriCl+2HO + Cl (Fig. 136); 2nd. Heating com- mon Salt, Binoxide of Manganese and Sulphuric acid, NaCl + MnO, + 2(HO,S03)=:Cl+NaO,S03 + MnO,S03 + 2H0. Best collected by displacement, as Fig. 136, or if Fig. 136. for any reason over water cold water is better than hot, care being taken to let it pass through as little as possible. Properties. — Chlorine is a gas of a greenish-yellow color, an acrid taste and disgusting suffocating smell. It becomes liquid under a pressure of 4*5 atmospheres at 60°. This gas has a strong afi&nity for the metals, so that many of them will inflame if thrown into it. Thus, for example, is it with Antimony, Arsenic, Potassium, etc., in powder, or Dutch gold leaf (made of brass). (Fig. 137.) Its affinity for Hydrogen is also very great ; mingled with that body it will combine slowly in diffused light, but ex- plosively in the direct rays of the sun, electric lamp, etc. To this attraction it owes its efficiency as a bleaching agent. By combining with and removing the Hydrogen from organic coloring matter it destroys it, and thus bleaches or removes all such substances. CHLORINE. 15S Bleaching. — In practice, goods to be bleached are first well washed and boiled in water with strong alkalies, Fig. 137. to remove all grease, etc. ; then they are saturated with chloride of lime mixed in water; then they are im- mersed in water containing a little sulphuric acid, which liberates chlo- rine from the chloride of lime con- tained in the cloth among its fibres. This efi'ects the bleaching most per- fectly. The cloths must lastly be washed for a long time in fresh water, to remove all trace of acid. To re- move stains from linen or cotton goods, in the small way, Chloride of Soda (Labarraque's Solution) or Chloride of Potash (Javelle water) which may be obtained from any apothecary, are very useful. The stained cloth should be immersed in the solution ; a little boiling water added, if necessary, or, in obstinate cases, the whole placed in the sun for some hours. The article should be thoroughly rinsed with fresh water before it is allowed to dry. Col- ored fabrics cannot be thus treated, as their color would disappear with the stain. Woollen cloths are not bleached with chlorine, but with fumes of burning sulphur, i. e. Sulphurous acid, SO... It is by an action similar to the above that Chlorine acts as a deodorizer, breaking up the offensive gases by removing tlieir hydrogen or like clomont. A little chlo- ride of lime thrown under a floor will thus alVord entire relief from the "attacks" of a dead mouse. Te&t — We recognize free Chlorine bv its smell, color, 154 CHLORINE. heavy fuivie with ammonia, curdy white precipitate with nitrate of silver, and bleaching of organic colors. Compounds of Chlorine and Oxygen. HypochloroilS Acid — CIO. An orange-yellow liquid, ob- tained by passing Chlorine over red Oxide of Mercury, 2HgO -f 2C1 = HgCl.HgO 4- CIO. Readily decomposed by heat into oxygen and chlorine. It bleaches powerfully, and combines with the alkalies to form hypochlorites, pos- sessing the same property. CMorous Acid — CIO3. A greenish-yellow gas, obtained by heating a mixture of Arsenious acid, Chlorate of Po- tassa, and Nitric acid. The nitric acid yields up some of its oxygen to the arsenious acid ; nitrous acid is formed, and afterwards converted back again into nitric acid by oxygen given off from the decomposed chloric acid. Thus AsOa -f H0,N05= ASO5 + H0,X03; and HO.XOs + K0,C105 = KO.X05+C103+HO. Hypochloric Acid — CIO4. A deep-yellow explosive gas, evolved by heating concentrated Sulphuric acid with Chlorate of potassa^ 3(KO,C105)-f 3(HO,S03)=2C10,-f ClO, + 3(KO.S03) + 3H0. Chloric Acid — CIO5. Obtained by boiling Chlorate of Potassa with Hydrofluosilicic acid. Test. — The chlorates evolve pure oxygen when heated. Perchloric Acid — CIO7. Shown above as one of the products in formation of Hypochloric acid. Compounds of Chlorine with Hydrogen. Hydrochloric Acid— H CI. Preparation. — 1st. When equal volumes of Hydrogen and Chlorine are exposed to the direct sun-light they unite explosively. 2nd. From Sulphuric acid and common Salt. XaCl -f H0,S03 = XaO,S03 -f HCl. Properties. — A powerfully acid gas, with an intense at- BROMINE. 155 traction for water. The latter absorbs 418 times its bulk of this gas to form the liquid known as Hydrochloric acid. Unites with metals, forming chlorides, with liberation of hydrogen, and with metallic oxides, to form chlorides and water. Uses. — It is a very delicate test for the salts of silver and for ammonia. It is employed in the arts for preparing Labarraque^s solution, Javelle waUr, bleacJiing powder, for the extraction of gelatine from bones, etc. It is used alone, or in aqua regia, to dissolve very many minerals, and to prepare the metallic chlorides. Chloride of Nitrogen — NCI3. A fearfully explosive oily liquid, formed by passing chlorine into a solution of sal ammoniac. Sym. Br. BROMINE. Eq. 78.26. Discovered by M. Balard in 1826. Named from )3pw/io?, a disgusting smell. Found in sea-water, especially of the Dead Sea, mineral springs, and native bromides. Sp. Gr. 2.96. Preparation. — Bittern, which is the mother-liquor of sea- water, after the less soluble salts have been separated by crystallization, contains various bromides. These are de- composed by a stream of chlorine passed through the liquid, and the bromine, set free, dissolves in a quantity of ether agitated with the bittern thus treated. Properties. — When separated by a complicated process from the ether, Bromine is a deep-red, volatile liquid, of a very suffocating and offensive odor; freezes at about 19'^ and boils at 145°; bleaches many vegetable colors ; unite;- directly with many of the metals, sometimes with ignition, forming bromides. Bromide of silver is considerably em- ployed in photography. Combines with Hydrogen to form HyUrobromic acid, 11 Br. Test. — Starch is colored yellow by free broniiiu'. 166 IODINE — FLUORINE. Sym. I. IODINE. Eq. 126.36. Discovered in 1812 by M. Courtois. Named from iqSj^j, violet-like. Found in sea-water, sea-weeds, some mineral springs, and as iodides of lead and silver. Sp. Gr. 4.94. Preparation. — By gently heating the bittern from kelp, which contains Iodides of Sodium, Magnesium, etc., with Sulphuric acid and Binoxide of Manganese. Thus, KI + MnO, + 2 (H0,S03) = I + KO.SOs +MnO,S03+2HO. Properties. — At ordinary temperatures a metallic bluish- black solid, having the form of rhomboidal scales or taper- ing octahedrons; at 225° it changes to a liquid, and at 347° to a rich intense violet vapor. It is but slightly soluble in water, which dissolves about O.OOY of its weight at ordinary temperatures ; in ether and alcohol it dissolves readily and forms dark reddish-brown liquids. Its chem- ical affinities are like those of chlorine and bromine, but being more feeble it is displaced from combination by these two metalloids. It unites with hydrogen to form Hydriodic acid, HI, and with oxygen to form Iodic acid, IO5, and Periodic acid, IO7, but none of these compounds are of practical importance. Test. — It unites with starch, in the presence of water, to form a beautiful blue iodide of starch. This iodide loses its color at a temperature of 165°, and recovers it again on allowing the liquid to cool. Uses. — Iodine alone, or in combination with potassium, is a remedial agent for goitres and scrofula. The iodides of potassium, sodium, ammonium, and cadmium are em- ployed in photography to iodize the collodion. Sym. F. FLUORINE. Eq. 18.7. Discovered by Sir. 11. Davy, but has never as yet been isolated in such a state as to admit of satisfactory inves- FLUORINE. 167 tigation. It derives its name from fluor spar m which it is chiefly found ; specific gravity, 1.32 (theoretical). Hydrofluoric Acid — HF. A highly acid gas obtained by acting on fluor spar (fluoride of calcium) with Sulphuric acid, CaF4-HO,S03=CaO,S03 + HF. Use. — It acts powerfully on all siliceous matters, and is therefore employed in etching glass. For this purpose the plate, or other object to be etched, is coated with wax; the design to be produced is scratched through this. Some Fluor spar in coarse powder is then spread in a shallow leaden dish (see Fig. 138), moistened with oil of vitriol warmed with a spirit lamp. As soon as ■^^°* ^^^' fumes comes off the lamp is removed, and the plate set face downwards for a minute or two upon the dish. The ex- posed parts of the glass are corroded by the fumes and acquire the appearance of ground glass, thus showing the design upon the smooth glass when the wax has been removed by scraping and rubbing with turpentine. Thermometer tubes, chemical bottles, etc., are often marked in this way. Plates of glass on which frost-like crystals have been formed, by spread- ing them with gum-water containing in solution, Nitre, Sulphate of Copper, or the like, may be thus etched so as to form beautiful objects for the magic lantern, or glass goblets may be permanently frosted by this process. A solution of HF in water etches likewise, but with a smooth surface. 14 158 CARBON. Sym. C. CARBON. Eq. 6. Carbon occurs in three forms : 1st. Diamond, whose name is a corruption of adamant (from a, privative ; and Sa^ua'w, / subdue), invincible. Hard- est of all substances, cannot be cut except by its own dust; but scratches all other minerals and metals. Sometimes colored, but usually limpid ; infusible at all temperatures; combustible at a white heat with formation of Carbonic acid gas ; of a high refractive and dispersive power ; feebly phosphorescent when brought into a dark room after ex- posure to light. It crystallizes in octahedra and tetra- hedra, oftentimes with curved faces. It is probably of vegetable origin. Uses. — As an ornament, cut as a rose or hrilliant; the former having the under surface flat, and the upper elevated, en dome, without table, and reflecting light from 24 facets ; the hrilliant is cut into symmetrical facets on both lower and upper faces. 2nd. For cutting glass, for delicate pivot-rests, and as a grinding and polishing powder. 2nd. Graphite or Plumbago. — A very friable substance, soft and greasy to the touch, and of a metallic leaden- gray lustre. It is largely worked at Ticonderoga, New York, and at Brandon, Yermont. It is sometimes found in brilliant six-sided spangles, which may also be arti- ficially produced by dissolving charcoal in melted iron. Uses. — Lead-pencils ; mixed with fire-clay, it is made into "black-lead" crucibles for melting gold, silver, etc.; it is rubbed over iron-castings to preserve them from rust — stove-polish; to relieve the friction of carriage axles, wheels of machinery, and even of clocks; to polish gun-bullets; smeared over the wax medals in an electro-plating bath to cause the deposition of gold and silver upon their surface. CARBON. 159 3rd. Amorphous Carbon. — In consequence of its infusi- bility carbon presents itself in a variety of aspects accord- ing to the structure of the body from which it was formed and the manner of its preparation, viz. : (a) Metallic Carbon. — A metallic coating formed by the contact of the carburetted hydrogen gases produced in the distillation of coal with the red-hot sides of the retort. It is an excellent material for the carbon points of the electric light, and for the positive pole of Bunsen's battery. (&) Charcoal is formed by burning stacks of wood which are covered over with leaves and dirt to prevent a free access of air. The charcoal of light woods, such as black alder and willow, is largely consumed in gunpowder. As a powder, charcoal is used for polishing copper and bronze; as a dust, it is sprinkled over meats to preserve them from decay ; in lumps, to absorb noxious gases. So the charring of the ground end of fence posts secures them from rot. (c) Coke is obtained by distilling off the water, tar, and gas from bituminous coal ; 100 tons of the latter affording 50 or 60 tons of coke. It produces a greater heat than any other fuel, except Anthracite, and is largely employed in blast furnaces, forges, etc. (d) Lampblack is condensed upon the sides of chambers, in which resins, fats, etc., are burnt with an insufficient draft of air. It is employed in painting; mingled with two-thirds its weight of clay, to form black drawing-cray- ons; intimately mixed with dry linseed-oil to make an indelible printer's ink. Manuscripts, written in an ink composed of lampblack and gum-water, have been exhumed at Herculaneum and Pompeii, still perfectly legible. (e) Animal charcoal is made by burning bones in close vessels. It serves as an antidote to vegetable and animal poisons, but its principal use is to refine sugar. After a while it loses its power of decolorizing syrup ; but it may 160 COMPOUNDS WITH OXYGEN. be revivified by drying-, saturating with Hydrochloric acid ^as, washing, and reburning. (See Franklin Institute Jour- nal, Y. 49, p. 250.) Ex. A rich solution of indigo, filtered through animal charcoal, loses its color entirely. Compounds with Oxygen. Carbonic Oxide— CO. Sp. Gr. 0.9*72. Preparation. — Heat 1 part of Ferrocyanide of Potassium with 10 parts of sulphuric acid. KaCeNgFe + 6(H0, SO3) + 6H0 = 6C0 + 2(KO,S03) + FeO.SOs + 3(NHA SO3) Properties. — A colorless, inodorous, poisonous gas ; ex- tinguishes flame, but burns itself with a purplish blue flame, easily extinguished. Seen in coal fires where there is a lack of air. Carbonic Acid — CO2. (Fixed air, choke-damp.) Sp. Gr. 1.52Y. Sources. — Combined with lime, as limestone, forms one- seventh of the solid crust of the earth's surface. United with iron, copper, zinc, etc., forms many valuable ores. Constitutes one-thousandth part of our atmosphere. Preparation. — By decomposing a carbonate by any strong acid. Ex. NaO,C02 -|- H0,S03 = Na^SOa + HO -f CO,. Thus we place in a vessel such as A (Fig. 139) some common washing soda (Carbonate of Soda), and pour upon it dilute Sulphuric acid. The gas is then freely developed, and may be collected by displacement. This gas is also produced in all ordinary cases of combustion and in respiration. The amount of CO2 exhaled by a man in twenty-four hours, is about 26-J ounces. This would give for the inhabitants of the world, about 820,000 tons per day. Fortunately, plants reverse this action. Properties. — The weight of this gas is very notable. It may be poured from one vessel to another and weighed CARBON. 161 readily on a large scale in a grocer's paper-bag, or in a wooden bucket. Many of its properties may be well exhibited by arrang- ing an artificial grotto, Fig. 139, and allowing the gas Fig. 139. from the bottle, A, to flow into it. This will settle like water at the lower part, and a taper will burn within until lowered beneath the surface of the gas. A little slide being then opened in the side of the box, the gas may be drawn off into vessels, poured from them over candles so as to extinguish them, etc. It directly interferes with and prevents combustion. It has therefore been used, by Sir Goldsworthy Gurney, in fire-engines which pour Carbonic acid instead of water upon a burning building, and for putting out fires in burn- ing mines. Does not support respiration ; and when formed in mines by explosions of fire-damp, it is the choke-damp so fatal to miners. Under the influence of light, it is decomposed in the leaves of plants. The carbon being essential to vegetable growth, is retained by the plant; while the oxygen is returned to the atmosphere, in order that animal life may be sustained. It is soluble in water, and when held in solution under pressure, makes soda- water. Liquid Carbonic Acid. — Under a pressure of 40 atmos- 14* 162 CARBON. pheres, or 600 lbs to the square inch, Carbonic acid gas is condensed to a colorless liquid. Solid CarbOBic Acid. — When a jet of this liquid is thrown into a metallic receiver filled with holes, the vessel is seen to fill rapidly with a flaky snow. This is solid Carbonic acid, formed by the great cold — about 150° — given out in the very rapid evaporation of part of the liquid Carbonic acid. By mixing solid Carbonic acid with ether, and evap- orating under the receiver of an air-pump, a temperature as low as-166° F. is produced. This mixture, as it were, burns the hand if placed upon it, and causes active in- flammation. Test. — Lime-water is so delicate a test that it is rend- ered cloudy by blowing the air from the lungs through it for a very short time Compounds of Carbon with Hydrogen. Protocarburetted Hydrogen — C2H4. (Light Carbu- retted Hydrogen). Exists native, as fire-damp in coal- mines, and the inflammable air of marshes — marsh-gas. Prepared by heating 4 parts of acetate of soda (which must be first dried), 4 parts of caustic potash, and 6 parts quicklime, powdered and mixed in a strong glass flask, 2cNaO,C,H303) + KO,HO + CaO,HO = 2(NaO,C02) + KO, CO2+ CaO, CO2+ 2 C2 H4. Properties. — A colorless, transparent gas. Sp. Gr. 0.555. Extinguishes flame, but burns itself with a pale yellow flame ; mixed with air and lighted, explodes. Bicarburetted Hydrogen — C4H4. Sp. Gr. 0.98. Also called Heavy Carburetted Hydrogen and defiant Gas. Preparation. — One measure of alcohol is heated with 3 ofsulphuricacid,CJT60, + 2(HO,S03)=2(HO,S03) + 2HO -f C^H^. To avoid frothing, we pour sand into the flask till all the liquid is absorbed by it. Properties. — A colorless gas, with a sweet, alliaceous COMPOUNDS WITH HYDROGEN. 163 odor; soluble in about 12 times its bulk of cold water; liquefi- able under great pressure ; not a supporter of combustion. Very inflammable, burning with a w^hite luminous flame. Combines with chlorine to form Dutch Liquid, C^H.Cl.,. Remark. — The two preceding gases are the principal constitu- ents of coal-gas. Prepared by distilling bituminous coal in large iron retorts ; purifying the gases evolved by passing them through vessels filled with spray of water (which absorbs their ammoniacal impurities), Fi-. 140. Fig. 141. 164 CARBON AND NITROGEN. and through vessels containing moist lime (which absorbs the sulphur and carbon compounds), and lastly, storing them in large, self-adjusting gas holders; whose principle is illustrated by the smaller apparatus figured in the cuts. Fig. 140, and Fig. 141. As the gas flows in, the inner drum rises, giving space ; as it escapes, this sinks, so diminishing the capacity of the vessel. Compound of Carbon with Nitrogen. Cyanogen— C^N or Cy. Sp. Gr. 1.82. Source. — Cyanogen is formed, in combination with potassium, by heating organic substances containing nitrogen, such as fibrine, gelatine, skins, etc., with potash. Preparation. — Obtained by heating Cyanide of Mercury. HgC,N = Hg-f C,N. Properties. — A colorless, soluble gas ; liquefiable by a pressure of four atmospheres. Its odor resembles that from bitter almonds. Burns with a dark blue flame fringed with purple. In chemical properties, it must be classed with chlorine and bromine ; uniting, like them, with hydro- gen to form an acid, and with the metals to form salts. It was the first one, among many compound bodies since discovered, which was found to play the part of an ele- ment ; and the discovery of this " Compound Radical," as such bodies are called, by Gay Lussac, in 1814, greatly simplified modern chemistry. Uses. — Its combination with hydrogen, Hydrocyanic, or Prussic acid, HCy, is a fearful poison, whose proper anti- dote is chlorine or ammonia, cautiously inhaled. Diluted, however, with 50 times its weight of water, it is employed to allay nausea, and as a lotion in skin diseases. Cyanide of Potassium, KCy, energetically dissolves the cyanides of gold and silver, and forms with them double cyanides, which constitute the gold and silver baths in Electro- BORON. 165 plating. Alone, Cyanide of Potassium is excellent foi fixing Collodion Positives. Compound of Carbon with Sulphur. Bisulphide of Carbon — CSa, Sulphocarbonic Acid. Sp Gr. 1.272. Preparation. — Prepared by passing sulphur vapor over ignited charcoal and condensing the result by cold. A transparent, colorless liquid, insoluble in water, of most disgusting smell. Uses. — To dissolve sulphur, phosphorus, many resins, oils, etc. Owing to its great refracting and dispersive power, it is employed in prisms of the spectroscope and other optical instruments ; in the construction of thermom- eters for measuring intense cold, since it cannot be frozen ; along with tallow and phosphorus, as a substitute for black-lead in electro-silvering large medals, etc. To re- move grease-stains. Syin.B. BORON. Eq. 10.9. Discovered by Davy, 1807. Preparation. — The double fluoride of boron and po- tassium is heated with an equal weight of potassium. KF,BF3 -f 3K = 4KF + B. Modifications. — 1st. As thus obtained, Boron is an amorphous olive-green powder, which burns when heated in the air to a point below redness, forming Boracic acid. In this condition it corresponds to charcoal. 2nd. As octahedra; which are very hard, highly re- fracting; fusible only under intense heat, and in all respects like Diamond. 3rd. As scaly, hexagonal plates, rosemblino; Graphite. Compound with Oxygen. Boracic Acid— BO3. Sp. Gr. 1.8. Source. — Discharged from small craters or soJJumi 166 SILICON. along Tvith sulphuretted hydrogen and steam, into the bottom of the Tuscan lagunes. The waters of these lagunes are evaporated until the Boracic ahosphoric, Tartaric, Racemic, and Gallic acids. A Tribasic Acid combines with three equivalents of the base, as the Tannic, Phosphoric, Citric acids, etc. A Basic or Sub-salt is one which contains fewer equiva- lents of acid than there are equivalents of Oxygen in the base, as Sub-Sulphate of the Sesquioxide of iron (Fe,03,S03). A Double Salt is one formed by the combination of two salts. The electro-negative body is usually the same in both salts, as KO,SO,+Al203,3S03+24HO, Alum, or the double Sulphate of Potash and Alumina; KCl-f- PtCla, double Chloride of Potassium and Platinum. \ POTASSIUM. 181 GROUP I. Sym. K POTASSIUM. Eq. 39. Isolated by Davy, in 1807, from moistened Hydrate of potasBa placed in contact with the poles of a very power- ful galvanic battery. Preparation. — When Carbonate of Potassa and charcoal are intimately mixed together and subjected to intense heat, carbonic oxide and potassium vapor are set free. The latter is solidified by cold, and collected in a proper receiver, KO,C02+2C = K-{-3CO. Properties. — A bluish-white metal, which is brittle and crystalline at 32°, soft at 60°, liquid at 130°. Its specific gravity being only 0.865, Potassium will float upon water. Enters directly into combination with the halogens, and with Sulphur, Selenium and Tellurium, burning vividly when heated with them. So strong is its affinity for oxy- gen that it cannot be preserved in the open air, but only in a vacuum, or under the surface of some liquid, like Naphtha, which does not contain oxygen. When a lump of Potassium is thrown upon water, it unites with the Oxygen of that compound, forming potash, and setting free the Hydrogen. The heat developed in this action is so great as to render the Potassium red hot, and to ignite the liberated Hydrogen, which burns with a flame tinged purple by the vapor of the Potassium, which also burns. Compounds with Oxygen. Teroxide of Potassium — KO3. Formed when potas- sium is heated in an excess of dry oxygen gas. Potassa — KO. Generated by the oxidation of potassium in dry air. Known in chemistry as a rongont only in the form of Hydrate of Potassa, K0,H0. Sources. — Found combined with Silica in Mica and Fel- 16 182 POTASSIUM. spar. Bj decomposition of these two minerals, it passes into the soil. The fertility of land depends in great mea- sure upon the . quantity of Potassa which it contains. From the earth it is taken up by plants, and it is from the ashes of burnt trees that the carbonate of potash, or pearl- ash of commerce, is obtained. Preparation. — This hydrate is manufactured by dissolv- ing Carbonate of Potassa in 10 or 12 times its weight of water, and adding to the boiling solution a quantity of caustic lime, equal in weight to half the Carbonate of Potassa used, KO,CO,+ CaO,nO=KO,HO-f CaCCO^. Uses. — The glass maker unites it with sand to make Silicate of Potassa, one of the components of glass ; the soap-maker unites it with a fatty acid to form soft soap : the chemist absorbs carbonic acid with it, and decomposes by it all those metallic salts, the bases of which are insol- uble in water. It is very alkaline, and unctuous to the touch ; it instantly alters, and finally destroys the skin, for which reason it is employed as an escharotic, under the name of caustic potash. Ignited with the insoluble silicates, it renders them soluble in acids : this operation must be performed in silver capsules. Compounds with the Halogens. CMoride of Potassinm, KCl, is extracted from kelp, the ashes of burnt sea-weeds. It is used in large quantities, as a source of potassa in alum manufacture. The slaty clay which is used for making alum is filled with bisulphide of iron, FeSa', hence, on roasting and exposing to air and moisture, sulphate of the protoxide of iron and sulphate of alumina are formed. But alum is a double sulphate of |30- tassa and alumina. Chloride of potassium is therefore em- ployed to decompose the sulphate of iron : FeO,S03-}- AI2O3, 3s63+KCl-fAq=(KO,S03-fAlA,3S03+24HO)-fFeCl. Also, to eflPect the decomposition of nitrate of limo in POTASSIUM. 183 one mode of manufacturing saltpetre: CaO,N05+ KCi= K0,N05+CaCl. Iodide of Potassium, KI, is procured by digesting 2 parts of iodine and 1 of iron in 10 parts of water; the pro- tiodide of iron so formed is afterwards converted into iodide of potassium by carbonate of potassa: Fe + I= Fel and Fel-f KO,C02=KI+reO,C02. Uses. — In the manufacture of the metallic iodides ; to dissolve the Iodide of Silver employed in iodizing photo- graphic paper, and as a remedy for glandular swellings. Compounds with Acids. Potassa Salts. Carbonate of Potassa — K0,C02. In commerce called Vegetable Alkali, Salt of Tartar, Dulcified Alkali, Pearl- ash, or simply Potash. Preparation. — Potassa, KO, exists in large quantities in plants, combined with various organic acids, such as Malic, Acetic, Oxalic, Tartaric, etc. These salts are all converted, by burning, into Carbonate of Potassa, and the latter may therefore be obtained by making a lye of wood- ashes, and evaporating until the carbonate of potassa crystallizes out. Birch-ash yields the purest potash, pine ashes the least; herbaceous plants furnish more than shrubs, and shrubs more than timber; the quantity afforded by the leaves is to that procured from heartwood as 25 to 1. Uses. — In the manufacture of soft soaps, crystal glass, Prussian blue, and sometimes to decompose the nitrates of lime and magnesia, employed in making saltpetre. When changed to the bicarbonate ov sal aeratus ^KO.CO., -f HO.COa), by passing a current of Carbonic acid through a solution of the carbonate, it is used in the treatment of gout and the like, and mixed with citric or tartaric acid, to make effervescing draughts. Sulphate of Potassa, K0,S03, obtained by neutralizing 184 POTASSIUM. the Bisulphate of Potassa (KO,S03+HO,S03), which is left as a residue in the manufacture of Nitric acid with KOjCOa, is used as a gentle laxative. In analysis, the former salt serves to detect and separate baryta and strontia ; the latter as a flux for salts, or metallic oxides, which are required to be acted upon by an acid at a high temperature. Nitrate of Potassa — K0,N05. Salt of Nitre, Nitre, Saltpetre. Source. — Formed abundantly in the hot weather suc- ceeding rain-storms, in certain soils of Spain, Egypt, Per- sia, and the East Indies, which are rich in potash. (See Ammonia.) Incrusts the interiors of many caverns in the West, and in Ceylon. Artificially prepared by the oxida- tion of ammonia in the presence of a powerful base in nitre plantations ; animal refuse of all kinds, the cleaning of sinks, stables, etc., are thrown together with old mor- tar, plaster from ceilings, etc., into great heaps. After three years these nitre beds are w^ashed, and yield to every cubic foot 4 or 5 ounces of nitre. This salt crystallizes in the form Fig. 145. Q^ ^^ hexagonal prism. A slice of this, cut perpendicular to its axis, viewed between two polarizing bodies, as in Fig. 54, or 55, shows the system of colored rings and dark brushes, indicated in Fig. 60, when the plane of its two optical axes co- incides with the plane of the polar- izer, and the system represented in Fig. 145, when these planes are slightly inclined. Uses. Nitre is extremely valuable on account of the facility with which it yields up its oxygen. It is con- stantly employed to oxidize the metallic sulphides into POTASSIUM. 185 sulphates, carbon into carbonic acid, etc. Ex. Rapid com- bustion {deflagration) of a mixture of carbon and nitre, or of sulphide of antimony (SbSg), or sulphur with nitre, when touched by an incandescent body. This property of nitre gives it wonderful adaptation for its use in Gunpowder. — Gunpowder, used in France, Prussia, and the United States in war, consists of 75 parts of saltpetre, 12 i parts of charcoal, and 12? parts of sulphur. The salt- petre starts the detonation by giving up all its Oxygen to the Carbon to form Carbonic oxide and Carbonic acid gases, the Potassium and Nitrogen being thus set free. The former straightway seizes upon the Sulphur to form vaporous Bisulphide of Potassium, the latter flies off as gas : K0,N05 + S^ -f 4C = KS^ + 2C0 + 2CO2 + N. The temperature at the moment of explosion rises to 2200°, high enough to melt gold and copper coin ; and dilates the liberated gases, already occupying an enor- mous volume, until an amount of powder which filled 1 cubic foot of the gun, after firing, expands to 2000 cubic feet. Besides this important use of nitre in gun powder, butchers employ it to preserve meats ; physicians as a medicine. Lucifer matches are made with it. Chlorate of Potash — K0,C105. Largely manufactured by passing Chlorine through a thin cream of 1 part of Chloride of Potassium and 2 parts of Hydrate of Lime dissolved in water : KCl -f 6CaO + 6C1 = KO.CIO, + 6CaCl. Ex. Kubbed with charcoal, sulphur, and phos- phorus the mixture explodes, in consequence of the rapid oxidation of these bodies by the Chlorate. XJi>es. — By the chemist and calico-printer as an oxidizing agent; in lucifer matches ; and in percussion powder for gun-caps. The friction tubes for cannon-firing are charged with a mixture of 2 parts of Chlorate of Potash, 2 of Sul- 16* 186 SODIUM. phide of Antimony, and 1 of powdered glass. A mixture of. Chlorate of Potash, dried Ferrocyanide of Potassium and Sugar has been used for blasting, under the name of white gunpowder ; but the ease with which it explodes by friction has rendered its manufacture dangerous. Test. — When a strong solution of Bichloride of Plati- num, is poured into a concentrated solution of a potash salt, a yellow double Chloride of Potassium and Platinum (KCl + PtCy precipitates. Sym. Na. SODIUM. Eq. 23. Discovered by Davy in 180Y, and obtained by him in the same manner as Potassium. Prepared like Potassium for commercial uses. Properties. — A bluish-white metal ; soft at common tem- peratures, melts at 194^. Decomposes cold water with the evolution of heat but not of light. The Oxide, Sul- phides, and Haloids of Sodium correspond in properties and mode of formation with those of Potassium. Sp. Gr. 0.9T2. Chloride of Sodium — NaCl. Sea Mineral, or Rock Salt. Sources. — Found in Poland, England, Spain, and other places as a rocky deposit, often of great thickness and extent. Obtained likewise by evaporating in salt-pans the waters of the ocean, and those pumped from the salt-wells of Western Virginia and Pennsylvania. Uses. — To season food ; in the manufacture of Sulphate and Carbonate of Soda, of Hydrochloric acid, the bleach- ing Chlorides, and Chlorine; in forming salt-glaze upon pottery ; in manufacturing soap ; in preserving meat. Sulphate of Soda, NaO,S03, is manufactured on a vast scale in Leblanc's process for making Carbonate of Soda, by causing Sulphuric acid to react upon common salt; thus, NaCl-f HO,SOs=NaO,S03+HCl. It was for- merlv also in favorite use as a saline cathartic, under the SODIUM. 181 name of Glauher^s salt, but it has gradually been replaced by Sulphate and Citrate of Magnesia. Carbonate of Soda, ]SiaO,C02, is prepared by throwing into an elliptical reverberatory furnace 1000 lbs. of salt cake, or Anhydrous Sulphate of Soda, obtained by the above reaction, intimately mixed with 1000 lbs. of dry chalk, and 350 lbs. of crushed coal. The Sulphate of Soda is reduced by the coal to Sulphide of Sodium, NaO,S03 4- 4C =NaS -|- 4C0 ; and this Sulphide effects a double de- composition of the Carbonate of Lime, to form Carbonate of Soda and Sulphide of Calcium, NaS + CaO,C02 = NaOjCOa + CaS. Fifteen hundred pounds of this crude artificial soda or black ash may be obtained from the pre- ceding charge. Crystallized from its solution, it is known in commerce as sal soda. Uses. — The soap-makers use vast quantities of black ash to make from it, by treatment with milk of lime, their caustic Soda, or Soda lye, employed in the manufacture of hard soap : NaO,CO, + CaO,HO = NaO,HO -f CaO, CO2. Used as a detergent by the calico-printer, and, under the name of washing soda, in the kitchen. It unites with the grease wherever present, and forms with it a kind of soap. In the laundry for softening hard waters, by forming with the soluble salts of Lime and Magnesia insoluble Carbonates. In the manufacture of glass. Treated with excess of Carbonic acid it is con- verted into Bicarbonate or Supercarhonate of Soda (NaO, CO2 -f H0,C02). It is mixed with Rochelle salt in the blue paper which is sold, along with a white envelo^^e enclosing Tartaric acid, by druggists, as Seidlitz powders. Phosphates of Soda. Phosphoric Acid forms with Soda several crystallizable salts, which differ from each other in the number of equiva- lents of Soda united with one equivalent of the acid, viz : 188 SODIUM. (a) The Tribasic 'Phospliates of Soda, which are three in number: — 1st. Neutral Tribasic Phosphate, or Subphosphate of Soda (3NaO,P05+24Aq). 2nd. Rhombic Phosphate of Soda, (2NaO,HO,P05 + 24Aq). From this salt all the other Phosphates of Soda are formed. It has been longest known, and is familiar under the name of Commercial Phosphate of Soda. 3rd. Biphosphate of Soda, (2HO,NaO,P05 + 24Aq). Test. — These three tribasic phosphates give with Ni- trate of Silver a yellow precipitate. They always require three equivalents of the salt, with which they react : thus, 3NaO,P05 ^ r3(NaO,N05) 2NaO,HO,P05 [-j-.3(AgO,N05) = 3AgO,P05+ j 2(NaO,N05) + HO,N05) 2HO,NaO,P05i (NaO,N05+2(HO,N05) (6) Pyrophosphate of Soda (2NaO,PO5+10Aq). Test. — Gives a dense white precipitate with Nitrate of Silver. Reacts with two equivalents of another salt : thus, 2NaO,P05+2(AgO,N05)=2AgO,P05+2(NaO,N05). (c) Metaphosphate of Soda (NaCPOs). Test. — Gives a gelatinous white precipitate with Ni trate of Silver. Reacts with one equivalent of another salt: NaO,P05 + AgO,N05=AgO,P05+NaO,N05. Uses. — Phosphate of Soda (2NaO,HO,P05) precipitates all the alkaline earths and metallic oxides. After the oxides of the heavy metals have been separated, it serves in analysis as a test for the alkaline earths in general; and after the separation of Baryta, Strontia, and Lime it is used, in conjunction with Ammonia, to precipitate Mag- nesia, as the basic Phosphate of Magnesia and Ammonia (NH40,MgO,HO,P05). Combined with Ammonia as mi' crocosmic salt (NaO,NH40,HO,P05), it is frequently pre- ferred to Borax as a flux before the blowpipe, because with many substances it gives a more brilliantly colored bead. LITHIUM. 189 Biborate of Soda— NaO,2BO3+10Aq. Borax. Sources. — For many years the crude Borax, or Tinea} of commerce, was obtained by evaporation of the waters of certain lakes in Thibet. Now manufactured from the Boracic acid present in the lagunes of Tuscany, by neu- tralizing it with Carbonate of Soda, and allowing the satU' rated solution to crystallize. Uses. — When two oxidizable metals, such as Copper and Iron, are to be soldered together, the brazier sprinkles their surfaces with Borax. This dissolves off the oxide, which would otherwise prevent their union, as fast as it is formed. The goldsmith also emploj's it, in both refining and soldering the precious metals. It enters into enamels to render them more fusible, and into the composition of easily melted glasses ; it is employed in fixing colors upon porcelain, and for the glazing of some potteries. The free Boracic acid, which is present in Borax, along with the Borate of Soda (commonly called Biborate of soda), has a strong affinity for metallic oxides at high temperatures. It consequently forms wi4h them and the Borate of Soda before the blowpipe double borates, which have diflferent colors, and which serve to detect the different metals; with Oxide of Chromium, emerald green; with Oxide of Cobalt, a deep blue ; with Oxide of Copper, a pale green: with Oxide of Tin, an opal; with Oxide of Manganese, a violet, etc. Syin.Li. LITHIUM. Eq.7. Isolated by Davy by means of the galvanic battery, and named from -ki^Ooi, a stone, because it is found chiefly in the minerals, lepidolite, spodumene, and pcfalife. Properties. — A white metal, fusible at 350°, and burn- ing with a brilliant white light. It is the lightest of metals. Sp. Gr. 0.5930. 190 AMMONIUM. Tests. — A purplish red color in the blowpipe flame, and one intensely bright red band in the spectroscope. Sym. NH4, or Am. AMMONIUM (hypotlietical). Eq. 18. Ammoiliacal Amalgam. — Ammonium has never been isolated, but is thought to exist in combination with Mer- cury in the compound which is formed when a concen- trated solution of Sal Ammoniac is poured upon Sodium Amalgam. The latter increases in bulk to 10 times its original volume, and acquires a pasty consistence, but nevertheless preserves its metallic lustre. On applying heat, Hydrogen and Ammonia are rapidly given ofiT, and pure Mercury left behind. From the character of its salts, Ammonium is placed among the alkaline metals. Oxide of Ammonium — NH^O. Ammonia. When Ammo- nia, NH3, enters into combination with anhydrous Sulphu- ric acid, SO3, it forms, not the (jrdinary salt. Sulphate of Ammonia, but a sulphate of very different properties. It is only when the hydrated acid, H0,S03, is combined with Ammonia that the regular Sulphate of Ammonia is formed. Therefore the basic water of the acid must have united with the gaseous Ammonia to form a new base, and this new base is what we shall henceforth regard as Ammonia, NH,0: thus, NH3 + HO,S03=NH,0,S03. Chloride of Ammonium, Muriate of Ammonia, Sal am- moniac — NH^jCl. The foregoing theory is strengthened by the fact, that when dry Hydrochloric acid is mixed with dry Ammoniacal gas, a white solid is formed which is ordinary Sal Ammoniac, and that this Sal Ammoniac, if dissolved in water, gives with Nitrate of Silver the 'same curdy precipitate as is formed when any other chloride reacts with Nitrate of Silver; that is to say, Sal Ammo- AMMONIUM. 191 niac is not Hydrochlorate of Ammonia, NH3HCI, but Chloride of Ammonium, NHiCl. Sources. — It derives its name from Ammon, the ancient appellation of Egypt, where it was originally manufac- tured by the dry distillation of camel manure. It was also termed Spirit of Hartshorn, because obtained from horn- shavings by heat. Now manufactured by neutralizing, with hydrochloric acid, ammoniacal liquor, or water laden with ammoniacal salts, tar, and gther impurities taken up in washing coal-gas. Uses. — Owing to its great solubility and the resulting depression of temperature, it is used in freezing mixtures; in the preparation of the sesquicarbonate of ammonia (2NH40,3C02), or smelling-salts of the shops. To re- move rust from metals, particularly copper; in dyeing; in preference to chloride of sodium and chloride of barium for salting photographic paper ; it is sprinkled over iron-filings previously mixed with one hundredth part of sulphur, to form a lute for cementing iron into stone. A mixture of the chlorides of silver and ammonium is sometimes em- ployed for silvering copper and brass without heat. Uses of other Ammoniacal Salts. Carbonate of Ammonia, NH40,C02, is preferred, in con- sequence of its volatility on heating, to the carbonate of soda for precipitating the metallic oxides and earths. It is principally employed to separate the alkaline earths from magnesia, and to separate also sulphide of arsenic, which •is soluble in it, from sulphide of antimony which is in- soluble. Molyhdate of Ammonia, ^'lI^O.MoO;,, when added in great excess to their acid salts, serves to detect the faintest trace of phosphoric and arsenic acids. Oxalate of Ammonia, NIl40,C.,03, is a most delicate test of lime, precipitating it as an oxalate, CaO.SOa + NH+O.CiOj ^CaO,C.208 -|- NH40,S03. Hydrosulphatc of Ammonia, 1 92 BAHIUM. NH^SjHS, is employed to detect many of the metals by precipitating them as differently colored sulphides, and is used like sulphide of potassium for bronzing electro-plated medals. ' GROUP II. Metals of the Alkaline Earths. Sym. Ba. BARIUM. Eq. 68.5. History. — Obtained by Davy, in 1808, from moistened Hydrate of baryta in contact with mercury, when the latter was made the positive pole of a powerful galvanic battery. It may also be procured by passing potassium vapor over baryta heated to redness in an iron tube. De- rives its name from j3api3$, henvy, owing to the great weight of its compounds. Properties. — A white metal, fusible under a red heat. Decomposes water with rapid evolution of hydrogen. Baryta, BaO, exists as a sulphate, heavy spar, which often constitute the vein-stone or gangue in mines, and as a carbonate, witherite. Obtained by calcination of nitrate of baryta. When heated to redness in an atmos- phere of oxygen, it is converted into the binoxide which is interesting as the source of binoxide of hydrogen. Uses. — Hydrated baryta, BaO, HO, and also the Chlo- ride of barium, BaCl, and Nitrate of baryta, BaO,N05, are employed to precipitate Sulphuric acid by forming with it, even in very dilute solutions, an insoluble Sulphate of baryta, BaO,S03. Fifty grains of nitrate of baryta mixed with 150 of sulphur, 100 of chlorate of potassa, and 25 of lampblack, constitute the '' green-fir e,^^ oi \he pyrotechnist. As a carbonate, BaO,C02, it is emplo\''ed in the analy- sis of siliceous minerals, which are insoluble in acids, forming when fused with them a silicate of baryta, and a soluble carbonate of the mineral oxide to be determined. STRONTIUM. 193 The sulphate (BaOjSOg) is the permanent white of water- color artists ; it is also employed to adulterate white lead. When mingled in excess with this latter pigment it forms Dutch white ; in equal amount, Hamburg, and in lesser quantity, Venice white. But it becomes, when ground with oil, translucent, and impairs the opacity of the lead paint. Character of the Salts. — Colorless and poisonous, the best antidote being Epsom salts. Give a white precipitate with sulphuric acid, which is insoluble in acids. Sym. Sr. STRONTIUM. Eq. 43.84. Discovered by Davy, at the same time and in the same way as Barium, which it closely resembles in properties. It is found native as a carbonate, strontianite, and as a sulphate, celestine ; from the former, which was first found at the mining village of Strontian, in Scotland, it derives its name. All the salts of strontia are distinguished by the crimson tinge which they impart to the blowpipe flame ; and " red-fire " is made by mixing 40 drachms of dry Nitrate of Strontia (SrCNOs), with 10 of Chlorate of Potassa, 13 of Sulphur, and 4 of Sulphide of Antimony. Sym. Ca. CALCIUM. Eq. 20. Isolated by Davy, in 1808, with the galvanic battery, from moist lime. Properties. — As obtained by the fusion of sodium with iodide of calcium (Cal -f Na = Ca -f- Nal), it is a light yellow metal, which is very malleable, and which slowly decomposes water at ordinary temperatures. It enters into combination with oxygen, chlorine, bromine, iodine, and sulphur, when heated with them ; the union being accompanied by vivid light. Sp. Gr. 1.578. Lime — CaO. Caustic, or Quicklime, is obtained by burning lime in kilns having the form of a cone, inverted 17 194 CALCIUM. and truncated. Four parts of coal and one of lime having been thrown in from above, the fire is lighted bv means of fagots and gradually spreads throughout the kiln. As fast as the carbonic acid has been driven off, the lime is removed bv openings at the base of the kiln, while fresh layers of carbonate of lime and coal are added at the top. Uses. — When the oxyhydrogen flame is turned upon cylinders of quicklime, it causes them to glow with the intense brilliancy known as the Drummond Light. Mixed with water, a hydrate of lime, which is commonly known as slaked lime (CaO,HO), is formed. The latter has the power of uniting with the carbonic acid which is present in the atmosphere, and forming with it a solid carbonate of lime. Hence its utility, when stiffened with sand, in mortars and cements. Lime is also employed to loosen hair from hides in tan- ning ; to purify coal-gas, by absorbing from it sulphuretted hydrogen and carbonic acid ; to set free the stearic acid used for candles, from the fatty base ; to defecate sugars, or to remove the acetic and lactic acids present in the raw syrup, by forming with them insoluble acetates and lac- tates. It acts as a manure, by decomposing the organic matter which is present in the soil, and making it soluble in water. One ounce of lime is soluble in about *rOO ounces of water ; and its solution, which is known as lime-water, is valuable as a test for carbonic acid, in consequence of the turbidity arising from the faintest trace of the latter. When a stream of chlorine is passed over masses of slaked lime, a mixture of Chloride of calcium and Hypo- chlorite of lime is formed, which is familiarly known as Chloride of lime or Bleaching-powder : 2CaO,HO -f 201 = CaCl+CaO,C10. The Chloride of Calcium, CaCl, alluded to above, has an intense avidity for moisture; and it is therefore used in the drying or desiccation of gases. CALCIUM. 195 Carbonate of Lime, CaO,Co2, in the amorphous condi- tion, constitutes the different varieties of limestone, oolite, chalk, alabaster, and lithographic stone. Crystallized in rhombohedra, it is distinguished as calcite and Iceland spar. Sections of this, as described on page 6t, show, with polarizing instruments, colored 2' rings and crosses, as represented in Fig. 57, and Fig. 146 ; the first with the polar- izer and analizer '' crossed," the last with these parallel. In six-sided prisms, CaOjCOa occurs as aragonite ; in minute granular crystals, as marble in its endless forms. It enters largely into the bony structure of men and animals, and is the chief component of corals and of shells. It is soluble in water containing carbonic acid ; and when the latter is driven off by heat or in any other way, it is again deposited. In this manner are formed the incrustations on the sides of steam boilers, which so frequently lead to explosions; and the stalactites, which depend from the ceiling, and the stalagmites, that rise from the floor, of caverns in limestone districts. Sulphate of Lime — CaO,S03+2HO. Gypsum is es- pecially valuable as affording a powder known as Plaster of Paris, when its water of cystallization has been driven off by a heat not exceeding 500°. This plaster has the singular property of expanding, when made into a paste with water, and then, in the course of a few minutes, of setting, or changing to a solid mass. It is therefore largely employed for copying medals, busts, statues, for moulds in stereotyping, etc., and as cement, stucco, etc. Tribasic Phosphate of Lime, 3CaO,P05, forms more than half of the bones of men and other animals. When converted to the acid, or superphosphate of lime (CaO, 2HO,P06), by heating with two-thirds its weight of sul- phuric acid, it is largely employed in the manufacture of phosphorus, and as a manure. 196 MAGNESIUM. Character of Lime Salts. — They are all colorless, and afford, with oxalate of ammonia, a copious precipitate of oxalate of lime, CaO,C203 + 2H0. Sym. Mg. MAGNESIUM. Eq. 12. Discovered by Bussy, in 1828. It is prepared by heating the anhydrous double Chloride of Magnesium and Sodium with metallic Sodium. The process for manufacturing on the large scale was patented and is carried on in England by Sonstadt ; in this country it is made under the same patent by the American Mag- nesium Company, Boston, Massachusetts. (See Journal of Franklin Institute, Vol. 51, p. 69. Sources. — Combined with carbonic acid, as a double carbonate of lime and magnesia, forming magnesian lime- stone, or dolomite. Exists in the waters of the ocean, as a chloride, and of many mineral springs, as a sulphate. Enters into the composition of many rocks and minerals. Properties. — Resembles silver in color and lustre, zinc in fusibility and volatility. Yery ductile, and malleable; crystallizes in octahedrons. Not acted upon by cold, oxidized by hot water. Burns in air producing a brilliant white light, capable of employ- ment for illuminating and photographic pur- poses. Sp. Gr. 1.7. In order to make its combustion regular in these cases, the mag- nesium, in the form of a narrow ribbon, is fed by clockwork, from Fig. 147. MAGNESIUM. 191 a brass nozzle, A, beyond which it burns. This appara- tus, known as a Magnesium Lamp, is shown in Eig. 147. The clock-work is contained in B C, its motion is con- trolled by the fly-wheel, B, and it is wound up by the key, D. The mirror, E F, reflects, and concentrates the light, and the whole apparatus may rest on a table, or be held by the handle, G. This light has been used to photograph dark interiors, coal-mines, the Pyramids, etc., and to take photographic portraits, at night. This light is superior in amount to a good lime light, and approaches even the elec- tric light obtained from 50 Bunsen 7 inch cells. In actinic force it surpasses all other artificial lights. Oxide of Magnesium — MgO. Magnesia; Calcined Mag- nesia. Prepared by driving off the carbonic acid and water contained in magnesia alba by long continued heat ; a soft, bulky, white, tasteless, and nearly insoluble powder. Carbonate of Magnesia — MgOjCOa. Occurs in nature, in rhombohedral crystals — magnesite. Mixed with hydrate of magnesia, it forms the subcarbonate of magnesia, or magnesia alba of pharmacy, 4(MgO,C02 -f MgO,HO 4- 6H0.) Sulphate of Magnesia— MgO, SO3+6HO. Epsom Salts. Formed by dissolving Magnesite in Sulphuric acid, and separating the sparingly soluble sulphate of lime by fil- tration ; thus, MgO.CO^ + nO,S03 = MgO.SOa -f HO + CO,. Phosphate of Magnesia and Ammonia— 2MgO,NII,0,POi 4- 12H0. When it is desired to remove magnesia from solution, it may be done by adding some soluble phos- phate, together with ammonia; when an insoluble phos- phate of magnesia and ammonia is formed. Silicates of Magnesia. — Occumative as Talc, 2(MgO, SiOa) -f 2MgO,3Si03 ; Steatite or Soapstone, MgO,SiO, 17* 198' ALUMINUM. 4-2MgO,3Si03; Meerschaum, 2MgO,3Si03 + 4Aq; Ser- pentine, 2(MgO,Si03) + MgO + 2Aq, and many others. Character of the Magnesian Salts. — Bitter to the taste. Many magnesian minerals have a silky lustre, and feel unctuous to the touch. Test. — A white precipitate, with Phosphate of ammo- nia. GROUP III. Metals of the Earths. Sym. Al. ALUMINUM. Eq. 13.7. First procured by Wohler, in 1827, by decomposing Chloride of Aluminum in a platinum tube, by means of Potassium, Al.Cls + 3 K = 3 KCl + 2 Al. Properties. — In color and hardness, aluminum closely resembles zinc. It may be rolled into very thin foil, and drawn out into fine wire. It conducts electricity almost with the rapidity of silver ; struck with a hard body, it gives a clear and musical ring. On account of its light- ness — being but 2^ times heavier than water — audits inalterability in air, many attempts have been made to employ aluminum as a substitute for silver, in articles of jewelry, and table use. Sp. Gr. 2.5. Sesquioxide of Alnmimiin, or Alumina— AI2O3. When this earth is found crystallized in oature, and of a dark red color, it is known as oriental ruby ; when blue, as sapphire; green, oriental emerald; if it is yellow, it is called oriental topaz; and if violet, oriental amethyst. To the dark-colored and dingy crystals the name of corundum is given, and to the granular masses, so valuable for polishing, the term emery is applied. It is obtained as a gelatinous hydrate, when carbo- nate of ammonia is added to the sulphate, or other salt of alumina : A1A,3 SO3 + 3 (NH40,C02) + Aq = ALUMINUM. 199 SHO^Al^Os + 3(NH40,S03) + SCO^ + Aq. In this con- dition it dissolves readily in potash and acids, but if rendered anhydrous by ignition, it dissolves with diffi- culty. Uses. — Alumina has a strong attraction for water, of which it retains no less than 15 per cent. ; hence, the value of clay as an ingredient of the soil. It forms with most coloring-matters, insoluble com- pounds, called lakes. If the dyer were to soak his cali- coes in the dyestuff alone, the color would be removed from the cloth at the first washing. He first immerses them in a solution of some mordant like alumina, which has an attraction for both the cotton fibre and the color- ing material, strong enough to resist the action of water. To obtain the alumina for this purpose, alum (KOjSOg + Al203,3S03 + 24HO), which has been manufactured by the process described under Chloride of Potassium, page 182, is decomposed by carbonate of soda ; the cotton fibre forms a strong mechanical combination with the alumina thus set free, by which it is enabled to hold the coloring- matter fast. Besides its above-mentioned use, alum is employed in the sizing of paper, the preparation of sheep-skins, and in clarifying sugars, etc. Silicates of Alumina. — When silicate of alumina (Al203,3S03) is combined with silicate of lime (CaO, SiOg), it produces a number of minerals, which have the remarkable property of boiling up, on being heated in the ' blowpipe flame, and are therefore called zeolites, from Cfw, I boil. Combined with the silicates of potassa, soda, lithia, or lime, silicate of alumina forms fcJd^pai^ and feldspar, when mingled with quartz and mica, produces the well-known gneiss and granite rocks. The beautiful topaz is a silicate of alumina combined with fluoride of aluminum, AljFj; and the j^ohemiau ganiet, so highly 200 GLASS. prized for its intense blood-red color, is a silicate of alu- mina colored by the sesquioxides of iron and chromium. Vses. — When the granite rocks crumble away beneath the slow but resistless action of storms and rain, they afford the different varieties of clay. The latter, when stained by sesquioxide of iron, is used as a pigment under the name of yellow and red ochre ; if free from stains of iron it is called pipe-clay, and is largely manufactured into tobacco pipes. A peculiar variety of clay is termed kaolin. It is of the highest importance, because it forms, by fusion with silicate of potassa and lime, porcelain and China. When the clay and other ingredients used in pottery are not so pure and fine, the various kinds of stoneware and earlhenware are formed. A porous clay, which has the property of drinking oil and grease into its capillary vessels, is extensively used for scouring woollens and cloths, under the name of fuller^ s earth. GLASS. When silica, obtained from quartz rock or pure white sand, is fused with alumina and the carbonates of potash and lime, a double silicate of potash and lime is formed, which is known under the name of Bohemian and crown-glass. The former can be submitted to intense heat without melting, and is therefore invaluable to the chemist in the combustion of organic bodies. The latter is combined with flint-glass to correct the chromatic aberration of lenses. If soda is used instead of potash, a double silicate of soda and lime is formed ; and this is familiar to us as French plate, and ordinary window-glass. The above silicates are mixed with clay and oxide of iron, w^hen it is unnecessary to preserve the transparency of the glass ; and in this manner wine-bottles, carboys, etc., are made. GLUCTNUM, ETC. 201 Character of Alumina Salts. — They all have an alum- like taste ; turn blue litmus-paper red ; give an azure with nitrate of cobalt before the blovi^pipe, and a bulky gelatinous precipitate with ammonia. Sym. Gl. GLUCmUM. Eq. 26.5 Discovered by Wohler. It derives its name from y^vxv?, sweet, in allusion to the remarkable taste of its salts. When combined with silica and alumina it forms the beautiful green beryl and emerald. Sym. Zr. ZIRCONIUM. Eq. 33.6. Isolated by Berzelius. It occurs in nature as a silicate, forming zircon and the bright red hyacinth. THORIUM (Th, 59.6), YTTRIUM (Y, 32.2), ERBIUM (Er, — ), TERBIUM (Tb, — ). Thorium is remarkable as occurring in the form of a protoxide, ThO, forming the earth, thoria. It was dis- covered by Berzelius, in 1829, in a rare, black mineral named thorite, which is found in Norway. Yttrium was found by Wohler, and Erbium and Ter^bium by Mosander, 1843, in a mineral called gadolinite, which occurs at Ytterby, in Sweden. CERIUM (Ce, 46.), LANTHANUM (Ln, 47), DIDY- MIUM (Dy, 48). The first of these rare metals was discovered by Klap- roth, and the other two by Mosander, 1839, in Ccritc. They are so little known that, until recent Iv, they wcie all confounded together, under the name of Cerium. 202^ MANGANESE. Metals Lately Discovered by means of the Spectral Analysis. Sym. Rb. RUBIDIUM. Eq. 85. Bunsen and Kirchhofif, 1860. Both Rubidium and Caesium were originally found in the mother liquor of mineral waters ; particularly of the salt-springs at Durk- heimer. They have since been met with in a few minerals, as lepidolite. Rubidium produces in the spectroscope two bright red lines beyond Fraunhofer's line A ; and hence in a part of the spectrum usually invisible. (See plate facing page 123. Rb.) Sym. Cs. CESIUM. Eq. 133.03. Bunsen. Distinguished by two blue lines in the spec- trum ; which are of great intensity and sharpness of out- line. (See plate facing page 123. Ce). Syin.TI. THALLIUM. Eq. 204. Crookes. Found in Lipari sulphur and pyritous ores. Gives a green line in spectrum. (See plate, Tl.) Sym. In. INDIUM. Eq. 37.07, According to Reich and Richter; but 35.918 as given by a later authority. Found in Freiburg ores of arsenical pyrites, blende, and galena. Gives dark blue lines. GROUP lY. Metals whose Oxides form strong Bases. Sym. Mn. MANGANESE. Eq. 27.67. Discovered by Gahn, in 17Y4. Found principally in the state of black oxide, MnOa, as Pyrolusite. Preparation. — An artificial oxide is obtained by calcining MANGANESE. 203 the carbonate in a well closed vessel. This is mixed with oil and ignited in a covered crucible, by which means the oil is converted into charcoal very intimately mixed with the oxide. The above process is repeated several times. The mixture is next made into a thick paste with oil and introduced into a crucible lined with charcoal, and filled in with charcoal-dust. This is then heated to redness, after which the cover is well luted down and the whole exposed for an hour and a half to the greatest heat of a wind furnace. The metal is found as a button at the bottom of the crucible. Properties. — Manganese is a greyish white metal like cast-iron ; oxidizes rapidly in the air ; in water it evolves hydrogen. Sp. Gr. 8.013, t.05, 6.850, and t.O, according to different authorities. Compounds with Oxygen. Protoxide — MnO. Forms the basis of the common salts of Mn. They are similar in form, or isomorphous, with those of mag- nesia and protoxide of zinc. They are neutral, and of a pale rose color. Sesquioxide— Mn203. Sources. — Braunite ; and, as a hydrate, manganite. Properties. — A feeble base, isomorphous with alumina and sesquioxide of iron. Binoxide— MnOa. Sources. — Pyrolusite, psilomelane. Uses. — When the materials employed in the manufac- ture of glass cantain prot-oxide of iron, this substance stains the glass green. To remove this stain, MnOj is added, which yields part of its oxygen to the iron, con- verting it into a sesquioxide, which has but little coloring effect, and being itself reduced to a sesquioxide, which is not a coloring body, although the deutoxide itself stains 204 MANGANESE. ficlass of a beautifQl amethystine tint: it is this MnO, which colors the amethyst. Mixed with acids, afifords an excellent oxidizing agent ; ignited, gives off one-third of its oxygen, leaving the red oxide: — SMnOj = (MnO,Mn203) -f 20; heated with concentrated sulphuric acid, it yields half its oxygen : — MnO, 4- H0,S03 = MnO,S03 + HO + ; extensively employed in manufacturing chlorine: — Mn024-2B[Cl=Mn CI + 2H0 + CI. It is largely used in making bleaching powder, 18,000 tons being annually consumed in England for this purpose alone. Permanganic Acid— MujOt. When manganate of potassa or chameleon mineral, K0,Mn03, formed by heating equal weights of caustic potash and binoxide of manganese, is thrown into water, it first becomes green, then purple, and at last claret- colored ; and a permanganate of potash, KO,Mn207, is formed. Use. — As an oxidizing agent. If permanganate of potash be added to sulphuric or hydrochloric acid contain- ing sulphurous acid in solution, the sulphurous acid is oxidized to sulphuric by the permanganate of potash, while the latter at the same time loses its color; it may therefore be emplo3^ed to detect the sulphurous acid. Sulphate of Manganese— MnO.SOs+YHO. Preparation. — Formed by heating the binoxide in sul- phuric acid. Use. — When cloths moistened wnth this salt are passed through a solution of bleaching-powder, an insoluble hydrate of the binoxide is thrown down upon the woollen or cotton fibre, and dyes it a permanent brown. Water and air test. Character of the Salts of Manganese. — They have a pale rose color and an astringent taste. Before the blow- pipe they give, with borax, an amethystine bead in outer Qame ; with carbonate of soda, a bluish-green bead ; with IRON. 206 hydrosulphate of ammonia, a flesh-colored precipitate; Tith the alkalies and their carbonates, give a white. Sym. Fe. moN. Eq. 28. Fig. 148. Sources. — Free in stones of meteoric origin ; as an ore, everywhere abounds. Properties. — White color, perfect lustre, highly mallea- ble, ductile ; most tenacious of all metals ; oxidizes in damp air, and decomposes water at a red heat; strongly mag- netic. Sp. Gr. 7.8. Protoxide — FeO. Preparation. — Precipitates as a white, bulky hydrate, when an al- kali is added to any protosalt of iron. Properties. — Absorbs oxygen ra- pidly, and changes to sesquioxide. It is a powerful base, and forms salts isomorphous with magnesia and ox- ide of zinc ; which have a pale green color and an astringent taste. Sesquioxide— Fe203. Sources. — Anhydrous, the specu- lar iron ore and red hcematite ; as a hydrate, brown hcem.atite. Properties. — Forms with acids, reddish salts of an acid reaction and astringent taste ; with the more powerful Dases it displays the part of an acid. Combines, for example, with protoxide of iron to form black oxide, Fcg 04= FeO,Fe203. The black oxide also exists in nature as the loadstone, forming a valuable ore of iron, and a source of magnetism. Fig. 148. Antidote for As. 18 206 IRON. Ferric Acid— FeOg. Preparation. — By oxidizing sesquioxide of iron with nitre, at a red heat. Properties. — Forms salts easily decomposed by organic matter ; and, with the exception of Ferrate of Baryta, very unstable. With chlorine, iodine, and bromine, iron forms proto and sesqui-salts. Sulphides of Iron. ProtosulpMde — FeS. Pre])aration. — Four parts of powdered sulphur are strongly heated with t parts of iron filings. Uses. — It is a black, brittle substance employed in the laboratory as a source of sulphuretted hydrogen. FeS + HO,S03=FeO,S034-HS. When 60 parts of iron filings, 2 of sal ammoniac, and 1 of sulphur, all in powder, are made into a paste with water and applied immediately as a luting to iron vessels, it quickly sets as hard as iron itself, by the formation of a sulphide. Bisulphide— FeSj. Sources. — Exists as iron pyrites or fooVs gold ; and appears in many cases to be derived from the deoxidation of sulphate of iron by organic matter. Combined with the protosulphide, forms magnetic pyrites (2FeS,FeS2), and with arsenic, arsenical pyrites or mispickel (FeSajFe As). Use. — Under the name of mundic, iron pyrites is largely employed in the manufacture of sulphuric acid to afTord sulphurous acid by ignition in the open air. W^s- pickel is roasted to form arsenious acid, AsOg — the white arsenic of the shops. Carbides of Iron. White Cast-iron is a compound of 4 equivalents of iron ' with 1 of carbon, Fe^C. Malleable iron is cast-iron from CARBIDES OF IRON. 20t which nearly all the silicon and more than four per cent, of carbon has been burnt out by being — 1st. Heated in contact with air — refining. 2nd. Heated with black oxide of iron — puddling. In this way but one-half per cent, of carbon is left in the purest bar-iron. Steel is malleable iron which has been heated to redness with charcoal fur about 48 hours — cementation. It contains from 1.8 to 2.3 per cent, of carbon. By Bessemer's process, malleable iron and steel are made from pig-iron without the aid of fuel, by causing hot air to pass through the liquid iron. The carbon is burnt away with the formation of carbonic oxide, and develops in its combustion sufficient heat to continue the operation without the assistance of external fire. This process is conducted in a large iron vessel (Fig. 149) Fisicot, is used to increase the siccative property of drying oils. Dissolved in lime-water, it is used as a hair-dye: the lime partially decomposes the hair, and the lead of the oxide. BISMUTH. 21Y by combination with the sulphur of the hair, forms Sul- phide of Lead, which stains the hair a permanent black. When litharge is roasted, at a temperature of 600°, it ab- sorbs oxygen, and is converted into Minium, or Red Lead, PbaOj, which is principally employed in the manufacture of flint-glass. A combination of the Chloride and Oxide of Lead (PbCl,tPbO) is used as a pigment, under the name of Turner^ s yel- low. Its soluble salts Fig. 151. form most delicate tests for Sulphuretted Hy- drogen, which forms with them a black pre- cipitate. This may be illustrated in an amu- sing manner as fol- lows : We make a drawing on paper with a solution of Acetate or Nitrate of Lead, thickened so as to work well with a little gum. This drawing is of course invisible ; but if the paper is damp- ened by sponging on the wrong side, and exposed to HS, escaping from a tube, it is rapidly devel- oped. Such a design as Fig. 151 is one well suited to this sort of " spiritual photograph." Sym. Bi. BISMUTH. Eq. 208. Discovered by Agricola in 1529. Source. — Found native in quurtz-rock in Saxony, Tran- 218 URANIUM, sylvania, and Bohemia, from which it is extracted by fusion in iron tubes, placed in an inclined position, so as to allow the metal to flow out from the lower end. Properties. — A hard, brittle, reddish-white metal, which fuses at 50T°, and crystallizes on slow cooling in very obtuse rhombohedra. Oxidized by air at high tempera- tures ; eagerly unites with Chlorine, Bromine, Iodine, and Sulphur. Sp. Gr. 9.t9. Uses. — The alloys of Bismuth with Tin and Lead melt easily, and on cooling expand greatly, for which reasons they are largely employed by die-sinkers, under the name of fvsible metal, consisting of 5 parts of Bi, 3 of Pb and 2 of Sn. This will melt in boiling water. Some of its compounds are used as pigments, and the Subnitrate (SPbOg, 4NO5+9HO) as a cosmetic and in medicine. Test. — Yellow precipitate with Chromate of Potassa; soluble in Nitric acid. Sym. U. URANIUM. Eq. 60. Discovered by Klaproth, 1*789, in pitchblende (2U0, U2O3), which contains nearly 80 per cent, of the Black Oxide of Uranium. Properties. — Steel-white color; slightly malleable; burns brilliantly in air at high temperatures; dissolved by Hydrochloric and Sulphuric acids, with the formation of a Protochloride, UCl, and a Sulphate, U0,S03, which is employed in giving a Canary color to glass, and has the remarkable power of rendering it fluorescent. (See pages 58 and 87.) TUNGSTEN — VANADIUM — MOLYBDENUM. 219 GROUP Y. Metals whose Oxides are Weak Bases, or Acids. Sym. W. TUNGSTEN. Eq. 92. Discovered by D'Elhugart, 1181. Sources. — Found inwolf ram, Tungstate of Iron, and Manganese (MnO,W03,3reO,W03), and scheelite, Tung- state of Lime (CaO,W03). Properties. — A very hard, difficultly fusible metal, of an iron-gray color. Sp. Gr. 11.6. Uses. — Tungstic acid, WO3, is used in calico printing and as an anti-combustion mixture with starch, in the royal laundry of England. Test. — Treated with Hydrochloric acid and digested with Zinc, yields a blue color. Sym. V. VANADIUM. Eq. 68.46. Discovered by Sefstroem, 1830, in a Swedish iron ore from Taberg, but its principal ore is the Vanadate of Lead, found in Mexico and Chili. Properties. — Vanadic acid is reduced by Potassium in a covered porcelain crucible, V03-j-3K=3KO + V. Test. — When salts of Vanadic acid are mixed with tinc- ture of galls they form a very black ink, ineffaceable by acids, alkalies, and even by chlorine. Sym. Mo. MOLYBDENUM. Eq. 47.88. Discovered by Hj el m , lY 8 . Source. — Molybdenite, MoS^. Prepa7'ation. — The ore is first roasted, MoS.+ TOss: M0O34-2SO2, and the Molybdic acid so formed is made into 220 TELLURIUM — ARSENIC. a paste with oil and charcoal, and exposed to a high heat in a crucible lined with charcoal, MoOs-f 3C=MoH-3CO. Properties. — White, brittle, and very difficult of fusion. Sp. Gr. from 8.615 to 8.636. Forms two basic oxides, MoO and M0O2, and a powerful metallic acid, M0O3. Test. — Purple precipitate with Terchloride of Gold. Sym. Te. TELLURIUM. Eq. 64.2. Discovered by Klaproth, 1795. Sources. — Found in Transylvania, rarely native, gene- rally as a Telluride of Gold, Silver, Bismuth, or Lead. Properties. — Sp. Gr. 6.65. Has the lustre of a metal, but so closely resembles sulphur and selenium that it is often classed among: metalloids. Sym. As. ARSENIC. Eq. 75. Source. — Generally occurs as an alloy with iron, cobalt, nickel, copper, or tin ; also as an Arsenate of the above metals, and, more rarely, in union with sulphur, forming realgar, AsSa, and orpiment, AsSg. Preparation. — When arsenical Sulphide of Iron, or mispickel (FeAs,FeS2), is roasted it undergoes oxidation, and its combined Arsenic is converted into Arsenious ^cid, AsO.v The latter is conducted by the furnace-flues into large chambers, where it condenses as a white mealy powder. By heating this acid with pulverized charcoal in a Hessian crucible, upon the top of which a second cru- cible has been luted, the reduced metal is sublimed as a coating on the upper crucible. Properties. — In its chemical properties Arsenic is nearly allied to nitrogen and phosphorus, but, on account of its brilliant steel-gray lustre, its high specific gravity, and its facility in the conduction of electricity, it is here classed ARSENIC. 221 among the metals. Heated to 35G°, it gives off an op- pressive garlicky vapor, which crystallizes on cooling in rhombohedra. Sp. Gr. 5.T to 5.9. Uses. — A small quantity of Arsenic is added to lead to produce a rounder shot. When partially oxidized by contact with moist air it is converted into fly-powder. Combined with Oxygen, as Arsenious acid, it forms sev- eral useful Arsenites. That of Potash has been long em- ployed in medicine under the name of Fowler''s solution. The Arsenite of Copper (2CuO,As03) is the delicate Scheele^s green. The double salt of Acetate and Arsenite of Copper — CuOjC^HaOs-f 3(CuO,As03) — is also used as pigment, and is known as Schweinfurt green. Arsenious acid (known in commerce as Arsenic or ratsbane) is more- over employed to prevent smut in grain, and as a soap for glass, by converting the Protoxide of Iron, which stains the glass green, into a harmless sesquioxide. Arsenic Acid, AsOs, prepared by oxidizing Arsenious acid with Nitric acid, has been employed as a substitute for tartaric and phosphoric acids in calico printing, but its use is attended with the same danger of poisoning to the workmen employed as there is in every other application of Arsenic and its compounds. The Bisulphide of Arsenic (realgar), AsSa, is an ingre- dient of the signal-light known as white Indian fire, and the Tersulphide (orpiment) is mixed with Arsenious acid to form King^s yellow. Tests. — Before the blowpipe evolves a peculiar odor of garlic; with ammonio-nitrate of silver, AsOj gives a yel- low precipitate, AsOa a dull red ; with ammonio-nitrate of copper AsOg gives a green precipitate. Detection of Arsenic. Marshes Test. — In a hydrogen generator, of the form in- dicated (Fig. 152), introduce some of the suspected sub- 19* 222 TITANIUM — TIN. Fig. 152. stance. If Arsenic be pre ent, a glass or porcelain plate, held in the burning jet of hydrt gen, will be coated with a me ;allic mirror of Arsenic. Reinsch^s Test. — Boil the suspected liquid, acidified by one-tenth its bulk of Hydro- chloric acid, for half an hour with bright copper foil. The reduced Arsenic will be depos- ited as gray metallic crust of Arsenide of Copper. Sym. Ti TITANIUM. £^, 24.33. Discovered by Klaproth, 1795. Sources. — Ilmenite (FeOjTiOa) and rutile, hrookite and anatase, which are nearly pure Titanic acid, TiOg, occur ring under different crystalline forms. Copper-colored cubes, consisting of Cyanide and Nitride of Titanium are frequently found in iron slags. Uses. — The Oxide of Titanium is employed in painting porcelain and in coloring artificial teeth. SyTn.'Sii. TIN. Eq.58. Sources. — The only important ore is Tin-stone, SnOg. . Extraction. — After the ore has been roasted and washed it is mixed with one-fifth its weight of charcoal, and with a little lime, as a flux to the flinty gangue, and reduced by intense heat in a reverberatory furnace. Properties. — A very malleable, brilliant, white metal, which fuses at 442°. .Sp. Gr. 1.29. When a bar of Tin is bent it gives out a peculiar sound, called the cry of Tin. ANTIMONY. 223 Burns brilliantly in air at high temperatures, forming the Binoxide, SnOj. Uses. — When molten Tin is poured upon the surface of sheet-iron or copper it forms a superficial coating of alloy, and the iron or copper so coated is extensively employed under the name of Tin-plate. The many alloys of Tin have previously been described under bismuth, copper, and zinc. An amalgam of Tin is employed for silvering mirrors. Neither the Protoxide, SnO, nor the Anhydrous Binoxide of Tin, SnOa, are employed in the arts; but when the Binoxide is combined with water it undergoes a remark- able change of properties, and forms two acids, Meta- stannic acid (SugOiclOHO), which is largely employed in whitening enamels, and, under the name of putty powder, for polishing plate, and Stannic acid (HO.SnOa), which forms in combination with soda, as Stannate of Soda (NaO,Sn024-4Aq), a much-used mordant. Of the three Sulphides of Tin, SnS,Sn2S3 and SnSj, the last is em- ployed, under the name of mosaic gold, in imitating bronze, and with electrical machines. Sym. Sb. ANTIMONY. Eq. 120.3. Discovered by Basil Valentine, at the end of the thir- teenth century. Sources. — Sometimes found native, frequently as an alloy with other metals ; but always extracted from the tersulphide of antimony — grey antimony ore SbSg. Propei^ties. — A brilliant, bluish -white, brittle metal, which fuses at 840^ Sp. Gr. 6.715. Usek. — The most important alloy of antimony is type- metal; which consists of 100 parts of lead and 20 of anti- mony and 5 of tin. For stereotyping, Pb 100, Sb IS, Sn 5. Compounds. — Antimony combines with both three and 224 TANTALUM — COLUMBIUM MERCURY. five equivalents of oxygen, sulphur, and chlorine. When combined with potassa and tartaric acid, the teroxide, SbOg, forms tartar emetic (K0,Sb03,T} ; ground with linseed- oil, it is employed as a substitute for white lead. When an alloy of zinc and antimony is dissolved in dilute sul- phuric acid, the hydrogen set free from the water of the sulphuric acid unites, while in a nascent state, with anti- mony, to form antimoniuretted hydrogen. ZngSb+S^HO, S03)=3(ZnO,S03) + SbH3. Test. — The salts of antimony give an orange-red pre- cipitate of tersulphide, with sulphuretted hydrogen. Sym. Ta. TANTALUM. Eq. 68.72 Discovered by Ekeberg, in yttrotantalite from Sweden, 1802. Sym. Cb. COLUMBIUM. Eq. 68.8. Found by Hatchett, in a black mineral from Massachu- setts named columbite, in 1801. GROUP YI. Noble Metals reduced from their Oxides by Heat alone. Sym. Hg. MERCURY. Eq. 100. Sources. — Occasionally found in the metallic state, but generally combined with sulphur, forming cinnabar HgS. By heating, cinnabar gives off its sulphur as sulphurous acid, and its mercury as a vapor, which is collected in condensing chambers. Properties. — Mercury is the only metal which is fluid at ordinary temperatures. It freezes at — 39°, and boils at 662®. Heated in the air to 650°, it is converted into the red oxide ; with chlorine, bromine, and many metals, it . SILVER. 225 combines at ordinary temperatures; and also with sulphur and iodine, if triturated with them. Sp. Gr. 13.5. Uses. — Largely employed to form an amalgam with silver and gold, in order to extract them from their ores ; in the construction of thermometers, barometers, etc ; as a medicine ; as an amalgam wnth tin in silvering mirrors. Compounds. — Oxygen, sulphur, chlorine, bromine, and iodine unite with both one and two equivalents of mercury. Of the compounds so formed, HgS is known as the valu- able pigment vermilion ; HgaCl, Subchloride of Mercury, and HgCl, are known in medicine under the names of calomel and corrosive sublimate ; the Bromides and Iodides of mercury are employed in photography. Tests. — With iodide of potassium, a precipitate first yellow, then red ; silver-like deposit on copper foil. Sym. Ag. SILVER. - Eq. 108. Sources. — Found native, and as a chloride; but prin cipally obtained from its sulphide, AgS. The latter is fre- quently associated with lead to form argentiferous galena. Uses. — For coins and domestic utensils, and (as a coat- ing to less valuable metals) in plated ware. Photography. — A thin organic film, as of collodion, spread upon glass, and charged with iodide, bromide, and free nitrate of silver, suffers a change under the influence of light by which it acquires the power of reacting with certain solutions called developers, so as to produce an opaque insoluble body. By applying this property, nega- tive pictures are produced in the camera. Chloride of silver, in contact with organic matter, blackens by mere exposure to light, and to this fact we owe the production of positive pictures on paper from the negatives taken in the camera. Nitrate of silver thickened with gum Arabic and colored by India-ink is used for marking linen indelibly. The linen 226 GOLD — PLATINUM. is first moistened with a solution of soda, which precipi- tates the oxide of silver upon the fibre of the goods. Un- der the name of Lunar caustic it is used as an escharotic. Test. — Hydrochloric acid or a soluble chloride, precip- itates a dense white cloud of chloride of silver, quickly changing to violet by exposure to the light. Sym. Au. GOLD. Eq. 197. Sources. — Found crystallized in cubes or octahedra, or in masses called nuggets. Properties. — Most malleable of metals; one of the best conductors of heat and electricity; fuses at 2016°. Un- afi'ected by any of the acids alone, but dissolved by a mixture of 1 part of nitric acid with 4 parts of hydro- chloric acid — aqua regia. Sp. Gr. 19.34. Uses. — In the state of pow^der, in painting porcelain, etc. Alloyed with copper, it is sufficiently hard for jewellers'- ware and coin. Employed to color glass a deep red. The cyanide of gold and potassium is used for electro-gilding. Test. — A mixture of protochloride and bichloride of tin precipitates from salts of gold the Purple of Cassius ; oxalic acid with heat a brown precipitate of metallic gold. Sym. Pt PLATINUM. Eq. 98.7. Sources. — Platinum, Palladium, Rhodium, Osmium, and Iridium are generally found associated together in the form of coarsely rounded grains. Properties. — Very lustrous, ductile, tenacious, white metal, fusible only by the voltaic battery or oxyhydrogen blowpipe. Sp. Gr. 21.5. Uses — Owing to its infusibility, and its power of resisting alkalies, and other chemical reagents, platinum is largely employed as the material of crucibles and stills Those intended for the concentration of sulphuric acid sometimes weigh upwards of 1000 ounces. By ignition of the double rhloride of platinum and ammonium, metallic platinum PALLADIUM. 22T Fig. 153 may be obtained in a very finely divided state, known as platinum sponge. This substance has a very strong ad- hesion for gases ; and it will condense a mixture of them to such an extent as to cause a chemical combination. Thus, if a jet of hydrogen is directed upon a piece of this substance in the air, the union of the H with from the air, will be so energetic as first to heat the Platinum sponge red- hot, and then ignite the hy- drogen jet. This action is applied to the useful purpose of procuring a light rapidly, in Dobereiner's lamp (Fig. 153). The jet of hydrogen, when turned on, heats the pla- tinum sponge in the little box, f, is itself ignited, and so serves to light a taper, or the like. Even massive platinum possesses a like power. Thus a wire of this metal coiled over the wick of a spirit-lamp, as in Fig. 154, will continue to glow by causing a slow combustion of the alcoholic vapor after the flame has been extinguished. This is called the " flameless lamp." Fig. 154. Sym. Pd. PALLADIUM. Eq. 53.3. ■ Discovered by Wollaston, 1803. Sources. — Forms from one-third to one per cent, of platinum ores. Properties. — A hard, ductile, white metal, very difficult effusion. Sp. Gr. 11.4. Ihes. — For graduated scales, and as Sliver, it is employed by dentists. 228 . ORGANIC CHEMISTRY. Sym. It. IRIDIUM. Eq. 99. Descatils and Tenant, 1804. Sp. Gr. 21.15. Properties. — Very brittle, hard, white metal, fusible only by the oxyhydrogen blowpipe, and voltaic current. It is the heaviest of elements. Alloyed with osmium, as iridosmine, it is used for pointing pens. Its salts assume, when in solution, beautiful colors, from which property, the name iridium (from Iris, the rainbow) is derived. Sym. Os. OSMIUM. Eq. 99.6. Tenant, 1803. Sp. Gr. 21.4. Properties. — A white, very brittle metal. It forms no less than five compounds with oxygen, and four with chlorine. Sym. Rn. RUTHENIUM. Eq. 52.2. Klaws, 1845. Sp. Gr. 11.2. Most infusible of metals. Sym. Rh. RHODIUM. Eq. 52.2. Wollaston, 1804. Sp. Gr. 12.1. A white, very hard metal, scarcely fusible before the oxyhydrogen blowpipe. ORGANIC CHEMISTRY. Organic Chemistry treats of those organized bodies which have been formed under the influence of the vital force, and of the organic compounds which can be derived from organized bodies by the action of chemical reagents. Both classes of substances above referred to, are dis- tinguished from inorganic substances in several ways : 1st. The mass of organic bodies consists of only six. out ORGANIC CHEMISTRY. 229 of the sixty-four elements ; viz., carbon, hydrogen, oxygen, nitrogen, and, to a lesser extent, sulphur and phosphorus. 2nd. But carbon, hydrogen, oxygen, and nitrogen, com- bine in so many, and such high proportions, that they alone, form a vastly greater number of bodies than is met with in inorganic chemistry. 3rd. While inorganic compounds are formed by the pairing together of elements, or of binaries, or of ter- naries, with each other to form substances possessed of a certain symmetry of constitution, no such regularity is observable in organic chemistry. 4th. Natural affinities seem often to be overruled by vital force, and organic compounds are formed in oppo- sition to the ordinary laws of chemistry. 5th. It thus happens that organized bodies are com- paratively unstable, and prone to decomposition after the vital force, which created them, has ceased to act. 6th. One element may frequently be substituted for another, without altering the essential characteristics of an organic compound. The substances met with in organic chemistry are most conveniently treated of under the following heads : I. Saccharine and Amylaceous Bodies. — Mostly nu- tritious substances with feeble affinities. They are com- posed of 24 equivalents of carbon, united with different proportions of oxygen and hydrogen. From them are derived the Alcohols and Ethers. II. Ethyl, diethyl, etc. — Compound radicals resembling I in their chemical relations hydrogen and the metals. III. Vegetable Acids. ly. Vegetable Bases : (a) Those found in nature. (6) Those formed artificially. V. Oils: (a) Fixed Oils or Fats. 20 230 STARCH. (b) Essential or Yolatile Oils. YI. Cyanogen — a compound radical which resembles chlorine in its relations — and its compounds. YII. Organic Coloring-Principles. YIII. Albuminous Bodies. I. SACCHARINE AND AMYLACEOUS BODIES. 1. Starch — C24H20O20. Sources. — The grains, roots, and stems of plants. It occurs in small, rounded grains, which vary greatly in size and appearance. Those of the tous les mots are about 3j^^ of an inch in diameter; and those of wheat, jQ^Q^th. Each grain is inclosed in a thin envelope, which is unaffected by cold water, but ruptured by the expansion of the starchy matter, on applying heat. Figure 155 represents some starch grains of the potato, as seen under the microscope, by ordinary light. Fig. 155. Fig. 156. Fig. 157. Figure 156 shows the appearance of the same, when viewed by polarized light, as indicated in pages 65 and 66, a black cross being here developed on each grain. Figure 15Y shows one of these grains, after it has been boiled, as viewed under a powerful microscope. Preparations. — In order to free the starch granules j from gluten and other substances contained in the seeds, j GUM — LIGNINE. 231 the latter, after being mashed, are washed upoa a cloth sieve with water ; the gluten remains behind. Properties. — An insipid, white solid, insoluble in cold, but slightly soluble in boiling water. By exposure for a length of time to a temperature of 400°, by gentle heat- ing in acidulated water, or by the action of diastase — a nitrogenized body formed from the gluten of germinating seeds — starch undergoes a peculiar change, and the sub- stance so formed, and which is known under the name of Dextrine or British Gum, is capable of solution in cold water. It is employed in the manufacture of envelopes, for dressing chintzes, and other cotton goods, in the fast- ening of mordants, etc. Arrow-root, tapioca, and sago, are varieties of starch. Test. — Iodine forms a beautiful blue compound with starch, which is insoluble. 2. Gum — C24H20O20. A term applied to a number of substances which exude from the bark of trees, and form glassy, tasteless, and Inodorous masses, generally of a globular form. Dis- solved in water, they form mucilage, which is used as a substitute for paste. Gum Arabic, Gum Senegal, and Gum Tragacanth, are the important varieties. By boiling with Sulphuric acid, Gum Arabic yields sugar — with nitric acid, mucic acid. 3. Lignine — C24II20O20. Modifications. — Woody Fibre ; Cellulose. Sources. — Found under many modifications : some- times it can be used as food ; as the pulp of roots, esculent plants ; at others it is indigestible ; wood ; shells of nuts : it is light and porous in elder pith or cork ; soft and pliable in hemp and cotton fibre. Fig. 158 shows Lignine of wood, as seen under the microscope. ;2 LIGNINE. Properties. — Tasteless, insoluble in water and alcohol, and incapable of nutrition. At low Fior. io8. temperatures, strong oil of vitriol con- verts it into dextrine, and finally into glucose. It is not colored by iodine. By the action of equal parts of the strongest nitric and sulphuric acids, it is changed into a very explosive body, gun-cotton, or pyroxyline. It has two modifications ; the one, explosive, is insoluble in a mix- ture of alcohol and ether; the other is readily soluble, negative cotton. The latter is largely employed in pre- paring photographic plates, and in surgery. This change is not well understood, but it is supposed that the ele- ments of Hyponitric acid are substituted for several equiv- alents of hydrogen ; thus, to form gun-cotton, C24H20O20+ 4NO5=C24Hi6(NO4)4O20 + 4HO; to form negative cotton, C24H20O20+ 6N05= C24HH(NO,)e02o+ 6H0. By acting on starch, grape-sugar, mannite, gum, and dextrine, with nitric acid of specific gravity 1.5, they are converted into a transparent, colorless jelly, known as xyloidin. Paper so treated acquires the appearance of parchment, and great combustibility. When wood is kept in dry air or under water it under- goes no change, but exposed to air, in presence of moisture, it absorbs oxygen, and experiences a slow decay, ereraa- causis, with the evolution of carbonic acid and water. The fertility of the soil depends in great measure upon the presence of decaying vegetable matter — humus, geine, ulmine — and the constant liberation of carbonic acid and water. When vegetable matter, such as aquatic and herb.v ceous plants, decay in marshy soils, peat is first formed, and afterwards, by the heat developed during decompo- sition, and by pressure changed into lignite, and finally CREOSOTE — PARAFFINE. 233 into coal. Bituminous substances, like naphtha, petroleum^ asphaltum, etc., have probably been formed from plants or marine animals by slow decay under water. When wood is subjected to destructive distillation it gives off illuminating gas and many other hydrocarbons, along with water, acetone, pyroligneous acids, creosote, pyr- oxylic spirit, tar, etc. Creosote — C28H16O4. A colorless, oily, transparent liquid, which boils at 391°. It has a burning taste and a smell like burned meat. It is highly antiseptic, and it is owing to the presence of Creosote in tar, smoke, and pyroligneous acid that these substances have preservative properties. Used both internally and externally in medicine. When tar is distilled, a light and heavy oil passes over and a hard residuum, pitch, remains. The principal con- stituent of the light oil is Eupione, CgHe., of the heavy oil, Paraffine, C20H21. Paraffine is a tasteless, inodorous, white solid. It is insoluble in water, but dissolves freely in ether and oils. In consequence of its perfect indifference to the strongest alkalies and acids, it has derived its name from the two Latin words parwm and affinis, "without connection." On distilling bituminous coal, illuminating gas (which consists mainly of light and heavy carburetted hydrogen), carbonic acid, sulphuretted hydrogen, salts of ammonia, etc., and a viscid, resinous liquid, called coal-tar, are formed. Coal-tar yields on distillation a very volatile, inflamma- ble oil, which has been largely employed in Germany, France, England, and in this country, before the discovery of petroleum, for illuminating purposes. It has likewise been used extensively as a solvent for caoutchouc, in the manufacture of water-proof goods. This coal-tar oil is found, by treatment with acids and 20* 234 SUGARS. alkalies, to contain three classes of bodies: 1st. Sub- stances having a basic reaction, picoline, aniline, and leucoline ; 2nd. Acids, of which the most important is carbolic acid, or phenol; and 3rd. Neutral Hydrocar- bons, some of which are liquid, as toluol, cymol, benzol, and others solid, as naphthalin and paranaphthalin. NapMhalin, C20H8, separates in colorless, crystalline plates from the oil which comes over last in the distilla- tion of coal. It melts at 176°, boils at 413°, and, heated to a still higher point, burns with a red, smoky flame. It has the same composition as paranaphthalin, from which it mainly differs in being freely soluble in alcohol. 4. Sugars. There are several varieties of sugar, all of which are sweet to the taste, soluble in water, and convertible into alcohol by fermentation. The most important are : — 1st. Cane-sugar— C24H2,022. Sources. — Chiefly obtained from the sugar-cane; also found in the sap of the sugar-maple, in the juices of the beet and other roots, and the stalks of Indian-corn. Preparation. — After its juices have been expressed from the plant, they are evaporated to a thick syrup, from which the sugar crystallizes on cooling. What remains is treacle, or molasses. Properties. — White, inodorous, very sweet, and soluble; by slow evaporation it may be made to crystallize in iprisms-^r ock-candy. It melts at 356°, and forms, on cool- ing, barley-sugSiT ; at a temperature of 420°, it gives up four atoms of water, and is converted into caramel, 2nd. Grape-sugar— CgiHasOag. Glucose. Sources. — Grapes, many other sweet fruits, and the solid part of honey. Preparation. — The juice of grapes is first freed from FERMENTATION. 235 acid by neutralizing it with chalk, then boiled down to a syrup, clarified, and crystallized. Also prepared by con- version of starch or lignine, page 232. Properties. — Not by any means as sweet or soluble as cane-sugar. Test. — Grape-sugar" instantly precipitates suboxide of copper, from a boiling solution of sulphate of copper con- taining potassa, while cane-sugar slowly affects it. FERMENTATION. This term is applied to a decomposition of an organic body, resulting from the decomposing force exerted by an- other organic substance, called o, ferment, which is itself in process of decomposition. The molecular movement that is taking place among the particles of the ferment appears to be communicated to the fermentable sub- stances with which it is in contact, and causes them to break up into their simpler constituents. There are many ferments: yeast {}Nh\c\\ is the frothy matter that forms on beer and other liquids in process of fermentation), blood, albumen, caseine, and juices of many plants, and other putrescent matters. They all contain nitrogen, and derive from it their peculiar proneness to decomposition. So likewise there are several kinds of fer- mentation, distinguished as the (a) Lactic. — When putrid cheese is mixed with water and sugar, the caseine contained in the former substance produces fermentation, and the sugar is converted into Lactic acid, CgHsOsjHO, carbonic acid, and water. (b) Butyric. — If this fermentation is allowed to proceed, the lactic acrd disappears and Butyric acid, (CyllvOa.HO) is found in its place ; thus, C,,H2s02s=4IIO + 811 -f 8002+ 2(C«H,03,HO\ (c) Viscous. — So also, when the juice of beets is ex- posed to a temperature of 100° for some time^ in contact 236 WINE-ALCOBTOL. with air, it is converted into lactic acid and a viscous mu- cilaginous substance resembling gum Arabic. (cZ) Vinous or Alcoholic. — Pure grape-sugar undergoes no change in or out of contact with air, but when mixed with jeast it is rapidly converted into water, carbonic acid, and alcohol, C4H50,HO ; thus, C24H28028=4HO + 8C02-f4(C,H50,HO). Alcohols and their Derivatives. 1. Wine-Alcohol. (a) Ether. Action of acid on alcohol. (6) Aldehyde, Acetal, Acetic Acid, and Acetone. Ac- tion of oxygen on alcohol. (c) Chloral, Mercaptan. Action of chlorine and sul- phur on alcohol. 2. Methylic Alcohol ; Wood Spirit, (a) Wood-ether. (6) Formic Acid. 3. Propylic, Butylic, and Amylic Alcohol; their bomo- logues and derivd,tives. 1. Wine-Alcohol — C4H50,HO. The alcohol obtained by fermentation, as above described, is very dilute. By successive distillations, however, it may be rectified until it contains but 10 per cent, of water. To obtain absolute or pure alcohol, common alcohol must be thoroughly mixed with half its weight of quicklime, and the spirit distilled from the mixture by the heat of a water-bath. Properties. — Pure alcohol is a limpid, colorless liquid, of a penetrating smell and agreeable taste. Its specific gravity at 60° is 0.T94. It boils at 113°, giving off a vapor which is very inflammable, and burning with a pale, smoke- less, hot flame. It has never been frozen, but at a tem- perature of — 146° becomes thick and tenacious, like melted wax. In solvent powers, it is inferior to water only, and dissolves many substances totally insoluble in ETHER. 237 water, like the resins. Not only is a great number of vegetable bodies, like the alkaloids, essential oils, etc., soluble in alcohol, but also the mineral alkalies and many salts. The process of malting, brewing, and bread-making depend upon the formation of alcohol. (a) Ether— C4H5O. Preparation. — A mixture is made of 8 parts by weight of concentrated Sulphuric acid and 5 parts of Alcohol, of sp. gr. 0.834, and heated in flask A. When its temper- 159. ature has risen to 300°, the heat is regulated so as constantly to maintain that temperature. Under these circumstances Alcohol and Sulphuric acid combine, and the Sulpho-vinic acid thus formed is afterwards decomposed into Sulphuric acid and Ether, C4H50,HO + 2(HO,S03)= (C4H50,2S03,HO) + HO) and (CJl50,2S03,nO)-f H0= C4H50-f 2(HO,S03). The Ether and water vapor eon- dense into the inner tube, around which cold water is kept flowing (in at d and out at g), and are collected in a vessel placed at its lower end. The process may be made 238 ALDEHYDE — ACETAL — ACETIC ACID. continuous, if alcohol is supplied to A ; for the acid serves merely to break up the alcohol which is constantly flowing into the flask, and at the end of the operation remains behind, while the ether distills over into the condenser. Properties. — Owing to its mode of formation, commer- cial Ether thus obtained is termed Sulphuric Ether. It is a colorless, limpid liquid, of fragrant, intoxicating odor, and pungent taste. At 60° its density is 0.72 ; it boils at 96°, and remains liquid under the severest cold. Ether dissolves phosphorus, a few salts, most oils and fats, and some other organic compounds. When exposed to air. Ether absorbs oxygen and is converted into Acetic acid, C4H303,HO. Transmitted through a red-hot tube, it is resolved into light and heavy Carburetted Hydrogen and Aldehyde, C4H30,HO. Its vapor, when inhaled with air, produces insensibility to pain. (&) Products of the Oxidation of Alcohol. Aldehyde is a thin, colorless fluid, of a suffocating, ethe- real odor; density 0.Y92 ; boiling point t2° ; and burns with a pale flame. It is soluble in water, alcohol, and ether; dissolves sulphur, phosphorus, and iodine, and has such an affinity for oxygen that it reduces many metallic salts. Acetal, C12H14O4, is a colorless liquid, formed by the slow action of moistened platinum black, upon the vapor of alcohol diffused through a bell-glass, to which air has free access. By prolonging the action of platinum black, Acetal absorbs still more oxygen, and is converted first into aldehyde, and finally into acetic acid. Acetic Acid, €411303,110, is manufactured in Germany by causing a mixture of dilute alcohol and yeast to flow over wood-shavings, which are exposed in a current of air in a cask pierced with holes. The best vinegar, however, is made by the natural souring of wine when exposed to the air, 04H5O,HO4-4O = C,H3O3,HO + 2HO. Pyrolig- ACETONE. 239 neous acid, formed by distilling wood in close vessels, is a very impure acetic acid, which is extensively employed in calico printing. Properties. — When concentrated it is a colorless liquid, of a pleasant, penetrating odor, and extremely sour taste It boils at 240°, giving off inflammable vapor; cooled below 60°, it solidifies in large transparent crystals ; at 60° its density is 1.06. It readily mixes with water, al- cohol, and ether, and dissolves camphor and several resins. All the Acetates are soluble. The most important are : — Acetate of Lead, PbCC^HgOa+SHO, Sugar of Lead is formed by dissolving Litharge in Acetic acid. It is a powerful poison. Employed in analysis, and externally in medicine. Besides this neutral salt, there are various basic Acetates, as 2PbO,3C4H303 and 3PbO,C4H3034-HO. The latter crystallizes in needles, from a solution of T parts of litharge and 10 parts of sugar of lead digested in 30 parts of water. It is used in the proximate analysis of organic compounds and in pharmacy under the name of Goulard^s Extract of Lead. Acetate of Copper, CuO,C4H303+HO, Distilled Yerdi- gris is obtained in dark-green crystals from a filtered solution of verdigris in hot acetic acid. It is used as a pigment. Yerdigris is a mixture of subacetates, procured by covering copper plates with pyroligneous acid or the refuse of grapes in wine-making. Acetate of Alumina, Al203,3(C4H303), is obtained by de- composing a solution of Sugar of Lead by Alum. Used as a mordant. Chloracetic Acid, C4C]303,HO, is formed by exposing crystals of Acetic acid, placed under a bell-jar filled with chlorine, to the direct rays of the sun. Three atoms of Hydrogen are replaced by 3 atoms of Chlorine ; thus, C4H3O3,HO + 6Cl=C4Cl3O3,HO-|-8n01. It closely resem- bles acetic acid, and forms analogous chloracetates. Acetone, C3H3O, Pyroacetic Acid is an inflammable 240 METHYLTC ALCOHOI* liquid obtained by destructive distillation of metallic ace- tates ; thus, 2(PbO,C,H303) = 2Pb04-2(C3H30) + 2C02. (c) Action of Chlorine and Sulphur on Alcohol. Chloral — C4HCL0^ . When dry chlorine is passed into absolute alcohol, aldehyde is first formed, and hydro- chloric acid. By continuing the process, still more hydrogen is replaced by chlorine, and at last chloral is formed; thus, C4H602+2C1=C4HA + 2HC1, and C^H^O^ + 6Cl=C4HCl302-f3HCl. It is an oily liquid, of a peculiar odor, which brings tears to the eyes, specific gravity 1.5, and boils at 201°. Bromine is likewise absorbed by alcohol, to form bromal, C4HBr302, and both are decomposed by caustic alkalies, with the production of a formate of the base, and chloroform or bromoform ; thus, KO,HO + C4HCl302=KO,C2H03 + C2HCl3. In like manner by the action of chlorine on light hy- drochloric ether, C4II5CI, one atom of hydrogen after another may successively be replaced by chlorine, until finally in the fifth distinct compound thus formed, sesqui- chloride of carbon, C4CI6, no hydrogen remains. Mercaptan — C4H(jS2, is a limpid liquid obtained by replacing, not the hydrogen in alcohol, but oxygen, with its congener, sulphur. 2. MethyHc Alcohol— C2H402=C2H30,HO. Preparation. — Wood-vinegar, obtained by the destruc- tive distillation of wood, redistilled and treated with CaO, HO, yields about 1 p. c. of this substance, which is also called pyroxylic spirit and wood naphtha. It boils at 152°, has a density of 0.*798, will burn feebly, is miscible with water, alcohol, and ether, and will dissolve most resins, as also negative gun-cotton, to form collodion. (a) Methylic Ether.— C2H3O. Prepared by heating the above with 4 parts of strong Sulphuric Acid. It is a gas. Density 1.617, (liquefied only by great pressure,) of which water w\\\ dissolve 33 vols. FORMIC ACID. 241 (b) When wood-spirit is exposed to the action of moist- ened platinum black, under a bell-jar, to which there is free access of air, oxygen is absorbed, and formic acid (so called from its occurrence in the bodies of red ants, formica rufa) is formed ; thus, C2H4O2 -f 40 = C2H2O4 + 2H0. Formic Acid — CaH^O^, is a clear liquid of acid taste, pungent odor, density 1.24, and when dropped upon the skin quickly blisters it. It boils at 212°, producing an inflammable vapor, and freezes at 32°. The alkaline for- mates are used in the reduction of metallic oxides. 3. It will be seen on inspection, that methylic-alcohol, C2H4O2, and wine-alcohol, C4II6O2; wood-ether, C2H3O, and sulphuric ether, C4II5O ; formic acid, C2H2O4, and acetic acid, C4H4O4, all differ from one another by C2H2. Now, bodies which vary by C2H2, or by a multiple of it, are termed homologous, and their number is very great. If we add C2H2 to the alcohols, ethers and acids pre- viously mentioned, we shall get long series of new alco- hols and acids, many of whose members are already known to us ; thus, Alcohols. Acids. Ethers. Methylic, C2H4O2. Formic, C2H2O4. Methylic, C2II3O. Vinic, C4H6O2. Acetic, C4H4O4. Common, 041150. Propylic, C6H8O2. Propionic, CelleOi. CgIItO. Butylic, C8H10O2. Butyric, CsIIsOi. Butylic, CsIIgO. Araylic, Cioni202- Valeric, C10II10O4. Amylic, CioHnO. C12HUO2. Capi-oic, Cl2Th204. C1JT16O2. GEnanthylic, CuIIuO^. Caprylic, CieHigOz. Caprylic, CielluiCi. Caprylic, CioTInO. Besides the wine-alcohol obtained in the fermentation of saccharine matters, various acrid volatile-oils, called fusel-oWs, are formed, which likewise yield on distillation alcoholic liquids. The fusel-oil obtained by fermenting the husk or marc of the grape, for example, yields propi/I- alcohol, C6Hs02, the fusel-oil of beot-root sugar produces 21 242 ETHYL — METHYL. hutyl ' alcohol, C8H10O2, and that of potato-brandy, amyl- alcohol, C10H12O2. As methyl-alcohol, and wine-alcohol, yield formic acid and acetic acid by oxidation, so also propyl, butyl, and amyl-alcohol, are converted by absorption of oxygen into propionic, butyric, and valeric acids ; thus, C^HgOa (wine- alcohol) + 40=2H04-C4HA (acetic acid), and CioHi.O^ (amyl-alcohol) + 40 = 2HO-fCioHio04 (valeric acid). By treatment with strong acids, the alcohols may be converted into ethers, as described on page 23T. As we pass ft-om the lower members of these homo- logous series, to those containing a larger number of equiva- lents, we observe a corresponding change of properties ; they constantly approach nearer the solid form, and their boiling points increase by a fixed quantity, in the series of acids about 35.88°. II. Ethyl, Methyl, etc. — Compound radicals, resembling in their chemical relations, hydrogen and the metals. Besides common Ether, C4H5O, a great many other bodies may be formed from alcohol, which possess the properties of ether, and are termed compound ethers, such as Hydrocliloric Ether, C4H5CI; Hydrobromic Ether, C4H5Br ; :Nritric Ether, C4H50,N05 ; Oxalic Ether, C4H5O, C2O3, etc, Now all these compounds agree in containing C4H5; and it appears as though C4II5 might be transferred from one compound to another without suffering decom- position, in the same manner as an elementary body like zinc or copper. To a body which, like C4H5, plays the part of an element, we give a distinct name, and speak of it as a simple body. C4II5, for example, is denominated Ethyl, and represented by the symbol Ae. Ethyl, like zinc, combines with the halogen bodies to form haloid salts, and with oxygen and sulphur to form oxides and sulphides. The oxides, in turn, combine with the different acids to form ordinarv salts : thus : — ETHYL. 'M3 Ethyl (symbol Ae) C4H5 Oxide of Ethyl, Ether ^4^rfi* Hydrate of Oxide of Ethyl, Alcohol C4H50,H0 Chloride of Ethyl, Hydrochloric Ether C4H5CI Bromide of Ethyl, Hydrobromic Ether C^HgBr Iodide of Ethyl, Hydriodic Ether C4H5I Cyanide of Ethyl = C4H5Cy Nitrate of Oxide of Ethyl, Nitric Ether C4H50,N06 Silicate of Oxide of Ethyl, Silicic Ether 3(C4H50),SiOs The theory stated above was proposed by Liebig, long before the compound radical C4H5 was ever known in the separate state. Afterwards it was isolated, as a colorless liquid, by Dr. Frankland, from Iodide of Ethyl, by expos- ing it to the action of finely-divided zinc, at a temperature of 330°. By reference to the above table of Ethyl com- pounds, it will be seen that ether, C4H5O, is an Oxide of Ethyl, and alcohol, C4H50,HO, is a Hydrate of the Oxide of Ethyl, and that they may be expressed by the formulaa AeO and AeO,HO. Ethyl may be made to enter into combination even with hydrogen and the metals, and a long series of related bodies may be formed, as — Hydride of Ethyl C4H5H=AeH Zinc-Ethyl C4H5Zn--^AeZn Stannethyl C4H5Sn=AeSn Bismethyl (C4H5)3Bi=Ae3Bi Plumbethyl (C4H6)3Pb2=Ac3rb2 Stibethyl (C4H5)3Sb=Ae3Sb Arsenethyl, etc (C4H5)3Asz=rAe3As, etc. And these compounds may be made to combine witli the halogen bodies, or with oxygen and the acids, to form crys- tallizable salts, as, for example : — Stannethyl AeSn=C4lT5Sn Oxide of Stannethyl AeSnOr=C4lT5SnO Chloride of Stannethyl AeSnCl^^C^lTgSnCl Nitrate of Stannethyl, etc AcSnO,N05=rC4H5SnO,N05. etc. 244 METHYL. Methyl. — In like manner, in all the Methyl-Ethers it will be seen that CaH^ enters, and is displaced from combination, as a whole. This compound radical (C2H3) has not yet been isolated, but it has been confidenth^ assumed to exist. It is known as Methyl, and represented by the symbol Me. Wood-ether is regarded as an Oxide, and wood-spirit as a Hydrated Oxide of Methyl; thus: — Methyl CgHg^Me Oxide of Methyl, Wood-Ether CsHgO^^MeO Hydrate of Oxide of Methyl, AYood-Spirit.... CJl30,HO=MeO,HO Sulphate of Oxide of Methyl, etc C2H30,S03. etc. Chloride of Methyl C2H3CI Iodide of Methyl, etc CgHgT, etc. Hydride of Methyl CgHgH Zinc-Methyl, etc CJIgZn, etc. Kakodyl C4H6As=3(C2H3l2A3 Kakodyl deserves especial mention. It is a compound radical, capable of entering into a large number of combi- nations, and of being displaced from them in the same manner as a metal. Its most important compounds are — Kakodyl (symhol Kd) C4H6AS Oxide of Kakodyl KdO Chloride of Kakodyl KdCl Terchloride of Kakodyl KdClg Kakodylic Acid KdOg Kakodylate of Silver AgO,KdOg Tersulphide of Kakodyl KdS Oxide of Kakodyl — KdO. Cadet's Fuming Liquid, Alkarsin. Preparation. — When equal weights of Acetate of Po- tassa and Arsenious acid are heated together, the acetone liberated by the decomposition of the Acetate of Potassa reacts upon the Arsenious acid to form Oxide of Kakodyl and Carbonic acid, 2(KO,C4H303)=2KO + 2C02+2C3H36, KAKODYL — PROPYL — BUTYL — AMYL. 245 and 2C3H3O + As03= C4H6ASO + 2CO2. This process may be conducted in an eartiien retort placed in a furnace, and having its beak connected with a U shaped tube (Fig. 160) plunged in a vessel filled with broken ice. In this U tube the Oxide of Kako- ^'^- ^^^' dyl will collect with some water which covers it. Properties. — A colorless, highly refrac- tive liquid; density 1.462, and boiling point 802°. It is highly poisonous, and attacks the eyes and lining membrane of the nose. It takes fire in air, producing water, car- bonic and arsenious acids. When treated with corrosive sublimate and hydrochloric acid it yields an extremely poisonous liquid. Chloride of Kakodyl. Kakodyl— Kd. Preparation. — Digested with zinc the Chloride of Kak- odyl "suffers decomposition, with the formation of Chloride of Zinc and Kakodyl itself, KdCl-fZn=ZnCl + Kd. Properties. — A colorless, transparent liquid, of great inflammability. It boils at 338°, and at 21° crystallizes in transparent square prisms. Combines directly with oxygen, sulphur, chlorine, etc. Its teroxide, alkargen, KdOa, is a very stable acid, capable of uniting with me- tallic oxides to form crystallizable salts. It is not poison- ous. In union with cyanogen, as KdCy, it is said to form the most violent of all poisons. Propyl, CfiH^; Butyl, CgHg; Amyl, CioHu; etc. Those are the compound radicals of the series of alco- hols and ethers homologous with wood-spirit and wood- ether. As oxides they form ethers, and as hydrated oxides alcohols. (Sec page 243.) Their alcohols, when oxidized, yield homologous acids. 21* 246 BENZOYL. Benzoyl, C14H5O,; Cinnamyl, C^.'R.O,; and Salicyl, CUH5O4. 1. Benzoyl— ChH^O,. Symbol, Bz. Benzoyl is a compound radical, not as yet isolated, which can be made to combine directly with chlorine, hy- drogen, oxygen, etc., and to fulfil the part of a metal. Its most important compounds are — Hydride of Benzoyl, Bitter-Almond Oil CJ4H5O2H Hydrated Oxide of Benzoyl, Benzoic Acid C,4H5020,HO Chloride of Benzoyl Cj^HgOjCl Benzoic Alcohol Ci4H70,H0 Hydride of Benzoyl — BzH. Bitter-Almond Oil This oil is obtained by distilling bitter almonds, after they have been crushed and the fixed oil expressed, with water. The water is essential to the formation of the oil, inas- much as it acts upon a crystallizable principle, called Amygdalin, which exists in the seed, and, aided by nitro- genous substances, likewise contained in the pulp, forms from it bitter-almond oil. Properties. — It is a thin liquid, of agreeable odor and high refractive power; its density is 1.043, and boiling point 356°. Exposed to the air, it absorbs oxygen with rapidity, and is converted into Benzoic acid. Benzoic Acid — BzO,IIO. It may be obtained in large quantities by heating some of the balsams, especially gum benzoin. Properties. — It enters readily into combination with the \ alkalies and metallic oxides to form soluble crystallizable salts. By prolonged heating with fuming nitric acid it forms two new acids, Nitrohenzoic, C,4(H4N 0^)03, HO and Binitrohenzoic, Ci4(H3(N04)2)03,HO ; in the former of which one atom, and in the latter two atoms of hydrogen are replaced by Hyponitric acid. These substitutions are BENZOL — ANILINE— CINNAMYL — SALICYL. 247 of constant occurrence, and should be studied in order to understand important operations in manufacturing chem- istry. Benzol — CiaHg. Preparation. — It may be formed by decomposing Ben- zoic acid by Hydrate of Lime ; thus, Ci4H604+2(CaO,HO^ = Ci2H64-2(CaO,C02) + HO, or by distilling bituminous, coal (see p. 233). Benzol has recently become of great importance, as the source of Aniline, by the following series of transformations : Benzol is first converted into Nitrobenzol, C12H5NO4, by heating with fuming nitric acid, and then the nitrobenzol changed to aniline by dis- tillation with acetic acid and iron filings, C,2H5N04-|- 12(FeO,C4H303) + 2HO=C,2H7N+6Fe203,12(C4H303). Aniline, C12H7, is an oily, colorless liquid, of density 1.028, and boiling point 360°. It enters into combination with acids and forms many beautiful crystallizable salts. That formed with sulphuric acid, the Sulphate of Aniline, gives with Bichromate of Potash the exquisite mauve color patented by Mr. Perkins, which was the first formed of the many commercial aniline dyes. Cinnamyl — CigHyOa, Symbol Ci. Like benzoyl, this radical, when combined with hydro- gen, yields an oil, the Oil of Cinnamon, C18H7O2II. Its hydrated oxide forms an analogous acid, Cinnamic acid, Ci8H7020,HO. It unites with chlorine to form a Chloride of Cinnamyl, CgH^OaCl, and forms Cinnamylic Alcohol, C,8H90,HO, corresponding to Benzoic Alcohol, CuH^O, HO. Salicyl-CuHsO^. As a Hydride, CUH5O4H, Salicyl forms an oil, which has been found to be identical with that distilled from the flowers of meadow-sweet. This artificial oil has been ob- tained from Salicin, C^eHisO^, the bitter principle of poplar and willow bark. 248 OXALIC AND TARTARIC ACIDS. m. VEGETABLE ACIDS. Tinder this section are included those acids which are not formed artificially by oxidation of the alcohols or by other means, but exist ready formed in plants. They are sometimes met with in the free state, but generally in combination with bases. The most important are — Oxalic Acid C^Og, 2 HO Tartaric Acid C8H40,o,2HO Citric Acid C,2H50ii,3HO Malic Acid C8H408,2HO Tannic Acid C54Hi903i,3HO Gallic Acid C7H03,2H0 Oxalic Acid— C406,2HO. It is found in combination with potassa or lime in many plants, and particularly in various kinds of sorrel (^Oxalis). Preparation. — It may be formed by digesting any sac- charine or amylaceous matter with moderately strong Nitric acid. Thus, 1 part of Sugar, 5 parts of Nitric acid of sp. gr. 1.42, and 10 parts of Water, when heated together, yield on cooling colorless crystals of Oxalic acid. The nitric acid gives up its oxygen to the sugar, and we have C24Hi80i8+360=6(CA) + 18HO. Properties. — Extremely sour, very soluble in water, highly poisonous, and capable of combining with the alka- lies, earths, and metals to form crystalline salts. It is bibasic, and forms two series of salts, one containing 2 equivalents of the basic body, the other 1 equivalent along with one atom of water. Will remove stains made by common ink. Sold for this purpose under the name of Salts of Lemon. Tartaric Acid— C8H,Oio,2HO. Found combined with potassa in many fruits, especially grapes, tamarinds, and pineapples. Preparation. — When the juices of these fruits are fer- mented, as in the manufacture of wine, the Acid Tartrate of Potassa is thrown down, and forms a coating on the ROCHELLE SALT — CITRIC ACID. 219 sides and bottoms of the cask, called Argol or Tartar. When argol is repeatedly washed, filtered with animal charcoal, and crystallized, it is converted into Cream of Tartar, or nearly pure acid Tartrate of Potassa, KO,HO, C8H4O10. From this substance, by neutralization with lime and subsequent removal of the bases by sulphuric acid, Tartaric acid may be obtained. Properties. — Large, white, colorless, transparent crys- tals, readily soluble in water. Strongly acid to the taste, and quickly reddens litmus. It is bibasic, and, like all the other vegetable acids, containing 2 equivalents of basic water, forms two series of salts, one containing 2 and the other 1 equivalent of the base. Use. — Tartaric acid is largely employed in calico print- ing, to liberate from bleaching powder the chlorine neces- sary to bleach part of the colored print, in order to form a pattern. Its most important salts are — RocMle Salt— KO,NaO,C8H,0:o+8HO. Tartrate of Potassa and Soda. It is obtained, by neutralizing Cream of Tartar with Carbonate of Soda, in very soluble crystals. It is used as a purgative. Tartar-Emetic — KO,Sb03,C8H40io+4HO. Tartrate of Potassa and Antimony. Preparation. — Equal parts of Cream of Tartar and Oxide of Antimony are boiled with 6 parts of water. Use. — Largely employed in medicine. Effervescing mixtures are composed either of Tartaric acid and Bicarbonate of ^od.n. {Soda powders), or Tartaric acid and Bicarbonate of Soda with Rochelle Salt (^Seidlitz 'powders). Citric Acid— CiAOn,3no. Exists in the juices of the lemon (citron) and, to a •smaller extent, of orange, currant, gooseberry, etc. Preparation. — A Citrate of Lime is formed, in the Hrst 250 MALIC AND TANNIC ACIDS. place, by neutralizing lemon-juice with lime, and after- wards decomposed by sulphuric acid. Properties. — On evaporation, the citric acid thus set free, separates in colorless crystals of great solubility, strongly acid character, and agreeable taste. It is, as its formula indicates, tribasic. By heating with Nitric acid, it is converted into Oxalic acid; with Caustic potassa, into Oxalic and Acetic acids. Uses. — In calico printing ; in imparting an agreeable flavor to cookery ; in making effervescent drinks, and as a Citrate of Magnesia, for a pleasant-tasting cathartic. Tests. — A white precipitate with baryta, strontia, and lead. Malic Acid— C8H,08,2HO. Sources. — It is found in large quantities in unripe fruits, such as the apple {Malum), pear, plum, etc. ; also in vegetables, such as the rhubarb, or pie-plant. Properties. — Forms soluble crystals, which melt at 181°. By heating, it is converted into two other acids, the maleic and paramaleic or fumaric acids, both of which have the formula C8H20e,2HO, and are therefore isomeric, that is, they consist of the same elements in the same proportion. Tannic Acid— Cs^H.^Oai.SHO. Tannin. Sources. — Found in the bark and leaves of the oak, chestnut, hemlock, and many other trees. Forms a large portion of nutgalls, which are excrescences upon oak leaves. Preparation. — It may be obtained by steeping pow- dered nutgalls in Sulphuric ether. Properties. — It hardens as a yellow substance, devoid of crystalline structure, which is soluble in water, arid of peculiar, astringent taste; it reddens litmus, and forms salts with bases ; but its acid characters are feeble. Uses. — With Sesquioxide of iron, it forms a Tannate, ORGANIC BASES. 251 which, when mixed with gum to hold the insoluble Tan- nate of iron in suspension, constitutes common writing ink. Besides its employment in ink making, it is used in enormous quantities in tanning. After the hair has been removed from hides, they are soaked in vats containing oak and hemlock bark. The Tannic acid so obtained unites with the Gelatine contained in the hides, and forms an insoluble compound with it, which is the basis of leather. Gallic Acid-C,H03,2HO. Preparation. — It is found, along with Tannic acid, in vegetable bodies, and produced whenever this acid is exposed to the atmosphere, or boiled with Sulphuric acid. Properties. — A crystalline body, insoluble in cold, but very soluble in hot water. It is converted by heating into Pyrogallic and Metagallic acids: thus, 0711305= CO2 + C6H3O3 {Pyrogallic acid), and CeHsOa = HO + CeH^O^ {Metagallic acid). Uses. — A Tanno-gallate of Iron mixed with Sulphate of Indigo forms blue ink. Gallic and Pyrogallic acids are also employed to develop photographs. IV. ORGANIC BASES. I. ORGANIC ALKALIES, OR ALKALOIDS. Some are found ready formed, others are obtained from plants by destructive distillation. They are always found in combination with peculiar acids, forming true salts. All contain nitrogen. In water, they dissolve sparingly, readily in alcohol, and on cooling, form beautiful crys- tals A few however, are oily, volatile liquids. They have a very bitter taste, and are highly poisonous: the proper antidotes are animal charcoal and tannin. The most important are : — 252 MORPHIA — CINCHONIA. Morphia C34TT,j,N06+2HO Narcotina , ^'48^^25^0,4. Cinchonia C40H24N2O2. Quinia ^4o^^2i^2^A- Stryclinia C42H22N204- Brucia 046^26^208. Veratria Og4H52N20j5. Caffeine Ci6H,6N404. Conia CieHj^NOg. Nicotina CiqH^N. Morphia— C3,Hi9N06+ 2H0 (crystallized). Sources. — Exists along with narcotina, codeia, tJiebaia, papaverina, opianine, resin, oil, gum, etc., in opium, or dried poppy-juice. They are found in combination with a peculiar acid, the meconic (from mecone, a poppy). In 100 parts of opium, there are 1 per cent, of Meconic acid, 10 of Morphia, and T of Narcotina. Preparation. — It is separated by digesting opium for several days in alcohol, and precipitating by ammonia. The morphia thus obtained, is purified by solution in boil- ing alcohol, from which it deposits on cooling. Properties. — It crystallizes in brilliant rectangular prisms, which contain 2 equivalents of water of crystal- lization. At a gentle heat the water is driven off, and the morphia solidifies into a resinous mass. It requires 1000 parts of cold, or 400 of hot water for solution ; of al- cohol, only 30 parts ; dissolves also in acids, fixed alka- lies, and alkaline earths. Use. — In doses of J to J of a grain employed in medi- icine ; so likewise the Sulphate, Muriate, and Acetate of Morphia. Tests. — Colored green by mixture of Nitric and Sul- phuric acids ; blue by neutral solution of Perchloride of Iron. CincliGiiia, C4oIl24N,02, and Quinia, C4oH24N'204. Source. — They are found associated together in the bark QUINIA AND ISOMERIC BODIES. 253 of the Cinchona tree, which g^rows extensively in South America, and is known in commerce as Peruvian bark. The former is found most abundantly in the pa.le or Loxa hark ; the latter in the yellow or red, the Galisaya bark. They are combined with Kinic acid. Preparation. — The powdered bark is dissolved in al- cohol, the alkaloid precipitated by lime or ammonia, then boiled in alcohol and converted into Sulphate. From solution, the Sulphate of Quinia, being less soluble, crjs- tallizes out first. Properties. — Cinchonia crystallizes in very beautiful transparent prisms. It has strongly basic properties, and forms many crystallizable salts. It turns the plane of polarized rays to the right. Quinia crystallizes less distinctly, but is more soluble than Cinchonia. It has an intensely bitter taste; rotates the plane of polarization to the left. Its most important salts are the Muriate and Sulphate of Quinia, C,,B.,,J^,0 ,,110,^0,^11^0. This is the neutral Sulphate, but there is likewise an acid salt. It forms with iodine a beautiful crystalline body, which has the same absorbent power upon light as tourmaline, and may be used as a substitute for it in the polariscope. Uses. — Quinia is very largely employed in medicine on account of its febrifuge and antipcriodic powers ; Sulphate of Quinia to display the phenomena of fluorescence. Isomeric Bodies. — If these Quinia salts be exposed to sun-light, or treated with excess of acid, they pass into a resinous condition, and constitute Quinoidine. This is in reality a mixture of two alkaloids, one of which has the same properties and is isomeric with Quinia, Quinidine, the other isomeric with Cinchona, Ciucho)iidinc : and when these two substances are exposed to a temperaturo of 250^ they are changed into two otluM- isomeric bodies, Quinicine and (\)}cho)iici))e. The nu^st remarkable dif- 22 254 STRYCHNIA — BRTJCIA — VERATfllA. ference between them all is in their action upon the plane of polarization ; for Quinia produces a powerful rotation to the left. Quinidine " " " rigbt. Quinicine " feeble " right. Cinchona " powerful " right. Cinchonidine " " " left. Cinchonicine " feeble ** right. Stryclmia, 0442:2,^204, and Brucia, C46H26N2O8. Source. — They are found associated together in the fruit and bark of Nux Vomica and in St. Ignatius Bean. In the former they are combined with lactic acid. Preparation. — They are precipitated by excess of hy- drate of lime, filtered from solution in boiling alcohol, and afterwards separated by cold alcohol. Strychnia crystal- lizes out first. Properties. — Small, transparent, colorless, very brilliant octahedrons ; soluble in QQQ'J parts cold and 2000 parts boiling water; very slightly soluble in cold alcohol or ether. Yery bitter and fearfully poisonous. Brucia is distinguished from Strychnia by its ready sol ubility in alcohol, and by giving, when its salts are mixed with Tartaric acid, no precipitate with Bicarbonate of Soda. Tests. — Moistened with Sulphuric acid, Strychnia gives with Bichromate of Potassa a beautiful violet tint, passing into pale rose. Brucia and its salts afford a bright scarlet color, gradually passing into yellow with Nitric acid ; on addition of Protochloride of Tin a fine violet. Ver atria— C 64H52N2O 16. Source. — Occurs principally in combination with Gallic acid in several varieties of Veratrum. Properties. — An acrid, fearful poison, producing, on contact with the nasal membrane, dangerous tits of sneezing. ETHYL AMMONIAS. 255 Une. — Sedative in neuralgia, when applied as an ex- ternal ointment. Test. — Strikes with Nitric acid a red color slowly chang- ing to yellow. Caffeine, C16H10N4O4, or Theine. Remarkable as being found in coffee-grains and tea- leaves, in the leaves of Paullinia sor^bilis, and in those of Ilex Paraguayensis, from which the universal beverages are obtained. Conia, CigHisN, and Mcotina, CioH^N. They differ from all other alkaloids in forming oily, volatile liquids. The first is the poisonous principle of hemlock, the second of tobacco. II. ARTIFICIAL OEGAUIG BASES, OR ARTIFICIAL ALKALOIDS. The best method of studying the production and con- stitution of these bodies is by comparing them with am- monia; for, like ammonia, they all contain nitrogen, have alkaline properties, and are capable of combining with acids to form crystallizable salts. They may be consid- ered, indeed, as ammonia, in which one or more equiva- lents of hydrogen are replaced by the same number of equivalents of the compound radicals, ethyl, methyl, phe- nyl, etc. ; thus N^ H N^ II N^C.H Ih i II i II H fCA r^^Hg fC^TIg " CJI^ Ammonia. Etliyl-ammonia, Bictb^d-ammonia, Triethyl-aimnoiiia, or Etliylamine. or Biethylamine. or Triethylainino. The Ethyl Ammonias. 1. Etliylamiiie-N(Cjr3)n,= CJI,N. Freparation. — Formed by healing strong ammonia with iodide of ethyl in hermetically sealed tubes: thus. C4H6l+Nn3=N(CJl5)ll3T, and distilling the product 256 BIETHYLAMINE — TRIETHYLAMINE with caustic potash, :N(C4H5)H3l -f £0 = NcC,H5)H2+ HO + KL Properties. — A thin mobile fliiicl, strongly alkaline, and combining, like Ammonia, to form many crystallizable salts. It forms a Hydrochlora.te of ethylamine, with the formation of white clouds, similar to those arising from the combination of Hydrochloric acid and Ammonia, liike Ammonia, it precipitates the Salts of Alumina, Magnesia, Iron, Manganese, Bismuth, Chromium, Tin, Lead, and Mercury. Biethylamine— N(C4H5),H= CgHn^^ and Triethylamine-N(C4H5)3= C.^Hi^N. Pre2)aration. — They are produced by reactions analo- gous to those between ammonia and bromide of ethyl ; ethylamine, or biethylamine taking the place of the former: thus, ]S"(C,H5)H,+ G,H5Br=X(C4H5)2H,Br ; and N(C4H5)2H,Br+KO=N(C4H5)2H+HO+KBr. Properties. — With the increase of equivalents of the elements composing them, there is a corresponding rise of boiling point; ethylamine boiling 54.4°, biethylamine at 133°, triethylamine at 195.8°. Their alkaline properties correspondingly diminish, though all form beautiful salts. As we have 0,H0 so nJ ^^[Js }.o,HO. IC4H5J Hydrated oxide of ammonium. Hydrated oxide of tetretliyl- ammonium. Hydrated Oxide of Tetrethyl-ammoniuin — :Nr(C4H5)4== ^161120-^ • Properties. — It is powerfully alkaline, and closely re- sembles potassa, or soda, combining like them with fatty acids to form true soaps, and with metallic salts acting precisely like potassa. In its excessively bitter taste, resembles the alkaloids proper. METHTL AND AMYL AMMONIAS. 25t The Methyl Ammonias. fC^Hg rC2H3 rCJTg fC^H nJ H N^'c^Hg NJC2B3 ^JC^a 3 !.0,H0 IC2H3J Methylamine. Bimethylamine. Trimethylamine. Hydrated oxide oi ^CgHgN. =C4H7N. r^CgHgN. tetremethyl-am- monium. Preparation. — As hydrated cyanic acid (C^NOjHO), when boiled with caustic potassa, is decomposed into 2 Eq. of Carbonic acid and 1 Eq. of Ammonia, so is Cyanate of Eth}^], or Methyl, into 2 Eq. of Carbonic acid and 1 Eq. of Ethylamine, or Methylamine: thus, C2N0,H0 + 2(KO,HO)=2(KO,C02) + NH3; and C,N0,(C,H5)0 or C2NO,(C,H3)0 + 2(K0,H0) =2(KO,CO0 + N(C4H5)H2; or N(C,H3)H,. Properties. — The first three are gases closely resem- bling ammonia. Methylamine smells slightly fishy, Tri- methylamine strongly so; the latter is found in consider- able quantity in the roe of herring. The density of Am- monia is 0.589, of Methylamine 1.08 ; the former is solu- ble in 77^0 its bulk of water, the latter in j-qq-q, and, con- sequently, is the most soluble of all gases. The Amyl Ammonias. rc,oH„ rc,jT„ rc.jT,, rc,on,n N H nJc,oH„ n C,„[I„ Nic,„n„ Olio Amylamine. Bianiylamine. Triamylaminc. Hydrated oxide of Te- =CioII,3N. =C2oH23N =<^3o^^33^' tramyl-ammonium. Properties. — A series of strongly alkaline bodies, whose basic power diminishes and boiling point increases as the series ascends; thus, Anniamine boils at 190.4°, Biamvl- amine at 338°, Triamylamine at 494.6°. 258 ARTIFICIAL ORGANIC BASES. Phenyl Ammonia. Aniline or Plienylamine— Is^(Ci2H5)H,= Ci,H,N. Preparation. — When Salic^dic acid, C14H4O42HO (p 241), is strongly heated it is decomposed into Carbonic acid and Carbolic acid or Phenol, C,2H602. The same body is found in the acid portion of coal-tar (p. 233). It so closely resembles the alcohols that it is assumed to be in composition a hydrated oxide of a compound radical, Phenyl, C12H5 (Sym. Pyl) ; and the body formed b}' heat- ing Phenol with Ammonia, Aniline, C12H7N (p. 259), has in like manner been regarded as a phenyl-ammonia ; thus, PylO,HO + NH3=2HO-fNcPyl)H2, or^d^H^N. Substitution-Products of Aniline. — Besides the substi- tution of compound radicals for the hydrogen in Ammonia, the hydrogen of the new artificial bases may in like manner be replaced by Chlorine, Bromine, Hyponitric acid, etc. ; thus — Ammonia NHg Aniline N(Cj^H5)IT2 Chloraniline N(C,2H4C1)H2 Bromaniline N(Cj2H4Br)H2 Bibrom aniline N(Cj2H3Br2)H2 Nitraniline N(Ci2H4N04)H2 III. ARTIPICIAL ALKALOIDS HOMOLOGOUS WITH ANILINE. As we had a hydrocarbon Benzol, CizHg (p. 246), de- rived from the radical Benzoyl, CHH5O2, so likewise from the homologous radicals, Toluyl, CieH^O^; Xylil, CigHgO^; Cumyl, C20H11O2, and Cymyl, C22H13O2, result the hydro- carbons homologous with Benzol, CiiHg, namely, Toluol, CuHg*, Xylol, CgHjo; Cumol, CigHij, and Cymol, C20H14. And as Benzol was converted into Nitrobenzol by fura- ARTIFICIAL ALKALOIDS 259 mg Nitric acid, so may its homologues be changed to homologous nitro-substitution hydrocarbons ; aad the ac- tion of Sulphuretted Hydrogen upon these last ifi the same as its action on Nitrobenzol, C12H5NO4, viz., G12H5NO4+ 6HS = Ci^HjN + 4H0 + 6S. We have formed in this manner: — Benzol, CjaH^H Nitrobenzol, C,2H5N04 Aniline, N(C,2H5)H2 Toluol, Cj^H^H Nitrotoluol, Cj^H^NO^ Toluidine, N(Ci4H7)H2 Xylol, CigHgH Nitroxylol, C,6H9N04 Xylidine, N(C,6H9)H2 Cumol, CigHjiH Nitrocumol, Cj8Hj,N04 Cumidine, taCis^n)^^ Cymol, C20H13H Nitrocymol, C20HJ3NO4 Cymidini. N(C2oH,3)H2 Properties. — They resemble, in their deri\ ation, forma- tion, and properties, Aniline. They form bfedutifully crys- talline salts. IV. ARTIFICIAL ALKALOIDS CONTAINING SEVE- RAL COMPOUND RADICALS. The Hydrogen in Ammonia may not only be replaced by a single compound radical, but also by several different ones. In this manner Ethyl, Methyl, etc, may occur in the same artificial base: — Ammonia NH3 I Ethylaniline NPylAeH Aniline NPyllTj 1 Biethylanilinc NPylAcj So from Hydrated Oxide of Ammonium NIl40,II0 ' " Triethyl-phenyl-ammonium N(PylAc3)0,II0 < ** Trietliyl-amyl-ammonium... N(AylAe3)0,I10 <* *' Metliyl-bietliyl-aniyl-ammo- nium N(AylAo,AIo)0,nO " *< Mcthyl-ctbyl-amyl-plienyl- ammonlum N(PYlAylAo:\IoH\110 Properties. — All these Ammonium bases are powerfully alkaline, and resemble strikingly the Hydrated Oxide of Tetretnyi-ammonium, p. 256. 260 OILS. V. OILS. The term Oil is applied to a great variety of bodies, which agree in the general properties of inflammability, sparing solubility in water, and ready solubility in alcohol or ether. It is usual to associate greasiness with oils, but this idea requires limitation. Fixed oils (see below) are greasy, volatile oils are not ; they are harsh to the touch. Mineral oils are intermediate. And when a cork is twisted into a bottle containing a fixed oil it makes no noise ; in other oils it squeaks. Classification of Oils. — They are most conveniently divided into three classes, according to their origin, viz., vegetable, animal, and mineral. The latter have been treated, under the changes produced in lignine by decay and distillation (p. 233) ; the former agree so closely in all their properties, that they are best considered together. Classification of Vegetable and Animal Oils. — Vegeta- ble and animal oils are of two kinds, (a) fixed and (6) volatile; so named from producing, the former a perma- nent, the latter a transient, stain when dropped on paper. Both classes absorb oxygen ; some slowly, others so rap- idly as to inflame spontaneously. In consequence of this difference, oils are farther divided into drying — those which, like linseed, poppy-seed, and walnut oils, become bard on exposure to air — and non-drying — those rancidify- ing only, as olive, palm, and most animal oils. In virtue of their siccative properties, drying oils are largely em- ployed in painting. Sources of Oils. — Oils are found in the stems, leaves, and fruits of plants, but abound chiefly in the seed. In animals they are stored up everywhere, but principally just beneath the cuticle ; also in the omentum and around the kidneys. Properties. — They are generally lighter than water, the FJXED OILS. 261 fixed oils varying in clensitj from 0.91 to 0.94, and the volatile from 0.846 to 1.097. They vary likewise in their melting points, some being solid at ordinary temperatures, others liquid. In general, the greater the proportion of carbon they contain the higher the melting point. {a) Fixed Oils, also called Fats. Preparation. — When found in vegetables, they are ob- tained by submitting the crushed seeds or other vegetable structure to pressure, or pressure and heat combined. From animals they are obtained by breaking up the adi- pose membrane. This may be effected sometimes by the decay of the cellular structure, in other cases by liquefac- tion and expansion of the fat, which runs out or collects, on boiling, at the surface of the water. Properties. — They are generally colorless, or of a slight 3'ellow tinge, bleaching on exposure to light; of faint odor and slight taste. In some cases, however, peculiar odors are imparted by volatile fatty acids, as to butter by butyric acid, or by various ethers. They are all insoluble in water, and, with the exception of castor-oil, but slightly soluble in alcohol. In ether, the essential oils, and ben- zol they dissolve freely. They can be heated to nearly 500° without much change, but beyond that point they are decomposed, and cannot therefore be distilled. When heated to about 500°, they change color and evolve ofifensive^odors ; at a little above 600°, they are decom- posed and distil, with the formation of solid and liquid hydrocarbons, water, fatty acids, and Acrolein, CoH^Oj — an excessively volatile, irritating liquid. 262 SAPONIFICATION. Composition. — They all consist of carbon, hydrogen, and oxygen ; for example, in 100 parts of the following oils there are Carbon. Hj'drogen. Oxygen. Olive 77.21 13.3G 9.43 Almond 77.40 11.48 10.82 Linseed 76.01 11.35 12.62 Castor 14.17 11.03 14.78 Whale 76.13 12.40 11. 5U Spermaceti 78.91 10.97 10.12 Hog's Lard 79.09 11.14 9.75 Suet 78.99 11.70 9.30 Butter 65.60 17.60 16.80 The fixed oils are not composed, however, of a single substance, but are, for the most part, mixtures of at least three closely-related, proximate fatty principles, viz., stearin (from crrmp, suet), margarin (from {.idpyapov, a pearl), and oleiJi (from iXatov, oil). The two former are solid, the latter liquid at ordinar}^ temperatures. As the amount of olein increases, so does the softness of the fat, while the boiling point correspondingly falls. Saponification. — Fats and fixed oils generally are to be regarded as chemical salts formed by the union of certain organic acids, such as Stearic, Margaric, and Oleic, with a base called Glycerin. These salts are distinguished by the names Stearin, Margarin, and Olein respectively. They are all incapable of dissolving in, or even mixing with, water. If however these fats are heated with a solution of caustic alkali, the glycerin is displaced by the more powerful base, and new salts of the alkali are formed, which are soluble in water and are known as soaps. (See next page.) If to the above alkaline fat-salts a strong acid, such as Sulphuric, is added, the base is in turn taken from the acids, and the latter are then set free, and are found to be white crystallizable bodies soluble in warm water and showing an acid reaction. SOAP AND CANDLE MAKINQ. 263 Stearin, CiuHnoOj^ + 3H0 = Glycerin, C6H503,3HO + 3 Stearic acid, CacHasOg^HO ; Margarin, CiosHio^Oi^+SHO = Glycerin, C6H503,3HO + 3 Margaric acid, €^4113303, HO ; Olein, C,hHio40,2 + 3H0 = Glycerin, CeH503,3HO + 3 Oleic acid, C36H3303,HO. And, in case of palm-oil — Palmitin, C,oA80i2 + 3HO== Glycerin, CeH503,3HO + 3 Palmitic acid, C32H3i03,HO. Process of Soap-Making. — The mixture of alkali and fat is heated together, by means of steam, in large iron vessels, called coppers. Salt water is then added to cut the viscid fluid so formed. The glycerin, being soluble in brine, is carried with it to the bottom of the copper ; the soap, being insoluble in both brine and water, rises to the surface of the latter, and is then ladled out, pressed, and cut into cakes. Process of Candle-Making. — The object to be attained in the manufacture of candles is to get the fatty acids in the free state and in a pure condition. This is eftected in a variety of ways: — 1st. By making, in the first place, a soap out of fat, by means of lime, and afterwards decomposing this soap with Sulphuric acid. Sulphate of lime, being insoluble, sinks to the bottom, and the fatty acids rise to the surface of the heated liquid. 2nd. By heating fats with Sulphuric acid. At a high temperature the glycerin of the fat and Sulphuric acid are mutuall}'" decomposed. Sulphurous and Carbonic acids are evolved and the fatty acids set free. 3rd. By injecting steam at a toiiip(>rature of 500° and 600° into heated fat, the latter is decomposed, and the glycerin and fatty acids, in a separate and very pure state, are distilled over, and may be obtained st}nirately. ^.ri;is is the admirable process of Air. ^Vilsou. 264 FIXED OILS. Besides stearin, margarin, and olein, certain fats contain peculiar proximate fatty principles; thus, Palm-oil yields Palmitin, C102H9SO12; Butter yields Butyrin ; Beeswax yields Cerin, C,08H,08O4, and 3Iyricin, 092119^04; Spermaceti yields Getin, C^Jl^Oi. By saponification of these fatty principles, we find that Palmitin, Cio,H9sO,2= Ghxerin, C6H503,3HO + 3 Pal- mitic acid, Cs.HaiOsjHO ; Butyrin = Glycerin, CeHjOcSHO -f (Butyric, Caproic, Caprylic, and Capric acids) ; Cetin, C6,He404 = Oxide of Cetyl, C3.2H35O + Palmitic acid ; Cerin, Cio8H,o80i= Oxide of Cerotyl, C54H55O -f Cerotic acid; Myricin, CeoHeO^ = Oxide of Melissyl, C92H92O4 + Pal- mitic acid. Spermaceti is therefore composed, in great measure, of Palmitate of Oxide of Cetyl, C32H350,C32H3i03; beeswax of Cerotate of Ox^de of Cerotyl, C5,H530,C54H5303. These various compound radicals and acids are homologues of Methyl and Formic acid; thus — Butyric " (C2H2X3) +C2HO3, .HO^CgH.Og.HO Gaproic " (C^H^xS) 4- " =C,2H,303,HO Caprylic " (C2H2X') 4- " =G,6H,503,HO Capric " (C^H^XO) + " =C2oHi,03JIO Palmitic " (C2H,xl5)+ " =C3,H3,03.H0 Margaric " (C2H2X16)+ " =C3,H3303,HO Stearic " (C^H.xH)-}- " -^36^3503- HO Cerotic " (C^H^x^e)-!- " =^3,11^03. HO Melissic " (C2l}.x29)-f =CeoH3,03,HO Glycerin, the hase in all these fat-salts, is a sweet syrupy liquid, of sp. gr. 1.27, which does not evaporate, but dis- solves freely in water. Mixed NO5 and SO3, convert it into nitro-glycerin, a body exploding with great violence by concussion, or at a temperature of 360^. ESSENTIAL OR VOLATILE OILS. 265 (6) Essential, or Volatile Oils. The term essential is applied to volatile oils, because they confer distinguishing smell and properties to the plants composing them. Preparation. — These Essential oils are found in the leaves, flowers, fruits, and seeds of plants. In some cases, as the orange-tree, the leaves, flowers, and fruit each yield a distinct oil. They are generally obtained by distilling the plant with water, the plant being in some cases fresh, in others salted or dried. When it is inclosed in cellular structure, as of orange or lemon-peel, it is procured by ex- pression. Though the boiling-points of these oils is above the boiling-point of water, they are carried over with steam at 212°, and condensed with it in a refrigerator attached to the still. Most of these oils are lighter than water, and float in a pure condition upon the surface of the water in the refrig- erator; a portion, however, of the oil is always held in solution, constituting what is termed 'perfumed or medicated waters. To sep- arate the oil from the perfumed water, they are poured into a Florentine re- ceiver. It is conical in form, and at the side is a spout, b c, communicating with the bottom, the orifice c of the spout being much lower than the mouth a of the receiver. The distilled product being poured into this vessel, the oil B separates from the water A, and occupies the upper part of the vessel. The water, as it rises above the bend of the spout, flows off at c, while the Essential oil may be from time to time removed by means of a pipette. When the oil, as happens with that from jasmine, violet, tuberose, narcissus, etc., is too small in quantity and too 266 ESSENTIAL OILS. delicate to be collected by expression or distillation, the flowers are laid between woollen cloths saturated with an inodorous fixed oil. The latter absorbs the essential oil of the flowers, and afterwards, by digesting the cloths in alcohol, an essence is obtained, free from fixed oil, which is insoluble in alcohol. Essential oils are mostly colorless when newly made and pure, but by absorption of oxygen they become yellow or brown, and even in some cases green and blue. Some of them, however, are bleached on exposure to light. They are generally of an agreeable odor, strongly aro- matic and even burning flavor, and a few are poisonous. They dissolve freely in ether and alcohol, and mix in all proportions with fixed oils. Classification of Essential Oils. — They are divided ac- cording to their composition, into (a) Hydrocarbon Oils, composed of Carbon and Hy- drogen ; (6) Oxyhydrocarbon Oils, composed of Carbon, Hydro- gen, and Ox3^gen ; (c) Essential Oils containing Sulphur, Most of the essential oils, however, are mixtures of a and b, and in many cases the latter, when isolated, is a solid, resembling camphor. To the hydrocarbon Berze- lius gave the name s^earop^ene, and to the oxyhydrocarbon, elaioptene from areap, fat, or iT^aiov, oil, and xtrjvb?, volatile). They may be separated by cold, which converts the cam- phor into a solid, or by distillation, when the hydrocarbon passes over first. By exposure to air the Essential oils suffer two kinds of cnanges : some absorb oxygen, and form with it crystal- line and oftentimes acid compounds ; others part with a portion of their hydrogen, which forms with oxygen water, jind solidify into resins. By the action of Chlorine, Iodine, and Bromine, Hy- OIL OF TURPENTINE. 267 drochloric, Hydriodic, and Hydrobromic acids are formed, along with compounds of these gases and acids, with the remaining portion of the oil. In violent changes, some- times thus produced, inflammation occurs. {a) Hydrocarbon Essential Oils. These present a remarkable sameness of composition, containing about 88 or 89 per cent, of carbon, and 11 or 12 per cent, of hydrogen, and may therefore be repre- sented by the formula C5H4. Their different varieties may consequentl}^ be regarded as isomeric modifications of C5H4, or CioHg, or C20H16, or C40H32. All these formulae represent equally well the composition of the oils by weight, one being sometimes preferred to the other merely on considerations relative to their different vapor densities. The most important are : — Oil of Turpentine, Camphene, C.^oBue, and Oil of Lemon, CjoHg. Preparation. — ^The former is obtained by distilling tur- pentine with water, the latter by expressing the yellow portion of lemon-peel. Turpentine is a viscid fluid, con- sisting of oil of turpentine holding rosin in solution, which exudes at certain seasons of the year from incisions in the bark of pine trees. Spirits of turpentine is impure cam- phene containing some rosin; burning fluid is camphene mixed with three or four times its bulk of alcohol. By the action of Hydrochloric acid Camphene and Oil of Lemons are each converted into two artificial camphors, much resembling common camphor in appearance and properties, one of them being solid and the other liquid at ordinary temperatures. The oils of orange-peel, etc mi, bergamot, pepper, juniper, ciibebs, copaiba, etc., are sim- ilar in composition to the above, and are all isomeric, but having a dift'erent specific gravity and boiling point. gel CAMPHORS. (5) Oxyhydrocarbon Essential Oils. These comprise most of the volatile oils used for medi- cine and perfumery. The three most important, oil of bitter almonds, cinnamon, and meadow-sweet, have al- ready been described as hydrides of the compound rad- icals benzoyl, cinnamyl, and salicyl. Of the remainder, Oil of Aniseed consists of a fluid oil and a crystalline solid. C.x,Hi,0,; Oil of Cumin consists of Cymol, CaoH^ (liquid), and Curainol, Q.y^'E.xX)^ (liquid) ; Oil of Thyme consists of several substances, chiefly Thymol, Q,^,,0, (solid) ; Oil of Rue consists of several substances, chiefly the liquid C20H20O0 ; Oil of Cedar-wood consists of Cedrene, C30H04 (liquid), and the solid Cs.Ho^O^ ; Oil of TTinter-green consists of Salicylate of Oxide of Methyl, CuH,0,,HO,MeO ; Oil of Talerian, consists of Yalerol, C12H10O2, Borneene (a camphor), and Taleric acid. Properties. — It will be observed that these oils are gen- erally composed of a fluid portion, which is a hydrocarbon, and a solid, containing, in addition to carbon and hydro- gen, oxygen. The latter, by oxidization, may sometimes be changed to acids. These solid essential oils, or stea- roptens, are sometimes included under the general head of CAMPHORS, From their close resemblance to the two crystalline ox- idized essences, originally known under this name, viz., Japan Camplior, C^oHigOo, and Borneo Camphor, CaJTijOa Preparation. — The former is obtained by distilling with water the roots and leaves of the Lairrus camphora, a tret* RESINS AND BALSAMS. 269 found chiefly in Japan ; the latter from the Drydbalanops .caniphora, a native of Borneo. Properties. — They dissolve sparingly in water, abun- dantly in alcohol and ether. When enclosed in a glass vessel they vaporize, and are afterwards condensed in small crystals upon the side of the vessel which is ex- posed to the light. In contact with Nitric acid the former is oxidized to Camphoric acid, C2oHi406,2HO ; the latter to Japan Camphor. By action of oxygen on volatile oils still another class of allied substances is formed, the RESmS AND BALSAMS. The type of this class is common rosin, or colophony y which is formed by the abstraction of 1 equivalent of hy- drogen in Oil of Turpentine by the oxygen of the air to form water; thus. Oil of Turpentine, C2oHi6+0=C2oHi5-|- HO ; and further oxidation of the body thus formed, C20H15, to Pinic and Sylvic acids, both of which have the formula C20H15O2. A mixture of these two acids constitutes rosin. Lac, or Gum Lac, as it is frequently termed, exudes from the punctures made in the Ficus tree by insects. It is soluble in alcohol, oil of turpentine, and hot solution of borax. It is of very complex composition, consisting of no less than five different resins. Largely used in varnishes, in hat making, and forms the chief part of sealing-ivax. Its most important varieties are Stick-lac, Seed-lac, and Shellac. Mastic, Dammar-resin, Sandarac, and Copal, are resin- ous products from trees growing in hot climates. They are largely employed in varnishes. Amber is a resin which has exuded, in some past geo- logical era, from trees now extinct, and which is cast up on the shores of the Baltic and the coast of Now Jorsoy 23* 2*70 ESSENTIAL OILS CONTAINING SULPHUR. in masses of a few ounces in weight. It is fashioned on the lathe into ornaments, and is made into v^arnish. Caoutcliouc, or Grum-elastic, India-rubber, and Gutta Percha — are the dried juices of certain tropical plants. They are insoluble in water and alcohol; sparingly soluble in ether and the essential oils. Largely soluble in chloroform. In oil of turpentine, especially when holding sulphur in solution, Caoutchouc dissolves to a viscid, sticky substance. By heating with sulphur the elasticity of Caoutchouc is increased, and it is rendered less liable to be affected by differences of temperature. The new substance thus formed, and which is known as Vulcanized India-rubber, is employed in the manu- facture of combs, brushes, knife-handles, etc. The Balsams, such as Venice Turpentine, Canada Bal- sam, etc., are natural solutions of resins in essential oils. Some, as Feru and Tolu Balsams, and Gum Benzoin, contain in addition benzoic or cinnamic acid. (c) Essential Oils Containing Sulphur. The two most important of this class are : — Oil of Black Mustard, CgHsNSa, and Oil of Garlic, CMS- Preparation. — The former does not pre-exist in the seed, but is formed in the process of distillation by the joint action of water and Myronic acid upon the pulpy matter of the bruised seed, after the fixed oil which it contains has been expressed. (See Oil of Bitter Almonds, p. 246.) Composition. — Oil of Mustard is supposed to be a com- pound of Sulphocyanogen, C2NS2 (p. 2T3), with a hydro- carbon, CgHs, known as allyl, forming Sulphocyanide of AUyl; thus, C8H5NS,= C6H5C2NS,. In like manner garlic oil is regarded as a Sulphide of Allyl, CeH^S. CYANOGEN AND ITS COMPOUNDS. 211 VI. CYANOGEN AND ITS COMPOUNDS. In consequence of its close resemblance to the halogens this important radical has already been described, p. 164. Like the halogens it forms one acid compound with hy- drogen, and many compounds with the metallic elements which have the properties of salts, viz.: — Hydrocyanic or Prussic Acid, HC^jN or HCy. (Sym. of Cyanogen, Cy.) Preparation. — Produced by decomposing Cyanide of Mercury with Sulphuretted Hydrogen, HgC2N + HS = HgS+HC,N. Properties. — A thin, colorless liquid, boiling at Y9° and freezing at 0°. It is very volatile, has a peachy odor, and is fearfully poisonous. Best antidote is ammonia. Its acid properties are very feeble. Rapidly decomposes, especially when exposed to light. Salts of Hydrocyanic Acid. — The Cyanides of Potas- sium and Sodium may be obtained by burning Potassium or Sodium in Cyanogen gas. For commercial use, how- ever, Cyanide of Potassium, KCy, is prepared by decom- position of Ferrocyanide of Potassium (p. 272). Cyanide of Mercury, HgCy, may be obtained by de- composing Cyanide of Potassium with Red Oxide of Mer- cury, KCy4-Hg0=K0 + HgCy. It is valuable as a source of Cyanogen. The Cyanides of Silver and Gold, AgCy and AuCya, Are largely employed in solution with Cyanide of Potas- ' Bium as baths for silver and gold electro-plating. Compounds of Cyanogen with Oxygen. With oxygen Cyanogen forms three isomeric acids :^ — Cyanic acid, C2NO ; Fulminic acid, C4N2O2 ; and 272 FERROCYANOGEN, ETC. Cyanuric acid, CgNsOg. The first is monobasic, the second bibasic, the third tribasic. Thus in combination with silver we have Cyanate of Silver, AgO,C2NO ; Fulminate of Silver, 2AgO,C4N202; Cyanurate of Silver, 3AgO,C6N303. Cyanic acid, C2NO, may be combined with Ammonia to form a crystalline Cyanate of Ammonia, 1^11^0,0^0. By heating or by exposure to air a little Ammonia is evolved, and the crystals are found to have undergone a wonderful change, and become urea. The compound of Fulminic acid with silver, 2AgO, C4N2O2, is a dangerously-explosive, crystalline solid. Compound of Cyanogen with Iron. Ferrocyanogen— CgNsFe, (Sym. Cfy). This radical has never been isolated. Preparation. — It may be obtained as a Ferrocyanide of Potassium, Ka-CeNgFe, by digesting iron filings in a solution of Cyanide of Potassium; Oxygen is absorbed, and we have 3KCy+Fe-f 0=-KO + K2,C6N3Fe. In larger quantities for commercial purposes, this salt is procured by heating the horns, hoofs, hides, or other parts of ani- mals with Carbonate of Potassa and iron filings. It is repeatedly crystallized from solution until it forms large, transparent, lemon-yellow crystals, known in commerce as Yellow Frussiate of Potash, KzCeNsFe+SHO. When Ferrocyanide of Potassium is added to solutions of metallic salts it forms oftentimes a beautifully colored precipitate, which is valuable as a test. The Potassium is simply replaced by the metal ; thus, KgCeNsFe -f 2(CuO,N05)=2(KO,N05) + Cu,C6N3Fe. Hydroferrocyanic Acid — HaCfy. Like Cyanogen, this radical also combines with Hydrogen to form an acid BASIC PRUSSIAN BLUE — FERRICYANOGEN. 273 But Hydroferrocyanic acid is entirely different from its corresponding cyanogen compound, being very permanent, and strongly acid. It is formed by decomposing Ferrocy- anide of Copper with Sulphuretted Hydrogen, CuaCeNaFe 4-2HS=2CuS + H^CgNaFe. Remarks. — It will be observed, that in combination with the metals and hydrogen, Ferrocyanogen is bibasic. Ordinary Prussian Blue, Fe4Cfy3, is formed when Ferro- cyanide of Potassium is added to a Sesquisalt of Iron : thus, 3K2Cfy-f2(FeA,3N05)=6(KO,N05)4-Fe,Cfy3. It is employed both in water colors, and in oil paintings, as an intense blue color, but it is not permanent. Dissolved in water by means of Oxalic acid, it forms blue ink. Basic Prussian Blue, Fe^Cfya + Fe.Os, is formed by exposing the white precipitate, which is formed when a ferrocyanide is added to a solution of an iron protosalt, to the air. Perricyanogen— Ci.NgFea. Sym. Cfdy. Preparation. — A salt radical, isomeric with Ferrocy- anogen, which may be obtained as a Ferricyanide, by passing chlorine into a solution of Ferrocyanide of Potassium. Properties. — It combines with three equivalents of Po- tassium to form Ferricyanide of Potassium, or, as it is termed in commerce, Red Prussiate of Potash, KjCfdy, and with 3 equivalents of the other metals, and of hydro- gen. It is therefore tribasic. Remarks. — With a Sesquisalt of Iron, Forricyanido of Potassium produces no precipitate; with a Protosalt, it forms TurnhuWs Blue, FcgCfdy. A radical, termed GobaJtcyanogcn, having cobalt in place of iron, and similar in its properties and compounds to ferricyanogcn, has been formed. Sulphocyanogen— C2NS2. Sym. Csy. Preparation. — A salt radical, which nmy bo obtained 274 ORGANIC COLORING PRINCIPLES. in combination with Potassium and Iron, by heating sul- phur with yellow Prussiate of Potash; K2C6N3Fe4-6S= 2(KC2NS2) + FeC2NS2. Properties.— It forms an acid compound with h v drogen, Hydrosulphocyanic acid, HCsy, and unites with metals to form salts. Those which are soluble, give a characteristic blood-red color with Sesquisalts of Iron, but no precipi- tate. Exists in the saliva. i^ewary^s.— Sulphur may be replaced by Selenium, and Selenocyanogen and its compounds, analogous to Sulpho- eyanogen and the Sulphocyanides, be formed. VII. ORGANIC COLORING PRINCIPLES. All colors may be obtained from organic substances, but the prevailing tints are red, yellow, blue, and green, of very various tones and intensities. They are all de- rived from vegetables, with the exception of cochineal. The Art of Dyeing consists in applying the pigment in such a way that it cannot be washed off. As a general rule, the coloring matter has not sufiacient affinity for the fibre of the fabric to resist washing. Recourse must then be had to an intermediate body, having a strong attraction for both the fabric and the coloring matter, which may serve to fasten the two together. Such a body is termed a mordant, and the three principal mor- dants are Alumina, Oxide of Tin, and Sesquioxide of Iron. When an infusion of a dye-wood, like logwood, is mixed, for example, with alum and a little alkali, the acid of the alum combines with the alkali, and sets alumina free. The alumina then combines with the coloring mat- ter, forming a precipitate, technically called a lake, which permanently attaches itself to the fabric. Alumina and INDIGO. 275 Oxide of Tin form bright, Sesquioxide of Iron, dull lakes. When the mordant is applied only to a portion of the fabric, by means of a pattern, all the coloring matter in the rest of the fabric can be washed out, and a figure cor- responding to the pattern will be left firmly fastened to the stuff. Coloring principles have, as a general rule, stronger affinities for animal substances, such as wool and silk, than those of vegetable origin, like cotton and flax. The most important organic coloring matters are : — Indigo. Litmus. Madder: Alizarin and Purpurin. Safflower : Carthamine. Brazil-wood and Logwood : Hematoxylin. Quercitron ; Fustic-wood ; Saffron ; Turmeric. Cochineal. Chlorophyle. Indigo— CieHsNO^. Preparation. — It is obtained by digesting the leaves of several species of the genus Indigofera for eight or ten days in water. A yellow substance is formed, which by oxidation changes to a deep blue, and constitutes commer- cial Indigo. By sublimation of the commercial, pure Indigo, sometimes termed Indigotine, may be obtained. Properties. — A tasteless, inodorous body, insoluble in water, but slightly soluble in alcohol. It dissolves in strong Sulphuric acid, and forms Sulphindigotic or Sul- phindylic acid, C,6H4NO,2S03,nO. This solution is used as a chemical test, and in dyeing. By deoxidizing agents, such as Protosulphate of Iron and Protochloride of Tin, the color of Indigo may be en- tirely removed, and white Indigo, Cmll,;^' 0,>, be formed. This unites with bases and forms with thorn soluble com- pounds, which are admirably adapted for dyeing purposes 276 LITMUS — MADDER — BRAZIL-WOOD, ETC, By exposure these solutions become deep blue. It is on ibis principle that dyeing with Indigo is performed. By boiling powdered Indigo with Hydrate of Potassa it is changed to Aniline, Ci6H5N02+4(KO,HO)-f2HO= CiJI,N^+4(KO,C02) + 4H (p. 241). Litmus — Archil, Turnsol or Cudbear. These blue col- oring matters are obtained from the Rocella tinctoria and other lichens by exposing them in a moistened condition to the action of Ammonia. Properties.-^ThQ blue color of litmus is changed to red by acids, and restored by alkalies, and it may be used, therefore, to detect their presence. It is largely employed as a red dye. It is a compound of several principles, as Ficro-erythrin, C24II16O4 ; Orcein, CuHgO^ ; Rocellinin, CigHgOy ; and different acids. Madder — Alizarin and Pur pur in. This is the finest and most permanent of red dyes. It is obtained from the root of the Rubia tinctoria, which is extensively grown in southern France, the Levant, etc. Besides yellow coloring matters, it yields the beautiful Madder purple, or Purpurin, Ci8H606+2HO, and Madder red, or Alizarin, C20II6O6+4IIO. The latter is the chief coloring principle of madder. It is feebly acid. By oxi- dization with Nitric acid both are changed to Oxalic and Phthalic acids, CooHeOe -f 2H0 -f 80 = 2(C203,HO) + LieHeOs- By appropriate mordants Madder furnishes likewise brown and orangie colors, and the exquisite crimson known as Turkey red. Safflower affords a yellow and a red dye {carthamin). Brazil-wood and Logwood. — The former yields a crys- talline solid, termed brezeline, which gives with mordants a beautiful red ; the latter, by digestion in water, affords crystals of Hematoxylin, CieH^Oa. Produces with iron ALBUMINOUS BODIES. 211 salts a permanent black, and with other mordants dif- ferent shades of purple and red. Bed ink is usually made by boiling about two ounces of Brazil-wood in a pint of water for a quarter of an hour, and adding a little gum and alum. Quercitron; Fustic-wood; Saffron; Turmeric. — Furnish yellow dyes. The color of Turmeric is changed to brown by alkalies, for which it may therefore be employed as a test. Cochineal. — A brilliant red dye, obtained by steeping the dried bodies of a little insect, the Coccus cacti, in water or alcohol. It is precipitated by alumina and oxide of tin, as carmine. Chlorophyle. — A waxy substance, of a green color, formed in those parts of plants which are exposed to light, and communicating to them their green tinge. VIII. ALBUMINOUS BODIES. The three most important are Albumen, Fibrin, and Casein. They all agree in yielding, as the first product of their decomposition by caustic alkali, protein (from pi'o- teuo, 1 am first) ; and some have supposed that the com- bination of protein with sulphur and phosphorus produced Albumen, Fibrin, and Casein. This is doubtful. Protein— C^.HnNaOa. A white, inodorous solid, capable of combining with both acids and bases. It is precipitated from its acid compounds by tannic acid and alkalies. The chemical formulae of Albumen, Fibrin, and Casein have not been determined, but they contain, as fir as can be learned with regard to bodies which, like these, are amorphous, in 100 parts: — 24 278 ALBUMEN — FIBRIN. Albumen. Fibrin. Casein. Carbon 53.5 52.7 63.83 Hydrogen 7.0 6.9 7.15 Nitrogen 15.5 15.4 15.65 Oxygen 22.0 23.5 Sulphur 1.6 1.2 Phosphorus 0.4 0.3 23.37 The above analyses show that they closely agree in composition, and they may indeed, under certain circum- stances, be converted into each other. Albumen. Source. — It is found nearly pure in the white of eggs, from which it derives its name, in the serum of blood, and in vegetables. Properties. — It exists in two states ; as a liquid in the white of eggs, the humors of the eye, serum of the blood, etc., and as a solid in the brain and nerves of animals, and in the seeds of plants. In the former condition it is color- less, tasteless, inodorous, and soluble in alkaline solutions; in the latter a translucent, horny, amorphous body. Liquid Albumen is coagulable by heat, by nitric, sulphuric, hydro- chloric and metaphosphoric acids, by metallic salts, by astringent bodies, like tannic acid and creosote, and by alcohol. Owing to its coagulation by corrosive sublimate. Albumen is useful as an antidote. Its coagulation by acids is due to its combination with them as a base ; by metallic salts, to its union with the oxide of the metal as an acid. Fibrin. — Like albumen it exists in two states; 1st, as the chief component of muscular fibre, whence its name, in the clot of blood, etc.; 2nd, as gluten, the adhesive, pasty mass obtained from cereal grains after the starch has been removed. Properties. — When fresh it forms white, elastic fila- ments, which are tasteless, inodorous, and insoluble, ex- CASEIN — GELATIN — KREATIN. 2Y9 cept in alkaline liquids. It coagulates spontaneously, and forms the clot in blood. The Fibrin obtained from venous blood, however, is not identical with that of arterial blood, and neither agree in composition with the Fibrin of the flesh. Casein. Source. — Is found in the curd of milk (caseum., whence its name), in the blood, and in peas, beans, and similar plants — vegetable Casein, or legumine. Properties. — It is soluble in alkaline solutions. Its solution in milk is due to the alkali present, and if the latter be removed by an acid, like lactic acid, the Casein coagulates and forms curd. The same effect is produced by the dried stomach of a calf, rennet. There are many other proximate organic principles con- taining nitrogen, such as Alhuminose, Pancreatin, Mu- cosin, Crystallin, MuscuUn, Ostein, Keratin, Synovin, Spermatin, etc, but we will consider only Gelatin and Kreatin. Gelatin. Source. — By the action of hot water on animal mem- branes, skin, tendons, and bones, they are made to dis- solve and to furnish solutions, which on cooling deposit a yielding, tremulous mass, called Gelatin. It is familiar as calves'-foot jelly, and in the dry state as glue and isinglass, or the dried swimming-bladder of the sturgeon. Properties. — As already mentioned (p. 251), the pro- cess of tanning depends upon the formation of an insoluble compound of the Gelatin contained in the hides with tannic acids. The Gelatin obtained from cartilages diifors from the above, and is termed chondrin. While Gelatin proper affords no precipitate with alum and acetate of lead, chon- drin does. Kreatin— C8H9N304,2HO. It is a colorless and beauti- 280 BLOOD. fully crystalline body, which may be obtained frona the juices of the flesh. Of the animal fluids we shall consider, 1. Blood. Description. — When freshly drawn it appears to be a homogeneous, red fluid, of slightly saline taste, peculiar odor, and somewhat unctuous touch. Under the micro- scope, however, it is found to consist of a nearly colorless Fig. 162. Fig. 163. ^^^^^^' serum of the blood, or liquor sanguinis, and ^W^ multitudes of little red [i«?^(^^\\y^ 1 ^^^^^' ^^® ^^^ corpuscles, ■^(q)! and colorless globules, (§)^^^^^ white corpuscles. Fig. 162 shows the corpuscles in the blood of a frog, and Fig. 163 as they appear in human blood. On standing, the fibrin and corpuscles form a coagulum or clot, and leave the thin, yellowish fluid, termed serum, in a pure state. The analysis of blood gives: — Water 784. Red Corpuscles 131. Albumen 70. Salts 6.03 Fatty substances and Extractive matters 6.77 Fibrin 2.2 1000.00 The salts found in the blood are chloride of sodium and potassium ; carbonates, phosphates, and sulphates of po- tassa and soda; carbonates of lime and magnesia; phos- phates of lime, magnesia, and iron. The extractive matters are kreatin, fatty bodies like seroline, and cholesterin which is likewise found in bile, oleic, margaric, and other acids. BILE — SALIVA — GASTRIC JUICE — MILK. 281 A most delicate test for blood is furnished by certain dark lines of absorption, seen with the spectroscope, p. 56. (See London Quarterly Journal of Science, April, 1865, p. 198.) 2. Bile. — It is a yellow or green fluid, of unpleasant smell and extremely bitter taste. It consists of various salts, fats, mucus, and other substances found in other solutions, along with a peculiar fat, termed cholesterin, and a resinous body, bilin. 3. Saliva. — It is characterized by the presence of a pe- culiar principle, termed ptyaline, and also contains sulpho- cyanogen. 4. Gastric Juice. — In addition to muriatic and lactic acids, and various salts, the gastric juice contains pepsin, to which its digestive power is chiefly due. 5. Milk consists of a watery fluid, in which are sus- pended globules of butter, surrounded by albuminous envelopes, and holding in solution various salts and milk- sugar. By churning these envelopes are broken, and the butter collects into a mass. APPENDIX. Extension has three dimensions, length, breadth, and thickness. These may be considered separately, in pairs, or all together. Extension in length is measured and expressed by certain arbitrary scales and units, shown in the follow- ing tables, where the relation of various units is also given. Measure of Length used in tlie United States. Miles. Furlongs. Chains. Rods. Yards. Feet. Inches. 1. 8. 80. 320. 1760. 5280. 63360 .125 1. 10. 40. 220. 660. 7920 .0125 .1 1. 4. 22. 66. 792 .003125 .025 .25 1. 6.5 16.5 198 .00056818 .0045454 .045454 .181818 1. 3. 3G .00018039 .00151515 .0151515 .060606 .33333 1. 12 .000015783 .000126262 .001262626 .00505050 .027777 .083333 1 Length and breadth multiplied, or taken together, give surface. Thus, a rectangular area measuring one yard on each of its sides we call a square yard, and by the same term denote any area of equal extent, whatever its shape. (282J APPENDIX. 283 ' <0 (>J (M r-( CD iMOl-l CO» cc '^ X Ph eS O O *S a fl Si 03 O ^ jn o CO >^ E ^ ^ O O) Cj H^ -s ^ ,d l€ d«>Sood-;^ u ^ p Q _; o S S ^ g 9 '?..'*. .<=j cS T-l O 00 t- (M pH O lO S^ O . ?3 iqo PM Ooc^-Oi^- • *: »- O) ^ »^ sss ,a O « 0} t— ■* S pq O^M fH 03 o .(nSooo •a M ctf >< <^ S' '^ ■?■:!; 5 ^ 6 2'S APPENDIX. Dry Measure. 4 gills = 1 pint. 2 pints = 1 quart. 8 quarts =^ 1 peck. 4 pecks = 1 bushel. Cubic Measure. 1728 cubic inches = 1 cub. foot. 27 '« feet = 1 '' yard. 128 <' " =1 cord. 40 feet round, 50 feet square, timber = 1 ton. Liquid Measure. 4 gills = 1 pint. 2 pints = 1 quart. 4 quarts = 1 gallon. 16 gallons = I half barrel 31| " = 1 barrel. 42 " = 1 tierce. 63 " =r 1 hogshead. 84 «' = 1 puncheon. 2 hogsheads = 1 pipe or butt. 2 pipes 1 tun. Tatle for Comparison of French and English Measures for Length. Metre Yards Feet Inches 1 = 1.093 3.280 39.390 2 = 2.187 6.561 78.741 3 = 3.280 9.842 118.112 4 = 4.374 13.123 157.483 5 = 5.468 16.405 196.853 6 = 6.561 19.685 236.224 7 = 7.655 22.966 275.595 8 = 8.749 26.247 314.966 9 = 9.842 29.528 354.337 Decimetre Feet Inches 1 = 0.328 3.937 2 = 0.656 7.874 3 = 0.984 17.811 4 = 1.312 15.748 5=r lAtO 19.685 6 = 1.968 23.622 7 = 2.296 27.559 8 = 2.624 31.496 9 = 2.952 35.433 Centimetre Inches 1 = 0.393 2 = 0.787 3 = 1.118 4 = 1.574 5rr 1.968 6 = 2.362 7 = 2.755 8 = S.149 9 = 3.543 Millimetre Inches 1 = 0.039 2 = 0.078 3 = 0.118 4 = 0.157 5 = 0.196 6 = 0.236 7 = 0.275 8 = 0.314 9- 0.354 Example of method employed with this Table to re- duce French to English measure. Required to reduce 4612 Metres to Eeet. 4000 Metres = 13123. feet. 600 " = 1968.5 " 70 '* = 229.66 " 2 " = 6.56 " 4672 = 15327.72 « Select from the table the number corresponding fo each digit in the given number, assigning the proper position to the decimal point ; then add all these quantities j their APPENDIX. 285 sum will be the required equivalent to the quantity stated. Table for Comparison of French and English Measures of Surface. Hectare. Decare. Are. Sq. Metre. Square Yards. Square Feet. 1 10 100 10000 11966.4 107698. 1 10 1000 119ei.64 10769.8 1 100 119.66 1076.98 1 1.19 10.76, etc. Tahle for Comparison of French and English Measures of Capacity. Kilolitre. Hectolitre. Decalitre. Litre. Decilitre. Centilitre. 1. 10. 100. 1000. 10000. 100000. 1. 10. 100. 1000. 10000. 1. 10. 1. 100. 10. 1. 1000. 100. 10. Gallons 220. 22. 2.2 .22 .022 1. Quarts 881.2 88.12 8.81 .881 .0881 .00881 Pints 1762.4 176.24 17.e2 1.762 .1762 .01762 Cubic Inches 6107-1. 6107.4 610.74 61.074 6 .1074 .61074 Stere 3= 1 cubic metre = 35.31658 cubic feet. Tahle, showing the Behavior of Solutions of Metals with Hydrosulphurio Acid and Hydrosulphate of Ammonia, employed successively. (Dr. Will.) The rarer metals are printed in italic. Elements precipitated from tlieir acid •olution by Hydrosulphukic Acid, as Bodies precipitated by HrDKOauLrHATK 09 Ammokia. lulpliides. ^- -_^^^-^_ ^ 'Soluble in Hydro- sulphate of Aiiima- Insoluble ii , Hy. nia, and reprecipi- drosiilphate o Am- As Sulphides. As Oxide s. A« Salts. tated by Hydioclilo- nioiiia. ric Acid. ''moW}"™'^"- Mercury ') Nickel ^ Alumina "1 Baryta, ^ Ulack ^ Strontia, Silver a Cobalt j Glucina rS-2 Lime, Arsenic^ ^9 o y Yellow. 2 '-' -a in combina- Tin J Lead >--l Manga-) Flesh- uoso J coloi''d. Chromium tion with phosphoric. GoUl Bismuth 'Thorina boraoic, i2 oxalic, and Platinum V ^ Copper Iron, Black. YUria d some other P acids. Iridium Cadmium, Y cllow Zinc, White. Cerium ill Magnesia '2L}>'-- Palladium " in-a- \ ■Rrown- «iM»i/ish-black. Zircon ia "o S c-^ c in conibi na- JiJiodium Titanium tion with phosphoric, Osmium M Tanialiuvi ^ acid. 286 APPENDIX. WeigM. — Three scales are in use. The Troy and Apothecaries' are commensurate, but the Avoirdupois has a dififerent standard.* Measures of Weight used in the United States. Avoirdupois. Tons. Cwts. Pounds. Ounces. Drachma. 1. .05 .00044642 .00002790 .OOU00174 20. 1. .0089285 .000558 .0000348 2240. 112. 1. .0625 .0U16 36840. 1792. 16. 1. .0625 673440 28672 256 16 1 The short ton contai QS 2000 lbs. Troy. Pounds. Ounces. Dwts. Grains. Pound Avoir. 1. .0S3333 .004166 .0001736 1.215275 12. 1. .050000 .0020833 14.58333 240. 20. 1. .041666 219.666 5760 480 24 1 7000 .822S61 .068571 .0034285 .00020571 1. Troy weight only is used in philosophical experiments. Apothecaries', Pound. Ounces. Drachms. Scruples. Grains, 1. 12. 96. 288. 5760 .08333 1. 8. 24. 480 .0104166 .125 1. 3. 60 .0034722 .041666 .3333 1. 20 .00017361 .020833 .1666 .05 1 * The Troy or Apothecaries* pound is to the Avoirdupois pound as 144 is to 175, but the ounces are as 480 grains to 4371 grains Troy or Apoth- ecaries'. So also the Apothecaries' drachm = 60 and the Avoirdupois drachm =» 27^2 grains Troy or Apothecaries'. APPENDIX. 287 I ^ 00 g, 03 >A 1 ss 1 S 1 S 1 CO II 52 °> s^' <» S o> « o ^ ■• Oi '"' ooco i ^ s? ^ 1 S^ 11 ^ II SI II S3 « ^^ » a 00 ^ 00 >" 1 00 OS ^ , ^s 05 o § 1 ^.t-: o 5" 3 II Q II rH *- ISS *- s i-i CO >n CO •o CO c^o § ^ I g 11 s <0 MO o c^ to 05 « ,-ieo la t^ o t-; o o r.r. t- os t- O5 00 a> to .- rH CO 1- o OOl- t- to II -^ cc d Tj< rH rH <© TJ) Tl4 • '^ «o t- CO t1< 00 t- IM 1 S8 1 ?? I £ ^ II © CO «dod CO ^ CO Tji CO CO Tt 00 CO gs •* oc o 1 00 1 oc 1 ^ li CO -*C0 1 oo 1 c o c^ nio - ^ (N ec (M is ♦ • Comparative Tables of '* Troy White Vitriol... Wintergreen Oil INDEX. Wood, 143 265 265 269 287 287 287 288 287 213 268 Brazil ll^„ Ether Fustic Log Naphtha Spirit 236 277 276 240 236 X. Xyloidin. Yellow, King's ••• <' Prussiate of Potash. «* Turner's Yttrium.. 232 221 272 217 201 Zinc 212 Red Oxide of 212 Silicate of 21L Sulphate of 213 ^^^^^ :::::::::■ m Zirconium 465 ° 003 836 399 2 %