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PRINCIPAL OF THE PATAPSCO FEMALE INSTITUTE, MARYLAND. tJTHOR OF THE FIRESIDE FRIEND &C. WITH A SERIES OF WORKS ON BOTANY, NATURA1. PHI LOSOPHV AND CHEMISTRY, DESIGNED FOR BEGINNERS AND MORE ADVANCED STUDENTS. Ndw EDI"jjlOl| BJ^I$E$) A^Dj^JDRftECTED. | SUfGEQN GiLNtRAUSOFncr I HUNTINGTON AND SAVAGE, MASON AND LAW, 216 PEARL-STREET. CINCINNATI:—H. W. DERBY &. COMPANY. 1850. av ?53SC I 850 Entered according to Act of Congress, in the year 1846, by HUNTINGTON &. SAVAGE, In the Clerk's Office of the District Court of the United States for the Southern District of New-York. CONTENTS. PAGE. CHAPTER I. Introductory. General views of Physical Science. Applications of Chemistry,.................................................. 7 PART I. CHAPTER II. General Remarks on the Imponderables. Heat. Expansion. Ther- mometers .................................................. 13 " III. Conduction of Heat. Radiation and Reflection. Latent Heat. Li- quefaction. Frigorific Mixtures............................. 24 " IV. Vaporization. Ebullition. Steam. Distillation. Gases and Va- pors ....................................................... 36 " V. Light. Decomposition of Light. Illuminating, Heating, Coloring, and Magnetic Rays. Flame. Phosphorescence.............. 48 " VI. Galvanism, or Voltaic Electricity................................ 64 " VII. Chemical Nomenclature......................................... 70 " VIII. Chemical Affinity............................................... 77 PART II. CHAPTER IX. Chemical Classifications. Division of Ponderables. Oxygen...... 93 " X. Chlorine....................................................... 100 " XI. Electro-negative Substances. Bromine. Iodine. Fluorine........ 105 " XII. Simple Electro-positive Substances............................... 114 " XIII. Hydracids...................................................... 123 » XIV. Nitrogen....................................................... 128 " XV. Nitrogen and its Compounds..................................... 140 » XVI. Carbon......................................................... 144 " XVII. Compounds of Carbon with Hydrogen............................ 167 " XVIII. Compound of Carbon and Nitrogen........,....................... 166 »» XIX. Silicon. Phosphorus............................................. 174 » XX. Sulphur........................................................ 180 iv CONTENTS. PAGE. CHAP. XXI. General Observations upon the Metals. First Class of Metals, or those which form Acids with Oxygen......................... W " XXII. Second Class of Metals. Alkaline Metals, or those whose Ox- ides are fixed alkalies, or alkaline earths. Order I. Metals which, with Oxygen, form the fixed alkalies................... 211 " XXIII. Second Class of Metals. Order II. Metals which, with Oxygen, form alkaline earths. Barium. Strontium. Calcium. Magne- sium....................................................... 218 " XXIV. Third Class of Metals. Earthy Metals, or those whose Oxides are earths...................................................... 224 " XXV. Fourth Class of Metals. Metals whose Oxides are not regarded as acids, alkalies, or earths..................................... 228 " XXVI. Fourth Class of Metals continued................................ 235 " XXVII. Fourth Class of Metals continued................................ 244 "XXVIII. Crystalization. Classification of Salts. Salts of the Oxacids....... 254 » XXIX. Salts of the Oxacids continued................................... 267 " XXX. Salts of the Hydracids or Hydrosalts.............................. 277 PART III. CHAPTER XXXI. Considerations on the subject of Organic Chemistry. Vegeta- ble Chemistry. Proximate Principles and Ultimate Ele- ments. Vegetable Acids................................ 284 '» XXXII. Vegetable Alkalies, Oils, Resins, &c......................... 293 " XXXIII. Alcohol, Ether, &c......................................... 301 » XXXIV. Sugar, Starch, Gum, &c.................................... 305 » XXXV. Fermentation.............................................. 319 " XXXVI. Animal Chemistry, or Animal Organic Bodies................. 323 PREFACE. Chemistry is a most comprehensive science;—while it in- structs the philosopher in the constitution of matter, it teaches man how to perform the most common operations in the busi- ness of life, such as the preparation of food, the warming and ventilation of apartments, soap making, washing, &c The arts of dyeing, glass making, engraving, and of preparing medicines, have their foundation in chemical science. From the intimate connection which subsists between the different branches of Physical Science, the Author of this work has been naturally led from the study of one, to that of others; and the pleasures and advantages she has derived from these pursuits, have induced the desire that they might be more gen- erally appreciated and enjoyed, especially by her own sex. Her series of works on Botany, Natural Philosophy, Chemistry, and Geology, she is happy to believe, have been studied by many who would not have felt the courage to encounter more erudite works. Teachers, diffident of their own acquirements, have been taken by the hand, and guided, along with their pupils, in paths which the Author had labored to free from difficulties. It is pleasant, to reflect that we are companions of the young in their search after knowledge, and that our thoughts thus be- come incorporated with their thoughts, when the mind, yet free from prejudice, is open to the reception of truth ;—it is a still higher satisfaction to believe that while imparting to the young mind scientific truths, we may be instrumental in im- planting the seeds of piety, to be developed with the mental germination, so that the blossoms of the intellect, may be ac- companied by the fruits of the soul. CHEMISTRY. CHAPTER I. INTRODUCTORY. GENERAL VIEWS OF PHYSICAL SCIENCE.--APPLICATIONS OF CHEMISTRY. 1. The Physical Sciences are so intimately connected that the study of one throws light upon the others. Natural Philoso- phy, Natural History and Chemistry are sister sciences pos- sessing many characteristics in comfton, but each distinguished Sy peculiar traits. 2. The object of all the Physical Sciences is the investigation of the material world. No object is too vast for the grasp of science, none too small for its observation. The celestial orbs, the lowly flowret and minute insect, are, alike, objects of scien- tific research; and all, in their own peculiar way, proclaim, " The hand that made us is divine." 3. Let us imagine the three sister sciences surrounded by the objects of their several researches ;—We see Philosophy turning from the contemplation of the heavenly bodies, to cast an approv- ing look upon the steam-engine, and mechanical powers, or to examine with her optical glasses the structure of a mite, or some object in the far distant regions of space. Natural History, the priestess of nature, crowned with the flowers of all climates, calls around her all animated things, whether of the earth, the air or sea. She also claims as hers the rocky foundation of the earth, its metallic treasures, the diamond of the mine, and the ocean's pearl. 4. And what of all that is above, upon, or under the surface of the earth, belongs to Chemistry since her sister sciences have appropriated to themselves the works of nature and of art 1 Chemistry claims the elements, of which all material substances 1. Connection of the Physical Sciences. %. Their object and scope. 3. The sister sciences. 4. Province of Chemistry. 8 INTRODUCTORY. are composed; she, under the direction of their great Creator, presides over their combination, and, at the appointed time, effects their dissolution, carefully garnering up her atoms, so that not one shall be lost. Chemistry, then, may be imagined as veiled from observation, and carrying on those secret processes of composition and decomposition which are intimately connected with the operation and suspension of the vital powers in plants and animals. In obedience to her laws, inorganized matter as- sumes various forms of beauty and regularity, as in crystals and diamonds, and, at her command, the hardest rocks crumble into dust. 5. The question is often asked, " does the study of the sciences tend to establish the mind in the truths of religion, and promote christian humility; or, rather, does not science put nature in the place of God, and heighten the pride of man, by filling him with lofty notions of his own powers, which can thus penetrate the mysteries of creation V We answer that such effects may arise from a superficial study of the sciences—he, who looks not beyond nature, to nature's God, who seeing a little, believes that he sees all of the mysteries of creation, cannot truly be called a philosopher. The discoveries of science demonstrate the existence of physical laws which must have originated in one Omniscient and Omnipotent mind ;—they exhibit nature as the mere creation of Almighty power, subservient to his will, and governed by his laws. Man, by the light of science, beholds himself as an atom in creation ; even his discoveries humble him ; for the more he learns of the wonders of nature, the more extensive seem the fields yet unexplored, and the more humble his own attainments. 6. It is the office of science to explain appearances, and to teach man to distinguish them from reality. Thus, we learn from Astronomy that the apparent motion of the heavenly bodies is not real, but caused by the motion of the earth ; we learn from Optics, that we do not see the real object before us, but its image depicted on the back part of the eye, and, there, contemplated by the mind. Chemistry proves, that what appears to be the destruction of matter is not such; but, that when a body seems to undergo a process of dissolution, its particles are only set free to enter into new combinations, and that no atom, which has been created, is suffered to be lost. 5. Effects of the study of the sciences upon the human mind. Religious influence of science. 6. Science teaches to distinguish the apparent from the real. That mat- ter is indestructible. Combustion not the destruction of atoms but of combinations. ' INTRODUCTORY. 9 7. Inquiries into the nature of compounds, and the various changes of which matter is susceptible, must be deeply interest- ing to every intelligent mind. But it is not alone for thepleasure of science that its pursuits are recommended; nor can we assent to the definition of a writer on Political Economy,* viz ; " that a philosopher' is a person whose trade it is to do nothing, and speculate on every thing." Chemistry is not merely a grave pastime for philosophers ; it bears an important relation to the useful arts; and most of the inventions of modern days owe their origin to this science, or depend on principles which Chemistry alone can explain. 8. Art and science are mutually dependent on each other ; the former works, the latter thinks. It would be as absurd to con- tend which is the more useful to society, the working man or the thinking man, as whether the hands or the brain are the more necessary in effecting mechanical operations. Thinking and working should go together; the more the working man thinks, or in other words, the more he combines science with mechanical skill, the more likely will he be to excel, and to im- prove on what others have done. The man of science who is skillful in manual operations, possesses a great advantage in being able to adapt to their proper use, his instruments of ob- servation and experiment, to supply their deficiencies, or to invent new instruments. ' 9. Mechanical operations are a series of philosophical experi- ments. The soap boiler, in combining oil and water through the medium of an alkali, illustrates on a large scale the doctrine of Chemical Affinity. The glass maker exhibits chemical pheno- mena, in melting together, and combining alkaline, saline, metallic and earthy materials ; in the effect of coloring matter upon the compounds thus formed ; and in cutting, grinding and polishing glass. The tanner, by a chemical process, converts the soft spongy skins of animals into leather, which is hard, tough, and impervious to water. The farmer in manuring his grounds, and in mixing soils of different kinds, is working on principles which he can only understand by a knowledge of the effects of chemical combinations. The physical sciences and the arts of life, must go, hand in hand, in the work of improvement Every advance in science gives a new advantage to the arts , and every improvement in the arts offers to science a fresh field •Smith, See Wealth of Nations, Book 1, Chap. 1, p. 15. 7. Relation of Chemistry to the useful arts. 8. Mutual dependence of art and science. 9. Common operations effected on scientific principles. Soap boiling- Glass making—tanning, &c. 10 INTRODUCTORY. of research, and new facilities for discovery. Thus, the philoso- pher and the artisan are mutually dependent on each other. 10. The process of bleaching linen and cotton was long and laborious, requiring weeks and even months for its completion, until by the discovery of chlorine, the manufacturer was present- ed with a liquid, which, by immersing the cloth in it for a few hours, produced the necessary effect. The same chemical agent, chlorine, is most usefully employed as a purifier of infected atmospheres, thus preventing the contagion of dangerous dis- eases. 11. The discovery of iodine may be traced to the observation of a soap boiler. In the refuse of soap 4ey, he discovered cer- tain corrosive properties for which he could not account. He applied to a Chemist, who, on subjecting the substance to analy- sis, discovered a new and important chemical element which he named iodine. 12. A striking instance of the benefits of science, in alleviat- ing human suffering, is to be met with in the needle manufacto- ries of England. The workmen are obliged to breathe an at- mosphere filled with minute particles of steel, which fly from the grindstones, used in pointing the needles. The irritation produced by this dust on the lungs caused consumption. Various expedients were resorted to ; but no gauzes or screens could ex- clude this fine and penetrating dust. At length the magnetic influence was resorted to, and masks of magnetized steel wire gauze were constructed ; the floating atoms of steel being thus arrested, the workman now breathes freely, in the assurance that he is not inhaling a fatal atmosphere. 13. The safety lamp, the lightning rod, the life boat, are gifts presented to man by science. Chemical science, is not only deeply interesting, as unfolding the laws and secret operations, of nature ; but eminently useful, considered in its relation to the diseases and wants of man and the progress of human improve- ment. 14. Scientific pursuits exercise on the mind itself, a healthfu and invigorating influence, by bringing into action and disciplin- ing the intellectual powers. In considering the variety of the works of creation, the grand and the minute so harmoniously combined, and the system by which the whole universe is con- nected in an infinite series of relations ; in observing the readi- 10. Practical applications of chlorine. 11. Discovery made by a soap boiler. 12. Application of the magnetic power. 13. Other applications of scientific discoveries. 14. The mind of man adapted to the study of nature. INTRODUCTORY. 11 ness with which the human mind seizes upon facts which unfold these dependencies and relations, and the elevation and enlarge- ment which such studies give to the soul, we are led to believe, that, as the earthly parent surrounds his child with the instru- ments and means of knowledge, so our Almighty Father made, beautified and enriched the material world, that He might thus, give lessons of wisdom to His children, and afford scope for the intellectual energies with which he had endowed them. 15. Chemistry begins where the other physical sciences end For example, Natural Philosophy considers the mechanical prop- erties of matter j Natural History examines the external organs or form of objects, with a view to their classification; while Chemistry, penetrating to their internal particles, examines their constitution. 16. Chemistry teaches the elements of which matter is com- posed, the properties of these elements, and their laws of combina- tion ; it also shows what are the component parts and properties of compound substances. 17. The foundations of chemical science are observation, ex- periment and analogy. By observation, facts are noted and im- pressed on the mind ; by experiment, new facts are brought to light; by analogy, we infer what is unknown from what is known. Thus, suppose a person to notice that when a certain vegetable substance, which is common in brooks and ponds and grows under water, is exposed to the sun, globules of air appear on its filaments, while no such globules of air are seen upon the weeds which are in shade. This is an observation. The observer, by inverting over it a wine glass filled with water, sees this air rising up through the water until it fills the glass. Having now se- cured a portion of the air, he is ready to try an experiment upon its nature. On introducing a burning taper into it,„he finds that the taper burns with greater brilliancy and fierceness than in common air. He has now ascertained that this air differs from the common air. He is then led by analogy to inquire, whether other green vegetables will not, in similar circumstances, give off air of the same kind. In this way we may suppose oxygen gas, might have been observed, experimented upon, and finally found to exist in a great variety of substances. 18. All the knowledge we possess of external objects is found- ed upon experience ; this furnishes facts, and the comparison of these facts establishes relations. Such inductions, connected 15. Distinction between the physical sciences. 16. Definition of Chemistry. 17. Foundations of chemical sciences. Definition of certain terms. 18. Process in the discovery of general laws. 12 INTRODUCTORY. with the intuitive belief that the same causes will produce the same effects, lead to the knowledge of general laws, and these laws constitute a science. Thus has Chemistry, beginning with scattered and isolated facts, advanced to its present distinguished rank among the sciences. 19. The properties of matter are either Physical or Chemical; the former are considered in Natural Philosophy, the latter in Chemistry. 20. The attraction of gravity or of large masses, has no in- fluence in chemical action; but, chemistry exhibits another species of attraction, called affinity, which operates only between the minute particles of matter. 21. Heat, Light and Electricity have important influences upon chemical combinations ; as they have not been proved to be ponderous or to have weight, they are called imponderable agents, the consideration of these agents, together with the laws of affinity, will constitute the First Part of the following works ;— Part Second will treat of the chemical elements of ponderable matter; or Inorganic Chemistry; Part Third will explain the chemical constitution of vegetable and animal substances, the study of which, constitutes Organic Chemistry. 19. Properties of matter. 20. Difference between I he attraction of gravity and that of affinity. 21. Division of subjects. PART I. HEAT, OR CALORIC. CHAPTER II. GENERAL REMARKS ON THE IMPONDERABLES.--HEAT.--EXPANSION BY HEAT.--THERMOMETERS. 22. The imponderable agents have a very important influence over all terrestrial matter. These agents are Heat, Light and Electricity, which last includes Galvanism. 23. It is not known whether these agents are strictly material substances, or only motions or affections of matter. We cannot confine and exhibit them as we can other material bodies, nor do the most delicate balances show that they^awm weight. It is thought by some, that since we cannot prove these agents to possess the common properties of matter, they ought not to be regarded as material existences. Some philosophers are of opinion, that they are merely the effects of vibratory and rotatory motions among the particles of matter ; and that their intensity depends on the velocity of their motions. But whether they be material existences, or only properties of matter, they are found to be subjected to physical laws. We shall therefore, con- sider them as invisible fluids, pervading nature, and requiring only the intervention of other kinds of matter to render them evident. HEAT, OR CALORIC. 24. Heat, in common language, is used to signify both cause and effect. By caloric* chemists understand the cause of which heat is the effect; it is the agent which produces in our minds, by means of external organs, the sensation of heat. The term igneous fluid, matter of heat, Src, mean the same as caloric. 25. Caloric is a subtle, invisible fluid, universally diffused, and highly elastic, that is, composed of particles that strongly repel each other, but possess an attraction or affinity for all other substances. 26. There are six sources of caloric, viz. 1. the Sun : 2. Com- • From color, a Latin word signifying heat. 22. Imponderable agents. 23. Different opinions with respect to the imponderable agents. 24. Definition of caloric. 25. Nature of caloric. 26 Sources of caloric. Mechanical means of producing heat. 2 14 EXPANSION OF BODIES BY HEAT. bustion: 3. Electricity: 4. The bodies of living animals: 5. Chemi- cal action: 6. Mechanical action. The mechanical means of producing heat are friction and percussion. The rubbing together of two pieces of wood is an example of friction, and the hammering a piece of metal, of percussion. By these means, wood and other combustibles may be set on fire : and many serious accidents have occurred in consequence, as the burning of factories, explosion of powder mills, and the like. 27. Caloric is capable of two modes of existence ; in the one, it is manifested to the senses, and its degrees of intensity may be measured by means of certain instruments. When in this state, it is called free caloric, sensible heat, caloric of temperature, &c. In the second case, the caloric is concealed from the senses, and is said to be latent or hidden. Expansion. 28. One of the most important and universal effects of caloric is, to expand all bodies into which it enters ; and that such is the effect of caloric is proved by the fact, that a body so expanded returns to its original bulk on cooling. Experiment. Let a small bar or cylinder of iron, a, be fitted to pass through the aperture at Fig. 1. o and let its length be ^^_ such that it will fit into ___m , . fllrli! tne notcn c' ®n heing ----1--------' llllli heated, it will be found a «j .© too large to pass through the aperture at b, and too long for the space c; when cooled it will contract to its original dimensions. 29. A very useful application of this principle is familiar to wheel wrights. It is highly important that the parts of a carriage wheel should be united in the firmest possible manner. For this purpose, when the wooden por- tions have been nicely joined, the iron band is constructed so small, that it cannot be forced on when cold. The band now being made red hot, it ex- pands, so as readily, to encompass the wheel; and in cooling, it contracts, compressing and binding the parts and joints together with an immense force. 30. It is supposed that caloric causes expanson, by insinuating itself between the particles of a substance, and driving them by its elastic force, to a greater distance from each other. Thus, a body when heated occupies greater space, and is of a less specific gravity, than when cold. 27. Free and latent heat. 28. Caloric expands bodies. Experiment to show the expansion of a solid body by caloric. 29. Application of this principle in the manufacture of carriage wheels. 30. Manner in which caloric causes the expansion of bodies. HEAT. 15 31. It might be inferred a priori* that the expansive effect of caloric would be opposed by the cohesive attraction of the particles ; and accordingly we find cohesion and caloric, univer- sally acting as antagonists to each other. Bodies exist in the solid, liquid or gaseous state, according to the prevalence of the cohesive or repulsive forces. In solids, the power of cohesion, is greater than that of repulsion, and the particles are held closely together. In liquids, the cohesion is so far overcome, that the particles can move freely among them- selves ; and in aeriform bodies, though cohesion undoubtedly exists, it is not apparent, on account of the predominance of the repulsive power. We should hence expect, that with the same addition of caloric, liquids would expand more than solids and gases more than either, and this is practically true. 32. It is demonstrable, that some bodies expand much more than others ; and that when any solid is heated gradually, through any range of tempera- ture, the hotter it becomes, the more it expands by the same acquisition of heat. For instance, if a metallic rod of known dimensions, be heated from 60° to 100° it will expand to a certain degree. If now another 40° of heat be applied to it, the increase of its dimensions will be greater than in the former case. And this is easily explained ; for the cohesion being partially overcome by the first addition of heat, the second portion will have less op- position to encounter and will produce a proportionally greater effect. 33. By the application of various degrees of heat, solid bodies may all, or nearly all be converted into liquids, as in the melting of ice, the fusion of wax, metals, &c. Liquids, by the further addition of caloric, may be converted into gases. 34. An instrument called the pyrometer,^ has been invented to show the degrees of intense heat, above those which we are able to estimate by the mercurial thermometer. Mercury boils and becomes vapor, at 660° ; above that point, therefore, it is incapable of measuring heat. The pyrometer depends for its operation, on the expansion of metals, and shows the different degrees of expansibility of different kinds of metals. The figure shows a rod of metal, A A, resting horizontally upon support- ers. One end of the rod is fixed, the other end touches the wheel work, B B, which is so connected with the index C that a slight motion of the wheels, causes a considerable movement in the index. The rod of metal, * By a priori is meant, beforehand, or prior to any reasoning or experi- mentin?, on the subject. t From the Greek pur, fire, and metron, measure, signifies^ measurer. 31. Expansion opposed by cohesive attraction. Why liquids expand more than solids, and gases more than either. 32. Expansion greater at certain stages of heat, with an equal increase of caloric, than at other stages. 33. Effects of heat in changing the state of bodies. 34*. Pyrometer. Its use and construction. Describe the figure. 16 PYROMETER. Fig. 2. on being heated by the lamps 1, 2, 3, expands and presses against the wheel, which communicates motion to the index. The more expansible is the metal, the farther the index will move on the plate. 35. The pendulum of a clock, in order to vibrate seconds, must always be of a given length ; but as metals expand with heat, the pendulum is liable to shorten in winter and lengthen in summer :—it follows that the clock will go faster in winter than in summer. By lengthening or shortening the pendulum, this evil may be remedied. About thirty-nine inches is found to be the length necessary for a pendulum to vibrate seconds. It may be readily understood why a short pendulum should Fig. 3. vibrate faster than a long one, when it is considered that the pendulum is the radius of a cir- cle, which circle is larger or smaller, according to the length of the radius. Thus suppose A and B to be two pendulums, of which B is the longer. B must describe the arc, c, d, of a circle, while A only describes the arc from e to f. 36. Various circumstances have rendered it most convenient to construct pendulums of metal, though their liability to expansion and contraction bv change of temperature, is an imperfection. If the temperature of the pen- dulum be raised, its dilatation will evidently remove its mass farther from Sf- iP?£" a? f .sus?ensi°n' and wiu cause its rate of vibration to be slower: while the diminution oftemperature will be attended with the contrary effect 35. Why will a clock go faster in winter than in summer? How may fong one f * hy d°6S * Sh°rt Pendulum borate fasterThana wa3tch.EffeCt °f expansi0n and contraction upon the balance-wheel of a HEAT. 17 Thus it would follow, that with every change of weather the rate of the clock would vary. In like manner, the swinging motion which the balance wheel of a watch receives from the hair spring which impels it, depends on the distance of the metal forming the rim of the wheel from its center. If this distance be increased the spring acts with less advantage on the mass of the wheel, and therefore moves it more slowly ; and if it be diminished, for a similar reason, it moves more quickly. It follows, therefore, that when a wheel expands by increased temperature, the rate of vibration will be dimin- ished ; and when it contracts by diminished temperature, the rate of vibration will be increased. A watch for the same reason, will fluctuate in its rate of keeping time with every change of temperature. Various ingenious inven- tions have been resorted to, to compensate for the irregularities, occasioned by increased or diminished temperature upon the metallic rod of the pendu- lum, or balance wheel of a watch. Expansion of Liquids. 37. Liquids, like solids, differ greatly in their several expansi- bilities by heat. In general, the less the heat requisite to boil a liquid, the more it will expand by a given increase of temper- ature. And further, liquids like solids are subject to an increas- ing rate of expansion, as the heat is raised higher. Experiment. Fill to o, o, rig. 4. two small matrasses, the one with alcohol, the other with water ; place under each, a pan of burning charcoal, or immerse the bulbs in boiling water. The alcohol will rise to a, while the water is at w. On cooling, the liquids will gradually return to their original bulk. As a general rule, those liquids expand the most uniformly through a steady rise of temper- ature, which require the strong- est heat to make them boil. Al- cohol boils with a lower degree of heat than water; it is, there- fore, exceedingly expansive; and the nearer it approaches the boil- ing point, the more rapidly its volume increases. 38. Since expansion by change of temperature changes the weight of a given bulk of a liquid, and this change of weight is in the inverse proportion to the expansion, it follows, that all the 37. Liquids vary in their capacities of expansion by heat. Experiment to show' the different effects of heat in the expansion of alcohol and water. General rule with respect to the expansion of liquids. 38 Manner of determining the degrees of the expansion of liquids. 2* 18 EXPANSION OF LIQUIDS. ordinary methods for determining the specific gravities of liquids may likewise be applied to determine their degree of expansion. The specific gravity of the same liquid at different temperatures is different, and always in an inverse proportion to the expansion: the less the specific gravity, the greater, in the same proportion, will be the expansion. 39. The French Chemists have determined the absolute expansion of mercury by means of an apparatus here represented, and which may be applied in the same manner in the case of other liquids. It depends on the hydrostatical principle, that two vertical columns of liquid communicating by a horizontal tube, will have heights in the inverse proportion of their densities. Fig. 5. A T and A' T' represent two ver- tical tubes of glass, which communi- cate with a hori- zontal tube P P. They are filled with mercury to the height nn. So long as the temperature is the same in every part, the surfaces of the mercury in the two vertical tubes must stand at the same level: but if the mercury in one tube, be reduced to the temperature of melting ice, and in the other be of a higher temperature, the expansion produced by the higher temperature, will cause the mercury in one tube to dilate in a greater degree than in the other, and to become specifically lighter; still the columns balance each other, the column of mercury in the tube A' J" will balance the lower column in the tube A T, at the lesser temperature. Exception to the general law of Expansion. 40. To the general law of expansion by heat, and contraction by the loss of it, water furnishes a most remarkable exception. On cooling water at the common temperature, it will be found to contract gradually until it is about 40° when it begins to expand until it becomes ice. Water, in becoming ice, increases in bulk ^ ; water in freezing becomes crystallized ; the particles begin to change their positions, shooting out into needles and crossing each other at various angles, as may be seen when water is freezing in a shallow vessel. It is supposed that this new arrangement of particles is the cause of its increasing in bulk, and the supposition is supported by the facts, that solutions of 39. Describe the apparatus for determining the absolute expansion of mercury or other liquids. 40. Effect of cooling water below 40°. Change which takes place at this temperature, and probable cause of this change. HEAT. 19 salts, in crystalizing are enlarged in bulk, and that several of the metals on solidifying after fusion, also expand, taking, at the same time, a crystaline structure. This property renders anti- mony so useful for casting types, and cast-iron for various utensils, as the metal on cooling, perfectly fills the mould ; whereas, if they followed the general law of condensing by the loss of heat, they would shrink, and receive an imperfect im- pression. 41. In the economy of a wise and good Providence, this pro- perty of water has very important consequences ; for if ice were heavier than water, the lakes, rivers, and even the ocean itself, in cold countries would become solid ice, and all animal life which now exists within them would be destroyed. It appears a wonderful provision of Almighty wisdom, that, for the con- venience and preservation of man and animals, water should be almost the only substance which does not continue to become heavier as it grows colder. Fig. 6. 42. Let a a' represent two ves- sels filled with water at the tem- perature of about 66° ; 6 b' are tin trays surrounding the upper part of one vessel, and the under part of the other, and filled with a freezing mixture, viz., ice and salt. The first effect of the cold is to reduce the temperature of the whole mass of water to 40°, at which point water is at its greatest density. After this, the cooling process in the vessel a, will be limited to the surface, where the temperature will gradually fall to 32°, at which point the water will freeze ; for the freezing water, being lighter than the water below, will remain on the surface. This is what takes place in lakes and large bodies of water. In the vessel a', where the cold is applied at the bottom, the effect is very different; for the water when cooled below 40° becomes lighter and rises, the warmer or heavier portions descend, in their turn become cooled, and again rise; other, successive portions follow the same course, until the whole, being reduced to 32°, or the freezing point, hardens into one solid body of ice. The process described in the vessel a, or where the cold is at the surface, is that which goes on in nature; that in the vessel a', is what would take place, did not water, unlike all other known substances, become lighter before it freezes, so that a stratum of ice-cold water at 32°, lies over a mass of warmer water at 40°. 43. The force with which water expands in freezing is im- mense, bursting not only earthen and glass vessels, but even 41. What would be the effect of cold on lakes and rivers if water became heavier as it changed to ice ? 42. Exp. 43. Expansive force of freezing water. 20 EXPANSION OF AERIFORM BODIES. Fig. 7. cannon and strong metallic vessels, and causing chasms in rocks. By this expansion water pipes are also burst, and pavements thrown up. Expansion of Aeriform Bodies. 44. In their expansion by heat, aeriform bodies differ from liquids and solids in three important points, viz;— 1st. Aeriform bodies expand more than liquids and solids with the same increase of temperature ; the cohesion of their particles being already more than counterbalanced. 2nd. They expand equally. 3d. They expand uniformly through all temperatures. 45. Experiment 1st. Hold, near the fire, a bladder partially inflated. The air with- in, being expanded by the heat, will soon distend the bladder. Experiment 2nd. Place an empty thermometer tube (Fig. 7.) with its open end in a glass of water, and apply the hand to the bulb a ; the heat of the hand will cause the air within the bulb to ex- pand so that a portion will rush out and rise in bubbles through the water; on re- moving the hand from the ball, the water will rise in the tube to fill the vacuum caused by the condensation of the air. Thermometers. 46. The senses being very fallible means of measuring heat, the wants of science demanded the invention of some instrument for that purpose. About the middle of the seventeenth century, the Florentine Academicians made an attempt towards such an invention; their imperfect thermometer consisted of a glass tube, with a bulb at one extremity, filled to a certain mark with alco- hol, and closed at the open end;—the expansion of this liquid, or its rise above the mark, indicated heat; and its contraction or fall below the mark, indicated cold. This instrument, called the Florentine glass, was introduced into England by Boyle. At 44. Particulars in which aeriform bodies differ from liquids and solids in their expansion by heat. 45. Exp. 46. Why was the invention of the thermometer important ? First attempt towards the construction of the thermometer. HEAT. 21 first, the supposition that a liquid could contract and expand in a tube closed at both ends, was ridiculed as absurd, and it was not until the philosophers of the day were convinced by the experiments of Boyle, that this fact was admitted. 47. The invention of the first thermometer,* is usually as- cribed to Sanctorius, an Italian ; this instrument depended for its effects on the expansion of air by means of heat. If a matrass be held in both hands by its Fig. 8. bulb, the warmth communicated will expand the air within, and expel a portion of it. Now immerse the mouth of the instrument in a ves- sel containing a colored liquid, (see Fig. 8.) and remove the hands; the air will gradually cool and contract, while the liquid will rise into the tube, to supply the place of the air which was forced out. The apparatus in this condition, constitutes the. Air Thermometer of Sanctorius. On the approach of a heated body to the bulb, the expansion of the enclosed air drives down the liquid in the tube ; thus, the lower the column of liquid, the greater is the degree of heat indicated ; this is the re- verse of what takes place in the common mer- curial thermometer, where the greater the height of the column of mercury, the greater is the degree of heat signified. The superior advantages of the air ther- mometer, consist in the great expansive property of air by which minute changes of temperature are rendered obvious. But this advantage is outweighed by the objections, that so great an expansion of air with a slight degree of heat would require an unmanageable length of tube for observing any consider- able increase of heat; and that the variable pressure of the atmosphere in- fluences air, independently of temperature, so that the air thermometer can only be depended on when the barometer stands at a fixed point. 48. A modification of the air thermometer, invented 160 years ago, by Sturmius, and revived by Prof. Leslie, in 1804, is extremely useful in some experiments. It consists of a glass tube, (Fig. 9.) bent like the letter U, and having a bulb, a and 6, at each extremity. It contains a colored liquid, commonly sulphuric acid, tinged with cochineal. If heat be applied to one of the bulbs, as at a, it will expand the air within, causing the descent of the liquid in one branch, and its ascent in the other towards 6. The distance the liquid moves, is measured by a scale attached to one of the branches, and divided into equal parts, called degrees. It is obvious that, with this instrument, we can only learn the difference of the temperature of the two bulbs. On this account, it is called the Differential Thermometer. * From the Greek therme heat, and metron measure, meaning an instrument to measure the degrees of heat. 47 Thermometer of Sanctorius. What causes the liquid to descend in the tube on the approach of a heated body while in the mercurial thermom eter the column of mercury rises under the same circumstances 1 48 Leslie's Differential thermometer. 22 DIFFERENTIAL THERMOMETER. Fig. 9. 49. Howard's differential Thermometer is very delicate. In form and principle, it resembles that of Leslie ; but the fluid it contains, is sulphuric ether, an extremely volatile substance. One of the bulbs is left with a minute opening, and a sufficient; quantity of the colored ether being intro-- duced, it is then boiled. The vapor of ether now rises and fills the tube, expelling the air through the aperture. While the ebullition is going on, and the tube is full of vapor, the opening is suddenly closed by fusing the glass.* The etherial vapor now indicates the changes of temperature, as the air does in the thermometer of Leslie, but as the vapor expands in one branch, it causes a pressure on that in the other, and the latter becomes liquid; thus relieving the countervailing pressure which would im- pede the motion of the ether, if the second bulb contained an incondensible gas or vapor. 50. As air is not extensively applicable for the purpose of a thermometer, and as the small expansibility of solids renders them almost useless for this purpose, Chemists have sought among liquids for one, combining the most advantages, with the fewest objections. It is evident that perfect fluidity and freedom of motion are essential; oils and viscid liquids, therefore, are unfit, though a thermometer of the former was recommended by Newton. To be of extensive application, also, the liquid should be one which boils with great difficulty ; for its indication can be taken only while it retains the liquid state ; and, for the same reason, it should be able to support a great degree of cold without freezing. Its expansion, also, should be as nearly as possible uniform, through a great range of temperature. Mercury or quicksilver, though far from perfect, possesses the necessary requisites in - a higher degree than any other known liquid, and is, therefore, in general „ use as a thermometer. ' ; 51. The principle scales in use, are 1st. The centigrade, or that of Cel- ,. sius, used principally in France and Sweden, and generally known over Europe. Of this scale the freezing point is marked 0°, and the boiling point 100°. 2nd. The scale of Reaumur, used in France before the revo- lution, and still retained in Spain, on which the freezing point is at 0°, and the boiling point at 80°. 3d. That of De Lisle, the use of which is confined to Russia; this is a descending scale, the boiling point being 0° and the freezing point 150°. 4th. The scale of Fahrenheit which is used in this country, Great Britain, and Holland. On this the freezing point is marked 32°, and the boiling point 212°, the intermediate spaces containing 180 equal parts or degrees. • Glass tubes thus closed, are said to be hermetically sealed. 49. Howard's Differential thermometer. 50. Objections to air and solids for extensive use as thermometers. Why oil is unfit. Requisites in a liquid to be used for this purpose. What liquid is then generally used for the thermometer ? 51. Different thermometer scales in use. Fahrenheit's thermometer 23 52. A temperature expressed in degrees of one of the above scales is easily convertible to those of another, by applying the following rules. 1st. To reduce any number of degrees of the centigrade scale to terms of Fahrenheit, multiply the number by 9, divide by 5, and to the quotient add 32. The converse process is as follows; subtract 32 from any num- ber of Fahrenheit's degrees, multiply the remainder by 5, and divide by 1; the quotient will express the same temperature in degrees of the cen- tigrade. Examples. Fig. 10. Centigrade. Fahrenheit. 100°x9=900-r-5=l80 add 32=212°. Fahrenheit. Centigrade. 212°—32=180x5=900^-9=100° 2d. The degree of Fahrenheit being in length to that of Reaumur in the ratio of 4 to 9 ; to reduce an expres- sion of Reaumur's scale to one of Fahrenheit, we must multiply by 9, divide by 4 and add 32; and, on the con- trary, to obtain an expression by Reaumur's scale equiv- alent to a given one by Fahrenheit's, we subtract 32, x multiply by 4 and divide by 9. Example. Reaumur. Fahrenheit. 16X9=144-^-4=36° add 32°=68°. 80°X9=720-^4=180° add 32°=212°. Fahrenheit. Reaumur. 212°—32=180x4=720^-9=80°. 68°—32=36x4=144-^-9=16°. Thermometers are sometimes constructed with differ- it scales affixed to the same tube, so that the corres- •ndence of the degrees of different thermometers may 2 at once perceived. The figure represents a ther- ometer, with Fahrenheit's and Reaumur's scales. 53. The mercurial thermometer is accurate in its indications of temperature, as high as 212° ; for though mercury, like other liquids, expands proportionally more at high than at low temperatures, the irregularity is exactly com- pensated by the expansion of the glass tubes. But above 212°, the glass expands more rapidly than the mercury, and the indications are less 52. Rule for reducing degrees of the centigrade ther- mometer to those of Fahrenheit, and for converting degrees of Fahrenheit to those of the Centigrade. Ex- amples. Rule for reducing degrees of Reaumur's ther- mometer to Fahrenheit's, and for converting degrees of Fahrenheit to those Reaumur. Examples. 53. Irregularities of the mercurial thermometer. xygen. . . 5th. The more oxydable of the two metals will always become positively uccited, and the other negatively. 147. Zinc and copper, are the metals commonly used in gal- vanic experiments. The cut represents a vessel (Fig 30,) con- Fig. 30. taining an acid, much diluted with water, and two plates, the one of zink, the other of copper, (as shown by the letters Z and C ;) to each plate is soldered a piece of wire, the two ends of which meet in the center, opposite the place of insertion. This is called a simple galvanic circle. It is supposed that when in operation, there is, in such a circle, a continued current of electricity, flowing in the direction of the arrows from the zmk to the fluid, from the fluid to the copper, and from the copper back to the zink. 146 Conclusions of Volta. Voltaic pile. Facts connected with the developement of electricity by means of the Voltaic pile, or Galvanism. 147. Metals commonly used in galvanic experiments. Galvanic circle. Vegative and positive poles. 56 LIGHT. When the wires do not communicate, the galvanic circle is said to be broken. The wire attached to the copper plate is negative, that to the zink plate positive. The wires are also called poles; thus we say, the copper is the ne- gative pole, and the zink, the positive pole. 148. The quantity of electricity developed by a single pair of plates being very small, Volta endeavored to devise means of increasing it; and was finally led to the invention of the Voltaic Pile. This instrument consists ol pairs of zink and copper plates, one above another. Each pair is called a simple element of the pile, the whole consisting of a series of simple elements or circles. Between each pair of plates is placed a piece of cloth wet with weak acid. Fig. 31. The figure represents a Voltaic pile, (Fig. 31,) commencing with zink, Z, and ending with cop- per C. The wires which meet in the center are the two poles. The direction in which the ar- rows point, is that of the electric current. In constructing the Voltaic pile, from thirty to fifty plates of copper, and as many of zink, are gen- erally used; these are placed in regular order, each pair of plates being separated by a piece of cloth ; thus a regular suc- cession of copper, zink and cloth, is kept up through the whole series. The pieces of cloth should be somewhat smaller than the metallic plates, and should not be so moist as to yield any of the liquid by the pressure of the superincumbent metals. The pile is contained in a frame composed of a base and cap of dry varnished wood, connected by stout rods of glass. 149. The pile is capable of affecting the electrometer, and of producing muscular action in a much greater degree than the single pair of plates. The zink being positive and copper negative, the electric equilibrium is restored on bringing them into communication by means of wires con- nected with each; as it is when the coatings of a charged Leyden phial are connected. But the causes of excitement being still in the pile, the equilibrium is instantly disturbed again, so that a continuous stream of the galvanic fluid is produced : that is one of the most striking differences be- tween the action of the pile and that of the common electric machine. By means of the pile, the Leyden phial may be charged and the effects of the latter are precisely the same as when charged in the usual manner. If the two extremes of the pile are touched at once by the moistened fingers, a shock is felt differing little in kind from that produced by the phial, but much less in degree ; but if, after the first effect, the contact be still kept up, a continuous and painful thrilling sensation is perceived; and if the electric current traverses any wound, burn, or excoriation, it causes it to smart severely. Volta remarked that the pain was greater on the side toward the negative pole; a circumstance in which Galvanism resembles common electricity. 150. Any number of piles may be combined by connecting the extreme copper plate, or negative pole of the first, with the extreme zink plate, or positive pole of the second, and so on; and all the effects of th-e pile will be increased according to the number of simple elements, or pairs of plates. 148. Construction of the Voltaic pile. Number and arrangement of plates. 149. Action of the Voltaic pile. Differences and resemblances in the action of the Voltaic pile and the electrical machine. 150. Connection of piles. GALVANIC BATTERY. 57 This form of the pile is not now in use, as others more powerful and more convenient have been substituted. 151. One of the first of these was Cruickshank's trough, (Fig. 32.) com- monly called the Galvanic battery ; it consists of a trough of dry wood, divi- Fig. 32. ded into cells, by partitions placed at equal distances ; each partition is made of a plate of zink, and a plate of copper previously soldered together and fitted accurately into a groove cut in the wood; the joints being made perfectly tight with cement. The same order of arrangement must be ■ observed as in the pile. This instrument is put into operation by filling all the cells about two thirds full of a saline or acid solution. Its effects ar» more powerful than those of the pile, and may be increased by connectin several troughs in the manner we have just described, (see § 150). 152. The actual contact of the metals, is not necessary, as is seen in the construction of Volta's chain of cups, (Fig. 33.) commonly known as the " Couronne des Tosses."* This arrangement, of which the ef- fects are greater than those of a pile of equal dimensions, consists of any number of pairs of zink and copper plates generally about one and a half inch square; the zink and copper plate of each pair are connected by a wire bent in the form of an inverted U: and the different elements are immersed in cups or glasses of acid, or saline liquids, in such a manner that the zink plate of one pair shall be in the same vessel with the copper of the succeeding. Thus the different cups are connected only by the wire which joins the two members of each element: and the different elements act on each other only * Couronne des Tasses, pronounced kouron da tas, literally a crown of cups. 151. Galvanic battery. 152. Couronne des Tasses. 58 GALVANISM. through the medium of the intervening liquid. The two extreme platei which are not immersed in the liquid, are not taken into the account, and may be used as means of connecting the two poles of the row. The electricity is supposed to be excited by the mutual action of the sur- faces of zink and copper, opposed to each other in the same cup, and is conveyed from one cup to another by means of the wire which connects two successive cups. 153. Modifications of the Galvanic Battery. Dr. Wollaston observing that in the trough of Cruickshank, the effect of one zink and one copper surface in each pair was lost, by soldering them together, he proposed to use double copper plates or to bend the copper plate so that it should en- tirely surround the zink one, but without allowing the two to touch each Fig. 34. other, (see Fig. 34.) In this way each zink sur- face z, is opposed to one of copper, c, and the pow- er is increased by one half. Batteries are now generally constructed on this principle-: and a fur- ther improvement is made by connecting all the plates to a bar of dry wood, by means of which they can be removed at pleasure; the trough is made of porcelain or some other nonconductor, and is divided into cells by partitions of the same material. The largest battery ever constructed is that of Mr. Children the plates of which were 6 ft. long, and 2 ft. wide. Hare's Calorimoter, (or mover of heat, (Fig.35.A.) consists of a number of square zinc and copper plates of any convenient size, alternating with each other in a wooden frame. Two rectangular tubs accompany the apparatus, one containing the liquid acid for exciting the electricity, and the other tohold water for washing the plates. By means of an upright cross bar with a rope and pulley, the frame containing the plates may be at pleasure immersed in, or removed from the acid liquid: and this facility affords great advantages : for it is as- certained that the greatest ac- tion of the galvanic battery is 153. Dr. Woliaston's improved battery. rimoter. Deflagrator. Mr. Children's battery. Ca)o GROVES' CONSTANT BATTERY. 59 Fig. 35. B. at the first instant of immersion; and it is, therefore, important to be able to immerse all the plates at once. Besides the effects of the calorimoter in igniting wires, during its action much hydrogen is evolved from the liquid, and the gas is sometimes inflamed by the great heat produced. (The figure at 1, represents the entire instrument ready to be plunged, and at 2, the top of the plates.) Another modification of the battery by Dr. Hare is called the Deflagrator from its great power of burning the metals. The battery most used at present, and which seems likely to super- cede the use of all others, is called Groves' Constant Battery, a section of which is repre- sented at (Fig. 35, b. ) a, a, a, the outer glass vessels or tumblers ; b, b, b, cylinders of zink, open above and below; c, c, c, porcelain cylinders closed at the bottom, to receive the platina slips ; d, d, d, bars of zinc connecting the zinc cylinder in one tum- bler with the platina slip of the next; e, e, e, platina slips attached to the end of the zinc bars. When in use, the outer glass vessel is filled with dilute sulphuric acid, and the inner porcelain vessel with strong nitric acid, and a connection be- ing established between the platina slip at one extremity and the zinc cylinder at the other as represented by the dotted lines, the galvanic current then flows in the direction indicated by the arrows. 154. Effects of Galvanism. While the phenomena of galvan- ism and electricity seem to be produced by the same agent, they differ remarkably in the following particulars, viz : 1st, in the greater quantity of the electric fluid developed by the galvanic battery, 2nd, in its low intensity, and 3d, in the incessant renewal of the excitement as often as the equilibrium is restored, so as to produce a continuous current. T© the last circumstance, is attributable the superiority of galvanism over electricity, in producing chemical decomposition. 155. The igniting effects of the galvanic pile are very re- markable. When the two poles of a battery in action are connected by a small wire, the latter becomes intensely heated and gives out a lio-ht so vivid, that the eye can scarcely endure it. With a powerful battery, substances not fusible by any other means, are melted almost instantly. Even platinum is melted by it, as, 154. Difference between electricity and galvanism. 15s! Igniting effects of galvanism. Exp. 60 GALVANISM. readily as wax by the flame of a candle. Of all substances,. charcoal emits the most intensely, brilliant light. Exp. Two slender slips of dense charcoal, or of plumbago,* should be selected, scraped to a point, and fixed to each of the connecting wires. The battery being now put into action, and the charcoal points made to touch by means of insulating handles attached to the connecting wires, they imme- diately become vividly ignited ; and if very slowly separated, an arc of in- tense light will fill the space between them. With the great battery of the Royal Institution at London, consisting of 2000 pairs of plates an arc ap- peared four inches in length, and the heat existing there was so great as to fuse whatever substance was placed in it. Wires, even of the least oxidable of the metals, being made the medium of connection between the poles, may be burnt almost instantly. 156. Brilliant combustions may be exhibited in the following manner. Place some mercury in a flat dish and connect it with the negative pole of a strong battery ; attach to the positive wire whatever is to be subjected to experiment, and make it touch the surface of the mercury. A point of fine iron wire burns in this manner with great rapidity, giving off vivid sparks in all directions, and producing an appearance like that of a brilliant star; the reflection from the bright surface of the mercury adding to its beauty. Gold-leaf burns with a beautiful green light the instant it touches the mer- cury, and is immediately converted into the purple oxide of gold. Silver and copper leaf, and even platinum wire, undergo vivid combustion. It is ne- cessary to keep the surface of the mercury quite clean during these experi- ments, that its conducting power may not be impaired. 157. If the two connecting wires of a battery are immersed in water, so that their points shall be within a short distance of each other, an effervescence, arising from the evolution of gas, will be immediately observed ; and the experiment may be so conducted, that the gas can be collected. When collected, it will be found to consist of oxygen and hydrogen, mixed in pre- cisely the proportion for forming water. The hydrogen is always evolved at the negative pole, and the oxygen at the positive, and by a contrivance of Dr. Wollaston, they may be collected and ex- hibited separately. This little instrument consists of a bent glass tube. At the bend is a small hole , through the" lower side of the tube ; each leg of the instrument is corked air tight. Through the corks, two platinum wires are passed, extending through the whole lengths of their respective portions of the tube, and almost meeting each other at the angle. If this instrument be immersed in a vessel of water, and each of the wires connected with one of the poles of a galvanic battery, ^-_. the two portions of the tube will shortly be found to contain gas; that in the positive part will be oxygen, in the negative hydrogen; and the hydrogen will be in bulk, twice that BladTJeaT"^ of the oxygen; such being the proportions 156. Combustion of substances placed on mercury by means of the bat tery. DECOMPOSITION OF WATER. 61 m which the gases unite to form water. But it is not necessary that the water decomposed, should be all in the same vessel. The experiment suc- ceeds equally well, if two straight tubes, open at their lower end, are immersed in separate vessels of water, provided the two vessels communicate by means of moisten- ed fibres of cotton. To effect the decom- position of water, only a weak galvanic battery is required; the voltaic pile, or a trough of 12 pairs of 4 inch plates being sufficient. Other compounds, of which the constituents are united by a stronger force, may be resolved into their parts by propor- tionally increasing the number of plates. 158. In proceeding to consider, the decomposing effects of galvan- ism, it is necessary to explain some of the Chemical properties of acids and alkalies.* Chemical properties of acids and alkalies. Acids have the property of changing to red, the blue color of certain vegetable in- fusions, as that of violets, or of purple cabbage. Alkalies, on the contrary, change the same blue infusions green ; and a color which has been changed by one of these substances, may be restored by a sufficient quantity of the other. Salts are chemical compounds of an acid and an alkali; and when the two are united in proper proportions, their characteristic properties are entirely disguised, and the salt is called neutral. 159. If we dissolve in water, Glauber's salt or sulphate of soda, (composed of sulphuric acid and soda,) and add to the solution, a little of the blue infusion of cabbage, the color will remain unaltered shewing that the compound is neutral. Let this solu- tion be subjected to the action of a galvanic battery of sufficient power, the liquid at the positive tube, will soon become red, proving the presence of an acid there, while at the same time, the negative tube will exhibit an alkali, as will be shown by the liquid in it, becoming green. Now this acid and alkali could only arise from the decomposition of the sulphate of soda ; and we are able, otherwise, to show that the contents of the two tubes, being mixed, will reproduce this salt. The sulphuric acid, and soda are both compounds, each containing oxygen, * This subject is more fully explained at § 180. Experiment with 157 Decomposition of water by means of the battery. a bent glass tube. Experiment with two strait tubes. 158 Characteristics of acids, alkalies, salts. 159* Decomposition of a salt by the galvanic battery. What would be the ultimate analysis of Glauber's salt? 6 62 GALVANISM. united to a peculiar combustible body ;* and by a galvanic ar rangement of high power, the acid and alkali are resolved into then- elementary parts, that is, to their ultimate analysis. 160. In all cases of proximatef analysis of salts, by the gal- vanic battery, the acid will be found at the positive pole, and the alkali at the negative; and, whenever by ultimate analysis in this manner we resolve a substance into elements, of which one is combustible, and the other non-combustible, the latter will be found at the positive, and the former at the negative pole. Mr. Faraday, who has paid much attention to the subject of galvanism, advances the following opinions :— 1st. That the poles have no attractive, or repulsive tendency. He prefers the term electrodos,\ which signifies the way or door for electric currents. 2d. When a compound is decomposed by galvanism it is said to be elec- trolyzed ; || the substances capable of decomposition are called electrolytes; the elements of an electrolyte are called ions.§ Electro-negative substances as oxygen, chlorine, acids, &c, he calls anions;% the electro-positive as hydrogen, alkalies, metals, &c, he calls calions.** 3d. Most of the simple elements are ions, that is capable of forming compounds decomposable by galvanism. 4th. A single ion by itself has no tendency to pass to either of the elec- trodes, or is indifferent to the voltaic currents. 5th. To account for the decomposition of water by galvanism, Mr. Faraday supposes a line of particles between the two electrodes, along which the current passes. When a particle of oxygen is evolved at the positive electrode, its hydrogen is not at once transferred to the opposite electrode, but unites with the oxygen'of the contiguous particle of water, on the side towards which the positive current is moving, then it passes to the next, and so on till it arrives at the pole. A similar row of particles of oxygen start from the negative electrode at the same moment and combine success- ively with the particles of hydrogen as they pass them on their way to the positive pole or electrode. This process is supposed similar to what takes place in all cases of galvanic decomposition. 161. Discoveries of Sir H. Davy. The Galvanic battery be- came in the skillful hands of Davy, the means of effecting the most brilliant discoveries. With this instrument, he ascertained the compound nature of the alkalies and earths, a fact which, * Sulphuric acid is compesed of sulphur and oxygen, soda of a metal called sodium united with oxygen. * t The analysis of sulphate of soda into the acid and the alkali is the proximate analysis; the farther analysis of sulphuric acid and soda into three simple elements is the ultimate or last analysis. $ From the Greek electron, and odos, a way. || From electron, and lus, to unloose or disengage. § Pronounced i-ons, from ion, going, participle of the verb to go. IT From ana, upwards, and odos, the way in which the sun rises. ** From kala, downwards, the way in which the sun sets. 160. What takes place in all cases of proximate and ultimate analysis of salts by the galvanic battery ? Mr. Faraday's theory of decomposition. 161. Decompositions effected by Davy. Strong proof of the elementary nature of a body. , DISCOVERIES OF SIR H. DAVY. 63 previously had been only suspected. This discovery has intro- duced a new era in the annals of Chemistry, and added several new metals to the list of simple elements. No known compound has been able to resist the decomposing power of galvanism ; and it is regarded as the strongest proof of the elementary or simple nature of a body, when it gives no signs of decomposition, on being subjected to the influence of this agent. 162. To account for the decomposing effect of galvanism, it is necessary to recur to the principle of electric attraction and repulsion. If two particles, united to form a compound mole- cule, are both brought into the same electrical state, they will exert a mutual repulsion ; and if this repulsion be more powerful than the force of their chemical attraction, they must necessari- ly separate, and the compound will be destroyed. Or, even if they be in opposite states of electricity, since they are both within the influence of the battery, that particle which has the strongest tendency to become negatively electric, will naturally become so by induction, and be attracted to the positive pole; and at the same time, a similar change in the opposite direction, will take place with the other particle. 163. Davy was led to infer that chemical and electrical at- tractions are effects of the same cause. Having brought a dry acid in contact with a metal, he found that the former became electro-negative ; an alkali, treated in the same manner, became electro-positive ; and when an acid and an alkali, both dry, were made to touch each other, electrical excitement was produced, the acid being negative and the alkali positive. Furthermore, those bodies which exhibit the greatest tendency,to chem- ical combination, are also prone to assume opposite electrical states ; and though two bodies, A and B, which, if successively brought in contact with C, would each assume the same electrical state, may be in opposite electri- cal states when in contact with each other; yet if they combine, their compound A B, is held together by weak affinities, and is easily decomposed. Examples of this kind may be found in the instances of chlorine and oxy gen ; each of these bodies is strongly electro-negative, when in contact with hydrogen, and each forms with it, a well-defined compound. But chlorine, though electro-negative when compared with almost all bodies, is electro- positive with regard to oxygen, and may be made to combine with it; yet the compounds formed by chlorine and oxygen, are decomposed with re- markable facility. 164. The electro-chemical theory, supposes the same electri- 162. Explanation of the decomposing effect of galvanism. Why com- pounds are destroyed by electrical repulsion. Why there should be a de- composition when the particles are in opposite states of electricity. 163. Davy's experiments to prove the connection between chemical and electrical attractions. Electricity of acids and alkalies. A body may be electro-positive with one body, and electro-negative with another. Why chlorine and oxygen form compounds which are easily decomposed. 64 GALVANISM. cal excitement to take place between atoms in contact with each other, as we have seen to be produced by masses; that the atoms remain in contact, that is to say, in combination, in consequence of the electrical attraction consequent on this excitement; and that their union ceases, whenever, by any cause, they are brought into the same electrical state, or when they are exposed to the action of any third body which is more highly excited than either ; for, in the latter case, the highly excited body will at- tract the particle which is dissimilarly excited, and repel that which is similarly so ; and this is what happens in the decom- position of a compound substance by the galvanic battery. 165. Following the same course of reasoning which led him to the discovery of the alkaline metals*, Davy made other useful applications of his theory. Although the metals, compared wit) oxygen, are all electro-positive, yet when compared with eaci, other, as in the case of zinc and copper, they may have opposite natural electric energies ; and from experiment, as well as from theory, it is shown, that the positive metal will have the strongest tendency to combine with oxygen. Thus copper is rapidly corrod- ed in acid, or saline solutions ; but in contact with zinc, iron and some other metals, copper becomes electro-negative, and remains bright, while the other metal is rapidly oxidized; this happens, also, in the galvanic battery. Davy found that a slip of zinc or iron, would protect from rust 150 times its surface of copper, though constantly exposed to the action of salt water; and he proposed to apply this principle to the preservation of the copper sheathing of ships. The rusting of fine iron or steel instruments, may be effectually prevented by fixing a piece of zinc in their handles or elsewhere, so that it shall be always in contact with the blade. Electro-Magnetism or Magnetic effects of Electricity. 166. The relations existing between magnetism and electrici- ty are daily becoming more fully developed, and present a most curious subject of philosophical research ; the facts already ac- cumulated constitute a new branch of physical science called Electro-Magnetism. 167. Professor Oersted of Copenhagen, in 1819 discovered that the metallic wire of a voltaic circle causes a magnetic needle * Sodium, potassium, &c. being metals found in the alkalies, soda, potash, &c. are termed alkaline metals. 164. Electro-chemical theory founded upon the preceding facts 165. Applications made by Davy of his theory, with respect to'the elec- trical attraction of the metals. Why copper is protected from rust or oxidation, by zinc or iron. Iron and steel protected by zinc. 166. Electro-magnetism. 167. Discovery of Oersted. GALVANOMETER. 65 when brought near it to deviate from its natural position. This discovery was a confirmation of what was generally supposed, viz; that electricity might be employed to communicate mag- netic properties to iron or steel. It had been observed, that a ship having been struck with lightning, the magnetic needle often had its polarity destroyed or reversed, and that the iron about the ship became magnetic. 168. Galvanometer. It being proved that every part of a wire in a closed voltaic circuit exerts an equal force upon the poles of a needle, the combining force will be increased by increasing the number of points. This can be done by coiling the wire into the form of a circle or rectangle ; the united force will de- pend on the number of coils, each coil exerting its own peculiar force. d Fig. 38. d, e, (Fig. 38,) are the two ends of a copper wire bent in the form of a rectangle, in the centre of which, and in a plane perpendi- cular to the plane of the wire, is placed a magnetic needle. A graduated circular plane mea- sures the degree of declination of the needle, which indicates the quantity of electricity circu- lating along the wires. If the positive voltaic current pass above the needle from north to south, or which is the same thing from e to a, and then pass around the south pole from a to 6, the effect will be doubled. The deflection of the needle may be increased by multiplying the coils, until its directive power shall be wholly destroyed, or even reversed. If at the moment the needle has attained this point, the voltaic currents be sent in an opposite direction, it will perform a revolution. Thus a needle may be made to revolve rapidly by changing the direction of the currents. Influence of voltaic currents on soft iron or steel. 169. If instead of the common magnetic needle, an iron or steei needle be suspended in the galvanometer, at right angles to the conducting wires, permanent magnetism will be communicated to the steel, and the iron will become powerfully magnetic, but will lose this property when the voltaic currents cease to cir- culate. This discovery was made about the same time by M Arago and Davy. 168. Galvanometer. Explanation of the figure. 169. Discovery of Arago and Davy. Explanation of Fig. 39. Expla- nation of Fig. 40. 6* 66 GALVANISM- Let an insulated copper wire be coiled in the form of a helix, as at d, connect the two ends of the wire b, 6,with the cups c, z, into which the poles of a battery may be inserted. If bars of soft iron or steel be placed in the coil, they will become magnetized the instant the voltaic currents begin to circulate around the coil. If the positive current flows from z around the coil, n will be the north pole and s the south pole. The poles will be reversed if the positive current flows from c. The magnetic properties of soft iron, though not retained, are very powerful while the voltaic currents are passing around it. Fig. 40. If a soft iron cylinder, about two inches in diame- ter and bent in the form of a horse-shoe magnet h, (Fig. 40,) be wound with copper-wire, and the ends a, b, connected with the battery, it will become a powerful magnet. On applying the armature*d it will be found capable of sustaining immense weights ;—magnets of this kind have been made to support from one hundred to a ton weight. The principle is the same as in the helix, (Fig. 39,) and aas in the galvanometer, (Fig. 38,) where by increas- 'ing the number of coils, the magnet becomes more powerful; but the force does not increase directly as the number of coils; for each additional coil is farther from the axis of the iron bar, and the power it exerts is inversely as the square of the distance from the axis. 170. Volta-Electric Induction. It having been found that an electrically excited body, induced electricity in other bodies brought near it, the fact was next discovered that the same effect is produced by electricity in motion. Let a copper wire be wound in the form of a helix, and the ends connected with a battery ; let another wire be wound around this, but insulated from it, and the ends connected with a gal- vanometer, currents of electricity will be induced in the insulated wire, as often as the battery current is broken. All the effects of galvanism may be produced by the insulated wire. * From armo, to arm a piece of soft iron applied to a loadstone or con- necting the points of a horse-shoe magnet. 170. Volta-Electric Induction. Explanation of Fig. 41 Fi<*. 42. SEPARABLE HELICES. 67 Separable Helices, (Fig. 41.) exhibit the phenomena of volta- electric induction in a striking manner; 6 is a hollow coil of coarse wire fixed upon a stand z; one end of the wire is con- nected with the cup, and the other with the steel break-piece or non-conductor, which is fixed to the stand, by the side of the coil; a is a coil of fine wire which may be placed over the coil 6; d is a bundle of wires which may be put into the copper coil c, and placed in the centre of the coil 6. The entire apparatus is represented at Fig. 42. Exp. Connect one pole of the battery with the cup on the left of c, (Fig. 42,) and move the other pole along the break- piece ; vivid sparks will be pro- duced at each interruption. Exp. Place the coil a upon b, and let the currents circulate as before. If the handles e, f, (Fig. 42,) which communicate with the extremities of the wire forming the coil a, be held in the hands, powerful shocks will be felt, as the wire conveying the battery current passes across the break-piece. Exp. Remove from the wires d, the copper coil c, and insert them gradually in the coil 6 while the currents are circulat- ing, and the sparks in the break- piece will increase in brilliancy until the wires reach the bot- tom, when the greatest effect will be produced. Fig. 41 Ampere's Theory of Electro-Magnetism and Magno-Electricity. 171. When two positive or two negative currents are passing in the same direction, and parallel, they attract, and when pass- ing in opposite directions, they repel each other;—Supposing 171. Ampere's theory and explanation. 68 GALVANISM. that all magnetic bodies, (the earth itself being included) derive their magnetic properties from currents of electricity circulat- ing, in reference to their axis, in one uniform direction of revo- lution, we are then able to account for all the phenomena of magnetism, electro-magnetism, and magneto-electricity. Fig. 43. Let us suppose that around the cylinder of steel (see fig. 43) at right angles to the axis, currents of positive electricity are constantly circulating in a direction opposite to that in which the sun moves The cylinder will be a magnet, n the north pole and s the south pole, and if it be poised upon a pivot, it will exhibit all the effects of the magnetic needle. Explanation. The needle turns to the east when the posi- tive current passes above it from north to south, because the currents in the magnet, and those in the wire, move in different directions. The needle is repelled, and turns so that the cur- rents may coincide. Bars of soft iron and steel become magnetic when placed in the helix around which currents of electricity circulate, because s similar currents are induced in them. The cause of the magnetic needle standing north and south, is on the theory of Ampere explained by supposing positive currents of electricity to be passing around the earth, in the direction in which the sun appears to move; thus converting the earth itself into a magnet, its north pole corres- ponding to the south pole of the magnetic needle;—if soft iron or bars of steel are placed in a north and south direction, they will become magnets by induction, the positive currents passing from west to east, because then they would coincide with the same currents in the earth which pass from east to west;—therefore the magnetic needle stands north and south, be- cause the currents of electricity circulating around the earth, and those circulating in the needle, will coincide only when the needle takes that direction. 172. Thermo-Electrical phenomena result from currents of electricity excited in metals by heat. If a magnet be suspended in a rectangle formed of a bar of antimony or bismuth, having its extremities connected with copper wires, and heat applied to one end of the bar, the needle will be deflected in one direc- tion, and when heat is applied at the other end, it will be de- flected in an opposite direction. This discovery was made by Leebeck in 1821. It has been found that a rotary motion may be produced by placing platinum and silver wires, soldered together in a circular form, upon a magnet, and applying heat. 173. The Electro-magnetic Telegraph is an invention by which voltaic electricity is applied to communicate intelligence between distant places. At one station is the battery with wires extend- ing to the other station, and so connected with a magnetic needle, 172. Thermo-electrical phenomena. 173. Electro-magnetic telegraph. THEORIES OF GALVANISM. 69 that when the wires are attached to the battery the needle is set in motion and by means of a pencil attached to it, those conventional characters are marked which are the symbols of certain words or ideas. The effects of this application of voltaic power in conveying intelligence with the rapidity of lightning, are beyond human calculations. 174. Electrography is an application of voltaic electricity, by means of which may be produced perfect metallic casts or copies of medals, coins, copper-plates, &c. The instrument used is called the Electrotype. Its effect depends on the decomposi- tion of some metallic salt, by which the metal is precipitated upon the object to be copied, either forming a mould for the cast, or raising lines which may be used for making impressions on paper and other substances. Fig. 44. B is a glass vessel (Fig. 44,) with divisions made by placing across it some porous substance as thick paste-board. Into one of the divisions is put a satu- rated solution of sulphate of copper, and the other a weak acid solution. The object C to be copied is soldered to one end of a wire, d, and a piece of zinc, Z, to the other end; the object is then immersed in the solution of copper, and the zinc in the acid solu- tion. Metallic copper then begins to be deposited upon the object C, copying, with perfect exactness the most minute lines and shades. In a few days a complete cast will be formed : this is separated from the matrix by gentle heat. Explanation. The sulphate of copper is decomposed into sulphuric acid and oxide of copper;—The acid, with the oxygen of the decomposed water go to the zinc ; while the hydrogen of the water and the oxide of copper go to the copper pole ; the hydrogen unites with the oxygen of the oxide of copper, and the metallic copper is deposited upon the metal or object to be copied. Theories of Galvanism. 175. 1st. The theory of Volta considers the contact of the metals to be the only cause of electric excitement; it attributes to the liquid used, no other agency than that of conveying the electricity by means of its conducting power, from one pair of plates to the next, and thus enabling it to accumu- late at the poles. 2d. The chemical theory is so called, because it regards the chemical action which goes on in the pile, viz., the oxidation of the zinc, as the original dis- turber of electric equilibrium. This theory, Dr. Wollaston supports by arguments drawn from various experiments. It is perfectly true, that the contact of the metals will produce electric excitement; but it is also equally true, that electricity is developed during chemical action. Furthermore, it 174. Electrography. Explanation of Fig. 44. 175. Volta's theory of galvanism. The chemical theory. Electro-chemi- cal theory. Mr. Faraday's theory. Dr. Hare's opinion respecting the eating effects of the battery. 70 CHEMICAL NOMENCLATURE. is observed that the activity of the pile is increased, when, by using a more powerful acid, the chemical action is rendered more violent. 3d. Davy's theory, or the electro-chemical unites the two preceding; it supposes that the electric equilibrium is first disturbed by the contact of the zinc and copper plates, and that the excitement is afterwards kept up, and increased by the chemical action between the liquid and the metal. 4th. Mr. Faraday has attempted to prove that the poles have no attrac- tive or repulsive tendencies but merely afford a path for the voltaic currents to enter the liquid, or are doors for electric currents. 5th. Dr. Hare does not attribute the heating effects of the battery to electricity, but supposes the fluid evolved by this machine to be a compound of electricity and caloric, in which the proportions of the two constituents vary according to circumstances; thus, in the use of his calorimoter, great heat is excited, while the electric tension is very small. 176. In examining the operations and effects of heat, light and electricity, it is not necessary that we attempt to theorize upon their nature, or to determine whether they are substances, or qualities of invisible substances. Such is the intimate con- nection between them that many philosophers suppose them to be modifications of the same power, or substance. We can- not but regard them with awe, as mysterious agents, whom the Almighty subjects, partially, to our will, but of whose es- sential nature we are ignorant. We know that they possess immense force, and though we seem to have them in some de- gree under our control, we are liable at any moment to be destroyed by their power. It is their Creator only, who knows the " hiding of their forces ;"—He only can restrain, and hold them in combinations so justly and wisely modified and balanced, as to maintain and preserve that beautiful harmony in the order of Nature and of Providence, which He has established. CHAPTER VII. CHEBIICAL NOMENCLATURE. 177. An important change of subjects now presents itself. The bodies we are about to examine, are such as we can either see, or handle, or can prove to possess weight; they are, there- fore, known to be material, and are called ponderable, in distinc- tion from the class of agents called imponderable. 178. The study of ponderable bodies naturally divides itself into two parts, called Inorganic and Organic Chemistry. By 176. Concluding remarks. 177. Meaning of the term ponderable. 178. Distinction between Inorganic and Organic Chemistry. The same elements enter into the composition of Organic and Inorganic matter. CHEMICAL NOMENCLATURE. 71 Inorganic Chemistry is meant the study of the elementary bodies, with their combinations, as existing in inorganized matter as water, air, earths, minerals, &c. Organic Chemistry treats of the chemical constituents of plants and animals, but offers no elements not found in inorganic substances. It is owing to the different proportions, and mode of combination, that organic com- pounds differ in their qualities so essentially from compounds that are found in the inorganic kingdom ; thus the blood of ani- mals and the sap of vegetables, are peculiar fluids resulting from the action of a living principle, deprived of which, both animals and plants become the prey of the chemical and mechanical forces which are constantly in operation around them. 179. Before proceeding farther it is necessary to explain the nature of certain bodies, to which we shall have frequent occasion to allude; after which, will be given a brief exposition of the principles and rules on which Chemical Nomenclature is founded. The important subject of Chemical affinity, will next be examin- ed, and the laws of chemical combination. These are necessary preliminaries to the consideration of the ponderable bodies. Though, at first, these subjects may seem obscure, the mists will gradually break away, and the science appear in its true and beautiful proportions ;—each advance then made, will reveal new and striking evidences of the immutable basis on which it rests ; convincing the student that Chemistry, if not itself a divine science, proclaims the divine origin of matter; clearly refuting the absurd idea, that a blind chance, brought the ma- terial atoms into existence, and presides over their combinations. 180. By the term salt, as used in Chemistry, is meant, a de- finite compound of an acid and a salifiable* base. An acid (see § 158,) is generally sour, soluble, capable of reddening the blue color of violets and of litmusf, and of com- bining with and neutralizing the salifiable bases. But some acids are not soluble in water, and therefore do not taste sour nor redden vegetable blues ; others do not neutralize the salifi- able bases, though they combine with them. According to a strict chemical definition of the term, an acid is a substance which combines in definite proportions with salifiable bases to form salts. * Salifiable from the Latin Sal salt, with an English termination, means capable of becoming a salt. f Litmus is prepared from a lichen, {Lichen rocella ;) it is of a blue color, and paper dipped in its infusion furnishes a delicate chemical test. 179. Preliminary subjects to be considered. 180. Definition of a salt. Of an acid. Salifiable bases. Neutral, super and sub-salts. Soluble salts. Various properties of salts. 72 SALIFIABLE BASES. Salifiable bases are all metallic oxides* except ammonia,f and the vegeto-alkalies.% All the soluble, salifiable bases, (including ammonia, but excluding the vegeto-alkalies,) have an acrid taste, and are highly caustic, turn to green, the blue of violets, restore the blue of litmus when it has been reddened by an acid, and combine with acids in definite proportions to form salts. These are the properties which constitute an alkali; and hence the salifi- able bases which do not possess them all, are not called alkalies. But there is no proof that the absence of these properties in certain salifiable metallic oxides is not owing to insolubility. The insoluble, salifiable bases possess only the last mentioned and most important of the alkaline proper- ties, that of combination with acids. Some salts exhibit the properties of neither acid nor base, and are called neutral salts; others are acidulous, which property generally arises from an excess of acid, but sometimes from the feebleness of the base; others are alkaline, generally from an additional quantity of the base, but sometimes from the weak neutralizing power of the acid. Acidulous salts are fre- quently called super salts, as super tartrate of potassa, &c; and salts ex- hibiting the properties of the alkaline base, are sometimes denominated suo-salts, as sub-carbonate of soda. Some salts are soluble, others are not so; all soluble salts have taste, and most frequently a disagreeable one; none of them have odor, but the car- bonate of ammonia. Some are colored, others colorless, and many of them are capable of crystallization. 181. If every substance, examined by the Chemist, were to be named as caprice or fancy might suggest, the memory would be capable of retaining but a very small number of the names. To obviate so great an inconvenience, a systematic nomencla- ture, expressive of the constitution of substances, was adopted by Lavoisier, Guyton-Morveau, and other French Chemists, about the year 1784. It is founded on the principle, that the name of every substance ought to express its composition, if a compound, or some striking property, if it be a simple body. The simple bodies already known, were permitted to retain their established names. In conformity with these principles, oxygen was named from * By metallic oxides is meant a compound substance composed of a metal and oxygen. Oxide of iron is oxygen and iron; oxide of gold is oxygen and gold, &c. It is not to be understood that every metallic oxide is a salifiable base; some oxides are acids, and some neither acids nor bases. t Ammonia is a compound of two gases, Nitrogen and Hydrogen. j Vegeto-alkalies are compound alkaline bases, obtained in the analysis of Vegetable substance. 181. On what principle is the systematic nomenclature founded? Origin of the names of some of the elementary bodies. Names given to the com- binations of simple electro-negative bodies with other bodies. Names of combustions of simple combustible bodies with each other. Nomenclature of acids. Nomenclature of salts. More definite mode of describing salts than by the terms super and suo-salts. NOMENCLATURE. 73 two Greek words, implying a generator of acids. Hydrogen literally mean s the generator of water. Chlorine signifies a green substance, &c. &c. The combinations of simple electro-nega- tive substances with other bodies are designated by names ending in ide, as oxides, chlorides, iodides, and bromides. And where these elements form more than one combination with the same body, the different compounds are distinguished by pre- fixing Greek ordinals, marking the relative proportions ; as prot- oxide of iron, aWo-chloride of mercury, trito-io&ide &c, the highest compound being called per*-oxide, per-chloride, &c, meaning that the body has been oxidized, &c. through all the stages possible. The termination uret, is given to names of combinations of simple combustible bodies with each other : as sulphuret of lead, phosphuret of carbon, carburet of iron, Sec. Where but one acid is formed by the union of the same ele- ments, its name terminates in ic; as muriatic acid, carbonic acid, &c. But it frequently happens that oxygen, by uniting in different proportions with the same body, forms several dis- tinct acids; when this is the case, the acid highest in oxidation is distinguished by ic, and a lower one by ous ; and the inter- mediate degrees of oxidation are expressed by the prefix hypo, signifying under. Thus, sulphur forms with oxygen, the four following acids, viz; sulphuric, hypo-sulphuric^, sulphurous, and hypo-sulphurous. The termination ate, expresses the salt of an acid, ending in ic ; and the termination ite, the salt of an acid, ending in ous. Thus we have sulphates, and hypo-sulphates, sulphites and hypo- sulphites. It has been stated, (§180), that the same acid and base, by combining in different proportions may form different salts: and that the name s«per-salt is given to those containing more acid, and that of sito-salt to those contain- ing more base than the neutral salt. These names are objectionable be- cause they do not express the proportions by which either ingredient is in excess ; so that different swper-salts, or different sub-salts of the same base and acid are confounded under one general appellation. To obviate this inconvenience, the number of equivalents or combining proportions of acid in the super-salts is denoted by Latin prefixes ; while Greek numerals point out the proportions of base in the sub-salts. Thus we have the neutral oxalate, the binoxalate, and the quadroxalate of polassa, the first of which contains owe atom, the second too, and the last four atoms of oxalic acid to each atom of base. Again, among sub-salts are the neutral acetate, the rff-acetate and the iris-acetate of lead; the first being composed of one equivalent of acid, and one of base, the second of one of acid and two of base, and the last, of one of acid to three of base ; * From the Latin per signifying through. f Hypo, signifies under, or below, thus hypo sulphuric acid means one which has a lower degree of oxidation than sulphuric acid. 7 74 SPECIFIC GRAVITY. and if there were a fourth compound consisting of one of acid to four of base, it would be the tetra acetate of lead. 182. The proportion of terms proto, deuto, trito, per, &c, when placed before the generic names of salts, refer not to the pro- portions of acid and base they contain, but to the degree of oxi- dation of the base. Thus the proto-sulphate of iron means the sulphate of the protoxide of iron, the per-sulphate of copper is the sulphate of the joer-oxide of copper, &c. Different salts may sometimes combine and produce what are called triple salts, or, more properly double salts. A double salt may consist of two acids and one base, of two acids and two bases, or, what is by far the most common, of one acid and two bases. The latter are bi-basic salts; such are the double tartrate ofpotassa and soda, which is the tartrate of potassa united with the tartrate of soda, commonly called Rochelle salt; tartar emetic is the double tartrate of antimony and potassa. Sometimes, the name of one base precedes, and that of the other, follows the generic name ; as the ammonic-sulphate of copper, which is the double sulphate of copper and ammonia. 183. Acids which are formed by the union of oxygen with another simple substance, are called oxacids, those composed of hydrogen and a radical are hydracids ; thus the proper chemical name of muriatic acid, (which consists of hydrogen and chlorine,) is hydro-chloric acid ; hydrogen and iodine form hydriodic acid; and hydrogen with bromine constitutes hydro-bromic acid. Specific Gravity. 184. The physical characters of bodies are often valuable aids in dis- criminating between different substances. Some of these characters, as the color, may be considerably affected by the presence of foreign substances. Among the most constant and valuable is specific gravity. The specific gravity of a substance is its weight, compared with an equal bulk of some other substance, taken as the standard of unity. This standard for solids and liquids is water, and for aeriform bodies, atmospheric air. If we weigh a solid body in air, and again weigh it suspended in water, it will be found, in the last instance, to Weigh less than in the first; and the loss of weight is ascertained to be the exact weight of an equal volume of the fluid displaced : thus, it is an axiom in hydrostatics, that the weight which a body loses when immersed in a fluid is equal to that of an equal bulk of that fluid. If, therefore, a solid body be not soluble in water, we take its exact weight in the usual manner; then weigh it suspended in pure water, and subtract this weight from the former,—the difference is the weight of a bulk of water equal to the solid. We now have the proportion, as the difference 182. The prefixes proto, deuto, &c, when placed before the generic name of the salts. Double salts. 183. Oxacids and hydracids. 184. Definition of the term specific gravity. Standard of specific gravity for solids and liquids. Mode of finding the specific gravity of a'solid not soluble in water. SPECIFIC1 GRAVITY. 75 just mentioned, is to the weight of the solid in air, so is one, (the assumed specific gravity of water,) to a fourth proportional, which is the specific gravity required. 185. The instrument used to determine the specific gravity of bodies is called the hydrostatic balance. BCD (fig. 45) is a balance; E a glass ves- sel containing water. Suppose we wish to determine the specific gravity of sulphur; we suspend a small bit, by a hair, or fine thread of silk, from the balance at C: we find it weighs in the air 12 grains. We then immerse it in the water as represented in the figure, and find it has lost weight: we add to the scale C, a sufficient number of grains to cause it to balance the Fig. 45. scale D. Suppose these grains are 6, this is then the weight lost by the immersion. We then say, as 6, (the difference between the bit of sulphur in water, and in air) is to 12, the weight in air so is 1, (the assumed speci- fic gravity of water) to 2, the specific gravity required; or thus, as 6 : 12:: 1:2. 186. If the solid, whose specific gravity you wish to find, is soluble in water but not in alcohol, ascertain first the specific gravity of alcohol and then take that of the solid with regard to alcohol just as before described. If the solid be soluble also in alcohol, any liquid in which it is insoluble may be substituted. 187. To find the specific gravity of a liquid, fill any convenient phial with distilled water and ascertain its exact weight, taking care that it shall be perfectly dry on the outside; then pouring out the water and drying the 185. Hydrostatic balance. 186. Mode of finding the specific gravity of a solid which is soluble in water. 187. To find the specific gravity of a liquid. 76 SPECIFIC GRAVITY. phial carefully, fill it with the liquid under examination and weigh it; the last weight will be to the former as 1 is to the specific gravity of the liquid. Another mode consists in ascertaining the comparative heights of the columns of the two fluids which are necessary to support a given column of mercury ; the specific gravities of the liquids are in the inverse ratio of their respective columns. 188. To ascertain the specific gravity of gas, it is first necessary to know that of, atmospheric air. Sir George Shuckburgh states that 100 cubic inches of air weigh 30.5 grains and this estimate is generally adopted as correct. Having exhausted a thin glass flask by means of the air pump, it is to be filled with the gas in question, and weighed. The proportion is exactly as in the case of liquids substituting the weight of an equal bulk of air for that of water. This is an exceedingly nice operation; and the following circumstances must be strictly observed,— 1st. The gas must be perfectly pure. 2nd. It must be absolutely dry. Moist gas is dried by passing it over pieces of chloride of calcium, or of pure potassa, which absorb the moist ure. 3d. The influence of atmospheric pressure, in decreasing the bulk, con- sequently increasing the specific gravity of gases must be taken into ac- count. The average height of the barometric column is 30 inches; if it should be more or less during the experiment, the apparent sp. gr. will be more or less than the true one. 4th. As the DUik °f a §as depends also on the temperature, if the ther- mometers of Fahrenheit do not stand during the experiment at 60°, the standard or mean temperature, a correction must be made upon the prin- ciple that gases expand by 1-180, of the bulk they occupied at 32°, for each additional degree of Fahrenheit's thermometer. 189. It is a remarkable characteristic of chemical union that the compounds resulting from it, for the most part, possess neither the external characters, nor the internal properties of their constituents. Thus, it is impossible to foretel from a knowledge of any two substances, what may be the nature of the body which will be formed by their combination. Chemistry requires, therefore, experiments, or trials, in order to prove, by every possible method, not only the nature of simple bodies, but the efl'ects which may be produced by their union with each other. 188. To find the specific gravity of gas. Circumstances to be regarded in weighing gases. 189. Characteristics of chemical union. Why experiments are necessa ry in chemistry. CHEMICAL AFFINITY. 77 CHAPTER VIII. CHEMICAL AFFINITY. 190. Chemical affinity is an attraction, which acts only at insensible distances, between particles of different kinds. The cause of affinity, is, at present, supposed to be, the same agent which produces galvanism and magnetism ; viz. electricity; though other agents, as light and heat, modify the action of this primary cause. Affinity, is of three kinds, viz ; Simple, Elective, and double Elective Affinity. 191. Simple Affinity is the union of substances without caus- ing any decomposition ; thus sulphuric acid added to soda, forms sulphate of soda, and potassa forms soap with oil and water. In these cases, no previous combinations are broken up. 192. Experiments to show that affinity produces compounds whose properties differ, essentially, from those of the components. Exp. 1st. Common liquid Hydro-Chloric Acid consists of a gas dissolved in water; it is very sour, inflames the skin and changes to red, the blue color of vegetable infusions ; these properties are derived from the gas it contains. Liquid ammonia, or spirits of hartshorn, is also a solution of a gas in water ; it possesses a well known pungent odor, acts as a caustic on the skin, and changes blue vegetable infusions to green. If drops of each of these liquids be spread with a feather on the bottoms of two glass vessels, the gases will escape from the water and rise. Now invert one of the ves- sels over the other, placing their mouths together, and they will both be- come filled with dense white vapor. After standing in the cold for a time, the vapor will condense on the sides of the vessel, forming a white crust, which has none of the characteristics of either of the two constituents, and which, though solid, is composed of two gases; this is the common sal am- moniac, or muriate of ammonia. Exp. 2nd. Pour diluted nitric acid, or aqua-fortis, on some fragments of copper, a violent action, attended with much heat, will take place, suffocat- ing red fumes will rise,* and, at last, there will remain a bright blue liquid, which is a solution of nitrate of copper, and contains both of the materials used. Exp. 3d. Pour nitric acid, slightly diluted, on powdered tin. As in the last experiment, red fumes will be given off, and the tin will be converted into a white powder, which is a compound of oxygen and tin, oxide of tin. Exp. 4th. Pour strong sulphuric acid, into a strong solution of Hydro Chlorate of lime. The two transparent liquids will be converted almost instantly, with great evolution of heat, into a white solid, the sulphate of lime. * These fumes are very poisonous, if inhaled by breathing, and should be avoided. 190. Definition of Affinity, its cause &c. Different kinds of affinity. 191. Simple affiinity- 192. Experiments to illustrate simple affinity. n* 78 AFFINITY. Exp. 5th. Caustic soda is very acrid to the taste, and blisters the tongue. Dissolve some of this in Hydro-Chloric acid and boil to dryness ; and the result is common salt, Hydro-Chlorate of soda. 193. A complete change of properties results from the chemi- cal union of bodies ; affecting their color, taste, odor and tem- perature ; causing them to pass from the solid, to the liquid or gaseous state, and vice versa ; and producing as great an altera- tion of their chemical, as of their physical characters ; so that we find it is impossible to judge beforehand, from the properties of two bodies, what will be the character of the compound they may form. 194. In most instances of chemical action, the temperature is altered. Sometimes, as in a case where the action is attended with the liquefaction of a solid, or the vaporization of a liquid, the temperature falls. But, in most cases, an elevation of tem- perature takes place, as is exemplified in the foregoing experi- ments 2nd, 3d and 4th, and in the following;— Exp. Mix a portion of strong sulphuric acid, with one fourth of its weight of water ; the liquid will become heated above the boiling point of water. In this, and many similar instances, the rise of temperature is attributable to a condensation and conse- quent diminution of volume, in the course of which some of the caloric of expansion is given off, and accordingly the above mixture will be found to measure less than the two liquids did before mixing them. 195. Change of properties affords a criterion by which it may generally be known whether chemical combination, or a mere mechanical mixture has taken place. There are a few cases in which the properties of one of the constituents are apparent in the compound. For example, the mixture of sulphuric acid and water, (see § 194,) still exhibits all the properties of sulphuric acid and will continue to do so, even when very largely diluted with water; yet there can be no doubt that a chemical union exists between its two ingredients. Again, if common salt be put into water, it will begin to dissolve, and will in a short time, disappear entirely. The disappearance of the salt, is owing to its uniting chemically with the water, yet every drop of the liquid exhibits the properties of salt. In these cases, the combining energy of the bodies concerned is but small, and their union can be overcome by means proportion ably simple. 196. It is an important law of affinity, that a substance is very differently attracted by other substances; so, that, though 193. General truths established by the preceding experiments. 194. Temperature affected by chemical action. 195. What fact is supposed to be proved by this change of properties? Cases in which this change does not take place. 196. Different degrees of affinity. SINGLE ELECTIVE AFFINITY. 79 it may have a very strong affinity for one, it will have a very weak one for another ; and in some cases, there may be no affinity whatever, between two bodies ; thus chalk and water may re- main together for any length of time, without combining. Some- times, in such cases, the union may be effected by the interven- tion of a third body, which may form, with one of the first, a compound capable of uniting with the other. For example, flint will not dissolve in water ; but if it be mixed with carbonate of potassa, and heated to redness in a crucible, a compound is formed which dissolves, readily, in water. 197. Single Elective Affinity. In elective affinity, there is an election or choice, and, of course, an exclusion. If we present to a compound, a substance which has for one of its constituents a greater affinity than they have for each other, the old com- pound will be broken up, and a new one formed, leaving one of the constituents of the old compound disengaged ; thus, baryta has an affinity for hydrochloric acid, and forms with it hydro- chlorate of baryta ; if, into its solution, sulphuric acid be poured, a white powder will fall to the bottom of the vessel. This is sulphate of baryta ; the compound having been formed, because baryta has a greater affinity for sulphuric, than for hydro-chloric acid. Exp. 1st. Camphor combines with alcohol, and forms a transparent solu- tion ; but on adding water, for which the alcohol has a greater affinity than for camphor, the latter is precipitated in the form of white scales. The following diagram illustrates this change: Alcohol and water. Alcohol i and > Water. Camphor ) Camphor. The compound solution of camphor is represented at the left of the dia- gram. The interior of the figure, shows the constituent principles, (alcohol and camphor,) and at the right is the substance added, (water,) to produce a decomposition. Above and below are the results of this decomposition. The lower horizontal line is turned downwards in the center, to designate that the camphor is precipitated; while the upper line, being straight, shows that the new compound, water and alcohol, remains in solution. Exp. 2nd. If sulphuric acid be added to carbonate of lime, sulphate of lime will be precipitated, and carbonic acid disengaged in the form of gas. 198. Precipitation is of great use in Chemistry, separating solids from solutions in which they may be held, and reducing the molecules of a body 197. What is implied by the term elective affinity? Example. Exp. 1st. Exp. 2nd. 198. Precipitates. Solution of Camphor. 80 COMPLEX AFFINITY. to a state of separation, which cannot be attained by any mechanical divi- sion. Thus, precipitates possess their medical activity. They are also in a state favorable for entering into new combinations. For example, silex pulverized as fine as possible, may be boiled with liquid potassa without dissolving ; but when silex is precipitated from a chemical solution, it not only dissolves, readily, in solution of potassa, but yields to the action of some of the acids. 199. Double Elective, or Complex Affinity takes place when two compound bodies, on being brought together, exchange their bases, and form new combinations. We will now compare the three kinds of chemical affinity: 1st. Let the simple substance, A, be presented to the simple substance, B, if there is an affinity, they will combine and form a new compound ; this is a case of simple affinity. 2nd. Let a simple substance, A, be presented to a compound one B C, and if A, have a stronger affinity for B than C has, the compound, B C, will be decomposed, and a new compound, A B, will be formed; this is a case of singie elective affinity. 3d. If a compound, A B, be presented to another compound, C D, the old compounds may be broken up, and A, uniting with D, leaves B, to unite with C, forming the two new compounds, A C, and D B ; this is a case of double elective affinity. In single elective affinity, three substances are present, and two affinities in action ; while in complex affinity, four substances are present, and four affinities in action. 200. Exp. Add to lime water a solution of sulphate of soda ; there is no decomposition, because the sulphuric acid of the sulphate, has a stronger affinity for soda, than for lime. If, instead of lime-water, we use Hydro- chloric acid, there is still no decomposition, because the soda, (of the sul- phate of soda,) has a stronger affinity for sulphuric, than for hydro-chloric acid. But let us take a compound of hydro-chloric acid and lime, (hydro- chlorate of lime) and mix this with the sulphate of soda, and a double de- composition will take place. The lime leaving the hydro-chloric acid, is attracted to the sulphuric acid, while the soda being disengaged, unites with the hydro-chloric acid. The tumbler which at first contained a liquid mixture of hydro-chlorate of lime, and sulphate of soda, now contains a solid precipitate, which is the sulphate of lime, (plaster of Paris,) over this solid stands a solution of hydro-chlorate of soda, or common salt, which ii at once recognised by its taste. This experiment may be illustrated by the following diagram. Hydro-chlorate of Soda. Soda Hydro-chloric acid } Hydro-cholrate and and \ of Sulphuric acid. Lime. ) Lime. Sulphate of Lime. 199. When Double Elective Affinity takes place. Examples of the three kinds of affinity. 200. Exp. To shew the effects of complex affinity. Sulphate ( of 1 Soda. ( AFFINITY. 81 The original compounds appear on the right and left, without the brackets, while their constituent principles are near them, within the brackets. The new products are above and below the horizontal lines. The upper line being straight, indicates that the muriate of soda remains in solution, and the dip of the lower line, indicates that the sulphate of lime is precipitated. 201. We here perceive a conflict of two series of attractions : 1st, those which tend to preserve the original compounds, and 2nd, those which tend to destroy those compounds, and to form new ones ; the former are termed quiescent affinities, the latter divelleni affinities. Double decomposition can take place, only when the divellent affinities are greater than the quiescent. Taking for example, the substances used in our last experiment, the affini- ties may be stated in numbers, thus. The attraction of lime for muriatic acid, ..... 42 Of soda for sulphuric acid,.......78 Quiescent affinities,..... 120 Attraction of soda for muriatic acid, ..... 52 Of lime for sulphuric acid,.......71 Divellent affinities,......123 The original compounds are then held together by a force equal to 120, while the force which tends to draw these apart, and to form new com- pounds, is equivalent to 123, the latter, therefore, or the divellent affinity being the greater, overcomes the former or the quiescent affinity. 202. Bergmann, of Sweden, first taught the doctrine of elective attraction. So much was he delighted with this wonderful law of nature, that he seemed not to observe how much affinity is modified by peculiar circumstances. Succeeding Chemists following his steps, seemed also to consider affinity as absolute and independent in its operations. Berthollet, a French Chemist of the present age, advanced some new opinions upon this subject. He con- sidered affinity as a mode of attraction, differing from gravitation only, in the subject upon which it operates, and that, in this respect, there is no real distinction between Chemistry and Natural Philosophy. Thus, accor- ding to the principles of Newton, the quantity of matter, must have an in- fluence upon combination; and it is, therefore, by Berthollet, laid down as an axiom, that " affinity, is manifested by quantity of matter, or that the chemical action of a body, is exerted in the ratio of its affinity, and quantity of matter." It follows from this doctrine, that quantity of matter may com- pensate for feebleness of affinity. Its supporters, not content with showing, what every Chemist must admit, that chemical action is, in a degree, in- fluenced by quantity of matter, &c, endeavored to prove that there is, in fact, no such law in nature as affinity ; but that decompositions are caused by the circumstances that merely go to modify affinity. Sir Humphrey Davy opposed the innovations, of Bethollet, and showed that in many respects, his doctrine was false. 203. The enlightened Chemist unites himself to no leader, to take for 201. Quiescent and divellent affinities. In what case only double decom- position can take place. How illustrated by the last experiment ? 202. Errors of Bergmann and others with respect to the unlimited power of elective attraction. 203. Dangers of allowing prejudice to affect the mind in search of scientific truth. 82 AFFINITY. granted all his opinions, and reject all which he does not approve. Even the young student, whose mind is unclouded by prejudice, is more likely to form correct opinions, upon the phenomena of nature, than that partial philosopher who has so long contemplated an object in one particular light, that he can see it in no other; or, who, delighted with some discovery of his own, regards the whole fabric of science of less magnitude, than the one atom which he has added to it. . 204. Causes which modify Chemical Affinity. Chemical af- finity is so governed by fixed and immutable laws, that under the same circumstances, its effects will always be uniform, and although disturbing causes do often influence its operation, and modify its results, yet this no more disproves the existence of those laws, than the fact, that a body does not fall to the earth when suspended by a cord, disproves the existence of the laws of gravity. In either case, the force of attraction is all the time acting, but is counteracted by opposing forces. Indeed, we are acquainted with most of the disturbing causes, and with their mode of acting ; and, in many cases, are able, from this know- ledge, to predict what will be the variation from ordinary re- sults. 205. The most important of the causes which modify affini- ty, are, cohesion, elasticity, quantity of matter, gravity and the ac- tion of the imponderables. 206. Cohesion forbids freedom of motion among the particles, and prevents them from coming into that contiguity which is essential to chemical action. Two substances in the solid state, seldom act on each other, although they may have a strong ten- dency to do so. The most favorable state for combination, is the liquid one ; the particles have perfect freedom of motion, and if they do not combine, when in this condition, it is fairly inferred, that they have no affinity for each other. Caloric is frequently used to overcome cohesion, and to bring bodies into the liquid state, by fusing them. 207. When a solid disappears in a liquid, without disturbing its transparency, it is said to dissolve ; the body which disap- pears is said to be soluble ; the liquid is called a solvent; the act of dissolving is called solution ; the liquid containing the dis- solved body, is also called a solution. When the body dissolved has changed its nature, and cannot be obtained tn its original state by evaporation, it is said to be in a state of dissolution ; 204. How far the laws of chemical affinity are fixed. The existence of these laws not disproved by a variation under peculiar circumstances. 205. Some of the causes which modify affinity. 206. Effect of cohesion upon chemical affinity. State most favorable for combination. Modes of overcoming cohesion, for purposes of chemical combination. 207. Solution. Difference between a solution and a dissolution. AFFINITY. 83 thus, mercury dissolves in nitric acid, but when the fluid par- ticles are evaporated, we do not obtain mercury again, but the nitrate of mercury. The combination of the mercury and nitric acid, is an example of strong chemical affinity, the nitrate of mercury having no resemblance to either of its constituent parts. On the contrary, after evaporating a solution of common salt, we have the same substance as we dissolved. 208. A solution, though transparent, need not necessarily be colorless. For example, blue vitriol gives a blue solution, which is yet transparent; but the color of ink is occasioned by very minute particles of black, solid matter, mechanically suspended, not dissolved in the liquid. Exp. Add to common ink, some drops of nitric acid; the ink becomes colorless ; add a little potash in solution, and the ink is again black. This experiment may be thus explained :—the coloring principle of the ink, which is a combination of gallic acid and iron, called the gallate of iron, is mechan- ically suspended in the liquid. When nitric acid is introduced, the iron having a greater affinity for it than for gallic acid, combines with it, form- ing nitrate of iron, and the coloring principle being now decomposed, the liquid is no longer black. On adding potash, the nitric acid withdraws itself from the iron and unites with the potash. The iron being now left disen- gaged, returns to the gallic acid, and the coloring principle, gallate of iron, manifests its existence by the blackness of the liquid in which it is sus- pended. 209. The property of dissolving, called solubility, is possess- ed by some bodies, in a much greater degree than by others. A body may be soluble in one menstruum,* and not in another ; almost any liquid, may for some particular purposes, be used as a solvent, but the most common solvents are water and alcohol. 210. When a soluble body is put into its menstruum, it goes on dissolving, till a certain quantity has disappeared, after which the liquid can dissolve no more of the same body; it is then said to be saturated, and the solution so obtained, is a satu- rated solution. A solution saturated with one body, may still dissolve another. The point of saturation of the same solid and solvent, varies with the temperature ; in general, the quantity dissolved is in- creased by raising the temperature. 211. Some bodies, of which common salt is an example, are no more so- luble in hot, than in cold water; and there are a few, as lime, magnesia, &c, which are even less so. * A menstruum, signifies a solvent. 208. The colorine principle in ink not in solution, Exp. 209. Different degrees of solubility. , 210. A saturated solution. When saturation takes place. Effect of tem- perature in varying the point of saturation. 211. Some bodies not more soluble in hot, than cold water. 84 NEUTRALIZATION AND EVAPORATION- 212. Neutralization is the mutual destruction, or change of properties, which sometimes takes place when two substances combine in certain pro- portions. 213. It might be supposed that the solubilities of different bodies, were in direct proportion to their affinities for the solvent; but this is not the case. Two bodies of equal affinities for water, may be differently affected by cohesion ; and, as cohesion is an obstacle to the operation of affinity, that will be least soluble which has most cohesion. The boiling point of a satu- rated solution is at present the standard of comparison ; for as the affinity of the dissolved body for the solvent, must necessarily oppose the escape of the latter in vapor, the boiling point will be higher as the affinity is greater. Accordingly, all sajjne solutions boil with more difficulty than the solvent alone. Sea water, for instance, has a higher boiling point than fresh water ; but, by boiling it in distillatory vessels, the water may be collected in a pure state, and the salts will be left behind in the vessel. 214. Bodies in solution, may, generally, be obtained again in the solid state, by evaporating the solvent; for the volatility of the latter and the co- hesive attraction of the dissolved body, are more than sufficient to counter- act affinity. Evaporation is usually performed in open, shallow vessels, placed over a sand bath and kept moderately warm. When the operation is slowly, and uniformly conducted, the solid usually separates in the form of regular, geometrical figures called crystals. The process of the formation is called crystalization. When the evaporation has been carried far enough for crystalization to take place, the fact may be known by the solution becom- ing covered with a film or pellicle. Another test, is, to place a few drops of the solution on the cold surface of glass or some other polished substance, if, in such case, a solid is deposited the point of crystalization has been reached. The evaporating vessel should then be removed, and set aside in some secure, dry place to cool. 215. The cohesion of insoluble bodies, may be overcome by fusion and vaporizing; thus, brimstone, on being subjected to heat, passes first into a state of vapor, and then condenses into the flour of sulphur, which, when ex- amined with a microscope is found to consist of small, crystaline grains. Bismuth and some other metals may be crystalized in the same manner. 216. In opposing caloric to cohesion, in order to promote affinity we must not go so far as to bring bodies into the state of vapor ; for then their elasti- city, will tend to remove the particles from the sphere of their action upon each other. Sometimes indeed, two gases or vapors unite; but the aeriform state is generally unfavorable to combination; indeed, a compound of a fixed and a volatile body may be generally decomposed by heat, which increases the elasticity of the latter, as, when limestone, {carbonate of lime,) is heated strongly, the gaseous, carbonic acid flies off, and quicklime remains. Strong pressure, by bringing the particles nearer to each other, sometimes causes two gaseous bodies to unite. When one of the gases to be combined is in- flammable, the union may be effected by setting fire to the mixture, or by 212. Neutralization. 213. Solubility not always in proportion to affinity. Effect of cohesion with respect to solubility. 214. Evaporation. Formation of crystals. Effect of a rapid evaporation upon the crystals. Various crystaline forms. 215. How may the cohesion of insoluble bodies be destroyed? 216. Effect of the elasticity of vapors. CHEMICAL AFFINITY. 85 the electric spark; in these cases, there is commonly a violent explosion, and it should only be done in strong vessels. 217. Experiment to show the effects of cohesion and elasticity on Chemical Affinity. Heat, as we have seen, (§ 216,) decomposes carbonate of lime ; but node- gree of heat has yet been able to decompose carbonate of potassa; this cir- cumstance would lead us to infer, that the affinity of potassa for carbonic acid is greater than that of lime; but, Exp. 1st. If limewater, (solution of lime,) be poured into solution of car- bonate of potassa, the insoluble carbonate of lime will fall as a white precipitate, and the potassa will remain in solution. This would seem to show that the affinity of lime for carbonic acid, is greater than that of potassa. But, in this case, it is supposed that the cohesion of the carbonate of lime, co-opera- ting with the affinity of lime for the gaseous carbonic acid, effects the decom- position in opposition to the real order of affinities. Exp. 2nd. If solutions of hydro-cholrate of lime and carbonate of ammonia be mixed, there will be a double decomposition ; carbonate of lime will be precipitated, and hydro-chlorate of ammonia will remain in solution. Exp. 3d. Mix hydro-chlorate of ammonia and carbonate of lime in the solid and dry state, place the mixture in a long necked vessel, and apply heat to it, the decomposition will now be the reverse of that which takes place in the preceding experiment. Carbonate of ammonia will rise in vapor, and be condensed in the cool part of the apparatus, while hydro-chlorate of lime will remain in mass at the bottom. Each of the acids used in the last two experiments, has affinities for both the lime and the ammonia; the preponderance of one pair of those affinities over the other pair, is determined, in Ex. 2, by the cohesion of the carbonate of lime, and in Ex. 3, by the volatility of the carbonate of ammonia. Gen- erally, when the affinity would admit of the formation of several modes of arrangement, one of which would produce an insoluble compound, (as the carbonate of lime for example,) that compound would be formed in prefer- ence to the rest, provided the materials are used in solution. But if the materials be in the dry state, and the operation be performed with the aid of heat, elasticity will determine the formation of a volatile compound, if such an one be among those which the substances present are capable of producing. 218. In respect to quantity of matter as modifying affinity, it may be re- marked that there are some cases where the use of a large excess of one substance, enables us to decompose another contrary to the established or- der of affinities ; the decomposition, however, is seldom complete. 219. Gravity sometimes interferes with chemical union, by causing the heavier body to sink, and thus be removed out of the sphere of the other's 217. Circumstance which shows the affinity of potassa for carbonic acid, to be greater than that of lime for the same acid. Experiment showing that cohesion, combining with a weaker affinity may effect decomposition. Substances which result from the mixture of solutions of muriate of lime and carbonate of ammonia. Effect of mixing dry muriate of ammonia and carbonate of lime. Expla- nation of the changes which take place in experiments 2d and 3d. 218. Efl'ects of using a large excess of one substance in producing decom- position. 219. Effects of gravity on chemical action. 8 86 LAWS OF CHEMICAL COMBINATION. action. The effects of gravity are illustrated, in the fusing together of two metals of different specific weights; the alloy being cast into an ingot, dif- ferent portions of it will be found to be unlike in composition; the part which was lowest in the mould, will contain a greater proportion of the heavier metal than the other end. The interference of gravity, is obviated by agitation and by stirring. 220. The effects of heat and galvanism, in producing decomposition have been noticed under the heads of the imponderables; we may farther observe, that the electric spark sometimes decomposes a compound gas through which it passes, and sometimes causes the union of two gases ; in the latter case, there is usually an explosion. These effects are commonly attributed to the heat of the electric fluid. LAWS OF CHEMICAL COMBINATION. 221. Some substances unite in indefinite proportions, as when we mix water and alcohol, water and sulphuric acid &c.; though but a drop of one be mixed with a very large quantity of the other, every drop of the resulting mixture will contain propor- tions of both. In such mixtures, there is, at first, an evolution of heat, sometimes, (as in the case of sulphuric acid and water,) very considerable: and when the mixture has become cool, its bulk will be less than that of the two liquids before mingling them. 222. Another set of bodies, unite in all proportions up to a certain point, beyond which no combination takes place. Exam- ples of this, are the solutions of salts in water, alcohol, &c, when any quantity of the salt not greater than that necessary to satu- rate the solvent, will be dissolved. In compounds of these two kinds, the affinities of the components are comparatively feeble; neutralization does not take place, for the properties of all the substances concerned are quite apparent; and the combination is destroyed by comparatively feeble means, as evaporation and the like. But these kinds of compounds are highly useful and important, as by their means we are enabled to present bodies to each other, under the circumstances most favorable to action. 223. There is a third class of combinations, far more numer- ous as well as interesting, than the other two. They are those in which the proportions of the constituents are regulated by certain fixed and invariable laws. In such compounds, the affinities of the elements are more energetic, than in the two former classes; the number of combining proportions of the same bodies is small, never, so far as is yet known, exceeding six ; and the elements neutralize each other. 220. Efl'ects of the imponderables, especially the electric spark, in pro- ducing decomposition and combination. 221. Bodies which unite in indefinite proportions. 222. Bodies which unite in indefinite proportions up to a certain point. 223. Combinations where the proportions are always definite. LAWS OF CHEMICAL COMBINATION. 87 224. 1st. Law of combination. Certain bodies combine in only one proportion. Thus chlorine and hydrogen, unite in the propor- tions of 36 parts, by weight, of the former, to 1 of the latter, and there is no method known of bringing them into combination, in any other proportions ; for if we mix 36 parts of chlorine gas, with 2 parts of hydrogen, there will, always, be 1 part of hydro- gen remaining uncombined ; or if we mix 72 parts of chlorine and 1 of hydrogen, only the proportions first stated will combine, the additional 36 parts of chlorine remaining in a separate state. 225. 2nd. Law of combination. When any two elements com- bine in more than one proportion, the larger quantities of one are multiples by 2, 3, 4, or 5, of the smallest quantity of the other. Oxygen and hydrogen, form two compounds with each other ; the first is Water, composed of hydrogen 1 part + oxygen 8 parts Deutoxide (or binoxide of hydrogen) 1 " -f- " 16 " JVitrogen and oxygen unite in five different proportions, form- ing compounds whose names and composition are as follows : Name. Parts of Nitrogen. Parts of Oxygen. Protoxide of Nitrogen, contains 14 for every 8=8\1 Deutoxide of " " 14 " 16=8x2 Hypo-nitrous acid " 14 " 24=8x3 Nitrous acid " 14 " 32=8x4 Nitric acid " 14 " 40=8x5 No other compounds of the above elements are known : and if oxygen and nitrogen be mixed in any other proportions, one or more of the above named bodies, would be the result, but no intermediate compound. 226. To the second law of multiples, there are a few apparent exceptions ; thus iron and oxygen combine in two proportions, which are 28 parts of iron to 8 oxygen, and 28 iron to 12 oxygen: the first quantity of oxygen being to the second as 1 to 1 1-2. Lead has three oxides, of which the composition is, Protoxide Lead 104 Oxygen 8=8X1 Deutoxide 104 12=8x1 1-2 Peroxide 104 16=8x2 But examples of this kind, are not sufficiently numerous to overthrow the general rule; and they can all be explained by the following hypotheses; 1st. We may suppose that the apparent anomaly, results from our not being acquainted with all the combinations of the same two bodies. Thus, if we should hereafter discover the existence of a compound containing 28 parts of iron to 4 of oxygen the oxides of iron would then accord with the law of multiples, viz., 224. 1st. Law of combination. 225. 2nd. Law of combination or law of multiples. The law of multi- ples illustrated in the compounds of nitrogen and oxygen. 226. Apparent exceptions to the law of multiples. Suppositions on which the apparent anomalies in chemical combinations may be explained. 88 LAWS OF CHEMICAL COMBINATION. Iron. Oxygen. 1st, oxide 28 (this is the supposed oxide.) 4=4x1 2nd, " 28 8=4X2 3d, " 28 12=4X3 The same reasoning would apply to the oxides of lead, and to other like cases; and it is in accordance with facts which have already been discov- ered. 2nd. We may suppose the anomalous compound to be formed, not by the direct combination of the two elementary substances, but by the union of two or more of the other compounds of those elements. Thus the first and last oxide of lead, might combine as follows, Lead. Oxygen. Protoxide 104 8 Peroxide 104 16 producing a compound 208 24 where the lead and oxygen are in the exact ratio of 104 to 12, that is, in the same ratio as in the compound now called deutoxide of lead. This latter may be, therefore, not a distinct oxide, but a compound of two oxides; which in that case would not furnish an exception to the law of multiples. This mode of explanation not only applies to exceptions in the third class of combination, (see § 223,) but to the whole of the first and second classes; where the apparent great diversity of proportions, may be occasioned merely by the combinations of five or six definite compounds. 227. 3d. Law of combination. The quantities of two bodies which respectively combine with a given quantity of a third body, are the precise quantities in which the first two combine with each other; and these are also, the quantities in which they would unite with a fourth body. Thus 36 parts of chlorine combine with 8 of oxygen, to form protoxide of chlorine ; and 36 parts of chlorine combine with 1 of hydrogen, to form muriatic acid (called hydro-chloric acid ) ; now 8 of oxygen and 1 of hy- drogen are precisely the proportions of those two bodies neces- sary for their combining to form water. 228. Bodies that unite according to proportional numbers, and the numbers expressing the combining proportions, are called proportionals, or equivalents. 229. By analyzing several compounds of a particular body, and reducing the numbers expressing the proportions of the constituents to their lowest terms, the combining proportions, or equivalent of that body is established. And if we do this for a great number of different substances, referring, al- ways, the number determined to some particular standard, a scale of chem- 227. 3d. Law of combination. 228. Proportionals and Equivalents. Different senses in which the word equivalent is used. 229. How may the combining proportions of a body be ascertained? Scale of chemical Equivalents, how established ? What substance is taken as the standard of unity in the scale of equivalents most commonly used, and what are the combining numbers of some simple bodies in relation to this stan- dard ? DISCOVERY OF THE LAWS OF COMBINATION. 89 ical equivalents is determined, which greatly facilitates the operations of the laboratory. Such a scale has been established by Chemists. It is of no importance what number is taken as the basis of the scale, nor what sub- stance is the standard of unity, provided the proportions be duly observed. In the scale most in use, hydrogen is taken as 1, and consequently, Oxygen is 8 Sulphur 16 Chlorine 36 Nitrogen 14 Potassium 40 Sodium „ 24* 230. The operation of the laws of combination is not confined to the simple substances, but has an equal influence over com- pound bodies. Thus 40 parts of sulphuric acid, which neutral- ize 48 parts of potassa, combine with 32 parts of soda: the same acid combines with potassa and with soda in other proportions, namely, SO (=2X40) to 48 and 80 to 32: so that the law of multiples, (see § 225,) likewise governs these combinations. The third law is equally uniform, (§ 227,) for the 48 of potassa and 32 of soda, which are equivalent to 40 of sulphuric acid, will also neutralize 54 of nitric acid, 37 of muriatic acid, &c. 231. The equivalents of compound bodies are found by taking the sum of those of their constituents ; thus, sulphuric acid, contain- ing 1 equivalent of sulphur, 16, and 3 of oxygen, (3 times 8=24,) is 40 ; nitric acid consists of 1 equivalent of nitrogen, 14, and 5 of oxygen, (5 times 8=40,) and its equivalent is 54. 232. From the difference of the combining proportions of the acids and al- kalies, it follows that their neutralizing powers must differ; for it is evident that the greater this power, the smaller must be the quantity necessary to produce the effect. Thus the neutralizing power of soda is greater than that of potassa, in the inverse ratio of 48, the combining number of the lat- ter, to 32, the equivalent of the former. 233. So well established are the laws of combination, and so sure is their operation, that it is very often possible to calculate the composition of a * In Dr. Thomson's scale of chemical equivalents, oxygen is employed as the basis and is assumed at 1, and therefore hydrogen must be 1-8 or ,125, sulphur 2, chlorine 4 1^2, &c. Dr. Wollaston, in his scale, calls oxygen 10, Berzelius takes it at 100 ; but in all these scales the same proportions are observed. The system of numbers which makes hydrogen the unit or 1 is generally preferred, as containing small numbers and few fractions. 230. Compound bodies influenced by the laws of combination, and the law of multiples. 231. How are the combining numbers of compound bodies found ? 232. Ratio of the neutralizing powers and combining proportions of acids and alkalies. 233. What fact would lead to suspect an error in analysis ? 8* 90 ATOMIC THEORY. body before it is analyzed. And if the result of an analysis is at variance with these laws, it is a sufficient reason for suspecting error in the opera- tion, and for repeating our experiments. 234. The discovery of these laws of combinations, is justly considered as one of the most important events in the history oi Chemistry. It has rescued the science from a chaos of confu- sion, and established it on the basis of certainty and demonstra- tion. For this discovery, science is indebted to the, genius and , industry of Mr. John Dalton of England. Atomic Theory. 235. Before proceeding to treat of the theoretical explanation of the laws of combination, and the atomic theory, it will be necessary to caution the learner against confounding the one with the other. The theory of Atoms is founded on supposition: and however strong may be the arguments by which it is supported, it may possibly be, hereafter overthrown. Not so with the laws of combination. The proof of their existence is founded on multitudes of experiments, and is wholly free from speculation; whether the atomic theory, therefore, be admitted or denied, the doctrine of laws ol combination remains unshaken. 236. This ingenious hypothesis was published by Mr. Dalton, to explain and account for the laws of combination which he discovered. This it does, on the assumption that all matter is composed of certain minute indivisible par- ticles, aggregated by attraction; that the particles of the same kind of matter have the same form, size and weight: and that they are inconceivably smaller than any division of matter, which can be obtained by mechanical operations. The word atom, implying a thing so small that it cannot be further cut or divided, is frequently used to designate these supposed indivisiblcparticles. The term molecule, is sometimes used in the same sense. 237. This theory being granted, the laws of combination, which seem in- explicable on any other ground, would follow of course. For since chem- ical combination would take place between the atoms; as, for instance, if a particle of water consists of one atom of oxygen, and one atom of hydro- gen, and the former atom weighs eight times as much as the latter, it is clear that any quantity of water must contain these bodies in the ratio of 8 to 1. Again, since no addition could be made of either constituent in a less quantity than an atom ; that is, if A and B form any other compound than A B, it must be 1 A to 2 B, 1 A to 3 B, &c, or 2 A to 1 B, 3 A to 1 B, &c. Thus one atom of oxygen to one atom of hydrogen, constitutes a particle of water, or protoxide of hydrogen, and two atoms of oxygen to one of hydrogen compose a particle of deutoxide of hydrogen; and as the oxygen is to the hydrogen, in water, as 8 to 1 ; so in the deutoxide of hydrogen, the compounds must be in the ratio of 16 to 1. Thus the law of multiples, is a necessary consequence of the atomic constitution of matter; and this ne- cessity is as peremptory in the case of compound particles, as in that of elementaly atoms. 234. Discovery of the laws of combination. 235. Distinction between the Laws of combination and the atomic theory. 236. How did Mr. Dalton attempt to explain the laws of combination ? 237. How does the atomic theory explain the laws of combination andoi multiples ? VOLUMIC THEORY. 91 238. The terms Equivalents, combining proportions, &c, of bodies, are therefore only other names for the weights of atoms in comparison with the particular body which is chosen as the unit.. 239. Some years ago, it was a received axiom that matter is infinitely di- visible, and the question remained at rest till revived by Mr. Dalton. The preponderance of proof seems, now, on the side of the atomic theory; and the laws of combination alone appear sufficient to establish it.* • The Volumic Theory. 240. A curious law was discovered in 1808, by Gay Lussac, which gov- erns the proportions by measure, in which aeriform bodies combine. It ap- pears from his experiments, together with those of many other eminent Chemists, that when two gases or vapors, combine, it is *in the ratio by volume of 1 to 1, 1 to 2, or some other simple ratio. Thus 1 volume of oxygen unites with two of hydrogen to form water ; 1 volume of vapor of sulphur with 1 volume of hydrogen to torm sulphuretted hydrogen, 1 volume of nitrogen and 3 volumes of hydrogen, form ammoniacal gas; 1 volume of muriatic acid gas and 1 volume of ammonia, constitute muriate of ammonia. 241. Further, from various considerations, it is inferred that the same law holds with regard to solid bodies which cannot be converted into va- pors by the action of heat; so that when such bodies enter into gaseous combinations, their vapors are in a simple ratio with those of the other con- stituents. Thus, carbonic acid is composed of 1 measure of the vapor of car- bon to 1 of oxygen gas. 242. Gaseous bodies sometimes undergo a condensation in combining, and sometimes not; but whenever a diminution of volume takes place, it likewise bears some definite and simple relation to the original bulk of the constituents, being one half, one third, &c. For example, no condensation takes place in the formation of muriatic acid gas, but one volume of chlo- rine and one of hydrogen form two volumes of the acid gas, on the other hand two measures of ammoniacal gas consist of one measure of nitrogen and three of hydrogen; so that here the two simple gases in uniting, are condensed to one half. Again two measures of nitrogen and one of oxygen, form one of protoxide of nitrogen ; th,e condensation is, therefore, one third. 243. Another curious result seems to flow from these facts. Water is considered as a compound of one atom of each of its constituents ; by expe- riment it is found that it contains two measures of hydrogen and one of oxy- gen. The protoxide of nitrogen, also consists of two volumes of nitrogen * Dr. Wollaston advocated the Atomic Theory in a very able disserta- tion upon the " Finite extent of the atmosphere," published in England in the Philosophical Transactions for 1822 ; and Professor Mitscherlich has treated of the same subject in his lucid observations upon the connections between the form and composition of bodies. 238. By what terms are the weights of atoms designated 1 239. The atomic theory not undisputed. 240. Law of volumes discovered by Gay Lussac. Explanation of this law. 241. Solids supposed to be subject to this law. Examples. 242. Condensation of gaseous bodies explained in reference to the volu- mic theory. 243. The volume of an atom of oxygen compared to the atoms of hydro- gen and nitrogen. 92 VOLTJMIC THEORY. and one of oxygen ; it contains, nevertheless, one atom of each. It there- fore follows, that the atom of oxygen is but half as large as the atoms of nitrogen and hydrogen. There are several other bodies, whose combining proportions, like that of oxygen is represented by half a volume; but for the greater part of substances, a volume and an equivalent are synonymous. 244. It is evident that the laws of combination by weight, and those which govern the proportion by volume must depend on the same circum- stances, the atomic constitution of matter. There is, however, one striking distinction between them. The proportions by weight in which two bodies unite, have no very remarkable dependence on each other. For example, 6 parts of atoms of carbon and 8 of oxygen form carbonic oxide ; now 6 is not to 8 in any simple ratio. The proportions by weight exist between the different quantities of the sajne body that combine successively with a given quantity of another body. But by the law of volumes, not only is there the dependence just referred to, but also an evident relation between the bulks of the two substances. 244. On what must combinations by weight, and by volume depend ? Distinctions between the two cases. END OF PART FIRST PART II. CHAPTER IX. CHEMICAL CLASSIFICATIONS.--DIVISION OF PONDERABLES.--OXYGEN. 245. By chemical analysis ponderable bodies are reduced to their ultimate elements ; these are divided into, 1st. Non-Metallic, 2d. Metallic. 246. The electro-chemical theory furnishes a convenient system of classification. The Non Metallic elements are divided in two classes, according to their electrical affinities ; those which are attracted to the positive pole, possess the opposite or negative electricity, and are called electro-negative. Those which are at- tracted to the negative pole, possess the opposite or positive elec- tricity, and are called electro-positive. 1st. Class. 2d. Class. I «x ( Hydrogen Oxygen Chlorine Bromine Iodine Fluorine bo Nitrogen Carbon Boron Silicon Phosphorus Sulphur Selenium. There are 42 metals, all of which are electro-positive. 247. The Electro-negatives combine with the electro-positives ; the former are called supporters of combustion ; the latter com- bustibles. The electro-negative substances unite, also, with each other; and, in this case, one of them is negative and the other positive. Such combinations, however, are extremely feeble, and their elements are, consequently, easily disunited ; but the facility of their decomposition causes them to act with great energy upon other bodies. 245. Division of elementary bodies. 246. System of classification. Division of non-metallic bodies. Number, and electrical character of the metals ? 247. Supporters of combustion and combustibles. Combinations of the electro-negative substances with each other. 94 OXYGEN GAS. 248. Equiv. by vol. 50 " weight 8 ( 1. Air=l. SP' 8r'\ 16. Hyd.= l. The simplest form under which we are acquainted with oxy gen is, that of a gas : in which state, like all other gases, it ia conceived to be a compound of a solid, ponderable basis, with caloric, and, perhaps, with light and electricity. Oxygen was discovered by Dr. Priestly in 1774 ; a discovery which was the cause of very important changes in the state of chemical science. It has been called dephlogisticated air, empy- real air, and vital air. Lavoisier gave it the name of Oxygen, supposing it to be the only acidifier in nature and it retains the name, though it is now known that there are some acids which contain no oxygen, and that many of the oxides have no acid pro- perties. 249. Mode of obtaining Oxygen Gas. Most of the oxides are decomposed by red heat; and if the operation be performed in proper vessels, the ex- pelled oxygen gas may be collected. Red Lead, which is the deutoxide of lead, yields oxygen when heated to redness in an iron retort; by this loss of oxygen it is reduced to a protoxide. Red oxide of mercury, treated in the same way, is resolved into oxygen and metallic mercury; nitrate of potassa, (nitre or salt-petre,) kept at a dull red heat in an iron or earthen retort, yields oxygen gas in considerable quantities. The residue is hypo-nitrite of Potassa. This mode is dangerous without a cautious regulation of the heat. Fig. 46. A, represents a furnace in which is placed the retort B, containing the substance which is to furnish the gas. C, is the pneumatic cistern (Fig. 46.) or water tube, D, the bell-glass receiver, E F, a shelf in-the cistern on which the receiver be- ing filled with water and in- verted, is placed. The wa- ter in the cistern rises a few inches above the shelf, so that ~ the water in the receiver is supported by atmospheric pressure. The gas issuing from the retort passes through a bent tube, and is conducted by it under the shelf, into the mouth * From the Greek oxus, acid, and gennao, to generate. The German Chemists call it sauerstoff, which, literally signifies sour stuff. 248. Equivalents and sp. gr. of oxygen. State in which we are acquaint- ed with oxygen. Its discovery. Synonymes. The name founded in error. 249. Substances from which oxygen may be obtained. Pneumatic cistern #c. Mode of obtaining oxygen. OXYGEN. 95 of the receiver, and being lighter than water, it rises in bubbles and dis- places the water in the upper part. This process continues until all the water in the receiver has gradually disappeared, and the vessel is filled with oxygen gas. 250. The black oxide of manganese, when pulverized and heated in a re- tort, also furnishes oxygen gas. From the state of peroxide, it is thus re- duced to that of deutoxide, losing about 128 cubic inches of oxygen for each ounce of the material. As this mineral often contains carbonate of lime which would introduce carbonic acid into the oxygen, it ought to be pre- viously purified by digesting it with very dilute muriate or nitric acid. The same oxide yields twice as much oxygen, if after being purified, it is made into a paste with sulphuric acid and heated in an earthen retort. In this case it is converted into protoxide of manganese, losing a whole equivalent of oxygen, instead of half a proportional as in the former case. The resi- due is Sulphate of Protoxide of Manganese .- the sulphuric acid combining readily with this oxide of manganese, though it cannot with the deutoxide or peroxide. 251. A process, eligible in small operations, but too expensive for large ones, is to heat chlorate of potassa in a green glass retort.* A spirit lamp is the best source of heat for this experiment. The salt may be made to yield, for each 124 grains, 48 grains or 141 cubic inches of oxygen gas; and there will remain in the retort 76 grains of chloride of potassium. The gas thus obtained is absolutely pure. In all these processes the gas may he collected over water. 252. Properties. Oxygen gas is transparent and colorless; and the least powerful refractor of light among the gases. It is said to emit light as well as heat, when suddenly and strongly compressed. It is tasteless and inodorous, a non-conductor of electricity, and is only very sparingly absorbed by water. It is the most perfect negative electric, having extensive and energetic chemical affinities, and combining with every elementary body without exception. It has neither acid nor alkaline properties, but some of its compounds are acids, some are salifiable bases ; and some are neither acids, nor bases. Oxygen frequently com- bines in several proportions, with the same body, producing en- tirely distinct compounds; and may even form with the same metal an acid, and a salifiable base—when this occurs, the acid is the compound which contains the greatest proportional quan- tity of oxygen. 253. Oxidation may take place in two modes; either slowly, in which case the progress of the chemical change is not percep- tible ; or rapidly, when heat and light are emitted, and the phe- * Green glass is preferable, because without great care, the more fusible white glass would be melted. 250. Oxygen obtained from the black oxide of manganese. 251. Oxygen from chlorate of potassa. 252. Properties of oxygen. Its compounds. 253. Two modes in which oxidation may take place. Rusting of metals. Combustion of wood, candles, &c. 96 COMBUSTION OF OXYGEN. nomena of combustion exhibited. Of the former, the gradual rusting of metals in the air, is an example ; while the combus- tion of wood, candles, &c, is an instance of the latter. 254. It sometimes happens that a higher oxide of a particular body, is produced by rapid, rather than by slow oxidation; but, on the other hand, the same compound may be formed by either mode. Thus the brilliant sparks that fly from iron on a smith's forge, and those struck from steel by a flint, are iron burning in the oxygen of the air ; and when cold these are found converted into the same oxide which is the basis of iron rust. The oxygen of the air, is the sole cause of its supporting combus- tion ; and, since this gas constitutes only f part of the whole bulk of the atmosphere, it might be supposed that bodies which bum in air, would burn much more vividly in oxygen gas. Fig. 47. Exp. 1st. Let there be two bell glasses A and B, communicating with each other by a flexible leaden pipe, with a stop cock at C. Suppose A to be placed over a lighted candle on the plate D, which communicates with an air-pump plate as represented at E. It will be found that the candle will gradually burn dimly, and will at last go out, if no fresh supply be al- lowed to enter the bell-glass; if, on repeating the experiment, the air be withdrawn by means of the pump, the candle will be rapidly extinguished. It is therefore proved, that a candle will not burn in a vacuum, and that it can burn but for a short time in a small portion of atmospheric air. Let the experiment be repeated with the following change. Let the air be exhausted from both vessels, the stop cock C, remaining open, until the bell B, is filled with water from the pneumatic cistern. The stop cock being closed, fill the bell glass with oxygen gas. Now introduce a candle under the bell A, then having placed the bell again on the plate of the air- pump, exhaust the air, until the candle is nearly extinguished, and then open 254. Effects of rapid and slow oxidation. Why the air is a supporter of combustion. Ex. 1st. OXYGEN. 97 Fig. 48. the stop cock so as to allow the oxygen from B, to enter. The candle will burn much more brilliantly, and for a longer time, than in the same portion 01 atmospheric air. Exp. 2nd. A slip of pine wood of the size of a match, ignited at one end, out not flaming, will be kindled instantly into flame, on being immersed in oxygen gas. ° Exp. 3d. A coil of fine iron wire, (Fig. 48.) burns in oxygen with beautiful scin- tillations. The wire must be tipped with sulphur, or some other combustible matter and ignited to commence the combustion. The globules of melted and burnt iron, if they fly against the bell glass, always break it; and they have even been known to per- forate, and pass through it. Exp. 4th. Phosphorus burns in oxygen, with a light so dazzling, that the eye can scarcely contemplate it. 255. After substances have burned for a time in oxygen gas, the combustion ceases; in many cases the gas disappears, and if the operation be performed in a bell glass ever water, the latter fluid will be seen to rise in the vessel, to supply the place of_ the consumed oxygen. This is the case- when iron or phosphorus is used; for the~23B oxygen unites with the latter, producing^ dense white fumes of phosphoric acid, which condenses upon the side of the vessel as the acid cools, or dissolves in the water; for phosphoric acid, though it first appears as a vapor, is naturally a solid, soluble in water. When iron burns in oxygen, the black oxide of iron is formed, and takes at once the solid state. In some cases there is no apparent diminution of oxygen gas, because the new compound is gaseous ; thus sulphuric acid, and carbonic acid, produced respectively, by burning sulphur and charcoal in oxygen, are gases, of the same bulk, as the oxygen employed in forming them. But oxygen gas has nevertheless been consumed ; for on examining the residual gas, it will be found to exhibit an entirely new set of proporties, being in fact a new body, a compound of the combustibles with oxygen. Accordingly, no combustible will burn in it. 256. Oxygen was formerly supposed to be the only supporter of combustion ; but, more recently, many other bodies are found to evolve light and heat, in combining with each other. This is particularly the case during the combustion of electro-positive Exp. 2nd. Exp. 3d. Exp. 4th. 255. Why water will rise in the bell glass after oxygen has beeo consum- ed. Production of phosphoric acid. Formation of the oxide of iron. Why in some cases, there is no apparent diminution of oxygen gas. Production of sulphuric acid—of carbonic acid. 256. Oxygen not the only supporter of combustion. Terms supporters of combustion and combustibles, to what classes of bodies applied ? Light and heat sometimes emitted by electro-positive bodies. The term combus- tion, how used at present ? 9 98 COMCUSTION. with electro-negative bodies; and the teim, supporters of com- bustion has been applied to all the latter, as distinguishing them from the former, which are called combustibles. But light and heat are often emitted by two electro-positive bodies, while com- bining with each other, as in the case of iron and sulphur, and copper and sulphur; so that the term supporters of combustion, can scarcely be regarded as proper, though, in accordance with custom, we may use it. The term combustion, also, is now used in a more enlarged sense than formerly, including not only, ra- pid oxidation, but all other cases of chemical combination in which heat and light are eliminated. 257. One of the first who attempted to explain the cause of combustion, was Stahl, a German. He supposed that a certain substance, which he called phlogiston, (from the Greek phlogizo, to burn,) formed a part of all combustible bodies, and that, in every case of combustion, this inflammable principle was disengaged. Now, as a metallic wire, after burning in oxy- gen gas, is heavier than before combustion, it follows, that instead of hav- ing parted with something in the process of combustion, it has actually gained in weight. Therefore, instead of giving out this imaginary phlogis- ton, it is found to have united with oxygen. Lavoisier, finding that the new discovery of oxygen gas destroyed the phlogistic doctrine, published the theory that oxygen is the only supporter of combustion. On this supposition, he conceives that in all cases of combustion, the solid base of oxygen gas unites with the combustible body ; and that the light and heat of the oxygen, being thus set free, give rise to the phenomena of combustion ; from this theory it would follow, 1st, that the specific calo- ric of the new compound, is always less than the mean of those of the con- stituents. And, 2d, that all combustibles, in consuming the same quantity of oxygen gas, must give out the same quantity of light and heat. Now both of these conclusions are contrary to experience ; besides which, as be- fore stated, the fundamental proposition, that oxygen is the only supporter of combustion, is likewise untrue. So that the theory of Lavoisier, is liable to serious objections. But, as Dr. Turner justly remarks, « It is easier to perceive the fallacy of one doctrine, than to substitute another that shall be faultless." 258. Substances which have been burned in oxygen, are no longer capable of combustion ; they are new bodies, having an entirely new set of properties. They have gained weight, and their increase is precisely equal to the oxygen consumed. Some bodies, on being heated after combustion, yield precisely the same quantity of oxygen which disappeared during the experiment, and thus return to their original condition. 259. Respiration. Oxygen is the only gas which supports respiration, and it is owing to the presence of this gas, that ani- 257. Stahl's theory of combustion. Lavoisier's theory. 258. Change in substances which have been burnt in oxygen. 259. Agency of oxygen gas in respiration. Exp. Showing the effect of oxygen upon the blood. How does oxygen affect the blood in respiration ? Arterial and venous blood. Change which takes place in the blood, in pas- sing through the lungs. RESPIRATION. 99 mals can live in common air. Physiologists agree that its effect in supporting life, depends on its action upon the blood. If a portion of this fluid be drawn from a vein, it is perceived to have a dark color, approaching to black ; put it into a bell glass filled with oxygen gas, and it will very soon become florid red; and the same change will ensue, though not quite so rapidly, if the blood be exposed to common air. The air in the jar being ex- amined, is found to have lost oxygen, and to have acquired an equal bulk of carbonic acid. This is precisely what takes place in respiration. The blood as it issues from the left cavity of the heart into the arteries, and is distributed by them through the system, is called arterial blood, and has the florid color. Having completed its circulation, it returns through the veins; and here it is found to have acquired a larger quantity of carbon, and become dark colored; in this state it is called venous blood. Before it goes again into circulation, it passes through the spongy organ, called the lungs; throughout which it is distributed in the countless microscopic tubes into which the veins have branched out, so as to expose the greatest possible surface. Here it comes in contact with the air with which the lungs have been inflated by the last inhalation; the excess of carbon in the blood combines with oxygen, and forms carbonic acid gas, which is exhaled with the nitrogen of the air; the blood thus purified and rendered fit for circulation, passes on through the appropriate vessels to the left cavity of the heart, and is again distributed through the system. The air which is exhaled, having exchanged oxygen for carbonic acid, is no longer fit for supporting combustion and respiration; and this is one of the reasons why crowded and strongly illuminated rooms, are unhealthy. 260. But although oxygen gas is the sole supporter of respi- ration, it is too stimulating in its effects on the human system to be inhaled in an unmixed state. If inhaled in any considerable quantity, it produces fatal inflammation of the lungs. It is sup- posed that warm climates are beneficial to comsumptive persons, because the air being warmer, is less dense than in cold climates, and each inspiration, therefore, brings a smaller quantity of oxy- gen into contact with the lungs, which, in a debilitated state, are unable to bear the more oxygenated, and consequently more stimulating air, of a colder climate. One cause of the unhealthy effect of breathing the air of crowded rooms. 260. Effect of breathing pure oxygen. Why persons with weak lungs require a warm climate. 100 CHLORINE. CHAPTER X. CHLORINE. 261. Equiv. by vol. 100 " weight 36 Sp. gr. 25. Air=l. 36. Hyd.= l. A. Chlorine gas was formerly called Oxymuriatic acid, from the belief that it was a compound of muriatic acid and oxygen. It was discovered by Scheele in 1774, who called it dephlogisticated marine acid. Fig. 49. ..... 262. Chlorine gas may be obtained by mixing strong muriatic or hydro-chloric acid and per-oxide of manganese, and heating the mixture gently. An effervescence arises, owing to the escape of the gas, which may be collected in a bell glass (Fig. 49.) over warm water; or the gas may be made to pass through a tube bent twice at right angles, a leg of which passes into a glass bottle. The gas, by its superior gravity, displaces the atmospheric air; when the bottle is full, which is known by the !| green color of the gas, it should be carefully closed. it In this process, a portion of the hydro-chloric acid Mjm is decomposed; its hydrogen combines with one W|f atom of the oxygen of the manganese, and forms water, while the chlorine is disengaged. Another.process for obtaining Chlorine is used when very large quantities are required. It consists in heating in a retort, A, (Fig. 50,) three parts of common salt (chloride of sodium) and one of peroxide of manganese, thoroughly mixed, and two parts of sulphuric acid, diluted with its own weight of water. The lamp being placed u der the retort, the mixture heats gradually, the chlorine gas being driven off, passes through the beak of the retort under the inverted bell ZTj glass C, which is at first filled with ^ i water; as the gas rises, the water | j subsides, until the whole receiver is | ] filled with chlorine.. "— The chemical changes in this ex- periment are as follows ; The sulphuric acid acting upon the solution of chlo- ride of sodium, disengages hydro-chloric acid ; the latter is decomposed by the peroxide of manganese (as explained in the former experiment); the sulphates of soda and manganese remain in the retort. 263. Chlorine gas is of a green color, slightly yellowish, and derives its name from the Greek word which signifies green. It 261. Equivalents and specific gravity of chlorine. Various synonymes. 262. Mode of obtaining chlorine with muriatic acid and peroxide of manga- nese. Rationale of this process. Mode of obtaining chlorine with common salt and peroxide of manganese. Explanation. 263. Some properties of chlorine. Effects of cold on chlorine gas. CHLORINE. 101 has an astringent taste, and a disagreeable, suffocating odor. It is exceedingly deleterious to the lungs, when inhaled, even though diluted with air. It is said to give out light, when suddenly compressed with great force ; a property belonging to no other gases but oxygen and chlorine. A pressure of 4 atmospheres, (about 60 lbs to the square inch,) reduces it to a bright yellow liquid which resumes the gaseous form instantly, when the pressure is removed. Cold water dissolves about twice its bulk of chlorine, forming a solution which has the color, odor and general properties of the gas itself; and hence the necessity of heating the water over which chlorine gas is to be collected. If exposed to a temperature of 32° Fahrenheit, while mixed with watery vapor, it forms a solid hydrate* which appears in the form of crys- tals, on the sides of the bottle ; this hydrate is liquefied by the warmth of the hand. 264. Chemical character. Neither heat, light, electricity, nor galvanism has been able to decompose pure chlorine ; it is there- fore considered, a simple element. When chlorine is in a moist state, the watery vapor may be decomposed, the chlorine combin- ing with the hydrogen of the vapor, and the oxygen which form- Fig. 51. • A hydrate is a compound of water with another body, often in definite proportions. 264. Why considered a simple element. Chlorine decomposes watery vapor in contact with it. Is an indirect oxidizing agent. 9* 102 CHLORINE. ed part of the same being liberated. As oxygen must be libera- ted whenever chlorine decomposes water, if an oxidable body be at the same time present, it will become oxidized; so that chlo- rine is often an indirect, oxidizing agent, of great power. Chlo- rine supports the combustion of some bodies. 265. A lighted candle being immersed in it, goes out after burning a short time, with a dull red flame. Phosphorus, and some of the metals, take fire spontaneously in this gas. In these cases, combination takes place between the burning body and chlorine, and the compound resulting is a chloride. Exp. The bell glass B, (Fig. 51.) represents the combustion of gold leaf in chlorine gas. The lower bell glass A, being filled with chlorine over the pneumatic cistern; the upper bell glass is exhausted of air by means of an air pump, and the pipe which is connected with the apparatus. On turning the stop-cock between the two bell glasses, the gas from the lower one rushes up to fill the vacuum, and the gold leaf is immediately inflamed, and burns with great brilliancy, forming chloride of gold. 266. As chlorine unites with simple bodies it cannot be an acid ; for acids combine only with metallic oxides, and not with the metals themselves. Besides, it has none of the other prop- erties of acids. It is the most intensely electro-negative body known except oxygen; and is, consequently, always found at the positive pole, when a compound of it, with any other substance than oxygen, is decomposed by a galvanic battery. Its affinity for metals is even greater than that of oxygen ; so that if a me- tallic oxide is" heated in chlorine gas, the oxygen is expelled, and a chloride of the metal is formed. 267. Some of the chemical properties of chlorine render it ex- tensively useful in the arts of life. It destroys vegetable colors rapidly ; the bleaching appears to depend upon the decomposi- tion of water which must be present. The bleaching effect is supposed to be owing to the oxygen, liberated from the decom- posed water, chlorine performing only the part of an indirect, oxidizing agent. There are other facts in support of the same opinion, one of which is, that certain highly oxidized bodies, as duetoxide of hydrogen, and manganesic acid, are powerful bleach- ing agents. For bleaching, on a small scale, as in removing from linen and cotton, the stains of fruit or other vegetable substances, a solution of chlorine ?as in water, may be used. But this solution in large quantities, gives off so 265. Chlorine an imperfect supporter of combustion. Compound which results from the burning of a metal with chlorine. Exp. 266. Proof that chlorine is not an acid. Its electrical affinity. Its af- finity for metals. 267. Various uses of chlorine. Its bleaching properties. The particular office of chlorine in the bleaching process. Proofs that oxygen is the active agent. Experiment to prove the bleaching power of chlorine. CHLORINE. 103 much gas as to be deleterious to the workmen; and the resulting hydro- chloric acid is injurious to the texture of cloth. Both these inconveniences are avoided by using the chloride of lime, commonly known as bleaching powder. Exp. Immerse a piece of litmus paper, or of printed calico in a solution of chlorine, or of chloride of lime, or into a jar of the gas itself; (in the lat- ter case, the calico or paper must be moistened;) the color will be discharg- ed in a short time. 268. Chlorine destroys animal and vegetable poisons, wheth- er existing as miasma in the atmosphere, or in other forms. The air of a sick room is purified by sprinkling the floor with a solution of chloride of lime or of soda. The putrescence of meat is arrested, and taint removed by the same substances, which, likewise, in a dilute state, form an admirable wash for the mouth. Chlorine, in the gaseous state, and in solution in water, is a certain antidote for Prussic acid ; and it seems highly probable that the bite of a rattlesnake, or of a rabid animal would not be followed by such fearful consequences, if, as soon as they occur, the wounds could be dressed with a solution of this gas. It is not ascertained whether chlorine acts directly upon the poisonous matter, or whether it is as in its bleaching property, an indirect, oxidizing agent. In either case, affinity for hydro- gen* is probably the cause of the phenomena. 269. When chlorine is passed into a cold solution of a fixed alkali, it is absorbed in considerable quantity, and forms a compound which exhibits the odor, the bleaching effects, and the atiseptic properties of chlorine. (A disinfecting liquid, prepared by M. Labarraque, is a form of chloride of §oda.) If this compound be heated, water is decomposed; 5 atoms of chlo- rine, take 5 of hydrogen, and form 5 of hydro-chloric acid, which unite with 5 of the alkali, forming a hydro-cMorate ; the 5 atoms of oxygen disengaged from the water, combine with 1 of chlorine, and constitute a particle of chloric acid, which also combines with 1 of alkali, and forms a chlorate. The solution thus contains nothing but two neutral salts, a hydro-chlorate and chlorate, and has no longer the distinguishing characters of chlorine. 270. Chlorine is detected by its bleaching properties, and by producing, in a solution of nitrate of silver, a white precipitate, the chloride of silver, which soon becomes dark colored, on ex- posure to light. * Wherever we commence in our instructions in science, we must occa- sionally, refer to what is yet unexplained. This is peculiarly the case in Chemistry. The three most important of the elementary bodies, are Oxygen, Hydrogen, and Nitrogen; they form combinations with all other known ele- ments. But in our system of arrangement, according to electro-chemical agencies, oxygen stands at the head of one division, and hydrogen at the head of another. We must therefore, in adhering to our arrangement, leave the consideration of hydrogen and nitrogen, till we have treated of the simple electro-negative bodies, though some of the latter are of much less impor- tance. 268. Effect of chlorine upon animal or vegetable poisons. Practical ap- plications. Probable cause of its action upon poisonous matter. 269. Disinfecting liquid, how prepared ? Effect of heating it. 270. Tests of chlorine. 104 CHLORINE AND OXYGEN. Compounds of Chlorine and Oxygen. 271. These two important electro-negatives having for each other very weak affinities, cannot be made to unite by any direct method ; but, indirectly, we are able to produce several distinct compounds; the most striking characteristics of these combina- tions is the extreme facility with which they are decomposed, either by heat, or by the action of other substances. This is owing to the very weak affinity of chlorine and oxygen for each other. None of these compounds has ever been found in nature. 272. Protoxide of chlorine 1 atom of chl. 36 to 1 ox. 8=44. Peroxide of chlorine 1 do chl. 36 to 4 ox. 32=68. The former of these compounds is sometimes called Hypo-chlorous acid, as also euchlorine, it being greener than chlorine. The peroxide is also called chlorous acid. The properties of these two substances may be advanta- geously studied by comparing them with each other. They are both gaseous, of a greenish-yellow color, and are copiously absorbed by water, to which they communicate their color, odor and some of their chemical properties. They are highly explosive, and dangerous compounds: the protoxide ex- plodes by the heat of'the hand, and the peroxide, at about the boiling heat of water. They bleach powerfully, but the protoxide reddens a vegetable- blue before it bleaches it, while the peroxide whitens it, at once. They in- flame phosphorus spontaneously; explosion takes place, and the phosphorus continues to burn in the two component gases, forming a compound of each. 273. Expansion is a necessary consequence of the decomposition of these gases ; for in each of them the two elementary gases are in a state of con- densation. In the protoxide, 4 measures of chlorine and 2 of oxygen, making 6 measures, are so condensed by combination as to form but 5 measures of the oxide. In the peroxide, the contraction is still greater, for 4 measures of this gas contain 6 of the component gases, of which 2 are chlorine and 4 are oxygen. The peroxide, therefore, explodes more violently than the pro- toxide. 274. Chloric acid is obtained in solution, by adding sulphuric acid to a solution of chlorate of baryta. The insoluble sulphate of baryta is precipitated, pure chloric acid remains in solution, and may be obtained in a solid state, by evaporation. It was formerly called hyperoxy-muriatic acid, its salts are still called, by some, hyperoxy-muriates. 275. Properties. Chloric acid combines with the alkaline 271. Names and composition of the compounds of chlorine and oxygen. Their most striking character. These compounds not found native. 272. What are the component parts, and chemical equivalents of the pro- toxide and peroxide of chlorine ? Comparison of these two substances with each other. Their properties. 273. Why expansion is a consequence of the decomposition of the protox- ide and peroxide of chlorine. 274. How is chloric acid obtained ? Synonyme. 275. Properties. Names of its salts. Its effect on oxidable bodies. De- flagrating properties of its salts. Action of sulphuretted hydrogen with chloric acid. , BROMINE. 105 bases, forming salts, called chlorates. It readily affords oxygen to oxidable bodies, acting on them with great violence. The chlorates, have the same property, deflagrating with great vio- lence on hot coals, and producing a violent explosion when mixed with phosphorus or sulphur and struck with a hammer or heated. The explosion arises from the rapid oxidation of the combustible part of the mixture, at the expense of the chloric acid. Chloric acid is also decomposed by sulphuretted hydrogen, the hydrogen forming water with the oxygen of the acid, while the sulphur and the chlorine are set free. 276. Perchloric Acid may be obtained by heating 1 part of water, 3 of sul- phuric acid, and 5 of perchlorate of potassa. White vapors arise in the receiver which become condensed into a liquid, on being mixed with sul- phuric acid, and distilled pure crystals, of perchloric acid appear. It is volatile, decomposable in heat at a higher temperature than that necessary to decompose chloric acid, and forms a class of salts, which, like the acid itself, deflagrate with combustibles. Its salts like the chlorates, are con- vertible by heat into oxygen and chlorides of metals. Perchloric acid is important, as affording the best method of distinguishing and separating po- tassa from soda ; for if it be poured into a solution containing these alkalies, or their salts, it precipitates the perchlorate.of potassa, which is nearly in- soluble, while the perchlorate of soda is extremely soluble and remains in solution. 277. The constituents of the two oxacids of chlorine are as follows ; Chloric acid. 1 chl. 36, add 5 ox. 40=76. Per-chloric acid. 1 chl. 36, add 7 ox. 56=92. CHAPTER XI. ELECTRO-NEGATIVE SUBSTANCES.--BROMINE, IODINE, FLUORINE. BROMINE. xide of iodine, containing even less oxygen than iodous acid. 292. Chloriodic Acid. 1 Iod. 124, to 2 chl. 72=196. This is a combina- tion of chlorine and iodine, procured by passing chlorine gas into a dry bot- tle containing iodine. It is solid, of an orange yellow color, very volatile, very soluble in water, and deliquescent. Its solution is strongly acid ; but when an alkali is added, instead of forming a chloriodate, we obtain a hydro- chlorate and an iodate. This 16 owing to the decomposition of water ; the oxygen of which combines with iodine and the hydrogen with chlorine. The iodic and hydrochloric acids thus formed, take, each, its portion of the alkali. Bromine and iodine combine and form bromide of iodine. FLUORINE.* 293. Fluorine has never been obtained in an uncombined state owing, as is supposed, to its very energetic affinities for other substances. It is one of the constituents of fluor spar, from which the compounds of fluorine are commonly obtained. It is considered an electro-negative body, as possessing intense affi- nities for simple substances, and forming with hydrogen, an acid called hydrofluoric. 294. Hydrofluoric Acid. This acid is obtained by heating a mixture of sulphuric acid and powdered fluor spar (fluoride of calcium). Fig. 53. Exp. The mixture must be made in a metal- lic retort, (Fig. 53.)(on account of the pecul- iar action of the acid on glass) and the vapor of nydrofluoric acid must be received in a close vessel c, of one of those metals. The vapoi passing through the tube 6 into the receiver, which is kept cool, by ice or cloths wet in cold water, is condensed into a liquid. This is hydrofluoric acid, and must be preserved in a closely stopped metallic bottle. 295. Hydrofluoric acid, in the liquid * Silliman justly remarks, that "it appears premature to place fluorine, a principle purely hypothetical, along side with chlorine and iodine, whose dis- tinct existence and peculiar energy are manifested in so many remarkable forms." 291. Iodous acid. 292. Composition of chloriodic acid. How procured ? Properties. Bro- mide of iodine. 293. Why is it supposed that fluorine has not been obtained in a separate state ? From what mineral are its compounds obtained; supposed proper- ties of fluorine. 294. How is hydrofluoric acid obtained ? Exp. 295. Its affinity for water. Its effects on animal and vegetable bodies. FLUORINE. Ill state, is very volatile, giving off dense white fumes if exposed in an open vessel, at the temperature of 60° F. Its specific gravity when pure, is but little above that of water ; but when combined with some water, it forms a less volatile hydrate of the specific gravity of about 1. 25. This acid has an affinity for wa- ter, even much greater than that of sulphuric acid. In combining with water, it produces very great heat, and causes a hissing like that produced when hot iron is quenched. It corrodes animal and vegetable bodies more powerfully than any other substance, producing a deep and dangerous ulceration when it is put on the skin. This action is the result of the powerful affinity the acid has for water. 296. It also acts on glass, dissolving the siliceous matter of that substance and destroying its transparency ; or even perfor- ating it when a sufficient quantity of acid is used. By this action, two compounds are formed ; the oxygen of the silex forms water with the hydrogen of the acid; while the silicon unites with the fluorine to form a colorless acid gas, called fluosilicic acid. This property of hydrofluoric acid affords means of etching or engraving on glass. The glass must be covered with a thin and uniform coat of wax, after which a figure is traced on it with a sharp steel point. If it be now exposed to the fumes of the acid, or wet with the liquid acid the glass will be corroded where the wax has been removed by the steel point, while the covered parts will be left untouched. 297. With oxides, hydrofluoric acid acts variously, combining with some to form hydrofluates, and decomposing others, in which case, water and a fluoride of the metal are the result. It is a powerful solvent, dissolving rock crystal, flint, and other siliceous matters, besides several other bodies which are not attacked even by nitro-muriatic acid. Sulphuric acid displaces this acid from any of the hydrofluates ; and then the hydrofluoric acid can be detected by exposing glass to the fumes as they rise. 298. Some Chemists are disposed to regard this acid, (instead of fluorine and hydrogen,) as a compound of fluorine and oxygen, called fluoric acid; and all phenomena relating to it are capable of explanation under this view. Thus fluor spar may be considered a fluate of lime instead of a fluoride of calcium; so that when sulphuric acid acts on this mineral, it may be sup- posed simply to combine with the lime and liberate fluoric acid. Some re- cent experiments, however, seem to yield conclusive evidence in favor of the first mentioned view of the subject, or, that the acid in question, is hy- dro-fluoric, consisting of fluorine and hydrogen. 299. Fluoboric Acid was discovered by Gay Lussac and Thenard, in an experiment intended to prove that the acid we have described under the 296. Action of hydro-fluoric acid on glass. Compounds formed by this action. Etching on glass. _ 297. Action of this acid with oxides. Its solvent properties. Is displaced by sulphuric acid. - .„.,.., a -j 298. Theory which considers this as fluoric rather than hydrofluoric acid. 112 FLUOBORIC ACID. name of hydrofluoric acid is an oxacid. Boracic acid being a compound of boron and oxygen, they endeavored by its aid, to obtain fluoric acid from fluor spar. If they succeeded, it would establish their opinion on the dis- puted point; for there being nothing present in the experiment but boracic acid and fluor spar, both anhydrous,* there could be no hydrogen in the pro- duct. But instead of hydrofluoric, (or fluoric,) acid they obtained a new gas, which does not act on glass; is very soluble in water, which it attracts so strongly as to produce dense white fumes in the air when the least moisture is present; and decomposes by water, forming boracic and hydrofluoric acids, borate of lime remaining in the retort. The discoverers believed that a por- tion of the boracic acid united to the lime and liberated fluoric acid; and that the latter immediately combined with another portion of boracic acid, to form the fluoboric gas which is therefore a compound of the two acids. The decomposition of the fluoboric gas by water, and the consequent de- position of boracic acid, they attributed to the superior affinity of water for fluoric acid, by which the latter was taken from its combination with boracic acid. 300. The chemical changes in this experiment appear to be as follows.— The two materials boracic acid and fluorspar (fluoride of calcium) being mix- ed and heated strongly in an iron tube or retort, the oxygen of a portion of the boracic acid, combines with calcium to form lime, fluorine combines with the boron, which has thus been deserted by oxygen, and forms the fluoboric gas; and, finally the remaining boracic acid unites with the newly formed lime, and borate of lime remains in the retort. The fluoboric gas being a compound of the electro-negative fluorine with the electro-positive boron, when it is passed into water the fluid is decomposed ; its hydrogen unites with the fluorine, and its oxygen with the boron, forming thus, boracic and hydrofluoric acids, of which the latter is wholly dissolved, while much of the former is deposited. The moisture of the air effects the same decomposition of this gas, the fumes being rendered quite opake by the particles of solid boracic acid. On account of the formation of these fumes, fluoboric gas is of use in testing the minutest quantities of vapor in gases. The strong af- finity of this gas for water, enables it to char animal and vegetable bodies with their oxygen and hydrogen, thus developing their carbon. 301. Fluoboric acid unites with alkalies forming salts called fluoborates. When potassium is heated in this acid, the fluorine combines with it, and boron is liberated ; the same decomposition occurs when potassium is heated with an alkaline fluoborate, which furnishes the best method for obtaining boron. This acid gas is always generated when boracic acid is brought into contact with hydrofluoric acid; and, accordingly, an easier process for ob- taining it, than the one given, (see § 299,) is to mix those two bodies in a retort and apply heat. Or it may be obtained by heating a mixture of bo- racic acid, fluor spar and sulphuric acid. The gas should be collected over mercury. * Anhydrous signifies without any water, entirely dry. 299. Discovery «f fluoboric acid. Nature of the gas obtained by Gay Lussac and Thenard with boron and fluorine. Its attractions for water Opinion of the discoverers of this gas respecting the changes which accom- pany its formation. 300. Another explanation of the chemical changes in this experiment Use of this gas as a test. Why it chars animal and vegetable bodies. 301. Salts of this acid. Other modes of obtaining fluoboric acid. FLUO-SILICIC ACID GAS. 113 302. Fluo-silicic acid gas, is a compound concerning the nature of which the same question may be raised, as in the case of fluoboric gas. It is gen- erated when hydro-fluoric acid comes in contact with silex,and may either be composed of fluorine and silicon (in which case the oxygen of the silex unites with the hydrogen of the acid,) or, it may be considered, as a com- pound of fluoric acid and silica. We shall treat of it under the first suppo- sition. It may be obtained by mixing, in a retort, powdered fluor spar and fine sand, (or powdered glass, of which silex is a principal constituent,) and heat- ing with a lamp. The gas is to be collected over mercury. 303. Properties of fluo-silicic acid gas. It is colorless and transparent, a non-supporter both of respiration and combustion, and forms dense white fumes in moist air. Its affinity for water, enables it to corrode the skin and to char vegetable matter. The fluorine in this gas being saturated with si- lex, it does not attack glass. It is soluble to a great extent in water, but is decomposed by it, with formation of hydrofluoric acid, and of silex which is deposited. The decomposition, however, is not total; some silex remains in solution ; and constitutes with the hydrofluoric acid, what is generally considered a distinct compound and called hydro-fluosilicic acid. If the watery solution be filtered to remove the deposited silex and then evaporat- ed, the vapor of hydrofluoric acid is expelled, and the original gas is given off unaltered; but if the evaporation be performed without filtration, the silex is redissolved, and the fluosilicic gas is reproduced. If this gas be passed into an alkaline solution the whole silex is deposited, and a hydrofluate of the alkali is formed. 304. The acidity of fluosilicic, and of fluoboric gases is by some, consid- ered doubtful. It can only be exhibited with the aid of water, in which case decomposition takes place, and other acid compounds are formed, to which alone the acid reaction might be owing. Accordingly, some Chem- ists consider these gases as only the per fluorides of boron and of silicon. The acid property, however, seems to be sufficiently established by the fact that these gases unite with gaseous ammonia and form solid compounds or salts. 305. The hydro-fluosilicic acid unites with alkalies and other bases. Its combination with potassa is of difficult solubility, and therefore this acid is sometimes advantageously used to remove potassa from solutions. 302. Nature of fluo-silicic acid gas disputed. When the gas is generated. Composition. How obtained? 303. Properties. Formation of hydrofluosilicic acid. Effects of passing this gas into an alkaline solution. 304. Arguments against, and in favor of the acid nature of fluosilicic and fluoboric acids. 305. Affinities of hydrofluo-silicic acid. 10* 114 HYDROGEN. CHAPTER XII. SIMPLE ELECTRO-POSITIVE SUBSTANCES.--(Not Metallic.) 306. The Non-metallic, electro-positive, substances are, as fol lows, viz: 1 Hydrogen, 5 Silicon, 2 Nitrogen, 6 Phosphorus, 3 Carbon, 7 Sulphur, 4 Boron, 8 Selenium. Hydrogen and nitrogen are gases : carbon, boron and silicon, are dark colored, insoluble and infusible powders, scarcely af- fected by acids, and forming weak acids by oxidation. Phos- phorus, sulphur and selenium are fusible, volatile, and combus- tible solids, producing strong acids by combinations with oxygen. They have affinities for the electro-negatives and are found at the negative pole where their compounds and those of the electro-ne- gatives are decomposed by galvanism. They have, also, more or less tendency to unite with each other, and several of this class combine with the metals. HYDROGEN. on^ t? ■ S by vol. 100 ) „ ( 0, 694 Air=l 307. Equzv. j y wdght 1 | Sp. gr. j f Hyd=1 Hydrogen is so named from the Greek hudor, water, and gennao, to generate, because it enters largely into the formation of water. It was formerly called inflammable air from its combus- tible nature and phlogiston, from the supposition that it was the matter of heat. It is one of the most important of all the inflam- mable substances ; existing in nature in a variety of combina- tions, and forming -J- part by weight, of water. Though known for centuries before, Mr. Cavendish, in 1766, first ascertained the nature of this gas as a distinct elementary substance, and experimented upon its properties. 308. Hydrogen is obtained by the decompositicn of water, which may be effected in several ways. 306. How are the Electro-positive substances divided ? General charac- teristics of these bodies. 307. Equivalent and sp. s:r. of hydrogen. Origin of the name. Synony- mes. Where existing. Discovery. 308. From what substance is hydrogen usually obtained ? Exp. 1. De- composition of water by galvanism. Exp. 2. Decomposition of water by heated iron. Exp. 3. Agency of sulphuric acid in promoting the decom- position of water. HYDROGEN. 115 Decomposition of Water by Galvanism. Fig. 54. Exp. 1. Let the two poles* of the voltaic pile, (Fig. 54.) be im- mersed in a vessel of pure water; the liquid will be decomposed; oxygen will be given off at the positive pole D, and hydrogen at the negative pole N. The gases may be collected by inverting over each pole a glass tube 0, and H, closed at one end, and filled with water. As opposite electricities attract each other, the oxygen is considered as electro-negative, and hydrogen electro-positive; and thus these two gases are placed at the head of their respective divisions. Hydrogen may also be obtained by decomposing water with red hot iron. Exp. 2. Put a coil of iron wire into a gun barrel, (Fig. 55.) open at both ends. The gun barrel is then passed through a furnace. To one end of the iron tube or gun-barrel is luted the neck of a retort A, containing water; and to the other, a bent tube E, of iron wire. A fire is now lighted in the furnace, and the water in the retort is boiled by means of an Argand lamp. The steam of the boiling water is decomposed in passing through Fig. 55. the coil of iron wire in the gun barrel; the oxygen combines with the iron which is found to be converted into the black oxide of iron; the hydrogen passes off into the receiver G. Exp. 3. Another mode of obtaining hydrogen by the decomposition of water, is very simple. Dilute some sulphuric acid with 8 or 9 times its bulk of water, and pour it into a retort, or bottle containing zinc or iron filings, f A violent effervescence will immediately ensue, owing to the es- * The wire used for the poles should be of platinum, as the oxygen would combine with iron wire. t The great heat evolved by mixing sulphuric acid and water would en- danger the vessel without due care. The acid should be gradually poured into the water; not the water into the acid. H 116 PROPERTIES. cape of hydrogen gas, which is always to be received over water. Here the oxygen of the water unites with the metal, forming an oxide; the latter next combines with the acid forming a sulphate of zinc or iron (according as the one or the other metal is used) and the hydrogen of the water is liberated. The use of the acid consists in its uniting with, and dissolving the oxide which forms around the metal, and which would, if not taken up, prevent the contact of the metal with the water. 309. Properties. Hydrogen is combustible, transparent and col- orless, a powerful refractor of light, and very strongly electro- positive. As commonly obtained, it has a faint, disagreeable odor, which, however, does not belong to the gas, but to volatile oil mingled with it. It is used for filling balloons, being the lightest body known in nature. It is about 14 times lighter than atmospheric air, and 16 times lighter than oxygen. Hydrogen has never been reduced to the liquid state. It has resisted all attempts to resolve it into more simple parts, and is, therefore; considered an elementary body. It is scarcely absorbed in water, and has neither acid, nor alkaline properties. It is not poisonous, but an animal confined in it, dies for want of oxygen; for the same reason, a burning body is extinguished on being immersed in this gas. Eig. 56. A lighted candle placed under a jar of hydrogen gas, t(Fig. 56.) is extinguished, though by its flame it will set the gas at the mouth of the jar on fire, and may be re-lighted, by having the wick brought in contact with the flame, when the combustion goes on, because there is oxygen to support it. Exp. Hydrogen is highly inflammable. Let some iron filings, water, and sulphuric acid, be put into a flask, (seeexp.3. §308.) and ajet of hydrogen will soon issue from a tube fitted to the mouth of the flask; this jet may he set on fire by a.lighted taper; and will burn suddenly, with a very faint greenish light. The color of the flame, however, appears to depend on impuri- ties, as the flame of the purest hydrogen, is scarcely perceptible. 310. If hydrogen be mixed with oxygen in proper proportions, and then set'on fire, the whole burns at once, with a loud explosion. The detonation takes place also, but not so violently, if air be used, instead of oxygen gas; the proportions for producing the most powerful explosion, are two measures of hydrogen, to one of oxygen, or five of air. These explosive mixtures may be kindled, not only by flame, and an ignited body, but also by the electric spark, and by platinum in that particular form called 309. Properties of hydrogen. Its elementary nature, &c. Exp. Inflam triable nature of hydrogen. 310. Explosive and inflammable nature of hydrogen and oxygen. FLAME. 117 spongy platinum. If a jet of hydrogen gas be directed against a piece of spongy platinum, the latter becomes red-hot, and sets fire to the stream of gas. An apparatus for procuring instantaneous light by means of spongy pla- tinum and hydrogen gas will be explained under the head of platinum. 311. The heat of the flame of hydrogen is very great, even when a jet of the gas is burned in the air ; but if the gas be pre- viously mixed with oxygen, the quantity of caloric evolved, is greatly increased; the heat of the flame thus produced, is con- sidered the greatest that can be produced by artificial means. For the first application of this fact to useful purposes, science is indebted to Dr. Hare, in the Fig. 57. construction of the oxyhydrogen, or compound blow-pipe. In this apparatus, the gases are confined in separate reser- voirs a a, (Fig. 57.) from which they are expelled through tubes b b, meeting in a conical piece c, in which the gases mix just be- fore they are to issue. By this plan, all danger is avoided; for the utmost that' can happen, is the explosion of the mixed por- f tion of the gases contained in the conical jet; a quantity too small to do any mischief. The flame of the compound blow-pipe, fuses the most refractory substan- ces in nature, as platinum, which is quite infusible in the most powerful furnaces. This flame is not extinguishable by water. 312. Flame. The reason why the flame of the mixed gases is so much hotter than that of hydrogen, burning in an atmos- phere of oxygen, will be obvious, if we reflect, that no combus- tible can burn, unless it be in contact with some other substance, which acts as a supporter of combustion. Now, when a column of the inflammable gas escapes into an atmosphere containing oxygen, only the surface of the column is in contact with the supporter, and consequently, only its exterior coat can burn. This being consumed, another layer of hydrogen is exposed, and burns in its turn ; so that the column is constantly growing small- er as it rises, till at last it terminates in a point. Accordingly an 311. Heat of the flame of hydrogen. Increase of heat from a mixture of oxygen and hydrogen. Compound blow-pipe. Dr. Hare's blow-pipe. 312. Flame. Cause of the great heat of the mixture of hydrogen and oxy- gen gases. Difference between ordinary flame and that of the mixture of hydrogen and oxygenases. 118 COMBINATION OF ordinary flame, (as a candle or lamp, or the blaze on the hearth,) is conical, and a mere shell of ignited matter; the interior con- sisting of unburnt, inflammable gas. In the compound flame, however, each part of hydrogen being already in contact with its particle of oxygen, the whole column is in combustion, throughout its mass. The simple flame, therefore, bears to the compound one, the same relation that the surface of the cone bears to its volume COMPOUNDS OF HYDROGEN AND OXYGEN. 313. Protoxide of Hydrogen, or water. 1 equiv. hyd. 1 to 1 equiv. ox. 8=9. Sp. gr. =1. Whenever hydrogen is made to combine directly with oxygen, either by explosion or otherwise, the compound formed, is water; nor will any variation of the proportions in which these gases are mixed, cause the forma- tion of any other product; and when either gas is in excess, that excess will remain unconsumed after the experiment. Thus, if two measures* of each gas, be mixed in a proper detonating tube, over mercury, and fired by the electric spark, it will be found after the explosion, that three measures have disappeared, and that mercury has risen in the tube to supply their place. The remaining one measure, consists entirely of oxygen; so that the whole of the two measures of hydrogen, have combined with one measure of oxygen. If three measures of hydrogen and one of oxygen, be exploded in the same manner, there will be a condensation of three measures, and the residual measure will be hydrogen. 314. Water formed by the combination of hy- drogen and oxygen gases. Exp. 1st. Hold a perfectly clean, and dry, glass vessel over a jet of hydrogen gas, the oxygen of the air com- bining with the hydrogen, will form an aqueous vapor, which will appear on the inner side of the glass. Exp. 2nd. Let a current of burn- ing hydrogen pass into the mouth of the tube a, (Fig. 58.) the glass cylinder 6, will soon appear | covered with dew from the condensation of the aqueous vapor, produced by the oxygen of the air uniting with the burning hydrogen. • By measure or volume, it is found that the. atom of hydrogen is twice as large as that of oxygen ; thus, as one atom of each unite to form water, and the weight of the atom of hydrogen is found, in comparison to oxygen to be, as 1 to 8, it follows that the specific gravity of hydrogen is 16 times less than that of oxygen. Fig. 58. 313. Equiv. and sp. gr. of water. Combination of hydrogen and oxygen. What proportions, m volume, of these gases unite to form water? 314. Ej.p. 1st. HYDROGEN AND OXYGEN. Fig. 59. Exp. 3d. A more complicated apparatus for shewing the formation of water by means of the combination of oxygen and hydrogen was invented by the French chemist, Lavoisier. " This apparatus consists of a glass globe (Fig 59.) with a neck cemented into a brass cap from which three tubes proceed, severally communicating with an air pump, and with reser- voirs of oxygen and hydrogen. It has, also, an insulated wire, for produc- ing the inflammation of a jet of hydrogen, by means of an electric spark. In order to put the apparatus into operation, the globe must be exhausted of air, and then supplied with oxygen to a certain extent. In the next place, hydrogen is to be allowed to enter in a jet, which is to be inflamed by an electric spark."—Dr. Hare. Exp. 4th. Let a (Fig. 60.) be a glass cylinder, filled with pure oxygen ; 6, a bell glass containing hydrogen, and partly immersed in a vessel of wa- ter,^. On opening the stop cocks, d d, the hydrogen rises through the capillary tube /, and on being inflamed by an electric spark, it burns with great force, and drops of water soon collect in the cylinder. Exp. 3d. Lavoisier's apparatus. Exp. 4th. 04673745 120 ANALYSIS OF WATER. Fig. 60. Analysis of Water. 315. We have shown by synthetic proof, that water is composed of two gases. The same fact may be demonstrated by a reversed method, that of analysis. Exp. When water, in the state of steam, is made to pass over heated iron, the metal absorbs the oxygen, and hydrogen gas escapes. The iron will be found to have gained in weight 8 grains of oxygen, for 1 grain of hy- drogen obtained. Figure 55, shows an apparatus, invented by Dr. Hare, by which steam is decomposed by passing over hot iron. The gun-barrel to which the retort is cemented, is fitted at its opposite end with a flexible leaden tube, for the purpose of conducting off the hydrogen gas. Within the gun-barrel (Fig. 61.) is introduced a quantity of iron turnings, or refuse card teeth. The glass retort is part- ly filled with water. A quantity of charcoal within the furnace being ignited, soor heats the gun-barrel to a red, and then to a white hea*. In the meantime, a chafing dish of burning coal is placed under the retort; the water soon boils, is changed to steam, which passes through the gun-barrel and parts with its oxygen to the metal, while the hydrogen escapes through the flexible leaden tube, and may be collected. It has been shown, (308, Exp. 1st.) that when water is subjected to the action of the galvanic decomposed, and hydrogen will appear at the Fig. 61. negative, and oxygen at the positive pole. Let a glass tube be filled with water, corked at both ends, and the two wires of the galvanic circle, then put through the corks. The water being acted upon by galvanic electricity, its elements separate, hydro- gen being attracted to the negative pole, and oxygen to the positive. ' 315. The composition of water may be proved by anal- ysis. Exp. Analysis of water by means of an apparatus in- vented by Dr. Hare. Analy- sis by galvanic action. DECOMPOSITION OF WATER. 121 Water._____ 316. The figure represents the com- parative bulk of the atoms of hydrogen and oxygen as they exist in water ; the form- er being twice as large as the latter, as is ascertained by the bulk of the two gases obtained by the decomposition of water. As the weight of the atom of oxygen is Chem. Equiv. 9. found to be 8, while that of the atom of hydrogen is 1, it follows that the specific gravity of oxygen is sixteen times greater than that of hydrogen ; so that if its ultimate atom had the-same bulk as that of hydro- gen, its combining number would be sixteen instead of eight. 317. Natural history. Water, as obtained from the usual sources, is impure. Rain water collected at a distance from buildings, is less impure than that from springs, or that which has fallen from the eaves of houses, but still contains several gases, the odoriferous matter of plants, with traces of animal and saline matter. The animal and vegetable matter contained in rain water, causes its tendency to putridity. Spring and river water, in addition to the same impurities which exist in rain water, contain several salts which they acquire from the soil, and of which sulphate of lime is one of the most frequent. To these salts, water owes the property commonly called hardness ; that is, the property of decomposing soap, (or of curdling it, as it is usually termed;) for soap, is in reality, a salt, being composed of acid and alkali; so that when it meets an earthy salt in so- lution, a double decomposition ensues ; the soap and the salt ex- change acids, and two new salts are formed, one of which floats on the surface of the water. A solution of pearlash, shows the presence of these salts, by producing a white precipitate. The white deposit on the inside of a tea-kettle, in which spring water has been much boiled, is a mixture of carbonate and sulphate of lime. 318. The spring water of some localities is harder than that of others, be- cause some soils contain more of soluble salts than others. The presence of these saline substances, not only communicates a somewhat nauseous taste to water, but injures its solvent powers in some particular instances ; 316. Comparative bulk of the atoms of hydrogen and oxygen. Specific gravitv of oxygen compared with hydrogen. 317. Impurities of water. Rainwater. Spring and river water. Cause of the hardness of water. Why hard water decomposes soap. Tests of the presence of salt in water. Cause of the white deposit on the inside of a tea-kettle. 318. Why the water of some springs is harder than others. Why soft water is better for making tea than hard water. Effect of boiling or freez- ing water in relation to its impurities. Distillation of water. 11 122 HYDROGEN. thus, it has been found that of equal portions of rain and spring water, the former will extract from a given portion of tea, a considerable greater quantity of its soluble matter than the latter. The gaseous and other vola- tile bodies contained in water, may be expelled by boiling it; they also par- tially escape, when water freezes, so that water in sufficient purity, for many purposes, may be obtained by melting fresh fallen snow. Such water is flat, tasteless and insipid; the liveliness of water, in its ordinary state, being due to the gases it holds in solution. But the only way of obtaining perfectly pure water, is by distillation in silver vessels, in which process, the saline impurities remain in the distilling vessel, while the water is con- verted into vapor and passes into the condenser.* 319. Physical Properties. Pure water is transparent,xcolor- less, tasteless and inodorous : a non-conductor of caloric, an im- perfect conductor of electricity, and a powerful refractor of light. It is the unit of specific gravity for solids and liquids, and is 828 times heavier than air. At 212° F., the barometer standing at 30 inches, the water boils; it freezes at 32°, and in congealing, shoots into needle shaped crystals, which cross each other at angles of 60 and 120°. 320. If the aeriform bodies that previously existed in water, be expelled by boiling, it absorbs every gas, but in very different proportions; some gases being dissolved in very minute quantities, while of others, water will take up several hundred times its own bulk. The quantity absorbed may be increased by pressure, and is in direct proportion to it; on removal of the additional pressure the excess of gas escapes with effervesence, as in the instance of common soda water. The gas contained in water under ordin- ary atmospheric pressure, is expelled by heat, or by removing the pressure with an air pump. Water has a very extensive range of affinities, and is, therefore, an important chemical agent; it is the most general solvent we oossess. 321. Water enters into two kinds of combination besides solutions, and in these it unites in definite proportions; these combinations exist 1st, in crystals ; 2nd, in hydrates. 1st. Many bodies in crystalizing from their solutions in water, carry with them a portion of water which constitutes an essential part of the crystal, and which cannot be separated without destroying its form and transparency. Water thus combined, is called water of crystalization. It is believed to be in a state of greater solidity in this combination than in the form of ice. It may be expelled by heat; and the crystal will then fall into powder. 2nd. Water exists in another class of compounds called hydrates. Some of these are liquids; for example, the strongest sulphuric acid of commerce * A coffee apparatus invented in France, makes the vapor of water pass through the ground coffee. The aromatic portion is thus extracted, with less of the bitter principle, than in the usual method. The water beingdis tilled before it comes in contact with the coffee, all the impurities of the for mer are left in the boiler. 319. Physical properties of water. 320. Absorption of gases by water. Effect of pressure on absorption Solvent power of water. 321. Compounds where water exists in definite proportions. Water of crystalization. Liquid, and solid hydrates. HYDRACIDS. 123 contains an atom of water to an atom of acid, and is therefore a hydrate of sulphuric acid; the strongest nitric acid, that can be produced consists of one equivalent of acid and two of water. Many hydrates, however, are solid ; and the water they contain is in the greatest state of condensation in which it is known. Much caloric is consequently evolved during the for- mation of hydrates ; thus, in the slaking of lime, which operation is in fact the conversion of pure lime into a hydrate, the heat evolved, amounts to 800° F. Some hydrates are decomposed by heat; but others retain the com- bined water at the highest temperatures. 322. Deutoxide of Hydrogen. 2 ox. 16, to 1 hyd. 1 = 17, its equivalent. This is called deutoxide, (or binoxide) because 2 atoms of oxygen combine with one of hydrogen ; and sometimes the peroxide, it being the highest combination known of oxygen with hydrogen. It was discovered by Thenard in 1818. This substance, cannot be formed by the direct union of the two gases. The only method at present known, is the oxidation of water by means of the peroxide of barium. In this process is added to water a portion of hydro- chloric acid, and the peroxide of barium; the latter, parting with oxygen, is reduced to a protoxide which unites with the hydrochloric acid, while the liberated oxygen unites with the water, converting it into deutoxide of hydro- gen. Sulphuric acid is added to precipitate the protoxide of barium. 323. The deutoxide of hydrogen is transparent and colorless. heavier than water, its sp. gr. being 1.452; it is volatile, inodo- rous, and has a metallic taste. It thickens the saliva, whitens the skin, and is, to a degree, caustic. It bleaches powerfully; its oxygen being considered the active bleaching principle. It is very easily decomposed, either by the contact of other bodies or by heat; and can only be preserved by keeping it at a temper- ature of about 32° F. If heat be applied to it in its concentra- ted state, half of its oxygen suddenly escapes with a violent ex- plosion, and the residual product is water. The deutoxide of hydrogen has not been applied to any of the arts, and at present is only interesting to the Chemist, as a peculiar and striking il- lustration of the doctrine of definite proportions.* CHAPTER XIII. HYDRACIDS. 324. A class of substances possessing acid properties are term- ed hydracids, (or hydro acids,) because they contain hydrogen as * See Thenard's Traitie de chimie, and other elaborate works on this sub- ject. 322. Proportions of the deutoxide of hydrogen. Name. Discovery. Manner in which it may be formed. 323. Properties. Decomposition. Effects of heat upon it. Its action wit>> T^Ptfils and nvides„ Tt.s aoolication to useful purposes. 124 HYDRACIDS. one of their elements. Acids are the most remarkable products obtained by the union of both oxygen and hydrogen with other bodies. And yet, these two gases, so powerful in their combi- nations with other bodies, and standing each at the head of two distinct electro-chemical classes, form by their natural combina- tion with each other, the mild, inoffensive compound, water, with no trace of acid properties whatever. Some of the oxacids or oxyacids, we have already noticed, as Chloric, Iodic, Bromic and Fluoric acids ; and as we proceed to consider the electro-positive bodies, we shall have occasion to describe other important acids formed by a combination of those bodies with oxygen. All acids are formed by the union of a substance called the base or radical, with an acidifying principle. In chloric acid, chlorine is the radical and oxygen the acidifier. 325. Of the radicals of the hydracids, some are simple bodies, and others compound. All the simple radicals are electro-negative, except sulphur; and even that is so while in combination with other electro-positive bodies. The compound radicals are electro-positive in relation to oxygen and other substances of the same class, but go to the positive pole, (and therefore, are electro-negative,) when just separated from combination with hydrogen or a metal. So that as regards the part, they act in composition of a hydracid, they may all, (both simple and compound,) be considered as electro-negative. They all have feeble affinities for compound bodies, but powerful ones for the simple electro-positive substances, and when their compounds with the latter are put into water, (provided they be soluble,) that fluid is decompos- ed, its oxygen unites to the electro-positive elements to form an oxide, and its hydrogen tfnites to the electro-negative radical to form a hydracid. If the oxide thus formed be a salifiable base, it combines with the hydracid to form a salt; if the compound put into water be insoluble, no action takes place. Thus common salt is chloride of sodium; dissolved in water it is muriate of soda, hydrochloric acid being formed by the chlorine and the hy- drogen of the water, and soda by the sodium and the oxygen of the water; but chloride of silver is quite insoluble in water, and undergoes no change in it. When a salt of a hydracid has been thus formed, the binary com- pound of the radical and the metal may be again obtained, by evaporating the solution to dryness, and heating the dry mass to expel the water which is re-formed. 326. The compounds of metals with the radicals of hydracids are called Haloid bodies, from their resembling salts in their characters and habitudes; the name haloid being derived from the Greek hale, sea-salt and oidos, like. 324. Why are the hydracids so named ? Products of the union of oxygen and hydrogen with other bodies, and with each other. The radical and acidifying principle of acids. 325. Radicals of the hydracids. Electrical nature of the simple and com- pound radicals. Effect of water in decomposing compounds formed between electro-positive and electro-negative bodies. Change which takes place in the chloride of sodium when dissolved in water. How may the chloride of sodium, or binary compound of the radical and metal, be again obtained? 326. Haloid bodies. Five most important radicals of the hydracids. Or- der of their affinities for hydrogen. Their affinities for oxygen. HYDRACIDS. 125 Indeed, as had just been stated, they appear to become salts on being dis- solved. The five most important of the simple radicals of the hydracids are, 1. Chlorine, 3. Iodine, 2. Bromine, 4. Fluorine, 5. Sulphur. Fluorine having never been obtained in a separate state, the comparative energy of its affinity for hydrogen is not ascertained. Neither is it known whether it can combine with oxygen or not. The other four radicals, are placed in the above list according to the order of their affinities for hydro- gen ; so that chlorine will decompose hydrobromic, hydriodic and hydrosul- phuric acids, forming hydrochloric acid and liberating the other radicals; Bromine acts in the same way with hydriodics and hydrosulphuric acids ; and iodine with hydrosulphuric acid only. The affinities of*hese bodies for oxygen, are in the inverse order of their attraction for hydrogen : sulphur having the greatest, and chlorine the least affinity for oxygen. 327. The hydracids may be obtained, by pouring strong sulphuric acid on certain compounds, of their respective radicals with a metal. The water, which even the strongest liquid sulphuric acid contains, furnishes hydrogen to the radical and oxygen to the metal; the metallic oxide thus formed, unites to the sulphuric acid and forms a sulphate, and the hydracid is left free. The hydracids are all, in reality gases ; those of chlorine, bromine and iodine contain equal volumes of the two constituents, united without any condensation, so that one volume of the radical and one of hydrogen constitute two volumes of the hydracid. The specific gravity of these three hydracids is therefore half the sum of the specific gravities of their constit- uents. The gaseous hydracids are generally heavier than air, and have strong attraction for water. Some of them are absorbed by that liquid tc the amount of several hundred times its bulk. During the formation of these watery solutions, condensation takes place, heat being evolved, and the liquid resulting is heavier than water. It is in this state of solution that the hydracids are used in chemical operations; heat will expel from the liquid the greater part of the gaseous acid. 328. The hydracid gases are decomposed when electrified with the proper quantity of oxygen gas, water being formed and the radical set at liberty; some of the metals also, decompose them with the aid of heat, uniting with the radical and liberating the hydrogen. The liquid hydracids, that is the solution of the gaseous acids, act differ- ently on different metallic oxides; with some protoxides, the acid combines to form salts ; with others, a mutual decomposition occurs, and water is pro- duced, together with a binary compound of the radical and the metal; but, in such cases, the latter compound is insoluble. Some of the peroxides yield a portion of their oxygen to the hydrogen of the acid, forming water and eliminating the radical; and thus are reduced to the state of protoxides, which combine with the radical acid and form salts. The first process given for obtaining chlorine, (§ 262,) is an example of this decomposition. With some oxides the hydracids do not re-act in any manner. 327. Manner in which the hydracids may be obtained. Nature and con- stitution of the hydracids. Attraction of the gaseous hydracids for water. 328. Their decomposition. What are liquid hydracids, and how do they affect metallic oxides ? 11* 126 HYDROCHLORIC ACID. 329. Hydrochloric or muriatic acid. 1 chl. 36, to 1 hyd. 1=37. Sp. gr. 18. 21 hyd.=l, 1.2694 air=l. This was at first known under the names of marine acid, and spirit of salt, and was regarded as an oxacid, formed by the union of oxygen with an imaginary base, named muriatium ; af- terwards it was called muriatic acid (from muria, sea-salt) which name it retained until the importance of shewing the constitu- ents of bodies by their chemical names had become fully estab- lished. Fie. 62. It is obtained by pouring strong sulphuric acid on chloride of sodium, (com- mon salt,) contained in a tubulated glass retort A, (Fig. 62) and applying heat at C. The tube of the re- tort, B passes under a re- ceiver filled with mercury and inverted over a mercu- rial trough. The water of thesulphuric acid furnishes oxygen to the sodium, and hydrogen to the chlorine; the newly formed oxide of sodium, unites with the sul- phuric acid forming sulphate of soda, and the hydrochloric acid being disengaged, pas- ses through the tube of the retort into the receiver. The dense white fumes which appear over the mercurial trough, are caused by the escape of some portion of the hydrochloric acid gas, which unites with the aqueous vapor of the atmosphere. 330. Physical Properties. Hydrochloric acid is colorless, transparent, and of a peculiar odor. It is irrespirable when pure ; but if diluted with air, may pass into the lungs, but, even in that case, it exerts a corrosive action on them. Its affinity for water is great, a volume of that fluid absorbing 480 volumes of the gas, and forming the liquid muriatic acid. 331. The process of forming hydrochloric acid, is very conveniently per- formed, by an apparatus called, from its inventor, Woulfe's apparatus. (Fig. 63.) The retort a, contains common salt and sulphuric acid ; a gentle heat being applied, the muriatic gas is disengaged and passes into the globe or first bottle, b, which, with the other bottles, contains water. The first bottle serves to condense any vapor which may be mingled with the muria- tic acid gas, and the liquid in this will then be an impure solution of muria- 329. Equiv. and sp. gr. of hydrochloric acid. Synonymes. Mode of ob- taining hydrochloric acid. Rationale of the process. 330. Properties. 331. Mode of obtaining hydro-chloric acid by means of Woulfe's appara- tus. Why should the bottles be kept cool ? Further proof of the affinity of this gas for water. CHEMICAL PROPERTIES. 127 tic acid. From the globe b, the purified gas proceeds through the bent tube to the next bottle, where a portion is absorbed by the water; the excess of gas then passes on, and a portion is, in like manner, absorbed by the liquid. Should some portion of the gas escape absorption, it may by the last tube be conducted under a receiver in the pneumatic cistern. The number of bottles may be increased or diminished. The straight tubes c, c, c, are call- ed safety tubes. While they oppose atmospheric pressure to the escape of the gas, they prevent the vacuum which would ensue from a sudden absorp- tion of the gas, and which might draw in the impure acid contained in the globe. Fig. 63. During this absorption a great condensation takes place, and heat is con- sequently evolved ; so that the bottles used to contain the liquid must be kept cool by ice, in order that the solution may be saturated. As a further proof of the affinity of this gas for water, if a piece of ice be put into a jar of the gas, it will be melted almost as rapidly as by a hot iron; and the gas is absorbed by the water thus formed. 332. Chemical properties. This gas possesses acid properties in a very high degree ; combining with salifiable bases, redden- ing litmus paper, «Stc. j many of the metallic oxides react on it by the aid of heat, water and chloride of the metal being formed ; several of the metals also decompose it by means of their affinity for chlorine ; in such cases, a chloride of the metal is formed and hydrogen gas set free. It is the only known compound of chlo- rine with hydrogen, and composed of equal bulks of chlorine and hydrogen gases, united without any condensation. 333. Nitro-hydrochloric or Nitro-muriatic acid consists of 1 part of nitric acid with 4 of hydrochloric. It was called by the alchemists aqua regia, on account of its remarkable property of dissolving gold and platinum. Soon after the acids are mixed, the liquid grows deeper colored, and, at last, becomes wine col- ored, and chlorine is evolved. On heating the mixture, chlorine and deutoxide of nitrogen are expelled, after which it no longer dissolves gold ; hence it appears that chlorine is the cause of its solvent property with regard to that metal. 334. Hydrobromic Acid is composed of equal volumes of vapor of bromine 332. Chemical properties. 333. Nitro-hydrochloric acid. 334. Composition of hydrobromic acid gas in respect to weight and vol- ume. Resemblance to muriatic acid. How obtained ? 128 NITROGEN. and of hydrogen. In odor, and in other properties it resembles hydrochloric acid. Thus it forms salts with some oxides, and is decomposed by others; it has a powerful affinity for water. It is obtained by exposing bromine to the action of sulphuretted hydrogen gas, when the former takes the hydro- gen, and sulphur is deposited ; or, by mixing bromine, phosphorus and water in a small retort and applying heat; in which case, the phosphorus and bro- mine join in decomposing water, the former taking the oxygen and the lat- ter the hydrogen. It was discovered by M. Balard. 335. Hydriodic Acid contains one volume in bulk of iodine vapor, and one of hydrogen gas, combined without alteration of bulk. It is consequently, constituted like hydrochloric and hydrobromic acid gases, which it also re- sembles in its general properties; being decomposed by the same agents and under the same circumstances. The analogy extends even to its odor and its solubility in water. As the affinity of iodine for hydrogen is less than that of either bromine or chlorine, those substances will each decom- pose hydriodic acid, forming the corresponding hydracid, and eliminating iodine. Hydriodic acid gas, may be made by bringing iodine into contact with sulphuretted hydrogen gas, when sulphur will be set free, and iodine will take its place ; but this process is not commonly to be preferred. The best way of procuring this gas, is to moisten a mixture of iodine and phos- phorus, in a very small retort, and apply heat, collecting the gas over mer- cury. As in the formation of hydrobromic acid gas, the oxygen of the water is taken by the phosphorus; so in this case, the hydrogen combines with iodine. The solution of hydriodic acid gas in water, or liquid hydriodic acid, is best obtained by passing hydrosulphuric acid gas into water in which iodine is held suspended ; the oxygen of the water disengages the sulphur, and the hydrogen combines with iodine. 336. We have treated of hydrofluoric acid, under the head of its radical, fluorine. Hydrosulphuric acid, will be considered under the head of s«Z- phuretted hydrogen, the name by which it is usually distinguished. Hydro- cyanic acid, is a hydracid of a very peculiar nature, but cannot be well un- derstood, until after the composition of its radical cyanogen shall have been explained. CHAPTER XIV. NITROGEN. 337. Equiv. \bH V°l\1(l0A Sp. gr. \ °>9722 ^V=1 » tv- I " weight 14 $ *?• sr' I u Hyd.=l Nitrogen is a permanent gas, and constitutes nearly four fifths of the atmosphere in bulk, If a lighted taper be covered 335. Composition of hydriodic acid gas. Its analogies with hydrochloric and hydrobromic acids. May be decomposed by them. Mode of obtaining it. Liquid hydriodic acid. 336. What other hydracids are there besides the hydrochloric, hydrobro- mic, and hydriodic ? 337. State in which nitrogen exists. Gas which remains when the oxy- NITROGEN. 129 with a large tumbler, or bell glass, the combustion will soon consume the oxygen of the air, and nitrogen will remain. For experiments, nitrogen may be better obtained by burning phos- phorus under a bell glass inverted over water. The phosphorus, combining with the oxygen of the air, forms phosphoric acid, which appears at first in dense white fumes, but soon settles upon the surface of the bell glass, and may be rinsed off in the water. The oxygen being now absorbed from the air, the bulk of the residue will be found, when cooled, to be condensed,* and on testing its properties it will be found to be nitrogen. Dr. Hare has invented the Fig. 64. apparatus here represented (Fig. 64.) for obtaining nitro- gen in large quantities. Phos- phorus is placed in a cup sus- pended in a glass vessel. Wa- ter is introduced by means of the tunnel T. The bladder, B, gives room for the expansion of the air which takes place when the phosphorus is burning. The nitrogen gas having been obtained by means of consum- ing the oxygen, it is expelled by pouring more water into the funnel, which taking its place in the lower part of the vessel expels the gas through the tube P, the stop cock being turned so as to admit it to pass. The gas is thus received into vessels for the purpose of experiment. Slight impurities consisting of carbonic acid, and vapor of phosphorus, may be removed by solution of caustic, potassa, or lime. Several other substances, having affinities for oxygen will absorb it slowly from air, among these, are, protosulphate of iron, and the alkaline hydrosulphurets. Carbon and sulphur, do not con- sume the oxygen of the air so completely as phosphorus does, and the pro- ducts of their combination are sulphurous and carbonic acids, which being both gaseous, would, therefore, remain mixed with the nitrogen, and require * The fact of this diminution of bulk is known by the water over which the bell glass is inverted rising higher in the glass than before the burning of the phosphorus. gen in an inclosed portion of atmospheric air is burned. Obtained for ex- periments. Objections to the use of carbon and sulphur. Obtained from animal matter. Explain fig. 64. 130 ATMOSPHERIC AIR. a separate process for removing them. Nitrogen is a constituent of animal matter, and may be obtained by its digestion in diluted nitric acid. 338. Physical and Chemical properties. Nitrogen is colorless, transparent, tasteless, inodorous, permanently elastic, and lighter than common air. It does not support the combustion of burn- ing bodies, neither will an animal live in it; but in neither of these cases, is it supposed to exert any positive action ; the ef- fects being due merely to the absence of oxygen ; as the innox- ious substance, water, will extinguish flame or destroy animal life by excluding the air, and consequently the oxygen which is necessary to support combustion and respiration. Indeed, ni- trogen seems to possess no active properties, and can only be described by negatives. It tends to combine mostly with the electro-negative bodies ; but even these affinities are not very energetic. As might be expected from its weak affinities, its combinations are generally decomposed with great facility ; the chloride and iodide of nitrogen, are decomposed with loud explo- sion by friction, slight increase of temperature, or the contact of other bodies. Water absorbs only a minute portion of ni- trogen gas. It has a peculiar affinity for caloric, and is an in- gredient in most of the fulminating compounds. 339. Nitrogen was discovered about the year 1770, by Dr. Rutherford of Edinburgh, and Scheele of Sweden. It was at first called mephitic gas, or non-respirable air, and afterwards by the French Chemists, named azote, or life destroyer, (from the Greek, a, to deprive of, and zoe, life.) The latter name implies active properties, such as this gas does not possess. For the name, azote, has been generally substituted that of nitrogen, (from the Greek word gennao to produce, combined with nitro,) signifying to produce nitro, or nitric acid. It constitutes £ of the atmosphere, exists in all animals and some plants, and in springs in Scotland and the state of New-York. Atmospheric Air. 340. The atmosphere is a mass of gaseous matter, surround- ing the earth and accompanying it in its revolutions. It pos- sesses weight, upon which property depends the action of the sucking pump, the barometer, and the support of water or mercu- ry in an inverted bell glass, above the level of the exterior liquid. On weighing a glass flask full of dry air, exhausting it carefully, and 338. Its physical properties. Is not a supporter of combustion. Its af- finities not energetic. Why its compounds are easily decomposed. 339. Discovery and name. 340. Nature of the atmosphere. Its weight. ATMOSPHERIC AIR. 131 weighing again, it will be found to lose weight by the exhaustion in the proportion of 30£ grains for every 100 cubic inches of air withdrawn ;— this being when the barometer stands at 30 inches, and the thermometer at 60° Fahrenheit. Air is, therefore, 831 times as light as water, and about 11260 times as light as mercury. It is taken as the unit of specific gravity for aeriform bodies. 341. From the observations of Dr. Wollaston and others, it seems to be established that the atmosphere is limited; and its extent is estimated at about 45 miles. As the air is more and more rare, as the distance from the earth increases, and as its expansive force decreases in the same ratio as its density, it follows, that there must be a point at which its elastic force is just counteracted by the earth's attraction. If the atmosphere were to expand without limit into space, the sun and the other planets would attract a portion of it to themselves, and would have atmospheres of the same kind as ours; a circumstance which is quite inconsistent with astronomical ob- servation. Dr. Wollaston, from a series of observations, considers that this extreme rarefaction might take place, but for the fact that the atmos- phere consists of indivisible ultimate atoms, that can be no farther rarefied. 342. The atmosphere is highly elastic and compressible. When the pressure upon a confined portion of it is doubled, it will be reduced to half its original bulk ; or, if half the original pressure be removed, it will expand to double its former bulk ; in other words, its density is directly as the pressure, and its bulk in the inverse ratio to that pressure. This law is good also, for all aeriform bodies, so long as they continue in the aeriform state. 343. The temperature of the air is lower as we ascend, for as it must ab- sorb caloric in order to expand, and this can be derived from no external source, it must render latent its own sensible heat; for radiant caloric passes through gaseous and aeriform media, without affecting them ; so that the higher strata of air, though nearer the sun, derive no heat from it. The decrease of temperature is estimated at about one degtee for every 300 feet; so that there is, in every latitude, some point in the atmosphere at which ice never melts. This point at the equator, is about 15207 feet from the earth's surface; and the distance decreases gradually toward the poles, where it is at the earth's surface. 344. The atmosphere is essentially composed of nitrogen and oxygen gases. Many other bodies are found in it, such as car- bonic acid, watery vapor, the odoriferous matters of plants, &c. &c.; of these, the first two are the most constant, and in the greatest quantity ; but even they vary in their proportions, which are never so large, compared to the whole mass, as to allow us to consider these bodies otherwise, than as accidental impuri- ties. The carbonic acid is never more than 6.2 parts in 10.000 of air. 341. Limited extent of the atmosphere. Dr. Wollaston's argument drawn from the limited extent of the atmosphere respecting ultimate atoms, 342. Elasticity and compressibility of the atmosphere. Temperature, 343. Gradual decrease of temperature, 344. Composition of the atmosphere. 132 ATMOSPHERIC AIR. Eudiometry. 345. After the discovery of oxygen, it was for some time believed, that the proportion in which it was contained in the atmosphere, varied at differ- ent times and places; and that the salubrity of a place, depended on the quantity of oxygen in the air around it. Hence the analysis of*air was call- ed "Eudiometry," or the "measurement of quantity," and this name has been retained, though the supposition from which it arose, has been shown to be false. Many eudiometers have been invented. They consist, in general, of tubes adapted to an apparatus for absorbing, or consuming the oxygen of a given quantity of air, and for measuring the residuum. The purity of the air is estimated by the quantity of oxygen which it is found to contain. Various substances which will absorb, or disengage the oxygen from a confined por- tion of air, and neither mix with, nor affect the volume of nitrogen, have been used in eudiometry. But the only analysis of air susceptible of perfect accuracy, is founded on the constancy of the proportion in which oxygen and hydrogen unite when burned together. 346. If we put into a strong tube inverted over mercury, 5 measures of dry air, and add to this, 2 measures of pure and dry hydrogen gas, and then explode the mixture by the electric spark, or otherwise, we shall find after the tube has cooled, that just three measures have disappeared, and that the mercury has risen to fill their places. Now of these three measures, two we know to be hydrogen ; and we also know that two measures of hy- drogen, by explosion, condense one measure of oxygen. If we add more hy- drogen to the residual four measures of gas, we can no longer produce an Fig. 65. explosion; whereas, if we had not originally added enough hy- drogen, there would still have remained an excess of oxygen after the experiment. . 347. Five measures of air, then, contain exactly one measure -0 of oxygen ; and the remaining four measures, on examination, will prove to be nitrogen. This is the composition of atmos- pheric air ; and the same unvarying result has been obtained at whatever season, height, or latitude the air may have been collected for experiment. So that it may be considered esta- blished that the atmosphere throughout, its whole mass, con- sists of nitrogen and oxygen gases in the proportion of 80 per cent, of the former, and 20 per cent, of the latter. The appara- tus for performing the analysis, has been made in various forms. It is always, essentially, however, a strong glass tube a, (Fig. 65.) open at one end ; and perforated near the closed end, by two metallic wires 6 b, of which the points are opposite anil within one tenth of an inch of each other. These wires serve for passing an electric spark into the mixture of gases. 60- 345. Origin of the term eudiometry. Construction and use of eudiome- ters. 346. Manner in which the constitution of the air may be demonstrated. Proportions Qf oxygen and nitrogen contained in it. These proportions do not vary. 347. Apparatus for analyzing the air. ATMOSPHERIC AIR. 133 348. The atmosphere is generally regarded as a mechanical mixture of the two component gases. Some, however, prefer the supposition, that it is a chemical compound. The reasons for the latter opinion are, briefly, 1st. That the proportions of nitrogen and oxygen are everywhere the same ; whereas, if air were a mere mixture, the heavier gas would be found most abundantly, in the lower strata. 2nd. The proportions are definite, and accord with the numbers established as the atomic weights of oxygen and nitrogen; agreeably to which, the atmosphere consists of two atoms of the latter to one of the former. But the investigations of Mr. Dalton, and especially of Dr. I. K. Mitchell of Philadelphia, have proved, that gases have a strong tendency to diffuse themselves through each other, contrary to gravity, and in spite even of the interposition of a bladder or thin sheet of india rubber ; and this, too, when no chemical affinity can be supposed to exist between them. If we fill a phial with hydrogen gas, and another with carbonic acid gas, connect them only by a capillary tube, and place them so that each gas shall be in its natural position, viz., the light hydrogen above, and the heavy carbonic acid below; it will be found after some time, that the carbonic acid has ascended, and the hydrogen descended, contrary to gravity in each case; and that the gases are equally mixed in both phials, fn this case, no chemical affinity has been supposed to exist between the gases operated on. Furthermore, the facility with which bodies possessing affinities for oxygen, attract it from the atmosphere, is too great to admit the belief that it is chemically combin- ed there. Again, the specific gravity and refracting power of the air, are arithmetical means between those of nitrogen and oxygen; whereas, in cases of chemical combination, these two properties seldom escape altera- tion. And lastly, by merely mixing the two gases in the proper proportions, we can imitate the atmospheric air perfectly; whereas, it is only with great difficulty that we can make them combine, so as to produce one of the un- doubted compounds of nitrogen and oxygen. It seems, therefore, highly probable that the atmosphere is a mere mixtirre of its components. 349. The oxygen of the air is the active constituent; to it are owing the agencies of air in supporting combustions and respirations, and in most of the chemical changes in which it is concerned. The use of the nitrogen is not fully ascertained. It is generally held to be a mere diluent, by means of which, the oxygen is prevented from stimulating the system too highly. There is, however, little doubt that some nitrogen is absorbed in the process of respiration. It might be supposed that the immense consumption of oxy- gen in combustions, respiration, spontaneous decompositions, and other operations, which are incessantly going on, would ultimately alter the pro- portions of the constituents of the atmosphere, to an extent that would ren- der it unfit to perform its office. Doubtless this would be the case without some compensating circumstance. Only one such circumstance is known, and that is vegetation. It is ascertained that plants in the day-time, absorb carbonic acid, of which they appropriate the carbon, and restore the oxygen to the atmosphere. In the night, the contrary process goes on ; the vegeta- bles absord oxygen and evolve carbonic acid. But it appears that the quan- 348. Objections to the theory that air is a chemical compound of the gases and not a mere mechanical mixture. Answer to these objections and argu- ments in favor of the theory. 349. Agencies of oxygen and nitrogen in the atmosphere. In what man- ner is it known, that air is replenished with oxygen, to make up that which it loses by combustion, respiration, &c. Do the other compounds of nitro- gen and oxygen resemble atmospheric air? 12 134 NITROGEN AND OXYGEN. tity of oxygen absorbed in the night, is less than that given out during the day; so that vegetation tends to preserve to the atmosphere its due portion of oxygen. Whether this cause is alone sufficient, or whether oxygen is furnished by other sources is a question yet to be decided. On account of the doubt which exists, whether air is a mechanical mix- ture or chemical compound of nitrogen and oxygen, we have treated of it under a separate head. All the certain chemical combinations of these two gases, are widely different in their properties, from this mild and inoffensive agent. Chemical Compounds of Nitrogen and Oxygen. 350. There are five compounds of nitrogen and oxygen, all of which conform strictly to the law of multiple proportions. The three highest in oxidation are acids; at the ordinary tempera- ture, their natural form is that of liquids, exceedingly volatile, and uniting in all proportions with water. The remaining two are gases, neither acid nor alkaline, and with little affinity for water. Definite compounds of oxygen and nitrogen. Protoxide of nitrogen, Nitrogen 14 added to oxygen 8 Deutoxide of nitrogen, " 14 " " 16 Hypo-nitrous acid, " 14 " « 24 Nitrous acid, " 14 « " 32 Nitric acid, " 14 « " 40 351. Protoxide of Nitrogen is the well known exhilarating gas, often called nitrous oxide. It is prepared, by heating nitrate of ammonia in a small glass retort, and may be collected over wa- ter, which should be warm, in order to prevent, as much as pos- sible, the absorption of the gas. Care must be taken that the temperature does not rise above 500° F.; the melted salt should be kept in a state of uniform and moderate effervescence, till the whole disappears or enough gas has been collected. The rationale is as follows. Nitric acid and ammonia constitute the salt called nitrate of ammonia. Nitric acid consists of nitrogen, 1 equivalent, and oxygen, 5 equivalents. Ammonia contains nitrogen, 1 equivalent, and hydro- gen, 3 equivalents. The 3 equivalents of hydrogen with 3 of oxygen form 3 of water; and the remaining 2 equivalents of oxygen with the 2 of nitrogen, constitute 2 equivalents of nitrous oxide. 352. Physical and chemical properties. Nitrous oxidp gas is colorless, has an agreeable but faint odor, and a sweetish taste, and dissolves in about its bulk of water at 60°. Its specific 3:0. How many chemical compounds of nitrogen and oxygen are there? Names and constitution of these compounds. 351. How is the protoxide of nitrogen prepared ? Rationale. 352. Properties. Why do bodies burn in this with more brilliancy than in common air ? RESPIRATION. 135 gravity is about 1.5. In mixture with an equal bulk of hydro- gen, it explodes violently, on the application of flame, or the electric spark. As a given bulk of this gas contains 2£ times as much oxygen as an equal bulk of air, bodies burn in it with proportionate brilliancy. Thus, a recently extinguished candle, of which the wick is still red hot is relighted, on being plunged into it, and burns with great splendor. Sulphur and phosphorus, previously ignited, burn very rapidly and brightly, when immersed in this gas. The combustibles, in these cases, unite with the oxygen of the gas, and set the nitrogen free. 353. Respiration. Exhilarating gas was shown by Davy to support respiration for three or four minutes, but no longer. It produces strong excitement, usually of an agreeable kind, with a rapid flow of ideas, and an irresistible propensity to some kind of muscular action. It has been supposed that by this test the real character of an individual was developed; but the grave sometimes become suddenly gay, the coward bold, the meek quarrelsome ; and it might as justly be said, that insanity ex- hibits the real disposition. Some instances have occurred in which instant and alarming insensibility, and mental derange- ment have resulted from its respiration.* 354. Deutoxide of nitrogen, called also binoxide, nitrous gas, and nitric oxide. Most of the metals, and many other oxidable bodies take a portion of the oxygen from nitric acid when brought into contact with it. In all such instances, the nitric acid is re- duced to some of the lower compounds of nitrogen and oxygen ; and, in a few cases it is entirely deprived of oxygen, so that pure nitrogen only remains. The degree of reduction depends on the comparative affinity of the metal for oxygen. In most cases, nitric oxide is one of the products, and in some, the only one. It is evolved when copper is acted on by nitric acid mod- erately diluted. If the operation be performed in the open air, the deutoxide of nitrogen which is evolved instantly combines with oxygen and produces nitrous acid, which appears in dense red fumes ; but if it be performed in close vessels, and in a re- tort the beak of which is plunged under water, the production of red fumes only lasts till the oxygen of the air in the vessel is * We have witnessed several cases of fainting and spasms in young per- sons after inhaling the exhilarating gas, and would never advise anyone to venture upon this dangerous experiment, but under the direction of a prac- tical and experienced chemist; and we might add also with a physician near at hand. 353. Its power of supporting respiration. Effects on the human system. 354. Synonymes. How produced from nitric acid ? 136 NITROGEN. consumed ; after which, the nitric oxide comes over very rapidly, and may be collected under an inverted bell glass filled with water. Fig. 66. 355. Let some copper filings be put into a retort, (Fig. 66,) and nitric acid be poured in at the tubulure; place a lamp under the retort, the beak of the latter being immersed in water below the perforated shelf which sup- ports the inverted bell-glass. A vio- lent action takes place between the copper and nitric acid, and the red fumes of nitrous acid, fill the retort and pass over into the pneumatic tub where they are absorbed by the wa- ter ; after this, the oxygen in the re- tort being consumed, a colorless gas appears, which does not unite with wa- ter, but ascends into the bell-glass taking the place of the water with which it had been filled. This is the deutoxide of nitrogen, or nitric oxide. 356. Physical and chemical properties. It is colorless; its specific gravity is 1.04, and it is sparingly absorbed by water. When oxygen, either alone, or in mixture with other gases, is admitted to a jar containing nitric oxide, brownish-red fumes of nitrous acid vapor appear; these are immediately absorbed by water. Nitric oxide forms feeble combinations with alkalies and alkaline earths; but as it has no action on blue tesj paper, it cannot be considered an acid. It supports the combustion of charcoal and phosphorus, which burn brilliantly in it; extin- guishes a candle and burning sulphur. Hydrogen does not ex- plode with it, but the mixture burns with a brilliant flame, of a a greenish white color. In all cases of combustion in this gas, the combustible becomes oxidized, and nitrogen gas is liberated from the deutoxide. It is irrespirable on account of its causing a spasmodic closing of the glottis. It is partially decomposed by a red heat, or by a succession of electric sparks. Iron filings attract part of its oxygen and convert it into the protoxide. Potassium, when heated in it, takes all its oxygen and liberates its nitrogen, and therefore affords an accurate mode of analyzing this gas. 357. As red fumes of nitrous acid, which are absorbed by water, are al- ways produced when nitric oxide is mixed with atmospheric air, this pro- perty of nitric oxide is made use of in eudiometry, or the analysis' of air in order to ascertain the proportion of oxygen. As in two volumes of nitric ox- ide, a volume of nitrogen is combined with one volume qf oxygen (occupying the same bulk as if merely mingled,)—to convert this nitrous oxide into ni- 355. Mode of obtaining deutoxide of nitrogen. 356. Physical and chemical properties. 357. Eudiometry by means of action of the protosulphate of iron with ni- *±k\j OX1Q6* NITRIC ACID. 137 trow acid, one volume of oxygen must be added. Of course, if nitrous acid be the product, one third of the deficit produced, would be the quantity of at- mospheric oxygen present.* 358. Hyponitrous Acid. When a mixture of nitric oxide and oxygen is confined over mercury, with strong solution of potassa, the alkali is gradually neutralized ; the two gases com- bining to form hyponitrous acid which unites with the potassa. This acid has not yet been obtained in a separate state. It was discovered by Gay Lussac. 359. Nitrous Acid, called fuming nitrous acid. It is very volatile, is usually seen in the form of a red vapor, and has, until recently, been described as a gas. It is properly a liquid, and may be obtained in that form, by heating nitrate of lead to a dull red heat. The receivers must be dry, and kept cool with ice or snow. The heat decomposes the nitric acid of the nitrate of lead, and resolves it into oxygen and nitrous acid. Nitrous acid is powerfully corrosive, of an orange color, pungent odor, and sour taste. It reddens litmus paper, and when added to solutions of the alkalies, seems to be converted into nitric acid, for the resulting salt is a nitrate, and not a nitrite. It boils at 82° Fahrenheit, and evaporates with very great rapidity, when exposed to air. When once mixed with air or other gases, it cannot be again liquefied without great pressure or intense cold. Nitrous acid can be obtained in the form of vapor, by mixing two meas- ures of deutoxide of nitrogen, with one of oxygen, in a glass vessel which has been dried and exhausted of air. The vapor cannot be kept over mer- cury, for it parts with oxygen to the metal; nor over water, for the liquid absorbs it. It unites with water in all proportions. A very weak solution is pale blue ; as more of the acid is gradually added, the solution passes through several shades of green and at last becomes orange colored, like the dry acid. It is supposed that water at first decomposes nitrous acid, resolv- ing it into nitric and hyponitrous acids, and that the blue tint is due to the latter. After the water becomes saturated to a certain point, this decom- position ceases, and the nitrous acid begins to dissolve unchanged. At this period, the red color of the nitrous, with the blue of the hyponitrous acid, produces the green. At last, the quantity of nitrous acid is such, that its color predominates over, and hides the other color entirely. 360. Nitrous acid parts, rapidly, with its oxygen to combusti- ble bodies, metals, &c, oxidizing some with such rapidity as to set them on fire. It is commonly reduced to deutoxide of nitro- gen ; but in some cases of violent action, it is totally deprived * For a description of Dr. Hare's apparatus for analyzing atmospheric air by means of nitric oxide, see Chemistry for Beginners, page 99. 358. Hyponitrous acid. 359. Nitrous acid. How obtained in the liquid form. Properties. Ob- tained in the form of vapor. Union of this acid with water. Changes of color in its solution. 360. Inflammable nature of nitrous acid, and decomposition. 12* 138 NITRIC ACID. of oxygen; and in others, it is reduced to protoxide of nitrogen It is totally decomposed by a red heat. 361. Nitric acid is known in commerce under the name of aqua fortis: There are two kinds, the single, and double; the latter being twice as strong as the former. This acid is procured by mixing nitrate of potassa, or nitre, commonly called salt-petre with strong sulphuric acid, and distilling the mixture. The proportions differ in different manufactories, and the quali- ties of the acid obtained, vary accordingly. The least quantity of sulphuric used, is half the weight of the nitric; the largest, is an equal weight. Experiment. Nitric acid on a small scale, may be pro- cured with the apparatus here represented ; a is a re- tort (Fig. 67.) containing pounded salt-petre and sul- phuric acid ; b, is a receiver communicating with the ves- sel c. The lamp, d, serves for heating the retort; the stands, with sliding rings, e e, support the retort, lamp, and receiver. Rationale. Sulphuric acid decomposes salt-petre (ni- trate of potassa,) by uniting with potassa ; the nitric acid being liberated passes from the retort into the receiver 6, and from thence into the bottle, c, and is ab- sorbed by water, of which the bottle contains a small portion. On examin- ing this water it will be found to be weak nitric acid. Those who manufac- ture nitric acid for pur- poses of commerce, make use of large iron retorts set in brick work (Fig. 68) and communicating with receivers made of earthen ware, furnished with stop cocks, the last of which has a safety tube commu- nicating with a vessel of water. 362. The theory of the operation in the manufac- tory of nitric acid, is ob- vious. Nitre is a com- pound of nitric acid and potassa, the sulphuric acid being added, combines with the potassa, and forms sulphate of potassa, excluding the nitric acid, which being vaporized by heat, is condensed in cool receivers. illlllOv; mntiiiiniiiiinimiiiiiiiiiumiiiii|nnini;ii 361. Common name of nitric acid. How procured. Exp. Rationale. Manufacture of nitric acid for commerce. 362. Theory of the operation in the manufacture of nitric acid. NITROUS ACID. 139 363. Nitric acid may be formed directly, for the purpose of demonstrating its composition synthetically, by passing electric sparks through a mixture of oxygen and nitrogen gases confined over a solution of potassa. It is believed that a portion of the native nitrates owe their origin to the formation of nitric acid from the elements of air, by the electric discharge during thunder storms; this acid being carried to the earth by the rain, acts on the oxides and carbonates with which it comes in contact. 364. Physical and chemical properties. Pure nitric acid is col- orless and transparent. It is commonly found of specific grav- ity'1.42. It gives off white fumes when exposed to moist air; unites with water in all proportions with the evolution of heat; is sour to the taste, reddens litmus paper and combines Avith salifiable bases to form neutral salts. It attracts watery vapor from the air. Its affinity for water enables it to melt snow very rapidly, by which liquefaction, great cold is produced. Nitric acid becomes red and fuming, by much exposure to light; for that agent decomposes it, resolving it into oxygen gas, which is evolved, and nitrous acid which gives the color. Deutoxide of nitrogen also decomposes nitric acid, taking part of its oxygen ; by which process the nitric acid and the deutoxide are both brought to the state of nitrous acid. By red heat it is totally decomposed into oxygen and nitrogen gases. It also readily parts with oxygen to most bodies which have an affinity for it, and is, therefore, a very powerful oxydizing agent. For this reason it increases the combustion of red hot charcoal; and al- so converts sulphur and phosphorus into sulphuric, and phos- phoric acids. It oxidizes tin, copper, iron filings, powdered zinc and some other metals, producing violent action. Animal and vegetable substances are powerfully attacked by this acid, and some of them, such as volatile oils, are set on fire by the rapid oxidation. It stains the skin yellow, destroying the cuticle, and causing deep ulceration if not speedily removed. The caustic power of nitrate of silver, (lunar caustic,) is due to the acid which enters into its composition ; and the acid is oc- casionally substituted for the salt, as a caustic. In all these cases, the nitric acid is deprived of a part of its oxygen, and is reduced either to nitrogen, or one if its oxides. 365. The salts of nitric acid, called nitrates, possess the 363. Nitric acid formed by electricity. Supposed origin of some of the native nitrates. 364. Physical and chemical properties of nitric acid. Decomposition by light. By deutoxide of nitrogen. By heat. Why a powerful oxidizing agent. Its effect on animal and vegetable substances. "365. Salts of nitric acid. 140 NITROGEN. power of imparting oxygen to other bodies by the aid of heat, and are therefore known as deflagrating salts. We shall consider them more fully under the head of salts. 366, The most delicate of all tests for nitric acid is indigo, the blue coloi of which is destroyed by it, and converted into a yellow. The mode of ap- plying the test is to dissolve some indigo in cold, dilute sulphuric acid, and add enough of the solution to produce a distinct blue color in the separated liquor; then drop in a little more sulphuric acid to takeaway the base with which the nitric acid is combined; the nitric acid, being thus set free, acts on the indigo. 367. History. Nitric acid was discovered by Raymond Lully an alchemist in distilling a mixture of nitrate of Bolona- and clay. Basil Valentine, in the 15lh century described it as the water of nitre. In 1785 Mr. Cavendish of England discovered it to be composed of oxygen and nitrogen. CHAPTER XV. NITROGEN AND ITS COMPOUNDS. Nitrogen and Hydrogen, or Ammonia. 368. Ammonia. 1 nit.=14> to 3 hyd.=S. Equiv. 11. This is a permanent gas, colorless, and transparent, of an irritating and pungent odor, and a burning and caustic taste. It is not respirable except diluted with air. If inhaled through the nostrils, it irritates them, and produces a flow of tears. It is used medicinally to neutralize acidity in the stomach, and is a powerful tonic and stimulant. Ammonia combines with all the acids, neutralizing them and producing a distinct class of salts, most of which are crystallizable and soluble. When ammoniacal gas is mixed with any gaseous acid, as the muriatic, carbonic, &c, dense white fumes appear, and the acid and ammonia combine to form a salt, which is depos- ited on the vessels as a white powder. Ammonia extinguishes burning bodies which are plunged in it. It will not burn in atmos- pheric air ; but a small jet of it burns in pure oxygen. When a lighted candle is put into it, the flame becomes yellow, and en- larged for an instant before it is extinguished, owing to a mo- mentary combustion of ammonia. Ammonia may be detonated by the electric spark when in mixture with oxygen. The products of the detonation are water and nitrogen, with a 366. Indiso a test for nitric acid. 367. History. 368. Composition and equivalent of ammonia. Physical Properties. Its combinations. White fumes of ammonia, how caused.' Effect of ammonia on burning bodies. Detonation. Decomposition by electricity and heat. AMMONIA. 141 little nitric acid. It is resolved into nitrogen and hydrogen gases by a suc- cession of electric sparks, or by passing it through red hot tubes ; and the two gases occupy twice the bulk of the ammonia. By adding oxygen to the mixed gases and exploding by the electric spark, it is found to be composed of one and a half volume of hydrogen to half a volume of nitrogen, conden- sed to one volume; or by weight, of 3 equivalents of hydrogen and 1 of ni- trogen. Ammoniacal gas is brought to the liquid state by a pressure of 6£ atmospheres, or about 97 pounds to the square inch. 369. The alkaline properties of ammonia are well marked. It turns the yellow color of turmeric paper brown ; but as the am- monia soon evaporates, the yellow color is restored. Although it is a strong alkali, its elasticity favors the decomposition of its salts ; so that they are decomposed by any of the fixed alkalies, or by the alkaline earths. This fact furnishes means of procur- Fig. 69. ing ammoniacal gas. 370. The materials commonly used are hydrochlorate of ammonia, (sal ammoniac) and slaked lime. The odor of ammonia is perceived as soon as they are mixed in a mortar. The proportions used are equal weights of the two articles. On heating this mixture in a glass retort (Fig. 69.) the gas comes over abundantly mingled with watery vapor. To separate the lat- ter, there should be an intermediate re- ceiver containing fragments of caustic potassa, or chloride of calcium. If the" latter is used, some of the gas will be! absorbed as well as the watery vapor." The dried gas should be collected over mercury. Rationale. The lime combines with hydrochloric acid, and the ammonia passes off in The gas of ammonia has a powerful affinity for water. Its solution is " aqua ammonia," and " spirits of hartshorn." It is the form under which ammonia is used in the operations of a labo- ratory. Aqua ammonia is ob- tained by passing a stream of the gas into distilled water. Exp. The retort, (Fig. 70) con- taining hydro-chlorate of am- monia and lime is subjected to heat; ammoniacal gas rises, and is received in a vessel containing jjj cold water, by which it is rapidly absorbed. Fip-. 70. 369. Its alkaline properties. Liquefaction of ammonia. Decomposition of its salts. 370. Exp. Mode of obtaining ammonia. Proof of its affinity for water. 142 HISTORY OF" AMMONIA. The solution is transparent and colorless. It is lighter than water. If exposed to the air, it absorbs carbonic acid, and is converted into bi-carbon- ate of ammonia. A very common and convenient method of obtaining the gas is by heating the solution in a retort. Exp. The retort a, (Fig. 71,) contains liquid ammonia which being heated by the lamp 6, ammoniacal gas evolves, and as it is lighter than air, it rises and takes its place in the upper vessel. The affinity of ammoniacal gas for water may be furthei shown by letting a small quantity of it escape into moist air, where on account of its union with aqueous vapor it will cause a cloudy appearance. If a piece of ice be passed into ajar of this gas, it is liquefied by it immediately; and the gas disappears, being absorbed in the water produced by the melted ice. Smelling bottles are filled with some salt of ammonia mix ed with a fixed alkali, to develope the ammoniacal gas. The usual materials are carbonate of ammonia, and carbon- ate of soda or potassa ; for the tendency of the fixed alkalies, iiBil f\ form oi-earbonates, enables their neutral carbonates to decompose car- bonate of ammonia. The odor is improved by the addition of some fragrant oils or spices. The salts of ammonia are inodorous, except the carbonate. But they are easily detected by the action of heat, and by the development of the odor of ammonia on adding a fixed alkali. Free ammonia may be also detected by the white fumes formed on the approach of a rod dipped in hy- drochloric acid; and by its temporary action on moist turmeric paper. (See IT 369.) 371. Nitrogen and hydrogen gases cannot be made to combine directly; but in their nascent state, or at the instant in which they leave other combinations, they then unite, and form am- monia ; this is always one of the products when animal matter undergoes decomposition, either spontaneously or by means of heat. History. Ammonia was long known as volatile alkali, spirit of sal ammoniac, hartshorn, &c. Dr. Priestly called it alkaline air. This gas was first procured from sal ammoniac (or salt of am- monia,) a salt obtained from the temple of Jupiter Ammon, in Lybia, to which is referred the origin of the name. 372. Hydrochlorate, or Muriate of Ammonia. This salt com- monly called " sal ammoniac''' is obtained by saturating hydro- chloric acid with ammonia or its carbonate. Its chemical equivalent is 63 ; it being constituted of 1 mu. acid 37 add 1 am. 17, add 1 water 9=63. Aqua ammonia. How obtained ? Properties of this solution. Effect of this gas upon ice. Smelling bottles. Tests for the salts of ammonia. 371. In what state nitrogen and hydrogen unite. History. 372. Hydrochlorate of ammonia. CHLORIDE OF NITROGEN. 143 373. Exp. 1st. Into one retort a, Fig. 72. (Fig. 72.) put a small quantity of hy- drochloric acid, and into another a, li- quid ammonia : from each liquid gases will be evolved, and passing into the cylinder unite and form dense white fumes, which at length settle in solid concretions on the inner surface of the glass cylinder; this precipitate is hy- drochlorate of ammonia. It may be formed directly by mixing equal measures of ammoniacal and*—-*-------—'--------'' ''— hydrochloric gases. Exp. 2d. Let A and B, (Fig. 73.) be two Fig. 73. flasks with bent tubes containing the gases which f meeting in the bottle C, are condensed, and form If hydrochlorate of ammonia. » 374. Nitrate of Ammonia is composed Jl of 1 atom of nit. 1 of am. and 1 of water, ^t It is readily formed by saturating nitric( b acid with carbonate of ammonia. The V_ solution affords crystals by evaporation. If evaporated at 100° Fahrenheit, the crystals are large, striated prisms. If at 212° Fahrenheit, the crystals are fibrous. And at 300°, no regular crystallization takes place. This salt in any form, is deliquescent. It dissolves in water so rapidly as to pro- duce great cold, which is increased if ice or snow be substituted for water. Heat decomposes this salt at about 400° Fahrenheit. Water and protoxide of nitrogen are the products. Suddenly heated to 600°, it explodes violently, forming water, nitrous acid, deutoxide of nitrogen, and nitrogen. The tendency which the ele- ments of the acid and alkali have to form other compounds, and the volatile nature of those compounds, will account for the explosion. 375, Chloride of Nitrogen. 4 Chl. 144 added to 1 Nit. 14 = 158 ; this substance from its composition may properly be called quadro-chloride, having/ow measures of chlorine. Chlorine does not combine with nitrogen, when both are in the gaseous state ; but if one of these gases is in the nascent state, it will unite with the other, if present. Chloride of nitrogen is the most explosive compound known, and is exceedingly dangerous. It is exploded by a gentle heat, by slight friction, by agitation, and by the con- 373. Exp 1st. Exp. 2d. 374. Composition of nitrate of ammonia. How formed. Crystals. Its deliquescence. Action of heat. Cause of explosion by heat. 375. Composition and equivalent of chloride of nitrogen. In what state chlorine combines with nitrogen. Explosive nature of chloride of nitrogen. Manner of transferring it. Cause of its ready decomposition. Violent ex- plosion, and products of the detonation. M, 144 CARBON. tact of many combustible substances ; as a rod dipped in olive oil produces detonation the instant of contact. Fig. 74. The experiment should be made on a globule no larger than (7^ a mustard seed, which should be placed at the bottom of a deep leaden vessel, the water will be dispersed, and the vessel, per- haps, rent. The manner in which this yellow oil-like fluid is transferred from one vessel to another, is by drawing it into a M glass syringe (Fig. 74.) having a pointed orifice, and a copper wire with a bit of tow wound closely round it for a piston ; thus a globule of very small size may be drawn into the tube, and de- posited in the vessel prepared for the detonating experiment. The facility with which the decomposition takes place, is due to the small affinity of chlorine and nitrogen, and their strong ten- dency to resume the gaseous form; and the great violence of the explosion, is of course, the result of their immense expansion in passing from the liquid to the aeriform state. The products of the detonation, are chlorine and nitrogen gases. This experi- ment should never be made without strong gloves and glass i i masks. Its discoverer, Mr. Dulong, received a severe wound, J J in experimenting with it; and Sir Humphrey Davy had his eyes £/ seriously injured in the same manner. 376. Bromide of Nitrogen. This substance has similar proper- ties to the chloride of nitrogen, and may be formed in a similar manner. 377. Iodide of Nitrogen. This is a black powder, obtained by pouring a solution of ammonia on iodine. It is very explosive ; but as one of the con- stituents is naturally a solid, the explosion is not quite so readily produced, nor so violent, as that of the chloride. It is resolved by the detonation, in- to nitrogen gas and vapor of iodine. The iodide of nitrogen is supposed to consist of 3 equivalents of iodine=;372 added to 1 nitrogen 14=386; and may properly be termed, a Teriodide of nitrogen. CHAPTER XVI. CARBON. orvo p • S by vol. 100. > 0 ( 3.05 Water =1 378. Equzv. j ywdgM 6 j Sp. gr. j 6 ^ Ry^ =1 Vegetable and animal bodies consist, essentially, of car bon, oxygen, hydrogen, and sometimes nitrogen. Many of them contain, also, several alkaline and earthy salts, and siliceous mat- 376. Bromide of nitrogen analogous to the chloride. 377. Properties and constitution of iodide of nitrogen. 378. Essential constituents of vegetable and animal bodies. Accidental components. Mineral substances most abundant in the bark of vegetables. Products of the combustion of organic bodies when burnt in the open air. Diflerent products when air is excluded. Volatile products of destructive distillation. Charcoal. CARBON. 145 ter, which are considered as accidental rather than necessary components. Growing vegetables derive their mineral substan- ces from the soil in which they grow, and these are found more abundant in the bark where the circulating vessels are situated, than in the wood. When organic bodies are heated in the open air, the atmospheric oxygen combines with carbon, to form car- bonic acid; and with hydrodgen to produce water ; and the pro- ducts of the combustion, being essentially gaseous, or very vola- tile, are dissipated, forming that very complex mixture of gases and vapors, called smoke. The alkaline and earthy salts, and siliceous matter not being either combustible or volatile, remain on the hearth, constituting ashes. But the results are quite different, when air is excluded. The organic matter is then decomposed by the agency of heat, and most of its elements re-combine in various forms. The volatile products of this process, (called destructive distillation,) are ex- ceedingly complicated. Among them, are impure vinegar, call- ed pyroligneous acid ; and acid and fetid oil, to which the name empyreumatic oil has been given ; carburetted hydrogen or illu- minating gas ; carbonic acid, ammonia, and watery vapor. The oxygen contained in these products, is that which belonged to the composition of the organic matter; and as this is never sufficient for the complete oxidation of the carbon and hydrogen, a large proportion of the former remains after the experiment. This, together with the ashes, constitutes charcoal. 379. There, are several varieties of charcoal, of very differ- ent degrees of purity, but all deriving their common character- istics from the combustible element, carbon. Lamp-black is one of the purest of the common varieties. It is obtained by burning refuse oils and resinous r itters in chambers hung with coarse matting. The smoke deposits free carbon upon the matting, whence it is swept off and collected. Ivory-black, is an animal charcoal, and is obtained by heating bones ex- cluded from air. It contains more earthy matter than vegetable charcoal, and is therefore more impure; but is best for some purposes. The ashes it contains, are principally phosphate and carbonate of lime, which consti- tuted the hardening matter of the bone. The ivory-black obtained in this manner, is that usually met with in commerce. The real ivory-black is ob- tained from ivory. All the varieties of pit coal, or mineral coal, are carbon, more or less im- pure ; and are supposed to be derived from the spontaneous decomposition of vegetable matter. Some of them burn with flame, on account of their containing bituminous matter. Sulphur is a very frequent ingredient; and 4 the matter of ashes abounds in them. The ashes of mineral coal, however, 379. Varities of charcoal. Lamp-black. Ivory-black. Mineral coal. Its origin. Why some kinds burn with flame. Difference in the ashes of mineral and vegetable charcoal. Anthracite. Plumbago. Coke. 13 146 DIAMOND. differ from those of vegetable charcoal. The greater difficulty of igniting them, is chiefly owing to their greater compactness and density. One of the densest and purest varieties of mineral coal, is Anthracite, which contains more than 90 per cent, of carbon. Plumbago, or black lead, is carbon combined with a very small proportion ofmetallic iron. Its com- position is variable. Coke, is a very dense and impure variety of carbon, obtained by the distillation of bituminous coal. The leading object of the distillation, is the furnishing of gas for illumination, which is' evolved in large quantity. Coke is the residual product. It is exceedingly difficult of combustion, but when burning in a blast furnace, gives an intense heat. Mixed with wood charcoal, it is largely used in smelting iron ores, and other metallurgic operations ; and its importance is such that coal is frequently distilled for the sake of the coke, though the gas be wasted. 380. Carbon in its purest form, as obtained artificially, may be made by passing the vapors of alcohol, ether, and the vola- tile oils, through porcelain tubes, heated red hot. The purest native variety of carbon, is the diamond, which is chrystallized carbon. Many attempts have been made to make diamonds, by fusing and by crystallizing carbon, but without success. It resists fusion, even in the intense heat of a power- ful galvanic apparatus, and no menstruum has been found to deposit it in crystals. The diamond is the hardest body known. It is generally colorless, but sometimes tinted. It has a highly crystaline structure, its primitive form is an octahedron. It is a most powerful refractor of light, to which, with the angular forms into which it is cut, it gives its brilliant play of colors, called its water. Newton conjectured the combustible nature of the diamond, on account of its great refractory power, before Fig. 75. any proof of this property had been obtained. It may be con- sumed by an intense heat in the open air, or by heating it strongly with nitre. But the most brilliant mode of burning diamonds, is in an enclosed por- tion of oxygen gas, acted upon by a jet of hydrogen. Exp. The figure (Fig. 75,) repre- sents a glass globe, having fitted to its neck, a copper cap, with an appa- ratus into which a stop cock is screw- ed, and from which a jet-pipe, a, pas- ses up into the-globe. Above this pipe, are two wires, c c, one of which is attached to the jet-pipe, the other passes through an insulating glass 380. How may carbon be obtained nearly pure ? Crystalized carbon. Properties of the diamond. Exp. showing the combustion of a diamond in oxygen gas. Product of the combustion of diamond in oxygen gas. Size and value of diamonds. CHARCOAL. 147 tube, to the outside of the apparatus, where it terminates at a. At the end of the jet-pipe, is a small platinum grate. On this, the diamond is plac- ed, in such a situation, that the stream of hydrogen which issues from the jet, plays upon it, and not on the platinum. The lower part of the ap- paratus, has in its side, an aperture, to which is affixed a tube with a stop- cock; and with this is connected a bladder filled with hydrogen gas. When the apparatus is used, the glass globe is removed from its stand, placed on an air pump, exhausted of air, and then filled with oxygen gas ; after which it is again screwed to the stand. The wire d, is then connected with the conductor of an electrical machine by means of a chain wire; a discharge of electrical sparks is then to pass between the wires cc. A stop cock being now opened, hydrogen gas being pressed from the bladder, issues through the jet-pipe a, and the diamond is heated to a white heat; after which, it takes fire and consumes. The product of the combustion of the diamond in oxygen gas, is carbonic acid, which is the same as that arising from the combustion of pure charcoal. The most splendid diamonds have been found in the East Indies, and in Brazil. They are esteemed the most valuable of all gems. Some few have been found as large as a pigeon's egg; these are considered as of immense value. 381. There are three modes of making wood charcoal. 1st. The most complete process is that used by manufacturers of gun powder, who require very pure charcoal. The process consists in distilling the wood in cylin- drical retorts of cast iron. 2d. The ordinary wood charcoal for fuel, is prepared by covering a pile of wood with earth, so as nearly to exclude air, and then set it on fire at the bottom. The combustion is slow, as but little air is admitted; but in time the volatile parts are driven off and car- bon remains. 3d. For chemical experiments, charcoal should be prepared by charring wood under sand or melted lead to exclude all the air. 382. Carbon, or charcoal in its purest form, is black, brittle, pulverulent, unaltered by the action of air and rrlrjisture at com- mon temperatures, and not affected by heat, even the most in- tense, when air is excluded. It is not volatile, is infusible and insoluble ; is not attacked by alkalies, nor, at commom tempera- tures, by any acid. Its specific gravity is said to be greater than that of diamond ; wood charcoal, on account of its porosity, floats awhile on water, but sinks as soon as its pores are filled with the fluid. Charcoal is an excellent conductor of electricity, but a very bad conductor of heat, especially when powdered. Charcoal has a remarkable antiseptic power, preventing the pu- trefaction of meat and vegetables when covered with it in a state of powder. On account of its indestructibility it is customary to cbar the end of posts that are to be set in the earth, and the inside of the water casks of ships. Grains of wheat, charred by the vol- 381. Modes of preparing wood charcoal. 382. Properties of carbon. Antiseptic property. Valuable as a dentri- fice. Effect in the decolorization of liquids. 148 CHARCOAL. canic eruption which buried Herculaneum in A.D. 79, were found perfect, eighteen centuries afterwards ; and knife handles recent- ly made in England and sold as antiques, at a high price, were manufactured from charred stakes driven into the bed of the Thames to prevent the passage of the Roman army, under Julius Cssar. Finely powdered charcoal is an excellent dentrifice, especially as the extreme hardness of its particles gives it a great polishing power ; It removes coloring matter from liquids of vegetable ori- gin ; thus dark colored wines and other liquors are filtered through it. The decoloring power is greater in animal, than in vegetable charcoal, on account of the greater quantity of earthy salts contained in the former. 383. Charcoal absorbs gases and vapors. This is a mechani- cal effect, depending on the porosity of the charcoal. Of the different gases, it absorbs different quantities, dependent on' the relative elasticity of the gases; the least elastic, and there- fore most easily condensible gases, are absorbed in the greatest quantities. Vapors are, therefore, more absorbable by charcoal, than gases, and liquids, still more than vapors. The gases will be given off by heating the charcoal. Fresh charcoal from box-wood, according to Sassure's experiments, ab- sorbed in 24 or 36 hours,— of Ammoniacal gas, of Sulphurous acid gas, of Carbonic acid gas, of Oxygen gas, of Nitrogen gas, of H^rogen gas, An application of the absorbing property of charcoal is made by using it in a powdered state for removing putrescence from meat which has been kept too long, also for cleansing docks, vessels &c. Bad water by being filtered through it may be made pure. 384. Charcoal is highly combustible in air, or oxygen gas; in the former, the combustion is slow, in the latter, brilliant, with emission of sparks. In either case, and in all other examples of the direct oxidation of carbon, the product is carbonic acid gas. If pure, the charcoal is consumed without residue. Charcoal is also oxidized by being heated with nitric acid ; but the nitrates, chlorates, and some other salts, yield their oxygen to it, very 383. Absorbing property. On what the absorbing power depends. What gases most readily absorbed ? Degrees of absorption of different gases by charcoal. Application of the absorbing property. 384. Combustion of charcoal. Product of the combustion. Action of charcoal when heated with nitric acid, or with deflagrating salts. Reduc- tion ofmetallic oxides by charcoal aided by heat. 90 times its bulk. 65 « 35 « 9.42 " 7.05 « 1.75 " CARBONIC ACID. 149 rapidly, at a red heat, causing the violent combustion, called deflagration. Metallic oxides, also, by the aid of heat, are se- duced by charcoal to the metallic state, upon which property are founded most of the processes for obtaining metals from their ores. There are many other processes, both in Chemistry and in the arts, in which charcoal is employed as a powerful deoxidizing agent. COMPOUNDS OF CARBON AND OXYGEN. 385. Carbonic Acid Gas. 1 Car. 6 to 2 ox. 16=22. This gas is constantly found in the atmosphere, being gene- rated by combustion, respiration, and many other processes. It is contained also in many solid mineral bodies ; thus chalk, mar- ble, Iceland spar, and limestone, all consist of the same compound of carbonic acid and lime, in different degrees of purity. This is the first gas that was distinguished from common air ; its discovery opened a new field of investigation, that of the elastic fluids, which has changed the aspect of pneumatic chemistry. The first steps towards its discovery, may be traced to the Alchemist Van Helmont, who observed that calcareous stones sometimes yielded an air, to which he gave the name of gas. Hales afterwards asserted, that this sort of air was an essential part of these stones; and he attempted to ascertain in what proportion it existed in them. Dr. Black, in 1775, dis- covered that this air was capable of being absorbed by lime and the alkalies, of neutralizing them, and causing them to effervesce with acids. Priestly studied its properties with much care, and the English Chemists usually ascribe to him the honor of its discovery. But the French assert that their countryman Lavoisier first determined the proportion of its constituent parts, and understood its nature. It appears that both Priestly and Lavoi- sier were at the same time engaged in studying and experimenting upon carbonic acid gas, and publishing in their respective countries the results of their investigations. 386. Carbonic acid gas was at first named fixed air, on account of its remaining in a fixed state in stones and rocks ; it has been called aerial acid, chalkly acid and gaseous oxide of carbon. It received its present name on the reformation of the chemical nomenclature. 387. It may be obtained by burning pure charcoal in oxygen gas, or by exposing almost any of its numerous and abundant combinations with the metallic oxides, to a strong red heat, in an iron retort. Exp. 1st. The easiest method of obtaining it is to pour one of the 385. Composition of carbonic acid gas. Where found? Importance ol its discovery. History. 386. Synonimes. 387. Modes of obtaining carbonic acid gas. Exp. 1st. Exp. 2nd. 13* 150 CARBONIC ACID. stronger acids, (as the hydrochloric) in a dilute state, upon small fragments of marble or other carbonate, in a flask or stopped glass retort. The hydro- chloric acid unites with the lime of the marble, forming hydrochlorate of lime. The liberated carbonic acid gas may be collected over mercury, or over water in the usual manner; or, as it is much heavier than air, it may- be received in a dry glass bottle or jar, standing with its mouth upwards ; in this case, the tube proceeding from the flask must be bent twice at right angles, and reach quite to the bottom of the receiving vessel. Fig. 76. Exp. 2d. Thus, into the double necked bottle, i^-y here represented, (Fig. 76,) put fragments of mar- ble, and pour through the funnel diluted hydro- chloric acid ; effervescence immediately ensues, and the disengaged carbonic acid gas, filling the bottle, passes out through the bent tube a, into the jar 6; and on account of its being heavier, crowds out the atmospheric air which the jar contained. When the jar is full, a lighted taper will be extinguished, if held just within its mouth. 388. This gas is transparent, colorless, tasteless, inodorous, and highly elastic; Its specific gravity is above 1.5 ; it extin- guishes burning bodies, and destroys the -life of animals immersed in it; these ef- fects are not due to the mere absence of oxygen, for they take place even when some oxygen is present. Thus charcoal, wood, candles, and other carbonaceous substances, are extinguished before the oxygen is consumed, by reason of the mixture of the latter with the carbonic acid, which is produced in the combus- tion. And hence persons are often suffocated by pans of burn- ing charcoal in apartments not sufficiently ventilated. The un- wholesome effect of crowded assemblies, is partly due to the carbonic acid produced by respiration. This gas acts on the system as a narcotic poison. It is often found in wells, pits, and caverns, being generated there by the spontaneous decomposition of organic matter, or of earthy carbonates. Before descending into such places, it is proper to let down a burning candle. If it be extinguished, the air is unfit to support respiration. Another test is clear lime water, which becomes covered with a pellicle of carbonate of lime when exposed to an atmosphere of this gas. It may be re- moved in such cases, by letting down buckets containing a mix- ture of lime and water, as the lime unites with the carbonic acid gas to form carbonate of lime; or it may be drawn up in buckets, and poured out like water. • ^-Properties of^-carbonic acid gas. Its effects on combustion and an- imali hfe. Pans of burning charcoal in close rooms.* Air of crowded as- semblies. Air of wells, pits, &c. Tests by which the presence of carbonic acid gas may be known. How may the gas be removed ? CARBON. 151 Fig. 77. 389. Put into a three necked bottle (Fig. 77,) two ounces of the carbonate of ammonia, and one ounce of orange colored nitrous acid, carbonic acid gas will be evolved and be visible as it rises in a cylindrical jar, fitted to the bottle. When full, it will press out beneath the cover at the top of the jar. Let the cover be re- moved, and a candle introduced within the vessel, and it will be extinguished. The gas can be drawn off at A; its current will be visible, and it will extinguish a burning candle held beneath the orifice. It can be drawn like a liquid, into a tumbler, (Fig. 78,) from whence it may be poured up- on a burning lamp which it will extinguish. Fig. 78. 390. As water absorbs carbonic acid gas, another mode of re- moving it from wells, &c, is to pour down a quantity of water. Animation, when suspended by the effect of this gas, has been restored, in some cases, by dashing cold water over the patient. Water absorbs its own bulk of carbonic acid gas, at the ordinary temperature and pressure of the atmosphere; under a greater pressure, a larger quantity is absorbed. Thus a pressure of two atmospheres causes water to absorb twice its bulk of the gas ; three atmospheres, three times its volume, and so on. By a pressure equal to thirty six atmospheres, carbonic acid itself becomes condensed into a liquid. 389. Experiment to shew that carbonic acid gas is heavier than atmos- pheric air. 390. Absorption of carbonic acid gas by water. Effect of pressure on this absorption. Soda or carbonated water. Describe Dr. Hare's appparatus for carbonating water. What takes place when the water is relieved from pressure ? S2 CARBONIC ACID. By compressing carbonic acid gas over water with a forcing pump, the water becomes highly charged with the gas, forming what is sold, as soda water, but, in general is merely carbonated water. Dr. Hare's apparatus for charging water with carbonic acid. Fig. 79. A, (Fig. 79,) is a condenser fastened into a block of brass furnished with a cortical brass screw, by means of which, it is easily attached to the floor. In this block are two valves, one opening inwardly from the pipe B, the other outwardly towards the pipe C. The pipe B, communicates with a reservoir of gas which the condenser draws in, and forces through the other pipe, into a strong copper vessel containing the water. The carbonated water is drawn out by means of a syphon D. When the pressure on the water is relieved, the greater part, of the gas escapes with effervescence leaving only what the water is capable of holding in solution, at ordinary atmospheric pressure. The remainder may be expelled by boiling the wa ter or by placing it under the receiver of an air pump, and exhausting tht air. 391. Water which contains carbonic acid gas, has a lively; brisk taste, sparkles when poured from one vessel to another and changes to red the blue color of litmus paper ; but thclatte* effect is only temporary, for the acid soon evaporates and th 391. Properties of carbonated water. Tests of carbonic acid in water- Cause of the crust which is deposited when spring water is boiled. CARBONIC ACID. 153 blue is restored. The insipid taste of boiled water is owing to its having lost the carbonic acid which spring waters always contain. The presence of this gas in water, may be detected by mixing it with clear lime, or baryta water ; it becomes milky, on account of the formation of an insoluble carbonate of lime or baryta. Care should be taken to have the alkaline water in excess ; for if the car- bonated water predominate, the precipitate is not formed, or is re-dissolved, those carbonates being soluble in excess of carbonic acid. On account of the latter property, the spring waters of a limestone district, often contain carbonate of lime in solution. On boiling, the excess of carbonic acid is expelled, the carbonate of lime is deposited, and by frequent repetition, the vessel in which it is boiled, becomes lined with a white calcareous crust. 392. Carbonic acid gas is a product of fermentation. If cider, beer, champagne, &c, be put into bottles, and tightly corked before the fermentation has entirely ceased, the gas which is generated during the remainder of the fermentation, is forced into the liquids under a considerable pressure, and gives them the effervescent quality or liveliness, which renders them agree- able. An overcharge of the gas, expels the cork or bursts the bottle; and this will happen when the liquors are bottled too soon. This occurrence often takes place in bottled yeast, which, in fermentation, gives off a large proportion of gas. 393. It has been remarked, (§349,) that carbonic acid gas is always present in the atmosphere, and that the vegetation of plants has an agency in decomposing it and restoring oxygen to the air. A small proportion of carbonic acid in the atmosphere is favorable to vegetation, by furnishing carbon to the plants; but in too large proportion it destroys vegetable life. It has been found that plants are benefitted by being watered with a solution of this gas. Carbonic acid combines with the alkalies, earths, and most of the salifiable metallic oxides, forming a class of salts called carbonates, many of whch occur abundantly as minerals, as carbonate of lime in its various forms of limestone, chalk, marble, Iceland spar, stalactite, &c. The carbonic is a very weak acid, and does not completely neutralize the alkalies ; therefore all the carbonates are decomposed by hydro-chloric, nitric and most other acids, carbonic acid escaping with effer- vescence. All the carbonates, except those of ammonia, potas- sa, soda and lithia are decomposed by heat. 394. Carbonic acid is the highest known oxide of carbon. It contains in bulk one volume of carbonic vapor and one volume of oxygen, condensed into one volume. 392. Cause of the effervescence and other peculiar properties of ferment- ed liquors. Bursting of the bottles containing such liquors. 393. Decomposition of carbonic acid gas by plants. Carbonates. Why easilv decomposed ? 394. Composition of this gas. How proved. 154 CARBONIC OXIDE. Its composition is proved by passing the vapor of phosphorus over a red hot carbonate, in which case phosphoric acid is formed and carbon set free ; or by passing a succession of electric sparks through the gas, by which means it is resolved into oxygen and carbonic oxide; or by electrifying a mixture of hydrogen and carbonic acid when water and carbonic oxide will be formed. It is also decomposed by being brought in contact with iron filings or charcoal at a red heat; the iron or charcoal takes half its oxygen, converting it into a carbonic oxide. Potassium takes the whole of its oxygen,- forming potassa and liberating carbon. 395. Carbonic acid gas has been liquefied by very powerful compression aided by exposure to cold. Mr. Faraday obtained it in this state by disen- gaging it from carbonate of ammonia by means of sulphuric acid, in a glass tube hermetically sealed, one end being immersed in a freezing mixture. The liquid acid was colorless, and floated upon the sulphuric acid and water, contained in the tube. The pressure under which this fluid was formed was estimated to be equal to that of thirty six atmospheres. A French Chemist* who had previously succeeded in liquefying this gas, announces that he has also obtained it in a solid state. Its solidification requires a cold equal to 100th degree of the centigrade below the freezing point; and, though the liquefied gas evaporates almost instantaneously, and with a vio- lent explosion, the solid continues some minutes exposed in the open air, and insensibly disappears by a slow evaportion. The first instance of a gas becoming solid and concrete is so much the more remarkable as it relates to a gas, to liquefy which requires the most powerful mechanical action, and which resumes with great rapidity its gaseous state when the compres- sion is removed. In the liquid state its elastic force is equal to that of gun- powder, while in the solid state the spring appears completely broken, the new body disappearing by slow evaporation. 396. Carbonic Oxide. Its constituents are, 1 atom of carbon with 1 of oxygen=14 its chemical equiv. It is never formed by the direct oxidation of carbon, carbonic acid being always the result of that process. Most of the processes for obtaining carbonic oxide depend on depriving carbonic acid of half its oxygen ; this is easily effected at a red heat, by charcoal and by several of the metals. Thus when a mixture of chalk and iron filings is heated to a red heat, carbonic acid is driven from the chalk ; the hot iron immediately takes a part of the oxygen from the carbonic acid and reduces it to carbonic oxide. When char- coal is used for this purpose, it is itself converted into carbonic oxide. The gas thus evolved may be collected over water. Other more easy and elegant processes are founded on the decomposition of oxalic acid and its salts by sulphuric acid. Oxalic acid is a crystalizable, poisonous, vegetable acid, which like nitric acid is incapable of existing in an uncombined state ; so that when not united to a salifiable base it always * M. Thilorier. See Silliman's Journal, Oct. 1836; and also the same Journal for Jan. 1837. Translations from Annates de Chimie. 395. Pressure under which it was formed. Solidification of carbonic acid. 396. Composition of carbonic acid gas. How formed. How obtained by heating chalk with iron filings ? How obtained by means of oxalic and sul- phuric acid. Dr. Hare's apparatus for separating carbonic acid gas from carbonic oxide. CARBONIC OXIDE. 155 contains water. Besides this water necessary to its existence, the crystal- ized acid consists of 3 atoms of oxygen and two of carbon. On heating this acid or its salts in a glass retort, with an excess of sulphuric acid, the lat- ter takes both water and alkaline base ; the oxalic acid, thus set free, re- solves itself into the two gaseous compounds of carbon and oxygen. These mixed gases being collected over mercury, the carbonic acid will be speedily absorbed by a little milk of lime or solution of potassa, and the carbonic acid remain pure. Dr. Hare's apparatus for purifying carbonic oxide by lime water. Fig..80. -The gases being obtained in the manner directed above, they are convey* ed by means of the pipe, P, (Fig. 80,) which is supposed to communicate with a reservoir of the mixed gasesj to the bell glass C, containing lime water. The lime water sinks into the lower bell glass, A, as the gases are introduced by turning the stop cock communicating with the pipe P. The lower pipe D, communicating wi^h the hell glass A, has affixed to it an In* 156 CARBONIC OXIDE. dia rubber bag; by pressing this with the hand, jets of lime water are thrown into the gas in the bell glass C, until all the carbonic acid having united with the lime, the carbonic oxide is left pure, and may now be trans- ferred to any receiver by turning the stop cock of the pipe P. 397. Carbonic oxide is transparent, colorless and inodorous; it is very sparingly absorbed by water; its specific gravity is 0.972. It has neither acid nor alkaline properties, and has no effect on lime water. It extinguishes burning bodies, and is ir- respirable, being like carbonic acid, a narcotic poison. It is in- flammable, burning in contact with oxygen with a pale flame. In this, and all cases of its direct oxidation, carbonic acid is the sole product. Exp. Place an inverted jar over a vessel of carbonic oxide which is burn- ing in a jet, as it issues from the tube at the mouth. The inverted jar will be filled with carbonic acid gas. The air furnishes another atom of oxy- gen=8, which uniting with the carbonic oxide=l4 makes carbonic acid=22. The blue flame of carbonic oxide is sometimes seen on the upper part of a charcoal or anthracite fire; the draught of air entering below, the com- bustion of the coal there produces carbonic acid, which, in rising through the mass of ignited coal, is decomposed and converted into carbonic oxide. 398. Carbonic oxide gas being mixed with half its volume of ■oxygen gas, the mixture may be exploded by an ignited body or by the electric spark, carbonic acid being the product. It may also be exploded in a similar manner by mixing it with protox- ide of nitrogen. By volume, the constituents of carbonic oxide are one measure of carbon vapor, and half a measure of oxygen gas, condensed into one measure. It was discovered by Dr. Priestly in distil- ling charcoal with the oxide of zinc ; but its nature and compo- sition was determined by Mr. Cruickshank. Carbonic acid with Ammonia, or Carbonates of Ammonia. 399. The neutral carbonate of ammonia is a dry white powder, having the odor of ammonia, though not in so high degree, and very soluble in water. It is never met with in commerce, and can only be formed by mixing one volume of carbonic acid gas, and two of ammoniacai gas, both in a perfectly dry state, over mercury. Both gases disappear entirely, and the white pow- der of carbonate of ammonia is deposited. 400. The Sesqui* carbonate, is the commercial carbonate of ammonia. It is procured in an impure state for the purpose of forming hydrochlorate of * Latin term, signifying one and a half. 397. Properties of carbonic oxide. Exp. To prove that carbonic oxide is combustible, and that the result of its combustion in the air is carbonic acid gas. Blue flame of carbonic oxide seen in coal fires. 398. Explosive mixtures with carbonic oxide. Constitution by volume. History. 399. Neutral carbonate of ammonia. 400. Sesqui carbonate of ammonia. How prepared. Its properties. How is the bi-carbonate of ammonia formed ? CARBON WITH HYDROGEN. 157 ammonia, by heating bones and other animal matter inclose vessels. Ani- mal matter being composed of carbon, oxygen, hydrogen, and nitrogen, the elements are separated by the agency of heatand recombined in other forms, one of which is the salt in question. The sesqui-carbonate of the shops, is procured by sublimation from a mixture of hydrochlorate of ammonia with carbonate of lime. On exposure to the air this salt becomes opake and pulvepulent, loses its odor and decreases in weight. It is then found to have become bi-carbonate of ammonia. Bi-carbonate of ammonia is formed as above, by exposing the sesqui-carbonate to the air. It is also obtained by passing a current of carbonic acid gas through a solution of the common u.' /ionate. On evaporating the solution, the salt crystalizes. CHAPTER XVII. Compounds of Carbon with Hydrogen 401. Carbon and hydrogen possess opposite properties in re- spect to their tendency to assume the gaseous form. They have a strong affinity for each other, and their compounds are remark- able for their inflammable nature. Carbon and Hydrogen form, with each other, at least, six definite compounds 1 1. Light carburetted hydrogen gas, consisting of 1 equivalent add to 2. eq. 2. Olefiant gas, " 2 " " 2. " 3. Faraday's bicar. hyd. " 6 " « 3. " 4. " Quadrocarburet, " 4 " " 4. " 5. Naphtha, « 6 " " 6. " ' 6. Naphthaline, " 3 « « 2. « Of these, the first two are permanent gases. The fourth is a vapor at common temperatures, but a liquid at 0° F ; the third and fifth are volatile liquids ; and the last is a volatile solid. 402. It is to be observed that several of these compounds present a re- markable exception to the laws of combination. The second, fourth and fifth consist of carbon and hydrogen in precisely the same ratio, that is, one equivalent of each element; yet they are totally distinct in all their physi- cal, and most of their chemical properties ; nor have we any right to sup- pose that a compound consisting of one proportional of hydrogen and one of carbon would resemble either of them. The constitution of these bodies seems to indicate that, for the formation of any specified compound, not only must certain proportions be observed in the quantities of the constit- uents, but also, that the concurrence of a particular number of atoms is ne- cessary. Thus, if we could compel three atoms of olefiant gas to cohere, we should probably obtain an atom of Naphtha ; and if two atoms of the 401. Affinity of carbon and hydrogen for each other. Different forms under which they combine. Names and composition of these compounds. States in which they exist. 402 Exception of some of these compounds to the laws of combination. 14 158 FIRE-DAMP. same gas were to coalesce, they might form an atom of quadrocarburet. The analysis of some organic bodies proves that slight variations in com- position, or different modes of combination may produce great differences in properties : there is but one other case, that of hydrophosphoric acid, in which the laws of combination appear so inexplicable as in the present. Until more light is thrown upon the subject, we must be content to attri- bute the difference of properties, among bodies containing the same elements in the same proportions, to the influence of the mode of combination* 403. Light Carburetted Hydrogen. The gas is also called sub- carburetted hydrogen gas, and bi-hydroguret of carbon. It was formerly known as inflammable air, and the air of marshes. It can only be obtained, in a separate state, by stirring the mud of stagnant pools, and collecting the bubbles of gas as they rise in an inverted receiver filled with water. It is formed in such situations during the spontaneous decomposition of vegetable matter. There is a rivulet running through the village of Fredonia, and another which passes by Portland Harbor, both in Chautauque County in the State of New York, from the waters of which bubbles of light carburetted hydro- gen gas are constantly rising. The supply of gas at Fredonia is sufficient for lighting the houses of the village, and a gasometer has been constructed for collecting it. The light house on Lake Erie at Portland harbor is com- pletely supplied with gas obtained from the rivulet above mentioned. The origin of the gas in these cases has not been traced. 404. This gas is colorless, transparent, tasteless, inodorous, sparingly absorbed by water, and of specific gravity 0.5555. It burns with a yellow flame; and if mixed with air or oxygen in proper proportions, it explodes violently, when touched with flame or the electric spark. Whether exploded, or burnt silent- ly, the sole products are carbonic acid and water. 405. Blowers and Fire-damp. Light carburetted hydrogen is often generated in large quantities in coal. Sometimes it is * Since these anomalies in the laws of chemical combinations began to attract the attention of men of science, they have been arranged under different heads : as Isomerism, from the Greek isos equal, and meros a part; polymerism from polus many and meros ; and metamerism, according to, and meros. Isomeric bodies are those which contain the same absolute and re- lative number of atoms of the same elements, and have, therefore, the same atomic weight; Polymeric bodies are those which contain the same relative, but not the same absolute number of atoms of the same elements, and whose atomic weights are consequently unlike. Metameric bodies are those which, while they contain the same absolute, and the same relative number of atoms of the same elements, yet constitute substances belonging to an en- tirely different class of bodies, or a diflerent order of chemical compounds. The carburets are therefore polymeric bodies. (Rep. of the British Association for 1835, pp. 435, 436.) 403. Synonymes of light carburetted hydrogen. How formed, and ob- tained ? Natural reservoirs of this gas. 404. Properties. Products of its combustion. FIRE-DAMP. 159 pent up in cavities where it was formed, and, being under great pressure, rushes out with much force, when a cavity is broken into ; a reservoir of this description, is called by the miners, " a blower?'' At other times, it issues silently from between the layers of coal. In either case, it mixes with the air of the mine, constituting the fire-damp of the miners, which, if set on fire, explodes with terrible violence, producing a shock which has been felt at a distance of several miles. By the explosion of the fire-damp, carbonic acid and water are produced; so that if it were possible for a miner to escape the effect of concussion, he would perish by suffocation in the mephitic gas, which the miners call choke-damp. Such explosions were frequent, in the British coal mines, till a few years ago ; and the annual loss of life occasioned by them, was truly deplorable. It was reserved for the genius of Sir H. Davy to discover means for preventing such dreadful accidents, and "the fear of them." Davy descended with the miners into the region of the fire-damp to obtain specimens of the gas. He found by experiments that the most explosive mixture was 1 part of gas to about 7 of air ; that 5 volumes of air would explode but feebly, and that over 14 volumes of air to 1 of gas would not explode at all. He also found that the most explosive mixture can not be kindled without the heat of flame ; that iron at a red heat and even at a white heat will not explode it. By means of a little instrument, called the safety lamp, whose simplicity is scarcely less admirable than its utility, the miner now fearlessly descends into dark caverns filled with combustible gases, and lamp in hand safely pursues his daily avocations, un- disturbed by the terror of destructive explosions. In the course of his experiments, Sir H. Davy assisted by previous dis- coveries of Dr. Wollaston, developed some facts respecting the nature of flame, a subject which had not previously been well understood, and which, as connected with our present subject we shall here introduce. Flame is found to be gaseous matter in a state of incandescence, and its temperature far higher than any to which solid bodies can be brought. This being the case, in order to extinguish flame it is only necessary to cool it; this may be effected by bringing it into contact with a sufficient quantity of solid matter which may convey away the heat by means of its conducting power. It would follow from this, that the greater the conduct- ing power, the less the mass of solid matter necessary to effect the object, and vice versa ; and consequently that metals would produce the effect more readily than any other bodies, the masses being the^ame. Some of these facts may be readily proved by simple experiments. If the point of aknife, or the end of a metallic wire be held very near to the flame of a candle, a 405. Blowers of mines, Fire-damp, its properties, &c. Choke-damp. Observations on the nature of the fire-damp which led to Davy's invention. Different temperatures of different flames. Gases kindled by solid bodies at different temperatures. Explosive mixture of light carburetted hydrogen and oxygen. 160 CARBON. dark spot will appear on the blaze opposite to the metallic point; the gas in that part being cooled below incandescence by the conducting body. If a very small flame be made with a cotton thread, passed through a cork shaving, and floating on oil, it will be extinguished by holding over it, and in contact with it, an exceedingly small ring of fine iron wire ; a ring of glass of the same size, will diminish the flame, and a larger glass ring will put it out, the sufficiency of conducting power being compensated by the greater quantity of matter. Wollaston had observed, that'" an explosive mixture cannot be kindled through a glass tube so narrow as 1-7 of an inch in diameter," and also that the mixture could not be exploded through fine wire gauze, which acts on the same principle as longer tubes. Now if a fine wire gauze be held upon a common flame, the flame will not pass through the gauze, but will appear as if cut off, (See Fig. 81.) On applying a lighted taper above the wire gauze, a flame will be produced on the upper surface, which is a con- tinuation of the flame below, (See Fig. 82.) The gas of which the flame consists, actually passes through the gauze, but is extinguished in its pas- sage, bv the cooling power of the wire. Fig. 81. Fig. 82. Fig. 83. Davy's Safety Lamp. (Fig. 83.) A is a cylinder or case of wire gauze, having no less than 625 apertures to the square inch, with a double top securely fastened to the brass rim B, which screws on to the lamp C. The whole is pro- tected and rendered convenient for use, by the frame and ring D. With this lamp the miner would not be exposed to suffocation for want of oxygen, since he would be admonish- ed by its becoming extinguished that an atmosphere which could not support the combustion of the oil, would not sup- port respiration. In gas manufactories, spirit ware-houses, and in all places where inflammable vapors or gases are likely to be genera- ted, as in the examination of foul sewers and drains, where artificial light is required, it is obvious that these lamps have very important uses, as well as in the lighting of mines. As different flames have diflerent temperatures, it will obviously be necessary to vary the texture of the gauze, according to the nature of the gas to be extinguished. Moreover it is necessary to observe, that some gases, as carbonic oxide, are kindled by a solid body at a dull red heat; others require a bright red, or a white heat, to set them on fire ; while some are not ignited without the direct application of flame. It happens, that light carburetted hydrogen requires a higher temperature for ignition than any other gas ; this is fortunate, because the wire gauze must, necessarily become heated, which would cause tha CARBON. 161 ignition of explosive mixtures, containing other inflammable gases and vapor. 406. Explosive mixtures, may be made to undergo a sort of slow combus- tion at a temperature below that of flame, and consequently without explo- sion. This fact may be demonstrated by immersing a small slip of platinum foil or wire, heated red hot, into a mixture of light carburetted hydrogen and air. The temperature of the heated metal will cause the oxygen to combine with carbon and hydrogen, enough heat being evolved by the chem- ical action, to keep the wire ignited, but not enough to set the gaseous mix- ture on fire. Upon this fact has been founded the flameless lamp, (Fig. 84.) A spiral coil offline platinum wire is placed vertically, so as to surround the cotton wick and rise a quarter of an inch above it. Some al- cohol being put into the lamp, the wick burns and ig- nites the platinum wire. In this condition, if place3 in an explosive mixture, and the wick be extinguished, the wire will continue to glow, giving light enough to guide the steps of the miner to a place of safety. 407. It appears that an explosive mixture of any com- bustible gas with oxygen, is necessary to the production of flame, and that an ordinary flame is a mere shell, the interior of which is filled up with gas, which is not ignited. This fact may be demonstrated by a few sim- ple experiments. • Exp. 1st. Hold a thin glass tube, b, (Fig. 85,) about the diameter of a small quill, and three or four inches long, so that its lower extremity shall be im- mersed in the flame a, of a large candle, the tube making an angle of about 45° with the axis of the flame; a portion of the gas 6, from the interior of the flame, will pass along the tube, and may be set on fire at its extremity. Exp. 2nd. With a fine pointed glass syringe, gas may be drawn from the interior of a common lamp flame, and on being gently pressed out, in contact^-fc^ with a spirit lamp will burn. t"Hi Exp. 3d. On cutting off the flame with wire|| =j gauze, and looking down upon it, it will be seen that^=^ the section is a luminous ring, of which the central part is quite dark Exp. 4th. Place a wooden hoop (Fig. 86,) of 6 or 8 inches diameter, and 2 or 3 inches broad, upon the water of the pneumatic tub. Within this hoop, pour some sulphuric ether, and set it on fire. A large flame will be obtain- ed, and it may be shown that combustion is not going on in its interior, by passing the hand through the water under the hoop, and up into the center of the flame, taking care not to touch its sides. Considerable heat will be felt, but it may be endured for a second or two without much inconvenience. "* 406. Slow combustion of explosive mixtures without flame. Heated pla- tinum immersed in a mixture of light carburetted hydrogen and air. 407. Experiments showiag that flame is a shell, the interior of which contains gas not ignited. 14* 162 CARBURETTED HYDROGEN. 408. But though the space within the flame be not in a state of ignition, there is oxygen contained in it, the motion of the inflammable vapor through the air being sufficient to cause the two to mingle to some extent. That oxygen is contained there may be proved by putting in some combustible requiring less oxygen than that which constitutes the basis of the flame. FiCT. 87. Thus if a piece of phosphorus be put in a small wire^cage at the'extremity of a wire bent at right angles, (Fig. 87,) it I may be passed up under the hoop into the flame ; the water will drain off through the cage, the phosphorus will soon melt. and at last take fire, and be consumed. Thus the inner part of the flame is not in a state of ignition, not because oxygen ^pg- is not present, but because it is insufficient to form an explo- pin . sive mixture with the inflammable gas. tSt* | 409. The luminousness of flames depends in general, on f 1 the presence of solid matter diffused through them in an in- candescent state, and not to their heat. Indeed the colorless flames, such as those of hydrogen and strong alcohol, are often hotter than the luminous ones; for the solid matter which makes a flame luminous, exerts a cooling influence proportionate to its conducting power. Pure hydrogen and oxy- gen, if set on fire in a strong glass globe, will give a strong light, because of the great compression. Of all flames, the white, containing a due proportion of all the rays of the spectrum, is most luminous; the colors of the rest are owing to the deficiency of some of the rays, and the consequent preponderance of others ; of the colored flames, the yellow is the most lu- minous. 410. The flames of common fires, candles, lamps, &c, consist of some of the compounds of carbon and hydrogen ; generally, of several mixed together. These gases arise from the decom- position which wood, oil, and the other organic matters undergo by the action of heat. The carburets of hydrogen, all undergo decomposition at some degree of heat, the higher carburets being more easily decomposed than light carburetted hydrogen ; the carbon and hydrogen burn separately ; and the particles of ignited carbon diffused through the flame of hydrogen, give it its luminous property. If the quantity of carbon is out of pro- portion to the supply of oxygen, a portion of it escapes unburnt, and is seen in the form of black smoke, which soon settles of it- self, on cold surfaces ; instances of this, are seen in the combus- tion of naphtha, oil of turpentine, and bituminous matters. But if the quantity of carbon be duly proportioned to the supply of ox- ygen, it is all consumed, and there is no smoke, as in the burning of strong alcohol. 408. Is the flame not ignited because there is no oxygen present ? How may it be proved that there is some oxygen within the interior of the flame. 409. Why the least luminous flames are, in general, the hottest. Differ- ent colored flames. 410. Flames of fires, candles, &c. Cause of black smoke. Why there is no smoke in the burning of alcohol. OLEFIANT GAS. 163 » Olefiant Gas. 411. This gas was so called from its oily appearance, when combined with chlorine. It is sometimes called hydruret of car- bon orpercarburetted hydrogen, and is obtained by gently heating, in a glass retort, a mixture of one measure of alcohol and three of strong sulphuric acid. The gas is freely evolved and is to be collected over water. If it be cloudy at first, it must stand some time over the water or be agitated with water before use. Ole- fiant gas is colorless, tasteless, nearly inodorous and of.specific gravity 0.97. It is very little absorbed by water, extinguishes flame, and does not support respiration. It burns in the air with a white flame of greater splendor than any other gas ; and when previously mixed with oxygen gas and set on fire, it de- tonates with exceeding violence. It is resolved into its elements by a succession of electric discharges, and it is more or less completely decomposed by passing through heated tubes, ac- cording to the degree of heat employed; a low heat only re- ducing it to light carburretted hydrogen, while an intense heat entirely separates its elements. 412. Olefiant gas derived its name from its property of forming an oil-like fluid by combination with chlorine. This combination takes place when the two gases are mixed, and the presence of light is not necessary to the re-action. The compound so formed is properly called hydro-carburet of chlorine, but from its volatility and etherial taste and odor is often denomi- nated chloric ether. It has a sweet and aromatic taste, boils at 150° F. dis- tills unchanged, and is decomposed in passing through red hot tubes. It produces a kind of intoxication, more resembling that of protoxide of nitro- gen than that of ardent spirits, and has been recommended as a stimulant in medicine. It dissolves freely in alcohol, but not in water; yet the alco- holic solution may be diluted to any extent. The solution of chloric ether in alcohol may be obtained by distilling a mixture of alcohol and chloride of lime ; and it is also formed when chlorine gas is passed into alcohol. If hydro-carburet of chlorine or chloric ether be confined under a bell glass filled with chlorine, and exposed to the sun, it is decomposed : the free chloric combining with its hydrogen, and leaving the carbon and chlorine of the compound in combination, constituting perchloride of carbon. Bromine and iodine likewise may be brought by indirect methods, into combination with olefiant gas, forming the hydro-carburets of bromine and of iodine; compounds bearing a close analogy to the hydro-carburet of chlorine. 413. Bi-carburet of Hydrogen. This according to Faraday is a transparent liquid, of an oily appearance having the odor of 411. Composition of olefiant gas. Synonymes. How obtained. Proper- ties. Products of its combustion. Decomposition. 412. Derivation of the name. Hydro-carburet of chlorine. Combinations of olefiant gas with bromine and iodine. 413. Composition and properties of bi-carburet of hydrogen. Decompo- sition. 164 CARBURETTED HYDROGEN. oil gas and a specific gravity of 0.85. It boils at 186° and freezes at 30°. It does not mix with water, but dissolves in al- cohol, ether and oils. It burns with a yellow flame giving out much soot; and its vapor explodes with oxygen gas or air. It is decomposed by chlorine in the sunshine, and by being passed through red hot tubes ; carbon being deposited in each case. 414. Quadro-Carburet of Hydrogen is a liquid at zero, but boils a little above that point; so that, at common temperatures it is a gas. In the fluid state it is lighter than any other liquid, having a specific gravity of 0.627. The density of its vapor is nearly twice that of air. It is combustible, giving a bright light, and much smoke ; and the vapor explodes with oxygen, produc- ing carbonic acid and water. Chlorine gas combines with it pro- ducing an oily liquid, which in taste, odor, and volatility bear a strong resemblance to the hydrocarburet of chlorine, but differ- ent from that substance in not yielding a chloride of carbon. It is largely absorbed by sulphuric acid, and forms with it a com- pound, the nature of which is not fully understood. Like the other carburets of hydrogen, it may be analyzed by detonating its vapor with oxygen gas, or by passing it over red hot peroxide of copper. 415. Naphtha appears on the shores of the Caspian Sea, and also in some parts of Italy. It is also separated from petroleum by distillation. A sub- stance which appears to be indentical with it, is obtained by distilling the tar formed in the process of manufacturing coal gas. It is a colorless liquid when pure ; but generally has a yellow tinge. It is very volatile, has a strong odor, and burns with a bright flame and much smoke. It dissolves in alcohol, ether, oils, and petroleum, but not in water. It is used to pre- serve potassium, sodium, &c. from contact with air. 416. Naphthaline is also obtained from coal tar, by sublimation after the naphtha has been distilled off. It is a white crystaline solid, heavier than water, of a peculiar odor and pungent aromatic taste. In the open air it slowly evaporates like camphor. It scarcely dissolves in water, but does so in naphtha, in some of the oils, and especially in alcohol and ether. It does not burn readily, but when inflamed burns rapidly with much smoke. Acetic, oxalic and sulphuric acids dissolve naphthaline forming solutions which have some shade of red. The solution in sulphuric acid is a distinct acid called sulpho-naphthalic acid. This acid has some curious properties, but has not been applied to any use in the arts. Its salts are all soluble and combustible. 417. Coal and Oil Gas. As organic substances consist of carbon, oxygen, hydrogen and sometimes nitrogen, among the 414. Composition and properties of quadro-carburet of hydrogen. Its combination with chlorine. With sulphuric acid. How analyzed / 415. Where is naphtha found ? Its properties and use. 416. How is naphthaline obtained? Properties. Its solutions in acid3. Sulpho-naphthalic acid. 417. Proportion of carburetted hydrogen in the products of destructive distillation. Bodies which afford large quantities of inflammable gas. CARBURETTED HYDROGEN. 165 numerous products of their destructive distillation, a portion of carburetted hydrogen is usually found. The proportion which it bears to the other products will, other things being equal, de- pend upon the relative quantities of oxygen and hydrogen con- tained in the substance distilled ; large doses of oxygen leading to the formation of more carbonic acid and water. Resinous, bituminous and oleaginous substances are found to contain more hydrogen, relatively to the oxygen, than other bodies of organic origin ; and therefore afford, by destructive distillation, large quantities of inflammable gas. Hence the preference is due to this set of compounds, in the preparation of carburetted gases for illumination. Coal furnishes carburetted hydrogen by being distilled at a red heat, in large iron retorts ; but as the bitumen contained in the coal is the source of the gas, the different varie- ties of coal vary greatly in their fitness for this purpose. The best of all is the coal of Lancashire, England ; but the Richmond, Va. coal yields a large quantity of gas; while the anthracite, such as Lehigh, Lackawana, &c. affords little or none. Of dif- ferent specimens, that is best for producing carburetted hydro- gen, which contains the most bitumen and least sulphur. 418. The combustion of a common lamp, or candle, is an ex- ample of the simultaneous production and consumption of oil gas. When flame is applied to the wick of a candle, the heat causes a portion of the wax or tallow to melt; by means of ca- pillary attraction the melted portion rises in the wick, and is decomposed by the heat applied, which at the same time sets the resulting gas on fire. The combustion thus commenced, will continue so long as there is matter to feed it; the heat of the flame constantly melting and decomposing fresh portions of the candle. In this operation, the wick is to be regarded only as a bundle of capillary tubes, serving to convey the fluid oil to the point where it is to be decomposed ; a glass capillary tube, will answer the same purpose. The wick being surrounded by in- flammable gas, and thus out of contact of the air, cannot burn, and contributes nothing to the flame. The gradual consumption of an ordinary cotton wick, is owing to the heat of the surround- ing flame, by which it undergoes destructive distillation ; and the crust of carbon which results, clogs the wick, in the case of a lamp, and prevents the free ascent of oil to supply the com- bustion. Part of this crust of carbon, or snuff as it is called, perhaps is derived from carburetted hydrogen which is decom- 418. Oil gas generated and consumed in a common lamp. Why a candle burns brighter for being snuffed, or a lamp for being trimmed. Why a can- dle recently, extinguished may be re-lighted without the actual contact of " flame. 166 CYANOGEN. posed by the heat in the interior of the flame. As soon as the exposed part of the wick of a candle becomes long enough to project beyond the flame into the air, it "undergoes combustion and disappears. A very simple experiment will show the re- solution of oil into inflammable gas by heat. Let a common tallow candle, with a thick wick, burn until the uncovered part of the wick is nearly an inch in length, and then extinguish it suddenly. So long as the wick continues red hot, a stream of smoke will ascend from it. This column of smoke, contains carburetted hydrogen gas, produced from the tallow which the red hot wick continues to decompose ; and if a piece of burning paper be applied to it at the distance of two or three inches above the wick, it will take fire, and the flame running down, will re-light the candle. 419. Bi-chloride of carbon discovered by M. Julin, consists of soft and white fibres, of an odor resembling spermaceti; it burns with a red flame. Proto-chloride of carbon is a limpid, colorless liquid. Chloride of carbon, called the new chloride of Liebig, is a limpid, colorless liquid. Per-chloride of car- bon, of Faraday, is a transparent solid, of an aromatic odor. Chloro-carbonic acid, affords a singular instance where two acidifying principles unite with one base to form an acid. It was discovered by Dr. John Davy who called it phosgene gas. It is formed by exposing equal volumes of chlorine and carbonic oxide to the solar rays, when rapid combustion takes place, and they contract to one half their volume. Chloral a compound of carbon, oxy- gen and chlorine was discovered by Liebig by the mutual action of alcohol and chlorine. It is an oily transparent liquid. Periodide and the protiodide of carbon, have been obtained. Bromide of carbon is formed by means of the periodide of carbon and bromine. CHAPTER XVIII. COMPOUND OF CARBON AND NITROGEN. CYANOGEN. 420. Bi-carburet of nitrogen or cyanogen. 1 nit. 14 to 2 carbon 12=26. This compound in many respects seems to act the part of a simple element. It was discovered by Gay Lussac. It is obtained by the action of heat on cyanuret of mercury contained in a retort. It is conducted over mercury. The cyanuret, (formerly prussiate,) of mercury is simply resolved by heat into cyanogen gas and mercury, its components. The vapor of mercury is condensed in the pneumatic trough, and the gas passes over. This gas is colorless, has a pungent odor, is condensible into 419. Compounds of carbon with chlorine, iodine and bromine. 420. Composition and discovery of cyanogen. How obtained? Properties Product of its combustion. Its solutions. CYANOGEN AND OXYGEN. 167 a liquid by a pressure of 3+ atmospheres; its sp. gr. is 1.8. It extinguishes burning bodies, but burns when set on fire in the air, producing carbonic acid, and liberating nitrogen gas ; it may also be exploded when mixed with oxygen gas. It is very soluble in water, and still more so in alcohol; and its solutions have acid properties; these, however, do not belong to cyanogen, but are due to acids which are generated by the reaction of the elements. 421. Cyanogen, though a compound body, is strongly analo- gous to the simple electro-negatives : tending to combine with metals and other electro-positive simple bodies, and forming with them compounds which resemble the chlorides, iodies, &c., these compounds are called cyanurets or cyanides. It also forms acids by uniting with oxygen and hydrogen, respectively. The name cyanogen, (from the Greek kuanos, blue, added to gennao,) implies generator of blue color ; and was given it by its discoverer Gay Lussac, from its being contained in Prussian blue, to the composition of which it is essential. The latter substance will be considered in treating of iron, which is its base. Compounds of Cyanogen and Oxygen. 422. Cyanous Acid. There are two isomeric compounds, or consisting of the same proportions of cyanogen and oxygen, viz. one equivalent of each; yet notwithstanding this indentity of composition, their properties are en- tirely distinct.* One of them, called cyanous acid of Liebig, forms salts possessing the property of detonating by friction or percussion; and is fre- quently called fulminic acid. One of its salts" is called fulminate of mercury. This compound, now much used for priming fire arms, under the name of percussion powder, is formed by dissolving mercury in nitric acid, and, after the solution has become cool, adding alcohol. In the violent action which ensues, nitrous and ethereal fumes are given off, and a white precipitate subsides, which is the fulminating murcury. By substituting silver for mer- cury, a fulminate of silver may be obtained, which explodes rather more readily than that of mercury. 423. Cyanous Acid of Wohler is formed when cyanogen gas is passed into a hot aqueous solution of an alkali, where water is decomposed and the cya- nite and hydro-cyanate of the alkali are formed, as the chlorate and hydro- chlorate are, in similar circumstances. The cyanite of potassa is best ob- tained by applying a low red heat to a mixture of equal parts of ferro-cyan- ate,(triple prussiate,) of potassa and peroxide of manganese. The cyanogen of the ferrocyanic acid takes oxygen from the oxide of manganese, and the * See Isomerism, note to § 402. 421. Resemblance to simple electro-negatives. Origin of the name. 422. Two compounds of cyanogen and oxygen. Cyanous acid of Liebig. Fulminates. 423. Cyanous acid of Wohler. Anhydrous cyanous acid. 168" CYANOGEN AND HYDROGEN. cyanous acid, so formed, unites with the potassa. The cyanite of potassa is then dissolved by boiling alcohol, and deposits as the solution cools. By dissolving this salt in cold water, and adding it to a solution of nitrate of silver, a cyanite of silver is precipitated; which, may be decomposed by a current of sulphuretted hydrogen gas. The sulphuret of silver is precipita- ted, and the cyanous acid remains in solution. It is decomposed in a few hours, being acted on by the water so as to form carbonate of ammonia. The same resolution of cyanous acid and ammonia is effected by boiling the cyanite of potassa in water, when carbonate of potassa remains and ammo- nia escapes ; and if a dilute acid stronger than the cyanic be added to solu- tion of cyanite of potassa, carbonic acid escapes, while the stronger acid forms salts with the potassa and ammonia. If an undiluted acid be used, the cyanous acid remains undecomposed a short time, and gives an odor like vinegar. Anhydrous cyanous acid was obtained by M. Wohler, by distilling anhy- drous cyanic acid, and collecting the products in cool vessels. Cyanous acid thus obtained is a colorless liquid, very volatile, which forms a soluble salt with baryta, and an insoluble one with oxide of silver and some other metallic oxides; the latter being totally soluble in nitric acid. 424. Cyanic Acid, consists of 1 Cyan. 26 added to 2 ox. 16=42. This compound is formed by boiling bichloride of cyanogen with water. Water is decomposed, its hydrogen combining with the chlorine and its oxygen with the cyanogen. By the evaporation most of the hydro-chloric acid is expelled, and on cooling the cyanic acid crystalizes. The crystals are colorless and at first, transparent; but they become opake if exposed to air, and give off water by gentle heat. This acid is nearly tasteless and volatile ; but if subjected to strong heat a portion of it is resolved into pure cyanous acid and oxygen. It is decomposed by potassium forming with its oxygen, both potassa and cyanuret of potassium. Compounds of Cyanogen and Hydrogen. 425. Hydro-cyanic or Prussic Acid^ consists of 1 Cyan. 26 added to 1 Hyd. 1=27. This acid by its combination with the oxide of iron produces Prussian blue. It was discovered by Scheele in 1780, but he only obtained it in solution with a large proportion of water. Gay Lussac first obtained it pure. It has never been found uncombined in nature; though it is said to exist in the leaves, flowers, and kernels of the peach, and al- mond, and in the bark of certain plants. Thenard however, speaks doubtfully of the existence of this acid in those vegetable substances. Most writers are silent on the subject; but Profes- sor Silliman says, that if peach, laurel, or almond water be combined with lime or an alkali, it will preciptate Prussian blue from a solution of iron. It is produced during many chemical operations; it results in some degree whenever any substance 424. Composition of cyanic acid. How formed. Its crystals. Solubility in water and acids. Properties. Decomposition. 425. Compounds formed by hydro-cyanic acid with oxide of iron. Dis- covery of this acid. Where found. How produced. CYANOGEN AND HYDROGEN 169 vegetable or animal which contains nitrogen is distilled and from the action of nitric acid on vegetable and animal substances, and of ammoniacal gas upon burning charcoal. 426. Hydro-cyanic acid is liquid, colorless, and corrosive. Its odor is strong, resembling that of peach blossoms. It red- dens litmus feebly. It is very volatile; boils at 79° F. and freezes at zero. The voltaic pile decomposes it, the hydrogen going to the negative, and the cyanogen to the positive pole. Its vapor is inflammable and detonates with oxygen gas. This acid consists of 1 volume of vapor of carbon, \ a volume of hy- drogen, and \ a volume of nitrogen condensed into one volume. Its action on the animal system is very destructive, as has been proved by the experiments of Orfila, Magendie and others. The end of a small tube having been touched to a drop of this acid was put into the mouth of a dog ; the animal made two or three rapid inspirations and fell dead. One drop of the acid was ap- plied to the eye of a dog, and the effects were scarcely less sudden than in the'other case. Prussic acid, says Thenard, is without doubt, the most active and mortal of all known poisons, and a knowledge of its effects, renders less extraordinary those sudden deaths by poison so common in the annals of Italy. It acts upon the system by destroying the sensibility and the power of voluntary contraction of the muscles. 427. When introduced with some iron under a bell glass with mercury, and adding water to the mixture, it gradually disengages hydrogen gas, and Prussian blue is produced. The production of this color furnishes a method of detecting the poison when used criminally. Portions of the stomach of a person supposed to be destroyed by prussic acid, are cut up and introduc- ed into a retort with water slightly impregnated with sulphuric acid. If, on testing them with a prepared solution of the protoxide of iron, prussian blue is formed, there must have been present, hydro-cyanic acid. The sul- phate of copper, furnishes a still more satisfactory test. Hydro-cyanic or prussic acid unites with most alkaline bases, forming salts which are calledprussiates or hydro-cyanites. These salts are poisonous. Prussic acid is used as a medical agent with some success but it is of too dangerous a nature, to be employed without great caution.* * The melancholy and mysterious end of the admired poetess L. E. Lan- don, afterwards Mrs. McLean, who was discovered dead with a phial of this poison in her hand, was the subject of much remark a few years since. In one of her novels, she made a prominent character terminate a wretched existence by using a liquid which she had prepared from " almond blossoms," to be kept ready for use in case of emergency. Who can estimate or con- trol the power of a morbid imagination ? 426. Properties of hydro-cyanic acid. Decomposition by the voltaic pile, &c. Action on the animal system. 427. Tests of the presence of hydro-cyanic acid. Union with alkaline bases. Use in medicine. 15 17D BORON. 428. Chloride of Cyatuogen, sometimes called cyanuret of chlorine, and cyanide of chlorine, was discovered by Berthollet; he named it oxyprussic acid, on the supposition that it was composed of prussic acid and oxygen. Gay Lussac, who afterwards studied its nature, called it chlorocyanic acid. It was not obtained in purity, until about the year 1827, when it was procured by exposing powdered cyanuret, (prussiate of mercury)moistened with water, to the action of chlorine gas contained in a closely stopped bottle. After a few hours, the color of the chlorine disappeared, the cya- nuret of mercury was converted into the solid bi-ehloride of mercury, (cor- rosive sublimate,) and a gaseous chloride of cyanogen filled the bottle. This acid is a limpid, colorless liquid at 10° ; and above this, at the com- mon pressure, it is a gas. When enclosed in sealed tubes, it is liquid at 68° Fahrenheit, being then under the pressure of 4 atmospheres created by its own vapor. It is poisonous to the animal system; the vapor is of- fensive and injurious to the eyes ; its taste is caustic. It is very soluble in water, and alcohol; it is absorbed by alkalies, and if an acid be then added, an effervescence takes place, carbonic acid is evolved, and ammonia, hydrochloric acid, and probably hydrocyanic acid are formed. It precipi- tates green, the solutions of the protoxide of iron; this precipitate becomes a beautiful blue by the addition of sulphuric acid, or sulphate of iron; but if potassa be mixed with the chloride of cyanogen before adding the salt of iron, this precipitate is not formed. 429. Perchloride (or bichloride) of Cyanogen. We have, in this compound, twice as much chlorine, as in the chloride of cyanogen; that is, 2 atoms of chlorine to 1 of cyanogen. It was discovered by M. Serullas, and is pre- pared by adding anhydrous prussic acid, to dry chlorine. It is solid at com- mon temperatures. Its vapor is acrid and poisonous. It is rapidly decom- posed by hot water, forming hydrochloric and cyanic acids. 430. Bromide of Cyanogen resembles prussic acid in its noxious quali- ties. On account of the danger, attending its preparation, and the difficul- ty of obtaining a sufficient supply of bromine, it has hitherto been little studied. Iodide of Cyanogen is obtained by heating a mixture of 1 part of iodine, and 2 of the cyanuret of mercury. The violet vapors of iodines which first appear, are succeeded by white fumes, arising from the decomposition of the cyanuret; these, when condensed in a receiver, settle upon its sides re- sembling flocks of cotton. The iodide of cyanogen is composed of 1 equiv- alent of cyanogen, 26, with 1 of iodine 124, its chemical equiv. is, there- fore, 150. 431. Boron. Equiv. 8. The discovery of this simple element is, by English Chemists, ascribed to Sir Humphrey Davy, who, in 1807 obtained it by exposing boracic acid to the action of 500 pairs of galvanic plates. The French Chemists assert that it was discovered in 1809 by Gay Lussac and Thenard. It ap- pears that, though Davy discovered the existence of such an element, he did not obtain it in sufficient quantity to determine its properties. 428. Synonymes of chloride of cyanogen. How first obtained pure. Properties. Its precipitates with protoxide of iron. 429. Composition of the perchloride of cyanogen. Discovery, prepara- tion and properties. 430. Bromide of cyanogen. Iodide of cyanogen. 431. Discovery of boron. Manner in which it was obtained by Davy. By Gay Lussac and Thenard. BORON AND OXYGEN. 171 Thenard says, "According to Davy, when boracic acid is brought in contact with the two poles of a very powerful battery, there appears at the negative pole, a small brown spot, which he attributes to the presence of boron, while the oxygen of the acid appears at the positive pole. But it is not possible, by this means to obtain an appreciable quantity of boron."* It was obtained by Gay Lussac, and Thenard, by heating equal parts of boracic acid, and potassium, in a porcelain or copper tube hermetically sealed at one end. The tube is heated to redness, one part of the acid is decomposed, giving off oxygen to the potassium; a portion of the oxygen of the undecom- posed acid combines with the newly formed oxide of potassium ; and the result of the operation, is the sub-borate of potassa, and boron. This salt is then dissolved into water, and the boron precipitated.f Berzelius re- commends as the easiest and most economical mode of preparing it, to de- compose the fluo- borate of potassa, by heating with po- tassium. 432. By Dr. Hare's method boracic acid is put with the po- tassium into a cop- per cup (Fig. 88.) supported by a cy- linder of copper C ; —A A are rods which support a large receiver. One of the pipes, P, com- municates with an air pump. The air being exhausted from the receiver, an iron rod heated to redness, is intro- duced through the cylinder B, until it touches the bottom of the cup. The cup is soon heated and a deep red flame ap- pears to cover the whole mass. On cooling, it is found that the potassium has taken from the acid its oxygen, forming the oxide of potassium,(potash,) while pure boron remains. Fig. 88. ^~~oy • Thenard Traite de Chimie, Tome I. p. 212. t Traite" de Chimie, Tome II. p. 137. 432. Dr. Hare's method of obtaining boron from boracic acid. 172 BORACIC ACID. 433. Boron appears at ordinary temperatures, as an olive green powder. It is insipid to the taste, inodorous, and insoluble, not only in water, but in ether, alcohol, or oils. It is a non-con- ductor of electricity; absorbs oxygen at a high temperature, giving off light, and it burns spontaneously in chlorine gas. It decomposes nitric acid, taking a portion of its oxygen, and thus forming boracic acid, while nitric oxide is liberated. Compounds of Boron and Oxygen. 434. Boracic Acid. 1 bor. 8 + 2 ox. 16=24. It is the only known compound of boron and oxygen. It was first obtained from Borax, or the sub-boratc of soda, a native alkaline salt. Boracic acid was discovered by Homberg, a Chemist of the Academy of Sciences of Paris in 1702. It was for many years known by the name of Homberg's sedative salt, and was obtained from the borate of soda by means of acids, which, uniting with the soda, liberated the boracic acid. Until its decomposition by Davy, and the French Chemists about 1808, it was regarded as a simple body. It was then found to be composed of oxygen and a very combustible substance which was named boron ; the lat- ter, as it cannot, by any known methods, be decomposed, is now ranked among the simple elements. 435. Natural History. Boracic acid is found in solution, in the hot springs of Lipari, in many of the small lakes of Tuscany, and in concretions upon their borders. It exists extensively in lakes in the East Indies, though usually in combination with soda, forming borax. It is found in the craters of volcanos, and is a constituent of boracic tourmaline, and some other minerals. So common has this acid become in commerce, that it is some- times used with soda in the manufacture of borax. For chemical experiments, and medicinal purposes, boracic acid is usually obtained from the decomposition of borax, or the borate of soda by sulphuric acid, and boiling water, sulphate of soda is formed, and boracic acid is lib- erated ; the latter, on evaporating and cooling the solution, is precipitated in shining, scaly crystals. The acid being now combined with some water ; is a hydrate ; but, by exposure to a strong red heat, it melts into a trans- parent glassy substance. Vitrified boracic acid should be preserved in well stopped bottles, other- wise it absorbs water from the air, and loses its transparency. In the state of a hydrate, its specific gravity is 1.48, in the purified or vitreous state, it 433. Properties of boron, &c. 434. Composition of boracic acid. From what first obtained ? Discovery. Synonymes, &c. How obtained from the borate of soda ? When discovered to be compound ? 435. Natural history. How obtained for chemical experiments and me- dicinal purposes ? Properties. Crystals of boracic acid. CHLORIDE OF BORON. 173 is 1.80. It is inodorous, and has a bitter, rather than an acid taste. It effervesces with the alkaline carbonates, though when applied to turmeric paper, it acts like an alkali, giving it a brown color ; it reddens vegetable colors. In solution with alcohol, it burns with a beautiful pale green flame. The form of crystals of boracic acid are hexahedral, they have a pearly whiteness, and feel smooth and oily like spermaceti. They contain, Boracic acid 24, or one equivalent. Water 18, " do. Equiv. of boracic acid 42. 436. Boracic acid, like hydrochloric and hydrofluoric acids, was long ranked among undecomposed bodies ; but like them, it is now found, both by analysis and synthesis, to consist of an inflammable basis, uniting to a supporter of combustion ; but while the base of boron combines with oxy- gen to form boracic acid, we have found the hydro-chloric acid having in- flammable hydrogen for^its base united to a supporter of combustion, chlo- rine. The hydrofluoric may still be regarded as of a doubtful nature, though at present, it is usually ranked among the hydracids. 437. Chloride of Boron is formed by the combustion of boron in chlorine gas. As one equivalent of boron 8, unites with 2 equivalents of chlorine, 72, the representative number of this chloride is 80; and it is usually called, on account of its com- position the bi-chloride of boron. Sir Humphrey Davy first observed, that boron takes fire spontaneously in an atmosphere of chlorine, and burns with a vivid light. Berzelius af- terwards commenced a series of experiments, to ascertain the nature of the compound formed by this combustion. He found it to be a gas which is rapidly absorbed by water, when double decomposition takes place, and hydro-chloric and boracic acids are produced. M. Dumas and M. Despretz have found that the bi-chloride of boron may be generated by the action of dry chlorine on a mixture of boracic acid and charcoal, heated to redness in a porcelain tube. 438. Fluoride of boron is generally known among Chemists, by the name of'fluoboric acid gas ; but its nature and composition, remain doubtful. If fluorine could be obtained in an uncombined state, and then united with the inflammable boron, the result would be an undoubted fluoride of boron; but, as fluoric acid has not yet been decomposed, its combinations are still regarded as of an uncertain character. " The chief difficulty in determining the nature of hydro-fluoric acid," says Turner, " arises from the water of the sulphuric acid which is employed in its preparation. To avoid this source of uncertainty, Gay Lussac and Thenard made a mixture of vitrified boracic acid, and fluor spar, and exposed it, in a leaden retort, to heat, under the expectation that as no water was present, anhydrous fluoric acid would be obtained. In this, however, they were disappointed; but a new gas came over, to which they applied the term of fluo-boric gas." The gas may be formed by the action of hydro-fluoric acid on a solution of boracic acid. Some suppose, that in the decomposition of fluor spar, (fluoride of 436. Acids which were formerly ranked among undecomposed bodies. 437. Chloride of boron. 438. Fluoride of boron. Synonyme. Its doubtful nature. Experiment of Gay Lussac and Thenard. Explanations. Fluo-borates. Properties of fluoride of boron. 15* 174 SILICON. calcium,) the two substances interchange elements, the calcium and oxygen uniting to form lime, and a portion of free boracic acid forming with the lime, while borate of lime, boron, and fluorine, enter into a direct combina- tion. The discoverers of this gas regarded it as a. compound of fluoric and boracic acids, and therefore named it fluo-boracic acid, and the salts which it forms with alkalies, fluoborates. While fluoric acid has a powerful action upon glass, the fluo-boric acid, (or fluoride of boron,) has no effect upon it, its affinity for silex being neu- tralized by the presence of boron. It carbonizes animal and vegetable sub- stances, extinguishes flame, and is irrespirable. When absorbed by water, for which it has great affinity, it forms a dense, fuming, and corrosive liquid, somewhat resembling sulphuric acid, equally powerful in its effects on ve- getable blues. CHAPTER XIX. SILICON.---PHOSPHORUS. 439. Silicon, Equiv. 8. We should, reasoning a priori, ex- pect that the simple, or undecomposjble elements might be more easily understood than compounds ; but this is not generally the case. Indeed, most of these elements, except some of the metals, are found in nature only in combination, from which, science alone has taught us how to disengage them. Thus, though silicon, in combination with oxygen, forms silex, one of the most abundant substances in nature, it has remained hidden from our observation, till within a few years; and it is only by difficult and complicated processes, that it has been obtained in quantities sufficient to render observations and experiments upon it, of a definite and satisfactory nature. 440. Sir Humphrey Davy by experiments with silex, or sili- ceous earth and heated potassium, discovered that the former is a compound of oxygen and a peculiar base, to which, on the supposition of its being a metal, he gave the name of silicium, corresponding to calcium and potassium, the metallic bases of lime and potash. This substance has continued to be classed among the metals, until Berzelius has proved that it is infusible, devoid of metallic lustre, a non-conductor of electricity, and in short is destitute of all the distinguishing characteristics of metals. On account of its resemblance to boron and carbon in being combustible, it is by late Chemists, ranked amono- the 439. Why simple bodies are less readily understood than compound. Ob- scure nature of silicon. 440. Discovery of the compound nature of silex. Change of the name silicium to silicon. SILICON AND OXYGEIt 175 non-metallic combustibles, and in corresponding terminology called silicon. 441. Berzelius states,* that pure silicon is of a dark brown color, exhibiting no metallic lustre even by rubbing, and like earthy bodies, opposes resistance to the body against which it is rubbed. It leaves a stain upon glass vessels, adhering strongly to them when dry. It is destitute of taste or odor, and has no action upon vegetable colors. It is a bad conductor of heat and electricity, burns neither in the air nor in oxygen, and remains unaffected by the flame of the blow pipe. It decomposes water, and becomes converted into silex by its union with ox- ygen. 442. Silicon was first ob- tained pure by Berzelius in 1824, by the action of potas- sium on fluo-silicic acid gas. Dr. Hare has invented a con- venient apparatus for this pur- pose. A bell glass (Fig. 89.) is so fixed that it may be con- nected with an air pump; a platinum wire is suspended within the bell glass, and a cup containing potassium hangs just below the wire. The air being exhausted from the bell glass, fluosilicic acid, (or fluo- ride of silicon,) is admitted, and the platinum wire ignited by an electric spark. The po- tassium is inflamed, and in burning, decomposes the fluo- silicic acid, giving rise to a peculiar d^ep red flame, and chocolate colored fumes, which condense into flakes forming, (except in color,) a.= miniature representation of af snow storm. On washing the precipitate which is collected after this combustion, pure silicon, which is insoluble, is obtained, the residue being chiefly fluoride of potassium. Compound of Silicon and Oxygen. 443. Silicic acid. 1 silicon 8+1 of oxy. 8=16. It was cab * See Memoire de Berzelius, Annals de Chimie, Tome xxvii. p. 341. Those who have not access to the original memoir may find an abridged transla- tion in the author's Dictionary of Chemistry, pp. 414—416.____________ 441. Properties of silicon. ..... 442. Dr. Hare's method of obtaining silicon from fluo-silicic acid. 176 »11UUU1>. led silicic acid, from its analogy with boracic and fluoric acids, and because, like acids, it saturates the alkalies. It is often called silex ; in the laboratory silica. It has long been known in the arts, and was called by ancient Chemists, vitriflable earth, because it entered into the composition of glass. It is extremely diffused in nature, being the principal constituent of most min- eral substances. It is found nearly pure in flint, white sand, quartz crystals, calcedony, and various other minerals. 444. It may be prepared by heating to a red heat flint, or quartz crystals,, and throwing them into water. 445. Physical and Chemical properties. Silica is a light, white powder, insipid, tasteless, and harsh to the touch. It has no effect on vegetable colors, is not caustic, and has no alkaline properties, except its affinity for fluoric acid, which acts power- fully upon it. It combines with fixed alkalies and metallic ox- ides, and is therefore termed silicic acid, and its compounds with alkaline bases, silicates. When dry, silica neither dissolves in water nor is absorbed by it, but in its nascent state, or when just precipitated, it dissolves freely in this liquid. It is a remarkable fact, that silica, on evaporation, should thus lose its pro- perty of dissolving with water ; and this offers an explanation of the vast collection of silicious crystals which nature presents in cavities of quartz, agate, and many other minerals of the same class ; and which may be re- garded as hydrates of silica, in which the water of crystalization exceeds in volume the mass of silica. In some hot springs as the geysers of Iceland, silica is found in solution, which is promoted by the soda contained in their waters. 446. When silica is fused with a large portion of potassa, a vitreous mass is produced which is soluble in water. This was known by the old writers under the name of liquor of flints. If the proportion of silica and alkali be reversed, (that is, a small portion of alkali added to silica,) and the mixture beJused, the result is a transparent, brittle compound which is insoluble in water, and is attacked by no acid except the hydro-fluoric ; this compound is glass. " Every kind of glass is a silicate, or a compound of silica and an alkali, and all its varieties are owing to differences in the proportions of the constituents, to the nature of the alkali, or the presence of foreign matter. Thus, green bottle glass is made of impure materials, such as river sand, which contains iron, and the most common kind of kelp or pearlashes. Crown glass for windows is made of purer alka!' 443. Composition of silicic acid. Its synonymes. Its existence in na- ture. 444. Mode of obtaining it. 445. Properties. Silicates. Its action with water. Crystals. 446. Liquor of flints. Glass. Cause of varieties of glass COMPOUNDS. 177 and sand which is free from iron. Plate glass for looking glass- es is composed of sand and alkali in their purest state, and in the formation of flint glass besides these pure ingredients, a quantity of red lead or litharge is employed."* Black oxide of manganese improves the transparency of glass, by oxidizing any carbonaceous substances in the materials used ; and boracic acid or borax are employed in making imitations of gems. Silica is also used in the composition of porcelain ; as pure clay without any silicious earth would shrink too much for this purpose. Compounds of Silica with Chlorine, Sulphur and Fluorine. 447. Chloride of Silicon is formed by the combustion of silicon in chlorine gas. It is liquid, limpid, and volatile, evaporating in open vessels, in the form of a white vapor. Its odor resembles that of cyanogen. Water changes it into muriatic acid and silica. 448. Sulphuret of Silicon. Silicon when heated with the vapor of sulphur, unites with it, forming a white earthy looking substance. Water converts it into sulphuretted hydrogen and silica. The former escapes with efferves- cense, the latter dissolves. 449. Fluoride of Silicium, or Fluo-silicic Acid Gas is composed of 1 Silicon 8 added to Fluor 10=18. In treating of hydro-fluoric acid, especially its action upon glass we found that in decomposing that substance a peculiar gas was generated. This is the fluo-silicic acid. It is a colorless gas, of a strong odor and caustic taste. It extinguishes combustion, is irritating to the lungs, and is not decomposed by heat. Its specific gravity is 3.57. Water acts upon it, precipitating silica in a gelatinous state. It forms white fumes with the atmosphere by combining with aqueous vapor. When distilled in a receiver containing water, it becomes covered with a silicious crust which at length covers the water, and it is necessary to shake the vessel and break this crust that the condensation may not thus be prevented. Moist substances exposed to this gas, become encrusted with it, so as to resemble petrifactions ; thus insects, reptiles, and vegetable substances, by being moistened and placed in an at- mosphere of this gas may be made to appear like natural fossils. It may be prepared for experiments by heating in a retort three parts of fluor spar and two of silica, with an equal weight of sulphuric acid ; it must be collected over mercury. When dissolved in water, it becomes the silico-hydro fluoric or silicated fluoric acid; the hydrogen of the water com- bining with the fluorine, and the oxygen with the silicon. PHOSPHORUS. EQUTV. 12. 450. Phosphorus combines so readily with oxygen and other * Turner. 447. Formation and properties of chloride of silicon. 448. Formation of sulphuret of silicon. 449. Composition of fluo-silicic acid. When produced. Properties. Action with water. How prepared for experiments ? Change when dis- solved in water. 178 PHOSPHORUS. substances that it is not found pure in nature. It is solid, but so soft and flexible that it may be bent with the fingers like wax. It may be cut with a knife. Its color when pure is white, but on exposure to air and moisture it assumes a brownish hue. When excluded from contact with the air, light gives it a red color. Its specific gravity is 1.77. Its odor is feeble, somewhat resembling that of hydrogen gas. It is always luminous in the dark, hence its name—the light-bearer, from the Greek phos, light, phero, to bear. 451. History. Phosphorus was discovered in 1669, by Brandt, an alchemist of Hamburgh, in his search for the philosopher's stone, or the art of converting the common metals into gold and silver. The preparation of phosphorus, however, remained a secret until 1737, when a stranger in Paris, communicated it to a committee of the French Academy of sciences. But the meth- od then used was tedious and imperfect. In 1769, Gahn of Sweden, in connection with Scheele, published a newly discov- ered process for obtaining phosphorus by distillation of bones. This is the one now generally followed. Phosphorus being thus easily obtained, chemists were able to study its properties. Much is due to the labors of M. Pelletier, who first combined it with sulphur and many of the metals ; to Lavoisier, who in- vestigated its combination with oxygen; to Dulong and Davy, who studied its different acids, and to Berzelius, who has ex- amined the combinations of these acids, with different bases. 452. The solid parts of the bones of animals consist, princi- pally, of the phosphate of lime, a salt formed by the union of phosphoric acid and lime. A man of common stature is said to have about one pound of phosphorus in his bones. Phosphoric acid is a compound of phosphorus and oxygen. From the de- composition of the phosphate of lime, in bones, phosphorus is obtained. The usual process is, to digest in sulphuric acid a quantity of calcined bones, (that is, bones burnt in an open fire,) reduced to powder. The phos- phate of lime is decomposed by the sulphuric acid, which, uniting with the lime forms sulphate of lime ; the disengaged phosphoric acid being now mixed with powdered charcoal, and strongly heated in an earthen retort, parts with its oxygen to the charcoal, forming carbonic acid, while phos- phorus passes over in the form of vapor, and may be collected by placing the beak of the retort under a receiver filled with water. When first ob- tained it is of a red color, owing to the presence of the phosphuret of car- bon, from which it may be purified by another distillation. 450. Why is phosphorus not found pure in nature ? Its physical proper- ties. Derivation of the name. 451. History. 452. Where does phosphorus exist ? Mode of obtaining it. PHOSPHORUS. 179 453. Phosphorus is highly inflammable, and gives off a gar- lic odor when burning. When exposed to the air at common temperatures it undergoes slow combustion, appearing in the light as a white smoke and in the dark as a beautiful blue lumi- nous cloud. It should be kept in water, as a slight degree of heat, in the open air readily kindles it to a flame. It melts at 99° F. takes fire at 108<>; and volatizes at 219°. 454. Perhaps no substance affords such a variety of brilliant experiments, especially for an evening's exhibition, as phosphorus. Exp. 1st. Words or figures drawn on the wall of a dark and warm room with a stick of phosphorus will leave traces, which in the night will appear like fire. Exp. 2nd. A few grains of phosphorus in the bottom of a wine glass will burn with brilliancy, and a succession of detonations, by pouring on water and sulphuric acid. Exp. 3d. Oil, in which phosphorus has been dissolved, when rubbed on the face and hands, exhibits the appearance of a lambent flame, playing over the features, accompanied with luminous clouds and flashes. Unless the phosphorus is entirely dissolved, this may prove a dangerous experiment j severe burns have been thus caused. Fig. 90. Fig. 91. Exp. 4th. The combustion of phosphorus in oxygen gas, (Fig. 90,) or even an enclosed por- tion of atmospheric air, is attended with a splendor too great for the eye to endure. Dur- ing combustion dense white vapors like flakes of snow will fill the jar. These vapors are phosphoric acid, consisting of phosphorus and oxygen. Exp. 5th. Eudiometry may be performed by consuming the oxygen of the air with phosphorus. If a cylinder of phosphorus be supported upon a wire within a glass matrass (Fig. 91,) inverted in a jar of water, the included air is gradually absorbed. In order to determine the quantity of oxygen in the air, we have only to ascertain the ratio between the quantity absorbed, and the quantity included. 453. Inflammable nature, &c. 454. Experiments with phosphorus. 180 PHOSPHORUS AND OXYGEN. 455. Phosphorus does not, at the ordinary pressure, burn in oxygen gas at a temperature below 80° ; but if the pressure is diminished, it becomes luminous in the dark, and burns. Ni- trogen, by rarefying the oxygen of the atmosphere, acts like the diminution of pressure, and singularly favors the combustion. Phosphorus forms combinations with most other combusti- ble bodies. With oxygen it enters into the composition of many minerals, and forms a large portion of the animal frame. It is employed in the arts for the construction of phosphoric matches, and in Chemistry for the analysis of air and the prepar- ation of phosphoric acid. It is a violent poison, though it is some- times used in medicine in very small doses. Combinations of Phosphorus and Oxygen. 456. There is an uncertainty with respect to the number of combinations of these two elements. Dr. Turner remarks that " under the term phosphoric acid, Chemists have hitherto in- cluded two distinct acids, phosphoric, and pyro-phosphoric, com- pounds which afford an instance of a fact of much importance to the atomic theory: viz. That two substances may consist of the same ingredients, in the same proportion, and yet differ essentially in their chemical properties." These are isomeric bodies* 457. There are three known acid combinations of phosphorus and oxygen, which contain different proportions of their constit- uent elements. 1. Phosphoric acid, 1 Phos. 12+2 Cx. 16=28. 2. Phosphorous acid, 1 Phos. 12-j-l Ox. 8=23. 3. Hypo-phosphorous acid, 2 Phos. 24+1 Ox. 8=82. 458. Phosphoric acid may be obtained by the combustion of phosphorus in oxygen gas, (see IT 454, exp. 4th.) It may also be obtained by burning phosphorus in an enclosed portion of atmospheric air, occasionally raising the receiver, in order to let in fresh supplies of air, until all the phosphorus is consumed. 1 grain of phosphorus requires about 15 cubic inches of com- mon air, and of course about 4 cubic inches of oxygen for its saturation. 459. This acid is white, solid, inodorous, and soluble in water, * See ir 402. with the note. 455. Circumstances under which phosphorus burns in oxygen gas, &c. Combinations of phosphorus. Uses. 456. Dr. Turner's remark respecting phosphoric and pyro-phosphoric acids. 457. Names and composition of acid compounds of phosphorus and oxy- gen. 458. How may phosphoric acid be obtained ? 459. Properties, &,c. PHOSPHORUS. 181 dissolving with a hissing noise, and forming if concentrated, a dense, oily liquid. Though decided in respect to its sour taste, its action on vegetable blue colors, and its effect in neu- tralizing alkalies, it does not decompose animal matter, like nitric and sulphuric acids. Fig. 92. 460. Phosphoric acid may be decomposed by heating with charcoal in a retort a, (Fig. 92,) placed over a furnace, 6, the beak of the retort being immersed in the basin of the water, c. The phosphoric acid loses oxygen, which, uniting with the vapor of carbon from the charcoal, forms carbonic acid gas : the phosphorus passes over, being volatilized when the retort is at a red heat, and appears in the basin, in the form of a reddish wax. 461. Pyro-phosphoric acid. Mr. Clark of Glasgow remarked that common phosphoric acid is, by heat, converted into a substance, which, though unchanged in its constituents or in their combining proportions, exhibits properties of an essentially different kind ; this new acid he called Pyro-phosphoric* acid. Phosphoric acid produces with the oxide of — silver a yellow salt, and renders a solution of albumen turbid. Pyro-phosphoric acid produces with the same oxide a white salt, and does not destroy the transparency of albumen. Pyro-phos- phoric is less energetic, it has less saturating power, and is separated from its combinations by phosphoric acid. And yet the only visible effect of heat on phosphoric acid is to expel water, which, we should infer, would render the acid more powerful, rather than diminish its energies. 462. Phosphorous acid. It was ascertained by Lavoisier, that the slow and rapid combustion of phosphorus produced two dis- tinct acids, the phosphorous and the phosphoric. At a high tem- perature, phosphorus, whether burning in common air or in oxy- gen gas, unites with its highest proportion of oxygen (two equiv- alents=zl6,) and produces phosphoric acid; at a common tem- perature it unites with but one equivalent of oxygen (=8) and forms phosphorous acid. 463. Sir Humphrey Davy first obtained pure phosphorous acid, by sublim- ing phosphorus through the perchloride of mercury,(corrosive sublimate.) The corrosive sublimate is put into a glass tube, connected at one end with a small receiver, (which is to he kept cool,) and at the other with a small tube containing phosphorus ; as heat is applied to the phosphorus, it rises in vapor, comes in contact with the corrosive sublimate, which it decom- poses by combining with its chlorine, and passes into the receiver in the * From the Greek pur fire, added to phosphoric. 460. Decomposition of phosphoric acid. 461. Discovery of pyro-phosphoric acid. Difference in the properties of phosphoric and pyro-phosphoric acids. 462. Different products of the slow and rapid combustion of phosphorus. 463 Mode of procuring phosphorous acid. 16 182 PHOSPHORUS AMD CHLORINE. form of a limpid fluid, which is the chloride of phosphorus. This, on being mixed with water, decomposes it; the chlorine unites with the hydrogen of the water, forming hydrochloric acid ; while the phosphorus attaches itself to the oxygen, producing phosphorous acid. The solution being next eva- porated to the consistence of syrup, hydrochloric acid is expelled, and the residue, which is a hydrate of phosphorous acid, becomes solid and crystaline in cooling. 464. From its tendency to unite with an additional quantity of oxygen, phosphorous acid is a powerful deoxidizing agent, and precipitates mercury, silver, and gold from their saline combination in the metallic form. On exposure to the air, or in contact with the nitric acid, it absorbs oxygen, and is converted into phosphoric acid. Phosphorous acid combines with salifiable bases, forming salts called phosphites ; it is acid to the taste, and reddens vegetable blue colors. Its odor resembles that of garlic. 465. Hypo-phosphoric acid. Is so named on the supposition that it con- tains a smaller proportion of oxygen than the phosphorous acid. It com- bines with salifiable bases forming neutral salts, called hypo-phosphites, which are all remarkably soluble in water. Silliman suggests that this acid may be a triple compound of oxygen, hydrogen, and phosphorous, or a hydracid, in which case its proper name would be fci/dro-phosphoric acid.* 466. Oxide of Phosphorus. Phosphorus is usually made into small sticks of a few inches in length. As it must be preserved in water, it is usually kept in vials of this liquid. After being for some time exposed to the action of water, it becomes encrust- ed with a whitish substance, which is called the white oxide of phosphorus. The red colored residue which appears after the combustion of phosphorus, is called the red oxide of phosphorus. Thenard considers these two oxides identical, except that the white oxide is in the hydrated state. Phosphorus and Chlorine. 467. There are two definite compounds of phosphorus with chlorine. One discovered by Davy, called the perchloride, the other discovered by Gay Lussac and Thenard, and called proto- chloride. Their component parts and chemical equivalents are as follows. * Silliman's Elements, Vol. 1. p. 429. 464. Properties, salts, &c. 465. Hypo-phosphoric acid. Its salts. Silliman's suggestion respecting its composition. 466. Formation of the white oxide of phosphorus. Red oxide. 467. Discovery and composition of the proto-chloride and per-chloride ot phosphorus. PHOSPHORUS AND HYDROGEN. 183 Protochloride of Phos. 1 Phos. 12+1 Chlo. 36=48. Perchloride of Phos. 1 Phos. 12+2 Chlo. 72=84. 468. The Protochloride of phosphorus may be obtained by passing the vapor of phosphorus over perchloride of mercury, (corrosive sublimate,) in a heated glass tube ; the perchloride of mercury yields one proportion of chlorine to the phosphorus and becomes calomel, or the protochloride of mercury. The phos- phorus has become a volatile transparent liquid, very caustic, and heavier than water. It decomposes rapidly in water in which case a solution of hydrochloric, and phosphorous acids is the result. Its vapor is combustible. 469. The Perchloride of phosphorus, sometimes called the bi- chloride and deutochloride is formed when dry phosphorus is burned in chlorine gas. (Figure 93) represents a tubulated glass bottle containing chlorine gas, into which some phosphorus being introduced, it burns spontaneously, throwing off brilliant jets of fire, and giving a pale white light. The bladder fastened to the tubulure is to give space for the expansion of the gas by heat, which, as the bottle is air tight, might other- wise, cause it to break. The white, solid, pulverulent substance which collects on the inside of the bottle is the per-chloride of phosphorus. It crystalizes in transparent prisms ; is volatile at a heat less than 212° ; decomposes water rapidly, forming with its elements, hydro-chloric and phosphoric acids. Some chemists regard the chlorides of phosphorus as acids, to which they give the name of chloro-phosphorous for the proto- chloride, and chloro-phosphoric for the per- chloride. When the per-chloride of phosphorus is heated with about one seventh of phosphorus, it passes to the state of proto-chloride. 470. Phosphorus with bromine and iodine forms compounds termed bromides and iodides of phosphorus, but they are little understood. Phosphorus and Hydrogen. 471. There are two compounds of phosphorus and hydrogen, viz. Proto phosphurettedHydrogen, and Per-phosphurelted Hydrogen 468. Proto-chloride of phosphorus. 469. Per-chloride. 470. Bromides and iodides of phosphorus. 471. Composition of two compounds of phosphorus and hydrogen. terminations in ide, uret, &c. The 184 PHOSPHORUS. As in the chemical nomenclature, binary* compounds of substances of the electro-negative class, which are not acid, are designated by the termination ide, as oxide, chloride, bromide, &c, so binary combinations of the electro-pos- itive class, which are not of a metallic nature, are distinguished by the ter- mination uret, as phosphuret, carburet, sulphuret, &c. When the compound is gaseous, the termination uretted is used, as carburetted hydrogen, sulphuret- ted hydrogen, &c. 472. Proto-phosphuretted Hydrogen is sometimes called the.fo- hydruret of phosphorus, and hydro-phosphoric gas. It was dis- covered by Sir Humphrey Davy in 1812. It may be obtained when the solid hydrated phosphorus acid is heated in a close vessel. It is a colorless gas, with a disagreeable odor. It does not take fire spontaneously in the atmosphere, as phosphuretted hydrogen does ; but when mixed with atmospheric air, or pure oxygen, it detonates violently with the electric spark, or when heated to 300° F., it inflames sponta- neously in chlorine gas. 473. Per-phosphuretted Hydrogen, (called also the Hydruret of Phosphorus,) may be obtained by boiling phosphorus in a small retort (Fig. *94,) with a hot solution of potash, which should entirely fill the vessel, and the beak of the retort should be made to dip into a vessel filled with the same solution. The gas, as it Fig. 94. is extricated, grad- ually expels the li- quid from the neck, and inflames, when allowed to es- cape into the air ; or it may be collected under a bell glass, also filled with the same alkaline solu- tion. One peculiar property of this gas is, that of spontane- ously inflaming on mixture with common air or oxygen gas. This combustion is accompanied with a beautiful appearance. After the explosion, circular, horizontal rings, or coronas, of dense white smoke rise in the air, which increase in diameter, and become fainter as they ascend,f it is decomposed by heat, emctricity, and the vapor of sulphur. Lights may sometimes be * A binary compound is one which consists of no more than two elements. t Some care is necessary in conducting this experiment, that as small a portion of air as possible shall be included in the retort, since the first bub- bles of phosphuretted hydrogen gas that are formed, will take fire as soon 472. Proto-phosphuretted hydrogen. Discovery. Mode of obtaining it and its properties. 473. Per-phosphuretted hydrogen, &c. Cause of lights seen at ni^ht in certain situations, &c. SULPHUR. 185 seen at night around burying grounds, and swamps where animal and vegetable substances are undergoing decomposition, " Travelling once," says Silliman, " through a deep valley, in a dark night, between Wallingford and Durham, Conn., I was surrounded by multitudes of pale, lambent lights ; these were every moment changing their position, and some of them were within reach of my whip ; they were yellowish, but not intense." Thus does science explain to us the mysterious " Jack o' the Lantern" and " Will o' the Wisp," as being mere exhalations of gases which, on rising into the atmosphere, spontaneously in flame. 475, Phosphuret of Carbon. The combination of phosphorus with carbon was first effected by M. Proust, in 1799; it is a soft, yellowish powder, destitute of smell or taste. It slowly imbibes moisture from the air, and then has an acid taste. CHAPTER XX. sulphur.—Equiv. 16. 476. Natural History. Sulphur is found, as a mineral, in various parts of the world, especially in the vicinity of volcanoes. It is obtained in large quantities from the craters of volcanoes. It is generally massive, sometimes in a state of powder, or crystalline form. Much of the sulphur of commerce, is obtained by applying heat in close vessels to the natural compounds of the metals and sulphur, especially to iron pyrites. The volcanic sulphur is probably the result of similar decompositions. Properties. Sulphur is a brittle solid, of a citron or greenish yellow color, inodorous, except when heated by friction on fire, and nearly tasteless. It is about twice as heavy as water. It is a very bad conductor of heat and electricity, and becomes negatively electrified when rubbed. 477. Sulphur fuses at about 216° Fahrenheit; it is fluid between 230° and 280° Fahrenheit, and when cast into moulds, forms the common roll sulphur, or brimstone. As the temperature rises, it thickens and becomes darker colored, till at between 425° and 480°, it is so tenacious that the vessel may be inverted without spilling it. At 428°, if poured into water, it becomes a plastic mass, and is used for taking impressions of medals, &c. as they come in contact with air in the retort, which will be in danger of being broken in the percussion. 475. Phosphuret of carbon. 476. Sulphur found in a natural state. Sulphur of commerce, how ob- tained ? Properties. 477. Affected by heat. Flowers of sulphur. Crystalized sulphur. 16* 186 sulphur. Above 480°, it liquefies again, but not so perfectly as at 248°. At 550°, or 600°, it sublimes rapidly; indeed, a slow evaporation commences below the freezing point. The vapor condenses on cold surfaces in the form of a crystaline powder, called flowers of sulphur. Sulphur may be crystalized by fusing several pounds of it in a large crucible, and allowing it to cool slowly. When a crust has formed upon the upper surface, it is to be perforated in two places by a hot iron rod, and the sulphur which remains melted, is to be poured out. If a sufficient quantity of sulphur has been used and the cooling very slow, octahedral crystals of sulphur will be found lining the crucible; otherwise the crystalization will be irregular and confused. 478. Sulphur is soluble in alcohol, provided the two bodies be brought together in the state of vapor; from this solution, water throws down the sulphur as a white hydrate called " milk of sulphur." This is the only combination of sulphur with water, the former being quite insoluble in the latter. 479. Sulphur takes fire on being heated above 300° in the open air ; it burns with a blue flame, and if the air be quite dry, produces sulphurous acid gas; if moisture be present, some sulphuric acid is formed also. In pure oxygen gas, the com- bination is far more rapid and brilliant; but the product is sul- phurous acid in this case also. Sulphur has numerous and im- portant uses in medicine. Mixed with charcoal and salt-petre, it forms gun-powder, the explosive property of which is owing to the sudden change of solids into gases. It is used for fire matches, for copying medals, and furnishes beautiful crystals for ornamental purpose. With iron filings, it is used as a cement. Ex. If a gun-barrel, (Fig. 95,) heated to a red heat, have a piece of sulphur placed in one end of it, the jet of ignited sulphurous vapor will burn iron wire, as if ignited in oxygen gas ; and the iron will fall in the form of fused globules ; these are the proto-sulphurets of iron. Hydrate of potassa expos- * ed to the jet, fuses into a sulphuret of fine red color. Combined with oxygen in the form of sulphurous and sul- phuric acids, sulphur is used in the arts of bleaching and dyeing. 480. Compounds of sulphur and oxygen. Of these there are four, all of them being acids. 1. Hyposulphurous acid, 1 Sulp. 16 added to 1 ox. 8=24. 2. Sulphurous acid, 1 Sulp. 16 " 2 ox. 32. 3. Hyposulphuric acid, 2 Sulp. 32 " 5 ox. 72. 4. Sulphuric acid, 1 Sulp. 16 " 3 ox. 40. 478. Sulphur with alcohol. Hydrate of sulphur. 479. Product of the combustion of sulphur. Uses. Exp. 480. Names and composition of the compounds of sulphur and oxygen. SULPHUROUS ACID GAS. 187 481. Hyposulphurous acid. This acid is only known in combination with bases, forming salts called hyposulphites. On adding a stronger acid, to lib- erate the hyposulphurous acid, the latter is immediately resolved into sul- phurous acid and sulphur. The hyposulphites are of no use in the arts ; their most interesting property, is, that their solutions dissolve large quan- tities of chloride of silver, giving intensely sweet compounds. 482. Sulphurous Acid Gas. This is always the principal product of the combustion of sulphur in air, or oxygen gas, and is the sole product when moisture is not present. But the best mode of obtaining this gas, is by depriving sulphuric acid of a portion of its oxygen. Most of the metals decompose sulphuric acid, becoming oxidized at its expense. Put 2 parts of mercury, and 3 of sulphuric acid, into a glass retort, and apply the heat of a lamp. The peroxide of mercury is formed, and unites with some of the undecomposed acid, forming persulphate of mercury, which remains in the retort; while the sulphurous acid gas escapes with efferves- cence, and is to be collected over mercury in the receiver. 484. Properties. Sulphurous acid gas is transparent and col- orless. Its specific gravity is 2.22, (double that of oxygen,) it is less elastic than any other gas ; being condensed into a liquid by intense cold, or by a pressure of one additional atmosphere. Its pungent and suffocating odor, distinguishes it from all other gases, When pure, it is irrespirable, causing a spasmodic contraction of the glottis. If inhaled with air, it excites coughing and is injurious to the lungs ; it is fatal to animals confined in it. Thus some naturalists make use of it to destroy the lives of butterflies and insects which they wish to preserve in the cabinet. It is incom- bustible, and extinguishes burning bodies. It has a great affinity for water, which, will absorb 33 times its bulk. The solution thus formed, has the odor and other properties of the gas itself, and may be substituted for it in many operations. It must, however, be kept in closely stopped bottles ; for, on exposure to the air, it rapidly absorbs oxygen, and is converted into sulphuric acid. Its strong affinity for oxygen renders it a powerful deox- idizing agent. 485. This gas and its solution in water, possess the property of bleaching, and are used for that purpose to some extent; thus straw bonnets are bleached by the fumes of burning sulphur; and a red rose, or dahlia held in the same fumes, or dipped in aqueous sulphurous acid, will become white, except where por- tions have been protected by folds in the leaves. But the bleach- ino- is not permanent, the coloring principle being only combined 481. Hyposulphurous acid. 482. How is sulphurous acid gas obtained ? Reduction of sulphuric acid, to sulphurous acid, by heating it with mercury. 484. Properties of sulphurous acid gas. Its affinity for water and oxygen. 485. Bleaching property. Effect of cold or pressure upon this acid. De- composition. Compounds. 188 SULPHURIC ACID. with sulphurous acid,—not destroyed. Consequently, the color returns, when, by exposure to the air, the gaseous acid has been dissipated, the stronger acids, also, will restore the color, and the alkalies, by neutralizing the sulphurous acid, produce the same effect. Sulphurous acid liquefied by cold or pressure, is exceedingly volatile, and, by its evaporation, produces cold enough to freeze mercury, and to liquefy some other gases. This gas is not decomposed by heat alone; but is deprived of oxygen, by being brought in contact with hydrogen, and some other oxidable substances, at a red heat. It combines with the salifiable bases forming salts, called sulphites. 486. Hyposulphuric Acid is formed when sulphurous acid is passed into water, in which peroxide of manganese is suspended. Theory. The latter parts with 1 equivalent of its oxygen which uniting with the sulphurous acid forms the hyposulphuric. This acid is of no use in the arts, nor in the laboratory. Its salts are generally soluble, even those of the bases with which sulphuric acid would form insoluble salts. 487. Sulphuric Acid is commonly known as oil of vitriol, having been at first, obtained by the distillation of green vitriol. Several of the salts of this acid have obtained the name of vitriol, from their glassy appearance; as green vitriol, which is a sul- phate of protoxide of copper ; white vitriol, sulphate of the oxide of zinc. 488. Physical and chemical properties. Pure sulphuric acid is transparent and colorless and of an oily consistency ; its taste is intensely sour, and its specific gravity, when most concentra- ted L85. It is one of the strongest acids known, combining with all the salifiable bodies, and even taking them away from almost all other acids, by its superior affinity It oxidizes many of the metals, and then combines with the oxides ; in some cases the acid must be strong, the metal being oxidized at its expense, as in the preparation of sulphurous acid gas, in other cases, the acid must be dilute, the water furnishing oxygen to the metal, and hydrogen gas being evolved. It has a very great affinity for water, uniting with it in every proportion. This combination is attended with condensation, on which account great heat is evolved ; the increase of temper- ature sometimes exceeds 212°. Snow is melted by mixture with this acid, and if the proportions be rightly adjusted, great de- crease of temperature is observed. It attracts watery vapor rapidly from the atmosphere, and is therefore used to promote evaporation by the air pump. , It is said that, in the course of a month, sulphuric acid will absorb water 486. Hyposulphuric acid. 487. Origin of the name, oil of vitriol, &c. 488. Properties of sulphuric acid, &c. Its affinity for water, &c. SULPHURIC ACID. 189 enough from the air, to double its weight; and that the affinity is not satis- fied till the weight of the acid is augmented sixfold. By reason of this affinity, sulphuric acid corrodes organic substances powerfully, causing their oxygen and hydrogen to unite and form water, while their carbon re- mains. It is on this account that this acid often appears deeply colored ; the color arising from the carbon of minute portions of vegetable water which have fallen in and been decomposed. Wood may be stained black by washing it with very dilute sulphuric acid, and then warming it so that the water may be dissipated and the action of the acid favored by the heat. Water acidulated with this acid, may also be used as a sympathetic ink, let- ters formed with it being rendered apparent on warming the paper. It dis- solves minute portions of charcoal and sulphur. The former communicates to it a blue green, or brown tinge and the latter a pink or brown; the color depending in each case on the quantity dissolved. 489. Its strength may be tested by its specific gravity or, by ascertaining the quantity of carbonate of soda required to neutral- ize a known quantity of the acid ; 100 grains of the alkali will saturate 92 of pure acid. Ordinary sulphuric acid freezes at 15°, F. below zero. Its boiling point is 620°, F. 491. The strongest sulphuric acid which can be prepared by the ordinary method is a hydrate, still containing one atom of water to one atom of acid. But it can be procured perfectly anhydrous by means of fuming sulphuric acid. This substance is the result of a very old process, still in use at Nord- hausen, in Germany. It is heavier than the common sulphuric acid and emits dense white fumes when exposed to air, especially if the atmosphere be moist. D consists of acid and water, in such proportions that it may be considered a compound of one equiv. of anhydrous, and one of hydrated sulphuric acid. The an- hydrous acid being volatile below 122°, while the hydrous requires a temper- ature of 620°, it is easy to separate them by distillation at a very gentle heat. The anhydrous acid passes over as a perfectly transparent and colorless vapor and is condensed in the cool receiver, into a white and crystaline, or a transparent, glassy solid, according to the rapidity of cooling.—It is liquid in summer, unless artificially cooled.—It has a greedy attraction for water, combining with the moisture of the air and forming dense white fumes if exposed; and if thrown into water it evolves great heat causing a hiss- ing and boiling like red hot iron. 492. Natural History. Sulphuric acid occurs abundantly in nature in combination with earths, forming salts, of which the most plentiful are sulphate of lime, (gypsum or plaster of Paris,) and sulphate of baryta, (heavy spar ;) but it is seen seldom in an uncombined state, except near volcanoes. A large deposit of sulphur in Java in the crater of an extinguished volcano is the source of a stream of diluted acid, which in the rainy season flows down the mountain, destroying the vegetation along its banks. Professor Eaton mentions a p'ond near Rochester, N. Y. the waters of which, especially in a dry season contain some quantity of it. This acid, or any of its soluble salts can be detected in solution, by the addition of 489. Tests of the strength of this acid. Freezing and boiling points. 491. Anhydrous sulphuric acid. How procured ? Separation of the hy- drous acid. Properties of the anhydrous acid. 492. Natural historv. Tests of sulphuric acid. 190 SULPHUR. solution of hydrochlorate of baryta when a heavy white precipitate will be formed, which is insoluble in acids and alkalies. 493. Hydrous Sulphuric acid, which is the common acid of commerce is obtained by the following process : apartments being prepared, lined with sheet lead, and 8 parts of sulphur to 1 of nitre (saltpetre) broken into fragments are put upon iron plates. The mixture being inflamed, the door is closed. The floor is covered with water to the depth of some inches, which water absorbs the acid as fast as it is formed. The acidulated water is drawn off and con- centrated by heat, in leaden boilers until found to ..e of the proper s^ "ific gravity. Rationale. The process of the combustion is the formation of sulphurous acid from the sulphur and deutoxide of nitrogen from the nitre. The latter combining with the oxygen of the air is changed into nitrous acid. The sulphurous and nitrous acids then combine with the watery vapor, and form a crystaline solid, composed of sulphuric acid, hyponitrous acid, and water. When this solid drops into water, it is instantly decomposed, the sulphuric acid being retained in the water, and nitrous acid and deutoxide of nitrogeu escape. The nitrous acid thus set free, as well as that formed by the deu- toxide and oxygen of the air, again combines with the moist sulphurous acid, and forms the solid, which sinks to the water and is again decomposed. This process continues until the whole of the sulphur and nitre is changed in- to sulphuric acid, and absorbed by the water on the floor of the leaden cham- ber. Sulphur and Hydrogen. 494. Hydro-sulphuric or Sulphuretted Hydrogen* consists of 1 sul.=16-fl hyd.=l. equiv. 17. This is a gas, formed by heat- ing sulphur in hydrogen, or by bringing sulphur and hydrogen together in a nascent state. Fig. 96. Let a portion of sulphur be put into a vessel, (Fig. 96,) to the neck of which is fitted a bag of hydrogen gas ; as the sulphur is heated it volatilizes, and its vapor rising unites with the hydrogen to form sulphuretted hydrogen. The gas may be collected over water. 495. Its specific gravity is 1.18, a little more than that of atmospheric air ; it requires a pres- sure of 17 atmospheres to reduce it to the liquid state. It is a colorless gas, of a most fetid o tor, as may be perceived in putrid eggs, or the washing of a gun-barrel. Its taste also is un- pleasant, of which the water of sulphuretted springs is an example. It is poisonous even when mixed with a large quantity of air. Small birds were destroyed by an atmosphere contain- ing rsVu part of this gas. It does not support combustion, but * Sometimes called hydro-thionic acid, from the Greek hudor, water, and theion, sulphur. 493. Hydrous sulphuric acid. Rationale. Sulphate of ammonia. 494. Combinations of sulphur with hydrogen. 495. Nature, and formation of sulphuretted hydrogen. Properties. SULPHUR. 191 burns with a pale blue flame; the products of its combustion are water and sulphurous acid. It also explodes on being ignited, when mixed with air, or oxygen. 496. Potassium, tin, and some other metals decompose this gas when heated in it, uniting with the sulphur and liberating the hydrogen. Elec- tric sparks, or a platinum wire ignited by galvanism, will also decompose it. In these experiments^ the hvdrog^n evolved is equal in bulk to the hy- dro-? ^huric acid decor, _ ,jsed. Hydro-sulphuric and sulphurous acids mutually decompose each other, the oxygen of the one uniting with the hydrogen of the other, and the sulphur of both being deposited. Nitric acid poured into a phial of this gas, decomposes it by furnishing oxygen ; sulphur is deposited, and water, and deutoxide of nitrogen are formed. Water at 60° F., if freed by boiling, from other gases, will absorb about its own bulk of this gas, and afford a solution which has the odor, taste, and chemical action of the gas itself, and may therefore be used as a test. This solution is very easily decom- posed by substances which yield oxygen, and even by exposure to air; the oxygen uniting to the hydrogen of the hydro-sulphuric acid, and the sul- phur being deposited. This cause accounts for the constant deposition of sulphur from the water of sulphuretted springs. 497. Hydro-sulphuric acid is an important test for metals, in solutions of which, it produces precipitates of metallic sulphur ets ; these precipitates are of different colors, by which we are enabled to ascertain what metal is present. The gas acts also on many insoluble metallic compounds; thus, white paint, (car- bonate of lead,) and the cosmetic pearl white, (oxide of bismuth,) are rendered black, owing to the formation of the black sulphur- ets of lead, and of bismuth. At sulphuretted springs, some lu- dicrous changes of complexion have occasionally happened to ladies beautified with pearl white. " The stream of gas is invisible, though represented in the figure to aid in understanding its design. ______________ 496. Decomposition. Absorption by water. 497. Action on metals, and metallic compounds. 192 SULPHUR. Chlorine may be used to purify an atmosphere contaminated with sulphuretted hydrogen. 498. Hydro-sulphuric acid, reddens litmus paper, and com- bines with the fixed alkalies, and with ammonia; its relations to the metallic oxides are perfectly analogous to those of the other hydracids. Liquid hydro-sulphuric acid. Mr. Faraday condensed this gas under a pressure of 17 atmospheres, so as to form a limpid and oily fluid 499. Hydrosulphurous acid, called bisulphuretted hydrogen, is a yellow, viscid, semifluid, heavier than water, and having, in a lower degree, the same odor and taste as hydrosulphuric acid. It is easily decomposed by heat into sulphur and hydro- sulphuric acid. It contains 2 atoms of sulphur, to 1 atom of hy- drogen. 500. Chloride of sulphur. This is a compound of one equivalent of each constituent, and is formed, directly, by passing chlorine over flowers of sul- phur gently heated. It is a volatile liquid of a red color, when seen in mass, but greenish yellow, when viewed in a thin stratum. It decomposes water rapidly, the chlorine taking the hydrogen of the water; at the same time sulphur is deposited, and sulphurous and sulphuric acids are formed. Its vapor also decomposes the moisture of the air, giving fumes which affect the eyes powerfully, and which probably consist of the same acid products. Bromide of sulphur is a red, volatile, oily liquid, which decomposes water with great violence, and which is obtained by the direct action of bromine on sulphur. It is decomposed by chlorine, and chloride of sulphur is formed. Iodide of sulphur is likewise formed by direct action of its elements, aided by heat. It is a dark solid and is decomposed by heat. 501. There is only one known compound of sulphur and car- bon. It contains 2 equivalents of sulphur, and 1 of carbon, and is therefore a bisulphuret of carbon. This substance, some- times called alcohol of sulphur, is obtained by passing vapor of sulphur over charcoal, heated red hot in a porcelain tube. It is to be conducted into a vessel of water, at the bottom of which; as it is heavier than water, it collects. It is a transparent liquid, of great refracting power, an acrid and pungent taste, and dis- gusting odor. It boils at 110° Fahrenheit, and evaporates so rapidly at common temperatures, as to cause great cold. It burns with a blue flame, producing sulphurous and carbonic acid gases. It dissolves sulphur, phosphorus, and iodine, with the last giving a beautiful pink solution. Chlorine decomposes it, and unites with the sulphur. It will not mix with water, but dis. 498. Acid properties. Liquid hydro-sulphuric acid. 499. Hydro-sulphurous acid. 500. Chloride, bromide, and iodide of sulphur. 501. Bi-sulphuret of carbon. Properties. Hydroxanthic acid. SELENIUM. 193 solves readily in alcohol and ether, from which solution water pre- cipitates it. When an alkali is put into the alcoholic solution, it becomes neutralized, owing to the formation of a new acid, which has been called hydroxanthic acid, from the yellow color of its salts. This latter acid appears to consist of carbon, sul- phur, and hydrogen, the hydrogen and an additional dose of carbon, being derived from the alcohol. 502. Selinium.—Equiv. 40. Sp. Gr. 4.32. Selenium was discovered by Berzelius in 1818. It had been observed, by a manufacturer of sulphuric acid at Fahlun, in Sweden, that the sulphur, after sublimation, deposited a reddish mass. This was submitted to the examination of the Swedish Chemist, who obtained, by analysis, a very minute proportion of an apparently new substance, the remainder of the mass being a compound of mercury, tin, arsenic, lead, copper, zink, iron, and sul- phur. This new substance, Berzelius named selenium, from the Greek, selene, the moon (on account of its resemblance to the metal tellurium, so called from tellus, the earth.) The sub- stance in which the sulphur and selenium were thus found uni ted, was iron pyrites, (sulphuret of iron,) from the mines of Fahlun. Selenium has since been found in combination with minerals in the Hartz mountains in volcanic products of the Lipari islands and in pyrites of the isle of Anglesea in England. It was regarded, by its discoverers, as a metal, but being an im- perfect conducter of heat and electricity, it appears to belong to the class of simple non-metallic elements. 503. Physical and chemical properties. It is solid at common temperatures, brittle,opake, and inodorous; at212° Fahrenheit, it begins to liquefy, and fuses at a temperature a few degrees higher. If partly cooled when in this state, it appears like wax, and may be drawn out by the fingers, into long, transparent, elastic threads, which appear red by transmitted light, but grey, and of a metallic brilliancy, when seen by reflected light. At 650° Fahrenheit it volatilizes, becoming a yellow vapor, suddenly cooled, produces a red powder, resembling the flowers of sulphur, except in color. If sublimed in the air, without taking fire, its u Protoxide of Chlorine 44 Sj Peroxide of Chlorine 68 ftj added to 1 Chlorine Ditto Ditto Ditto 508 Repeat the names and equivalents of the Electro-negative and Elec- tro vositive non-metallic elements with the state in which they are obtained. 509 What are the binary compounds of these elements, and their equiv- alents'? Which are acid, which alkaline and which neutral ? 196 TABLE OF CHEMICAL ELEMENTS. " .» » J'i EUTRAL. .£ 'i 'I. acid- I. i o» g. y added to K) Electro-Negative. u\ fc) fe; 1 Bromine 6 Oxygen Bromic acid 115 Ditto 1 Chlorine ................................Chloride of Bromine 111 1 Iodine 5 Oxygen Iodic acid 164 1 Hydrogen 1 Oxygen ................................Water 9 1 Ditto 2 Ditto ................................Protoxide of Hydrogen 17 1 Ditto 1 Chlorine Hydro-chloric acid 37 1 Ditto 1 Bromine Hydro-bromic acid 76 1 Ditto 1 Iodine Hydro-iodic acid 125 1 Ditto 1 Flourine Hydro-fluoric acid 11 1 Nitrogen 1 Oxygen ................................Protoxide of Nitrogen 22 1 Ditto 2 Ditto ................................Deutoxide of Nitrogen 30 1 Ditto 3 Ditto Hypo-nitrous acid 38 1 Ditto 4 Ditto Nitrous acid 46 1 Ditto 5 Ditto Nitric acid 54 1 Ditto 4 Chlorine ...............................g Chloride of Nitrogen 158 1 Ditto 3 Iodine ..............................SJodine of Nitrogen 386 1 Ditto Bromine ........................Ammo-Bq Bromide of Iodine (?) 1 Ditto 3 Hydrogen nia. 17 1 Carbon 1 Oxygen ................................Carbonic oxide 14 1 Ditto 2 Ditto Carbonic acid 22 2 Ditto 3 Chlorine ................................Perchloride of Carbon 120 1 Ditto 1 Ditto ................................Proto-chloride of Carbon 42 1 Ditto 2 Hydrogen ................................Subcarburetted Hyd. 8 2 Ditto 2 Ditto ................................Fercarburetted Hyd. 14 2 Ditto 1 Nitrogen ...............................Cyanogen 26 1 Boron 2 Oxygen Boracic acid 24 1 Ditto 2 Chlorine ................................Chloride of Boron 80 1 Ditto Flourine ...............................Fluoride of Boron 1 Silicon 1 Oxygen ................................Oxide of Silicon 16 1 Ditto Chlorine ................................Chloride of Silicon (?) 1 Ditto 1 Flourine Fluo-silicic acid gas 13 1 Phosphorusl Oxygen Phosphorous acid 20 1 Ditto 2 Ditto Phosphoric acid 28 2 Ditto 1 Ditto Hypo-phosphorous acid 32 1 Ditto 1 Chlorine ................................Proto-chloride of Phos. 49 1 Ditto 2 Ditto ................................Per-chloride of Phos. 84 Ditto Bromine ................................Bromide of Phos. (?) Ditto Iodine ................................Iodine of Phos. (?) 1 Ditto 2 Hydrogen ................................Proto-phosphuretted Hyd. 14 1 Ditto 1 Ditto ................................Per-phosphuretted Hyd. 13 1 Sulphur 2 Oxygen Sulphurous acid 32 1 Ditto 3 Ditto Sulphuric acid 40 1 Ditto 1 Ditto Hypo-sulphurous acid 24 2 Ditto 6 Ditto Hypo-sulphuric acid 72 1 Ditto 1 Hydrogen Sulphuretted Hyd. 17 2 Ditto 1 Ditto Bi-sulphuretted Hyd. 33 1 Ditto 1 Chlorine ................................Chloride of Sulphur 62 Ditto Bromine ................................Bromide of Sulphur (?) Ditto Iodine ••..............................Iodide of Sulphur (?) Ditto Carbon Bi-sulphuret of carbon (?) 1 Selenium 3 Oxygen Selenic acid 64 1 Ditto 2 Ditto Selenious acid 56 1 Ditto 1 Ditto ................................Oxide of Selenium 48 Ditto Chlorine................................Chloride of Selenium (?) 1 Ditto 1 Hydrogen Hydro-selenic acid 41 Ditto Phosphorus................................Phosphuret of Selenium (?) Ditto Sulphur ................................Sulphate of Selenium (?) We see that ammonia is the only alkaline compound of this class of substances. METALS. 197 METALS. OR THE SECOND CLASS OF ELECTRO-POSITIVE ELEMENTS. CHAPTER XXI. GENERAL OBSERVATIONS UPON THE METALS.--FIRST CLASS OF METALS, OR THOSE WHICH FORM ACIDS WITH OXYGEN. 510. The metals varygreatly among themselves in their phys- ical properties. Some, as gold and platinum, are the heaviest sub- stances known; while others, as sodium and potassium are lighter than water. Mercury is liquid at the common tempera- ture and can be solidified only by cold far below that of the freezing point of water; but platinum remains solid even under the influence of the most intense heat. In their chemical affini- ties, metals differ greatly. Potassium and sodium have so great an attraction for oxygen, that they become oxidized from mere exposure to the air ; while silver and gold can with difficulty be made to unite with oxygen. 511. The distinctive characters of the metals are as follows ; 1st. They are all good conductors of electricity and heat; the former passes through them instantaneously, the latter progres- sively, though rapidly. 2d. They are positive electrics, that is they go to the negative pole in the galvanic series, when combined with oxygen, chlorine, iodine, bromine, or sulphur ; and their oxides have the same des- tination, when combined with acids. 3d. They are opake ; they reflect the light powerfully, and with a peculiar glitter, termed the metallic lustre. This pro- perty is retained by the metals when divided into the minutest particles. 4th. Though good conductors, they are bad radiators of heat. 5th. They are fusible at different degrees of heat; and when melted retain their lustre and opacity. 6th. They possess in different degrees a peculiar tenacity, which renders them malleable and ductile, or capable of being extended under the hammer or drawn into wire. 7th. They are capable of combining with oxygen, thus forming oxides that bear a metallic appearance ; those oxides, by uniting with acids, saturate them and form salts. 510. Variety in the properties of metals. 511. General characteristics. 17* 198 METALS. 512. Of all substances in nature, none have, from the earliest ages of the world, more attracted the attention of mankind than the metals. To the experiments of the alchemists, in their at- tempts to transmute the baser metals into gold and silver, the science of chemistry owes its existence. Yet notwithstanding the researches of the alchemists, so late as the fifteenth century, only seven metals, appear to have been discovered; viz. gold, silver, iron, copper, lead, mercury, and tin, with a few ores and combinations with other metals. 513. The metals have been variously classified by different writers. It has been common to arrange them accordino- to their relative affinites for oxygen, which vary so much, that while one class part with oxygen, by application of a slight degree of heat, another class retain it so strongly that it requires the greatest power of the voltaic pile to effect their disunion. But though the extremes, in respect to affinity for oxygen, may widely differ, there are many metals included between those which part easily with oxygen and those which strongly retain it which renders it difficult to class them upon this principle. It is well for science, that its foundations stand firm, though some of its superstructures may fall. Though in mental and moral science, classifica- tion varies with almost every writer, yet truth is immutable, and those va- rious classifications are but as so many mirrors in which she is exhibited in different lights. The same is true in the physical sciences; one mode of classification brings out in hold relief one set of properties, and another mode brings into light other properties, which, but for this kind of distinc- tion, might not have been duly observed. Classification. 514. "We shall arrange the metals into four classes. 1st. Those which form acids with oxygen. 2d. The alkaline metals, or those whose oxides are either fix- ed alkalies, or alkaline earths. 3d. Earthy metals, or those whose oxides are earths. 4th. Metals whose oxides are not regarded as earths or alka- lies. 515. The Metals of the first class, or those which form acids with oxygen, are 13 in number, as follows, viz. arsenic, anti- mony, columbium, litanium, chromium, molybdinum, tellurium tungsten, vanadium, uranium, manganese, cobalt, and tin. 512. Early attention of mankind to this class of substances. 513. Various classifications of metals. 514. Division of metals adopted. 515. Metals of the first class. ARSENIC. 199 516. Arsenic.—Equiv. 38. The name is supposed to be deri- ved from the Arabic, arsanak, signifying strong and deadly quali- ties. It was noticed in combination with sulphur, by the Greek phi- losopher Dioscorides under the name of sandarac. In 1773, Brandt discovered it to be a distinct metal. The substance usually call- ed arsenic is the arsenious acid or white oxide of arsenic. Arse- nic has a metallic lustre, resembling that of polished steel; it is brittle and granular in its texture. Exposed to the air it be- comes tarnished, and covered with a blackish substance, which appears to be a protoxide of arsenic. Thrown upon burning coals, arsenic burns with a blue flame, volatilizing in the form of white vapors, and with a strong smell of garlic. It is some- times found pure and native, but it is more commonly combined with the ores of other metals, especially iron and cobalt ; by roasting these ores, the arsenic, which is very volatile, vaporizes and condenses in receivers prepared for the purpose. 517. Two compounds of arsenic and oxygen are known to exist. Arsenic. . Oxygen. Arsenious acid, 38 or 1 equiv. 12 or IJ equiv. Arsenic acid, 38" " 20 or 2i equiv. 518. Arsenious Acid, sometimes called the white oxide of arse- nic, and rats bane, is a white substance, offensive to the taste, and a deadily poison, not only when taken into the stomach, but when applied to a wound, or when its vapor is inhaled. Though soluble in warm water, a portion of the acid, in the form of a white powder, will be found supended as the liquid becomes cool. This circumstance has often led to the detection of attempts to destroy life by this poison. There are diflerent tests by which the presence of this mineral may be detected. In the solid state, it may be known, in the open air, when heated, by its peculiar odor, like that of garlic. In solution it forms a white pre- cipitate with lime water; and a yellow sulphuret of arsenic with hydro-sul- phuric acid. Sulphuret of potassium, and sulphuret of sodium precipitate this substance in yellow flakes; but it is necessary to add some drops of acetic or hydro-chloric acid that may unite with the base of the sulphurets, otherwise there will be no precipitate. Writers on medical jurisprudence by omitting this circumstance, have led to errors in attempts to detect the presence of arsenic. In so important a trial as that of determining the presence of arsenical poison in the stomach of a deceased person, there should be a resort to various tests, and therefore while one portion of the contents of the stomach is subjected to the action of one test, other portions should be tried by other means. The nitrate of silver precipitates a white powder in solution of arsenical compounds, which, with ammonia, forms a 516. Derivation of the word arsenic. Discovery. Mode of obtaining the metal. Properties. Native slate. 517. Compounds of arsenic and oxygen. 518. Synonymes of arsenious acid. Properties. Various tests. 200 ANTIMONY. yellow arsenite of silver. Ammoniacal sulphate of copper produces an ap- ple green precipitate, which is the arsenite of copper or Scheele's Green. The effect of arsenic upon the animal system is speedy and violent. The per- hydrate of iron with ammonia, is one of the best antidotes for this poison. Owing to the property of this substance of preserving dead bodies from de- cay, the stomach and intestines of those who have been poisoned with it have been found undecomposed some years after death. 519. Arsenic Acid may be obtained by boiling arsenious acid with nitric acid, which yields a portion of its oxygen, giving off nitric oxide. This acid has a sour metallic taste, reddens vegetable blues, and forms with alkalies neutral salts, called arseniates. 520. Arsenic in powder, takes fire in chlorine gas, forming chloride of ar- senic. It unites with iodine by a gentle heat, forming the iodide of arsenic, which is a deep red compound. Bromine, by mere contact with metallic arsenic, burns with vivid light and heat, forming a volatile bromide of arse- nic. Arseniuretted hydrogen is highly destructive to animal life. A German philosopher, M. Gehlen, in making experiments with it, inhaled its vapor, and died in consequence, with intense suffering. It extinguishes combus- tion, but is itself kindled by burning bodies, and burns with a blue flame. The Sulphurets of arsenic exist as natural minerals. The red sulphuret is known by the name of realgar; a yellow sulphuret is called orpiment; this is the basis of the paint known as king's yellow. The sulphurets of arsenic, though poisonous, are less so than the acids. 521. Antimony.—Equiv. 44. The name of this mineral is de- rived from anti, against, and monakos a monk, the improper use of it as a medicine, by a German monk, in the 15th century, having caused the death of many of his fraternity. What is termed crude antimony in commerce, is the native sulphuret of this metal. In its pure state, antimony is a shining metal, of a silvery white color, a scaly texture, brittle, and gives off a peculiar odor, on being rubbed. It melts below red heat; and when suffered to cool slowly, often presents upon its surface marks of crystalization, resembling fern-leaves. It fuses at 810° F. and sublimes in dense white fumes, combining with oxygen. When in a state of powder it inflames spontaneously in chlorine gas, and burns with a bright white flame. The product is a liquid, which becomes solid on cooling. This chloride from its consistence was formerly called butter of antimony. The per-chloride is obtained by adding nitro-muriatic acid, hydro-chloro-nitric, to antimony; it is a volatile, fuming liquid. 522. The Protoxide of antimony is obtained by dissolving in water, proto- chloride of antimony ; a white powder is precipitated called powder of alga- roth, which is a sub-chloride of antimony. A solution of potash being ad- ded to this powder, the chlorine combines with the potash, and the metal uniting with the oxygen of the water, forms the protoxide of antimony. When heated to redness in an earthen crucible, antimony disengages a thick white smoke, which being condensed, forms a white crystaline substance 519. Mode of obtaining arsenic acid, its properties and salts. 520. Combinations of arsenic with chlorine, iodine, bromine, hydrogen and sulphur. 521. Supposed derivation of the name. Antimony of commerce. Pro- perties. Chlorides. 522. Protoxide. COLUMBIUM. 201 formerly called argentine flowers of antimony ; this is similar in its composi- tion to the protoxide. 523. Deutoxide of antimony. When metallic antimony is digested in strong nitric acid, the metal is oxidized at the expense of the acid, and a white hydrate of the peroxide is formed; on exposing this substance to a red heat, water and oxygen gas are disengaged, and the peroxide is reduced to a deutoxide. As this combines with alkalies, it has been called antimo- nious acid. 524. The Peroxide or antimonic acid forms salts with alkalies called an- timoniates. It is changed by heat into the deutoxide. 525. The Sulphuret of Antimony is found extensively as a native combina- tion ; it may also be prepared by art, by fusing antimony with sulphur, and the compound is, in all respects, similar to the native mineral. When this sulphuret is slowly roasted in a shallow vessel, it gradually loses sulphur, and attracts oxygen, and may then be melted into a glassy, semi-transparent substance, which is called the glass antimony. The medicine known as tartar emetic is a triple compound of tartaric acid, protoxide of antimony and potassa, called antimoniated tartrate of potassa. 526. Alloys of antimony. Antimony may be made to com- bine with most of the metals. A very slight mixture not ex- ceeding the 2-q^ of the whole mass is sufficient to destroy the ductility of gold, and even its fumes alone will produce that effect. Combined with lead, it becomes the alloy called type metal, which is used {ox printing types. 527. As a medicinal agent, when properly employed, this metal is highly valuable. It was not, however, until long after its discovery that its nature seems to have been well understood. From its fatal operation in many instances, the French parlia- ment, early in the seventeenth century, at the suggestion of the medical faculty, proscribed the use of this medicine. This de- cree was, however, soon revoked and antimony again received in favor. 528. Columbium.—Equiv. 144. This metal was discovered by Mr. Hachett of England in 1801, who detected it in a black mineral belonging to the British Museum, which had been sent by Gov. Winthrop from New London in Connecticut, to Sir Hans Sloane, founder of the museum. The new substance was named Columbium, by its discoverer, in honor of the country from whence it had been sent. The mineral from which co- . lumbium is obtained is now found in Chesterfield, Mass. and Haddam, Conn. 529. Professor C. TJ. Shepard succeeded in obtaining the metal, by the de- 523. Dentoxide of antimony or antimonious acid. 524. Peroxide, or antimonic acid. 525. Sulphuret of antimony. Glass of antimony. Tartar emetic. 526. Alloys of antimony. 527. Medicinal properties. 528. Discovery of columbium. Origin of the name, &c. 529. Indentity of tantalum and columbium. 202 TITANIUM. composition of the mineral. But this is one among the refractory metals which are extracted with difficulty from rare minerals. Their discovery reflects honor on those who have so industriously sought them out, and gives new interest to science : although this metal, hitherto, has not been ap- plied to any useful purpose in the arts. About two years after the discovery of columbium, Ekeberg a Swedish Chemist extracted the same substai.ee from the mineral called tantalite, and supposing it to be a new metal he called it tantalum. In 1809, Dr. Wollas- ton proved that this was indentical with columbium, and tantalum was ac- cordingly stricken from the list of simple bodies. 530. Columbium is of a dark iron color. It is very hard, in- soluble in acids, and soluble in alkalies. It unites with oxygen but in one known proportion, one equivalent of the metal, 144, being combined with one of oxygen 8=152. This compound, sometimes called the oxide of columbium, reddens litmus paper, and combines with salifiable bases, properties which are charac- teristics of acids. The salts of this acid are called columbates. 531. Titanium. History. Discovered in 1781, by Mr. Gregor of Cornwall, England, in black sand; but its character was not then fully ascertained. Afterwards, in 1795, Klaproth publish- ed an analysis of a crystalized mineral, known at that time as red schorl; though he did not entirely succeed in reducing it to a metallic state he inferred that it was the oxide of a new metal, which he named titanium. In 1822, Dr. Wollaston discovered this metal in some minute copper-colored crystals, presented to him by the Rev. Dr. Buckland, who had found them in the slag of an iron furnace at South Wales. They conducted electricity, had a specific gravity of 5, 3, and were so hard as to scratch a polished surface of rock crystal. They become oxidiz- ed, by being heated with nitre, and were converted into a white substance. which was considered an oxide of titanium. Similar crystals of titanium have since been found at other iron works, where they have sometimes been mistaken for iron pyrites. In its purest native state, this metal is combined with a small portion of iron, which renders it slightly magnetic. It is infusible, tarnishes in the air, and is easily oxidized by heat. 532. The protoxide of titanium is of a blue color, and is supposed to exist in the mineral called anatasse, but its composition and properties are doubt- ful. With lime and silex it forms the mineral called sphene. 533. The peroxide exists nearly pure in the mineral called titanite or ru- tile. When pure, this oxide is nearly white; it possesses some acid pro- perties, and is sometimes called titanic acid. The oxides of titanium have been used in porcelain painting. Silliman states that titanium is found 530. Properties of columbium and its combination with oxygen. Oxide of columbium. Its salts. 531. History of titanium. Properties of crystals of titanium. Resem- blance to iron pyrites. Titanium combined with iron, &c. Properties of the metal. 532. Protoxide. Anatasse. Sphene. 533. Peroxide. Properties, &c. CHROMIUM. 203 frequently in the primitive rocks of the United States. Its equivalent number is not fully known. 534. Chromium.—Equiv. 32. So named from the Greek. kroma, on acconnt of its tendency to form colored compounds. It was discovered by the French chemist, Vauquelin, in analyzing the chromate of lead, a beautiful red mineral from Siberia. It is a white and brittle metal, susceptible of high polish, and only imperfectly fused at very high temperatures. It is not changed by air, but absorbs oxygen at a red heat. Sulphur, phosphorus and chlorine are the only combustible, non-metallic elements which combine with it. It exists in nature only in the state of a chromate or an oxide. 535. Many of the gems owe their beautiful tints to this metal. Its acid gives the red color to the ruby: its oxide the green color to the emerald. Chromate of iron, is found in marble and serpentine, to which they are probably indebted for their beau- tiful variety of colors. New Haven and Milford in Connecticut, and Baltimore in Maryland, furnish fine specimens of chromate of iron. 536. Protoxide of Chromium is a green, pulverulent substance, infusible, undecomposable by heat, and insoluble in water. It was discovered by Vauquelin. It may be obtained by decom- posing the chromate of mercury at a very high temperature. The mercury is disengaged in vapor, and the chromic acid re- solved into oxygen and the protoxide of chromium. This oxide is sometimes found on the surface of chromated lead; it is this which causes the green color of the emerald and many mag- nesian rocks. It is employed in the arts ; it is used in porcelain painting to give a fine green color ; and is the coloring used in artificial gems which are made to imitate the emerald. There is a brown oxide which some suppose to be a distinct substance composed of one equivalent of chromium and one of oxygen ; it has been called chromous acid, and deutoxide of chromium. By others it is considered a mixture of green oxide and chromic acid. . • i i , 537. Chromic Acid exists in nature, in combination with lead, forming the chromate of lead of Siberia and Brazil; it imparts to the ruby its peculiar hue of dark red. It may be obtained from its concentrated solution in ruby red crystals. It is very 534 Derivation of the name chromium. Discovery, properties, &c. Combination with oxygen, and non-metallic combustible elements. How found in nature ? 535. Coloring properties, &c. ../..• 536. Properties, discovery, and mode of obtaining protoxide of chromium, Its use. Brown oxide of chromium. 537. Chromic acid. 204 MOLYBDENUM. soluble in water, has a sour taste, and forms colored salts, called chromates, with alkaline bases, and metallic oxides. When ex- posed to strong heat, oxygen is disengaged, and the acid changes to the green oxide. It destroys the color of indigo, and most vegetable and animal coloring matters; a property advanta- geously employed in calico printing, and which depends on the facility with which it yields its oxygen. It gives with mer- cury, a cinnibar red ; with silver, a carmine red; with lead, orange yellow; with tin, green; and with borax, a beautiful emerald-green color. 538. Fluo-chromic acid gas is disengaged, when a mixture of fluor spar and chromate of lead is distilled with sulphuric acid, in a leaden retort. This gas acts rapidly upon glass. Chromium forms a red gas with chlorine, called chloro chromic acid gas; it is obtained by the action of fuming sul- phuric acid on a mixture of chromate of lead, and chloride of sodium. A chloride of chromium, is obtained by transmitting dry chlorine over a mix- ture of chromium and charcoal, heated to redness in a porcelain tube. This chloride is a crystaline sublimate of a purple color. Sulphuret of Chro- mium is a dark gray substance, consisting of one equivalent of each of its elements. Phosphuret of Chromium is a porous substance, of a light gray color. 539. Molybdenum.—Equiv. 48. The name of this mineral is from the Greek molubdaina, lead, it being at first confounded with black-lead, or plumbago as were all metals which are light, friable, soft, of a greasy feel, and which stain the fingers, or paper. Scheele first proved that plumbago is a carburet of iron, and molybdenum the sulphuret of a new metal. It has not been found pure, in a native state; the sulphuret of molybdenum is common in the Alps, and Austria, and is found, in small quantities, in the primitive rocks of the United States. 540. When the sulphuret of molybdenum is distilled in nitric acid, molyb- dicacid is obtained, in the form of a yellowish white, heavy powder. This being mixed with oil, and placed in a crucible lined with charcoal, is heated intensely, and the acid disengaging its oxygen, is reduced to a pure metallic state. It has never been obtained except in small globules of a gray color. It is among the most infusible metals. At the ordinary temperature, it has no action upon oxygen ; but at a red heat, it unites with it forming a white sublimate of molybdic acid. 541. The protoxide of molybdenum is black, the deutoxide, or molybduous acid is a brown, and molybdic acid is yellowish-white. Berzelius states that there are three chlorides of molybdenum. A native sulphuret of molybdenum, of a ruby-red color has lately been discovered. This metal has yet been of little use in the arts; but its coloring properties are peculiar, and may, hereafter, be advantageously applied. 538. Fluo-chromic acid gas. Chloro-chromic acid gas. Chloride of chromium. Sulphuret of chromium. 539. Derivation of the name Molybdenum. By whom distinguished from plumbago ? In Avhat state, and where found. 540. How is it obtained ? Properties. 541. Character of its oxides and acid. Chlorides. Sulphuret. Uses of the metal. TUNGSTEN. 205 542. Tellurium.—Equiv. 32. Was discovered in 1782, by M. Muller, in the gold mines of Transylvania, and named by Klaproth, from Tellus, the earth, in accordance with the ancient method of naming the metals after the planets. Tellurium has been found in the state of an alloy, with gold, silver, lead, cop- per, iron, and sometimes with all these metals united.* It is brittle, of the color of tin, with some lustre. It fuses readily, and is the most volatile of all the metals, except osmium and mercury. When distilled in close vessels, it sublimes, and its vapor condenses into brilliant metallic drops. When heated in contact with the air, it oxidizes, and burns with a sky-blue » flame, edged with green. It gives off a gray smoke, of a pun- gent, nauseous odor, resembling that of the vapor of selenium, and which has been compared to the odor of decayed horse- radish. This vapor condenses into a white oxide of tellurium. It unites both with alkalies and acids, to form salts. Tellurium is a rare mineral. Silliman supposes it exists in the town of Munroe in Connecticut. 543. Telluretted Hydrogen gas may be obtained by mixing together oxide of tellurium, hydrate of potassa, and charcoal, at a red heat, and acting upon the mixture by dilute sulphuric acid. The combination of hydrogen and tellurium which ensues, is a gas which, like sulphuretted hydrogen, manifests acid properties. It forms a claret colored solution with water, burns with a black flame, and deposits the oxide of the metal. 544. Tungsten.—Equiv. 96. This metal was first discovered in Sweden ; its name signifies, in the Swedish language, heavy stone. It is the heaviest metal known, except iridium, gold, and platinum. The ores of this metal are tungsten or tungstate of lime, yellow oxide of tungsten, and wolfram or tungstate of iron, and manganese. In these ores, tungsten exists in the state of tungstic acid, and has been found native in no purer form. The mineral is first decomposed in order to obtain the acid ; the latter, in the form of a whitish powder, is then made into a paste with oil, and heated intensely in a crucible, lined with charcoal. The pre- sence of small metallic globules, indicates the reduction of the metal. It is of an iron gray color, of a brilliant lustre, and so hard as scarcely to yield to the file. It is very infusible. 545. The oxide of tungsten is formed by the action of hydrogen gas on * For the process of obtaining the metal from its ores, see the author's Die. of Chem., article Tellurium. See also Silliman's Elements, Vol. II. p. 160. 542. Discovery of tellurium, and origin of its name. With what metal found? Properties. White oxide of tellurium. Localities of tellurium. 543. Telluretted hydrogen gas. 544. Discovery of tungsten, &c. Origin of the name. Ores of this me- tal. How obtained from its ores ? Color &c. 545. Oxide of tungsten. Tungstic acid. Chlorides. Localities of tung- Bten ores. 18 20^ MANGANESE. tungstic acid, at a low heat. It is of a dark chocolate color ; and when polished resembles copper. This oxide does not unite with acid to form salts. Tungstic acid is of a yellow color; it has no action on litmus paper ; its acid properties are so feeble, that its salts are readily decomposed by most other acids. Tungsten unites in three proportions with chlorine, forming chlorides. The ores of tungsten have been found in the cobalt mines in Chatham, and Monroe in Connecticut. 546. Vanadium.—Equiv. 68. It was recently discovered by M. Sefstroin, director of the school of mines at Fahlun in Sweden. It was named from Vanadis a Scandinavian deity. Its properties resemble those of chromium, with which it might easily be confounded. Professor Del Rio, many years since, supposing that he had found a new metal in the brown lead ore of Zimapan in Mexico, sent some specimens of it to the French chemists at Paris, who pronounced them to be merely impure chromium. Since the discovery of vanadium the opinion of Del Rio has been confirmed, and the ore pronounced to be a vanadiate of lead ; the same substance has been lately discovered in a mineral from Wanlockhead in Scotland. Like chro- mium, it appears to possess peculiar coloring properties. Vanadic acid is red, and fusible. The oxide is of a dark brown color. 547. Uranium.—Equiv. 208. It was discovered in 1789, by Klaproth, and named from the Greek, uranos, the heavens. The ores which contain this metal, are very rare. Combined with carbonic acid, it forms chalcolite, or green mica. Its ores are reduced with difficulty, and it has only been obtained in small quantities. It is of a dark grey color, hard, and brittle. The protoxide is of a dark green color; it unites with acids, forming salts of a green color. It is employed in the arts, for giving a black color to porcelain. The peroxide is of an orange color, and most of its salts have a similar tint. It is used for giving an orange color to porcelain. 548. Manganese.—Equiv. 28. It is never found native in the metallic state, the substance known in the arts by this name, being an impure oxide. Owing to its great affinity for oxygen, it is usually found in nature combined with it, though sometimes in the state of a phosphate, and a sulphuret. " The black oxide of manganese was described by Scheele, in the year 1774, as a peculiar earth; Gahn subsequently showed that it contained a new metal, which he called magnesium, a term since applied to the metallic base of magnesia, and for which the words manganesium and manganum have been substituted." Turner. The pure metal may be obtained by heating, for an hour or two, over a powerful air furnace, a mixture of the black oxide, oil, and charcoal, in a black lead crucible; on cooling the mixture, metallic masses will be found with the charcoal at the bottom of the cru- cible. 549. This metal, in some of its properties, resembles iron ; it 546. Vanadium. Its discovery and name. Mistake of the French chem- ists. Acid and oxide of vanadium. 547. Discovery of uranium. Name. Ores. Properties. Compounds with oxygen. 548. How is manganese found in nature ? By whom discovered. Orig- inal name. How obtained pure ? 549. Properties. Action with air or oxygen, or with hydrogen, nitrogen, &c. Phosphuret. Chloride. MANGANESE. 207 is of a gray color, very hard and brittle. It is very infusible, readily acted upon by air, tarnishing and at length crumbling into a brown powder. At the ordinary temperature, it has no action on atmospheric air, or oxygen gas ; but at a high temper- ature, it soon oxidizes. It is not acted upon by hydrogen, ni- trogen, boron, or carbon, and does not easily combine with sul- phur, though a natural sulphate of manganese exists. At a high temperature, it combines with phosphorus, forming a white, and brilliant phosphuret. It absorbs chlorine rapidly, forming a very soluble, greenish chloride. 550. The protoxide, or green oxide of manganese, is obtained by igniting the deutoxide in contact with hydrogen or charcoal. Its rich green color on exposure to the air, changes to brown. The deutoxide, or brown oxide, remains when the peroxide is heated to afford oxygen gas. It is found in large native crystals, in the Hartz moun- tains. The peroxide, called also the black oxide, is that which, by heat, disen- gages half an equivalent (4 parts,) of oxygen, and is therefore commonly used for the purpose of obtaining oxygen gas. To obtain oxygen gas from the peroxide of manganese, it is sufficient to apply red heat to the latter, but if sulphuric acid be added to the peroxide of manganese, the presence of the acid appears to increase the disposition of the peroxide to give up its oxygen, by combining with the deoxidized manganese. This is a case of disposing affinity. This oxide occurs in large masses of an earthy appear- ance, and mixed with other substances, such as oxide of iron, carbonate of lime, and siliceous earth. It is sometimes found in groups of crystals, and is an essential ingredient in a mineral called black wad. 551. A red oxide of manganese, supposed by some, to be a mixture of the peroxide, and the deutoxide, and by others, a def- inite, compound, imparts to glass or borax a beautiful violet color ; the amethyst owes its rich color to the presence of this oxide. If a mixture of 1 part of powdered black oxide of manganese, and 3 parts nitrate of potassa, be thrown into a red hot crucible, and continued there until no more oxygen is disengaged, a green-colored, fused mass is obtained, called mineral chamelion, from its property of assuming different colors. On putting this substance into water, a green solution is obtained, which soon passes into blue, purple, and red; at length a brownish matter, the red oxide, subsides, and the liquid becomes colorless. These phenomena are explained as follows : the peroxide of manganese, when fused with potassa, absorbs oxygen from the atmosphere, and is thereby converted into manga- nesic acid, which unites with the alkali; the changes of color, are owing to the combination of manganesic acid with different proportions of potassa. By evaporating the red solution rapidly, small, prismatic, purple crystals are obtained ; these are the manganesiate of potassa. There is also supposed to be a manganesious acid, or an acid with a small- er proportion of oxygen. The manganesiate of potash, being acted upon by 550. Protoxide. How obtaned. Deutoxide. Peroxide. Use of sulphu- ric acid in the process for obtaining oxygen from the peroxide of manganese. 551. Red oxide of manganese. Mineral chamelion. Manganesic acid. how formed T Manganesious acid. 208 COBALT. substances that attract oxygen, as alcohol, and carbonate of manganese, loses its red color, and becomes a green manganese of potash, the acid in the latter being reduced to the manganestoiw, containing but three equiva lents of oxygen, while the manganesic contains four equivalents. 552. Chlorine gas for chemical experiments, and liquid chlorine for bleaching, are usually obtained by the agency of the peroxide of manganese in combination with hydrochloric acid. The acid, consisting of one equiv- alent of chlorine and one of hydrogen, is decomposed by the loss of its hy hydrogen, which, by uniting with one equivalent of oxygen given off by the peroxide of manganese, produces one equivalent of water. The chlorine being set free, passes off in a gaseous state. The loss of oxygen by the manganese, having converted the peroxide to a protoxide, the latter unites with an equivalent of undecomposed hydro-chloric acid, and forms a hydro- chlorate of the protoxide of manganese. Manganese unites with chlorine in two proportions, forming a pink colored proto-chloride, with one equiva- lent of each element; and a per-chloride with one equivalent of manganese and four of chlorine. The latter is prepared by putting sulphuric acid into a solution of manganese, and then adding fused sea-salt. The hydrochloric and manganesic acids mutually decompose each other, producing water and the per-chloride of manganese ; the latter is a vapor, which at first appears of a yellowish green tint, but condenses into a dark colored liquid. When the per-chloride vapor is introduced into a flask, the sides of which are moist, the color of the vapor changes instantly, and a rose-colored smoke appears. Manganese combines with fluorine, forming a fluoride of manga- nese, which at first appears in the form of a greenish yellow vapor. When mixed with atmospheric air, it assumes a beautiful purple red color. It acts on glass. On account of rendering glass colorless, the black oxide of manganese was formerly, called by the artists, glass-maker's soap. Accor- ding to Pliny it was used two thousand years ago. 553. Cobalt, Equiv. 26. The name is derived from, Kobalas, the supposed demon who infests mines, impeding the operations of the miners, and destroying their lives. Though employed in the fifteenth century for the purpose of coloring glass blue, it was not known to be a simple element until obtained from its ores by Brandt of Sweden, in 1733. It is hard, brittle, of reddish grey color, and weak metallic lustre. It is magnetic, a proper- ty which was formerly ascribed to the presence of some iron, but a magnetic needle has been made of pure cobalt. It is found in connexion with ores of iron and copper, but chiefly with arsenic. When the arsenical ore of cobalt is heated, the arsenic exhales in vapor, and the oxide of cobalt remains. This operation is carried on extensively in Saxony; the labor being performed by criminals who are condemned to be thus slowly destroyed, for crimes which incur the punishment of death. The white oxide of the arsenic of commerce is mostly thus obtained. 554. Protoxide of Cobalt, is formed when cobalt is slowly 552. Process for obtaining chlorine by the aid of per-oxide of manganese. Chlorides and fluoride of manganese. Fluoride of manganese. 553. Origin of the name Cobalt. Discovery. Properties. Ores. How obtained from the arsenical ore ? 554. Protoxide of cobalt. Peroxide. Statement of M. Gmelin respect- ing the formation of cobaltic acid. Zatfre. Smalt. Powder-blue. Use of cobalt in the manufacture of porcelain. COBALT. 209 oxidized by being heated in the open air. It is at first blue, gradually becomes darker, and an intense heat melts it into a blue-black glass. The Peroxide is formed by igniting the pro- toxide, and exposing it to the action of the oxygen of air; it rapidly absorbs oxygen, becoming first of an olive-green color, and then black. By continued powerful heat a portion of oxy- gen is expelled, and the substance becomes again a protoxide. Though we have classed cobalt with the metals which form acids with oxygen, there is some doubt as to the existence of a Cobaltic Acid. M. Gmelin from a solution of ammonia and nitrate of cobalt obtained crystals of a double salt, supposed by him to consist of nitrate, and cobaltate of am- monia, the latter consisting of cobaltic acid and ammonia. The Zaffre of commerce is an impure oxide of cobalt. Smalt is formed by heating the oxide of cobalt with a mixture of sand and potassa ; the result is a beautiful blue colored glass. This, when ground fine, is called powder blue ; it is used by laundress- es as a very delicate bluing for muslins and laces, in paper manufactories to give a blue tint to paper, and is employed in painting. Cobalt,being the only blue color which will endure the heat of a furnace, is highly valuable to manufacturers of porcelain. The ancients are supposed to have used this oxide, mixed with oil in their painting ; and this is given as a reason for the blue drapery and skies, in some old pictures being so durable. . 555. Sympathetic Ink may be made by digesting the oxide of cobalt in hydro-chloric acid, and diluting with water. Words written with this so- lution of hydro-chlorate of cobalt will be invisible till brought near the hre, when the writing will appear of a bright green tint. The acetate and ni- trate of cobalt will present a blue color on being warmed. Fig. 98. Let a paper fire-screen (Fig. 98,) represent a landscape where the trunks and leafless branches are sketched in Indian ink, and paint the foliage and fore-grounds with the hydro-chlorate, and the sky and dis- tant mountains with the acetate or nitrate of cobalt; while the picture is cold, it represents merely the out- line of a landscape, or a winter scene, ". as at a ; on bringing it near the fire, jit will be transformed to a summer landscape, with green trees and a clear blue sky, as at b. On being removed from the fire, the scene will gradually lose its verdure, and resume its winter dress The cobalt of commerce was at first wholly furnished by bax- onv The ores of this metal are now found abundantly in Swe- den' in a mine in Cornwall in England, and in a various parts of America. In Franconia, in New Hampshire, cobalt is lound 555 Sympathetic ink. Localities of cobalt. 18* 210 TIN. in arsenical iron ore; and in Chatnam, Connecticut, associated with nickel. It has been found in many specimens of aerolites or meteoric stones. 556. Tin.—Equiv. 58. This appears to have been among the few metals known in the first periods of history. It is named by Moses in connexion with " gold, silver, brass, iron, lead, and every thing that may abide the fire." The Phoenicians obtained it in commerce, passing in their wonderful voyages the pillars of Hercules,* and visting Britain, the Ultima Thule f of that period. The most ancient and extensive tin mines are in Corn- wall in England. It is found in primitive mountains, in Saxony, Siberia, France, and Mexico. The alchemists, who often divided their attention between the mysteries of astrology and alchemy, considering that there were some secret sympa- thies between the planets and the metals, named tin, Jupiter, because like that planet it had a brilliant appearance. It was called also by the Latin name, stannum. 557. Tin Plate, in which form this metal is used for a variety of purposes, consists of sheets of iron coated with tin. Tin Foil is made from the finest tin, beaten out with a hammer. Tin is a white, brilliant metal, with a silvery lustre. It is neither very hard nor ductile and has, little tenacity. It is flexible, and in bending gives a peculiar crackling sound. It is among the most fusible of the metals ; it is vaporized by the heat of the com- pound blow pipe. It is so soft as to be cut with a knife, or scratched with a pin. Its odor and taste are peculiar ; it tar- nishes on exposure to the air. If steam be passed over tin heat- ed to redness, it decomposes the water and combines with the oxygen, while the hydrogen gas is disengaged. 558. Tin and Oxygen. The protoxide of tin is obtained when tn is kept for some time melted in an open vessel, or in contact with the air; oxygen is absorbed and the product is a gray powder. The Protoxide has riuch an affinity for oxygen, that when heated to redness in open vessels it unites with another proportion, and becomes the peroxide. The latter is of a straw yellow color ; and exhibits the character of an acid capable of uniting with potash and other alkalies. It has been called by Berzelius stannic acid, and we have therefore classed tin among those metals which form acids with oxygen. 559. Tin combines with sulphur, forming a blueish and metallicproto-sul- phuret, and a beautiful gold-colored bi-sulphuret, which is used to give a golden color to bronze, and japanned articles, and to excite electrical ma- chines. Nitric acid oxidizes but does not dissolve tin. The nitro-muriatic * Straits of Gibralter. f The remotest land. 556. Ancient use of tin ; its localities. Names. 557. Tin Plate. Tin Foil. Properties of tin. Combination with oxy- gen. 558. Compounds formed by tin with oxygen. 559. The combinations of tin. Alloys. METALS. 211 acid dissolves it with effervescence, forming a salt called the per-muriate of tin, which is employed in dyeing, especially to change the color of cochineal from crimson to a bright scarlet. The proto-chloride of tin is prepared by boiling tin filings in hydro-chloric acid. It is much used as a deoxidizing substance, especially for precipitating metals from their solutions. The bi- chloride, formerly called the fuming liquor of Libavius, is a volatile liquid, which emits copious white fumes. It inflames the oil of turpentine; and has a strong attraction for water, which changes it to the permuriate. The bi-chloride may be formed by heating metallic tin in an atmosphere of chlo- rine; it contains two equivalents of chlorine, united to one of the metal. Alloys of Tin. The alloys of tin with copper in different proportions form bronze, bell metal, and a beautiful white substance used for the reflectors of telescopes. CHAPTER XXII. METALS OF THE SECOND CLASS. Alkaline metals, or those whose oxides are fixed alkalies, or alka- line earths.—Order 1, Metals which with oxygen, form the fixed alkalies 560. The metals of this class, from their apparent doubtfu" character, were at first called metalloids.* They differ from copper, lead, gold, &cc, and other well known metals in their less specific gravity, some being lighter than water. In their metallic lustre, and in uniting with oxygen to form oxides which, in their turn form salts with acids, they exhibit distin- guishing properties of metals. Order 1.—Metals, which, with oxygen, form the fixed alkalies, as potassium, sodium and lithium. 561. The metals of this order have so great an attraction for oxygen, that they decompose water at the moment of contact; the resulting oxides are distinguished by being soluble in water, are hot, and biting to the taste, change vegetable blue colors oreen, and yellow colors brown, and have a caustic action on animal substances. They are called alkalies, and their metallic bases are called alkaline metals. Ammonia is an alkali, but its base is not a metal, like the bases of po- * The Greek termination is from eidos, similar to; the term metalloids signifies similar to metals. 560. Why were the metals of this class called metalloids ? Order 1. Order 2. . f , 561. Attraction of these metals for oxygen. General properties ol the oxides' of these metals. What alkali has not a metallic base ? 212 POTASSIUM. tassa, and soda ; it being a compound of nitrogen and hydrogen. Sir Hum- phrey Davy, after having discovered potassium and sodium, in two of the alkalies, was induced to make a series of experiments upon ammonia, with the expectation of discovering a metallic base, ammonium. But instead of this the decomposition of ammonia resulted in the disengagement of the two non-metallic elements, hydrogen and nitrogen. 562. Potassium.—Equiv. 40. This metal is obtained by the decomposition of potassa, (or potash,) which was, formerly, considered as a pure alkali, but is now known as the oxide of potassium. Sir Humphrey Davy, about the year 1807, became deeply interested in experiments on voltaic electricity ; having first observed its power in separating the elements of bodies known to be compound, he was led to examine its effects on potash and soda, until that time ranked among undecomposable elements. His first attempts on those alkalies, were made upon their aqueous solutions, but the water only was decomposed. He then caused a thin piece of pure hydrate of potassa, to com- municate with the opposite poles of a powerful voltaic appara- tus. The potassa soon became fused ; oxygen gas was evolved at the positive pole, and small metallic globules appeared at the surface connected with the negative pole. The active and comprehensive mind of Davy, on witnessing the success of the experiment, anticipated the great changes which his discovery was destined to produce in chemical science. Possessing the rare combination of ardent enthusiasm with cool philosophical research, he must have contemplated the victory of his genius with peculiar emotions. He foresaw that the elevation of his fame must be commensurate with that im- mortal science, the boundaries of which his labors have done so much to enlarge. 563. The discovery of potassium, by Davy, stimulated the French Chem- ists to new efforts, and Gay Lussac and Thenard, in 1810, succeeded in ob- taining the metal, without the aid of electricity, and in greater quantities than Davy had done. Their process consists in bringing fused hydrate of potassa, in contact with iron turnings, heated to whiteness in a curved gun-barrel. The iron attracts the oxygen from the alkali, and its metallic base is disengaged. The curved gun-barrel is represented at a, b, and/; (Fig. 99,) the iron turnings are placed within, between /, and 6, which part is covered with a lute of infusible clay, made of five parts of sand, and one of potter's clay. Between a and 6, are placed pieces of solid hydrate of potassa. A tube of safety is to be luted to the end, a, and immersed in mercury in the glass vessel, m. To the smaller end of the barrel, is fitted a piece of copper tube, and to this, a small copper receiver h, which is to receive the potas- sium. A tube of safety, i, communicating with this receiver, dips into 562. What substance contains potassium ? History of the discovery ol the metallic bases of potassa and soda by Davy. 563. Process discovered by Gay Lussac and Thenard, for obtaining po- tassium without the aid of electricity. POTASSIUM. 213 mercury contained in the vessel, 6. The furnace should now be heated until the barrel between b and/, or that portion containing the iron turn- ings, is of a white heat, the other parts of the barrel being kept cool by the application of wet cloths. The barrel having become white hot, the hydrate of potassa is melted by igniting charcoal contained in the moveable cage, k, and will then flow down upon the ignited iron turnings, hydrogen gas which was contained in the hydrate of potash, will issue through the safety tube, i ; the oxygen of the potassa will combine with the iron turnings, while the potassium passing off in vapor, will be condensed in the copper receiver at h. Fig. 99. 564. Properties. Potassium (orkalium) resembles other metals in many properties, but differs from most of them, in being of a less specific gravity than water. Its affinity with oxygen is so great, that it cannot be preserved, except immersed in some sub- stance, from which oxygen is excluded, such as ether, or naphtha, or in exhausted glass tubes, hermetically sealed. At 32° Fahrenheit, it is brittle, and when broken, exhibits through a microscope, a white, crystalline appearance. It is solid at the common temperature, though soft, and easily mould- ed with the fingers. In color and lustre, it resembles mercury ; its specific gravity is 0.865. It becomes fluid at 150° Fahren- heit, and at a red heat, sublimes in the form of a greenish vapor. On exposure to the air, it tarnishes, becomes of a bluish color, and changes into the protoxide of potassium. When heated with oxygen gas, it burns with intense light and heat; exhibiting a rose colored flame, and forming, by its combination with oxy- gen, the deutoxide of potassium. When thrown upon water, potassium acts with great violence, swimming on its surface, and burning with great splendor ; hydrogen, is evolved and ox- 564. Resemblance of potassium to other'metals; its difference in one particular. Why potassium cannot be kept in the open air. Properties. Effects of exposure to the air. Of burning in oxygen gas. Action with water. 214 POTASSIUM. ide of potassium or potassa, is found in solution. If ice be used instead of water, it burns with equal force. This effect is owing to its rapid absorption of oxygen, from which so much caloric is disengaged, that the hydrogen gas, resulting from the decomposition of water, is inflamed. 565. Protoxide of potassium, or potassa, is commonly known by the name of potash, from the pots or vessels in which it was made It was at first called kali, and vegetable alkali, on account of its being procured from the lixiviation of vegetable ashes ; but it is now known to exist in earths, and mineral combinations, from which it is imbibed by plants. The potash of commerce, is chiefly obtained by evaporating the ley of wood, or vegetable ashes. Plants of a soft texture are found to yield more of the saline matter, than those with woody fibre. Resinous wood affords little alkali; for which reason, the ashes of pine wood are little valued in families for soap-making. Potassa is a white solid substance, highly alka- line, and of a greater specific gravity than potassium. It has so great an affinity for water, that it readily absorbs it from the air, forming with it the hydrate of potassa, composed of 1 equivalent of potassa, and 1 of water. 566. The peroxide of potassium is formed when potassium burns in the open air, or in oxygen gas. It is yellowish green, and gives the alkaline tests with vegetable colors. It was dis- covered by Gay Lussac and Thenard. Fig. 100. The hydrate of potash, or caustic potash, is the perox- ide of potassium, combined with 1 equivalent of water; and such is the affinity between them, that the water cannot wholly be expelled by the most intense heat. It is a white, solid mass, which fuses at a red heat, disen- gaging caustic, alkaline vapors. This substance is often cast into sticks for the use of surgeons, who employ it as a caustic. Pure hydrate of potassa is obtained by boiling a solution of potash or pearlash with quick lime. This solution is then to be filtered through a funnel, the throat of which is covered with folds of linen ; but since potash absords carbonic acid rapidly, when exposed to the at- mosphere, Mr. Donovan invented the filtering apparatus here represented, (Fig. 100.) A is the filtering funnel, having its throat obstructed by a fold of linen to serve as a strainer ; the solution be- ing poured in through the mouth at 6, the funnel is closed by a cork fitted to the tube, c, and connected at a, with the receiving vessel, D. The filtration will now proceed at the slow rate which the nature of the operation re- quires, and without exposure to any more air than was contained in the vessels at the beginning. 567. Potassium inflames spontaneously in chlorine gas, and burns with 565. Synonymes of the protoxide of potassium. Potash of commerce, how obtained ? Different proportions of potash in plants. Properties of potash. 566. Peroxide of potassium. Hydrate of potassa. Mode of obtaining pure hydrate of potassa. Donovan's filtering apparatus. 567. Combinations of potassium with chlorine, iodine, bromine, &c. SODIUM. 215 great brilliancy, forming chloride of potassium. This chloride is also formed when potassium is heated in hydrochloric acid gas, hydrogen being at the same time evolved. Potassium has a stronger affinity for chlorine than for oxygen, as its oxides are decomposed by chlorine gas. Iodide of potassium is formed, with an emission of light, when the two elements are heated in contact. There is a Bromide of potassium formed by saturating hydrate of potassa with bromine. Hydrogen and potassium unite in two proportions, forming in the one case, a gray solid hydruret, and in the other, a gaseous hydruret, destitute of color. Thenard states, that when potassium is heated in ammoniacal gas, the hydrogen of ammonia is disengaged, and the potassium unites with the nitrogen, forming nitruret of potassium. The sulphuret of potassium is readily formed by the combination of the two elements by means of heat. It has a red color, and is very fusible. Potassium unites with phosphorus, forming a phosphuret. It also com- bines with cyanogen, forming a cyanide or cyanuret of potassium. 568. Sodium.—Equiv. 24. This metal in many of its proper- ties resembles potassium. And was discovered by Sir H. Davy, soon after his discovery of potassium. It may be obtained by the same electrical and chemical processes, with pure hydrate of soda; but requires, in its decomposition, a stronger voltaic power, and a higher degree of heat. Properties. It is brilliant like silver, when kept from the air ; is solid at the common temperature, soft and ductile like wax. It is somewhat heavier than potassium, its specific gravity at 59° Fahrenheit, being 0.972. It therefore nearly floats on water. It is less fusible than potassium ; becomes fluid at about 190° Fahr., but does not vaporize, except at a very high temperature. Its attraction for oxygen is less energetic than that of potassium. Its combustion with this gas does not take place till near igni- tion ; it then burns with a yellow flame, and bright scintillations, producing a yellow compound, which is a mixture of the pro- toxide and deutoxide of sodium. It fuses on cold water, with a hissing noise, appearing like a globule of silver, and gradually melting away ; but without emitting light. On hot water, there is an appearance of sparks and flame. In this combustion, the sodium unites with the oxygen, forming soda. Sodium tarnish- es on exposure to the air, in consequence of its attraction for oxygen ; and like potassium, should be preserved in some sub- stance in which it is insoluble, and which is free from oxygen. 569. The protoxide of sodium, or soda, is obtained by burning sodium in dry atmospheric air, or when sodium is oxidized by burning on water. It is solid, white, caustic, turns to green vegetable blue colors, deliquesces by attracting carbonic acid from the air, and becomes efflorescent. It exists in nature, only 568. Analogies of sodium and potassium. Properties. Attraction for oxygen. Combustion in oxygen. Action with water. Effect of air on so- dium. 216 SODIUM. in combination with acids, and some metallic oxide. Like the protoxide of potassium, its affinity for water is such, that, at the highest temperature, it always retains a certain quantity ; and can only be obtained in the state of a hydrate, or with 1 equivalent of water. The peroxide of sodium, is obtained by heating sodium to red- ness in an excess of pure oxygen. It is an orange colored sub- stance. It is resolved by water, into oxygen and sodium, and loses part of its oxygen by heat. " Soda, (or rather the hydrate of soda,) is distinguished from other alkaline bases, by the following characters. 1st. It yields with sulphuric acid, a salt, which, by its taste and form, is easily recognized as Glauber's salt, or sulphate of soda. 2nd. All its salts are soluble in water, and are not precipitated by any re-agent. 3d. On exposing its salts by means of platinum wire to the blow pipe flame, they communicate to it a rich yellow." Turner. 570. Chloride of Sodium. This union of sodium and chlorine is the compound so well known in all countries, as common salt. This substance, which exists extensively in nature in a solid form, as in rock salt, and in solution in salt springs and sea-wa- ter, was formerly called muriate of soda, being regarded as a compound of muriatic acid and soda. But as it may be formed by the direct combination of sodium and chlorine, it is evident that it is a binary compound consisting of a metallic base and a simple non-metallic element. When sodium is burned in chlorine gas the result of the combustion is chloride of sodium. It may also be formed by heating sodium in hydro-chloric gas, the chlorine unites with sodium and hydrogen is liberated. Sea-water is a hydro-chlo- rate of soda, but by evaporation becomes chloride of sodium; for hydro- chlorates are changed into chlorides by heat, or by evaporation. Hydro- chlorate of soda, for example, consists of hydro-chloric acid and soda, (oxide of sodium,) the hydro-chloric acid gives off its hydrogen, and the soda its oxygen ; these uniting form water, which passes off by evaporation, while the chlorine is left in combination with sodium. The hydro-chlorate of potassium, in the same manner, forms chloride of potassium. The chloride of metals are changed into hydro-chlorates by the decomposition of water; the hydrogen of the water uniting with the chlorine of the chloride forms hydro-chloric acid ; and the oxygen of the water forms with the metal an oxide, and again the combination of the hydro-chloric acid with this oxide constitutes a salt called a muriate, or hydro-chlorate. 571. Properties. The chloride of sodium (common salt) is 569. Protoxide, how obtained ? Properties. Peroxide. How is soda distinguished from other alkaline bases ? 570. Composition of chloride of sodium. Synonymes. How proved to be a binary compound ? How produced. How does sea-water become chloride of sodium ? Chlorides of metals changed into muriates. 571. Properties of chloride of sodium. LITHIUM. 217 transparent and colorless: it crystalizes in cubes. Its taste, though used as a standard of comparison for saline bodies, can- not be defined, except negatively, that is, it is not sour, bitter, sweet, metallic, or astringent. It is grateful and agreeable ; it decrepitates at red-heat, and suffers igneous fusion without being decomposed. By an increased heat, it vaporizes in a white smoke, which condenses in the cold. It is remarkable for being equally soluble in cold, as in hot water; it is al- most insoluble in alcohol. In the arts, salt is often used to in- crease the intensity of fire ; this it does by accumlating and transmitting heat to the surrounding combustibles. It gives to flame a yellowish tinge. 572. Chloride of soda {chloride of oxide of sodium), is formed when chlorine gas is passed through a solution of soda or its carbonate. "It emits an odor of chlorine, and possesses the bleaching properties of that substance in a high degree. When kept in open vessels it is slowly decomposed by the carbonic acid of the atmosphere with evolution of chlorine ; and the change is more rapid in air charged with putrid effluvia; because the carbonic acid produced during putrefaction, promotes the decomposition, of the chlo- ride. On this depends the efficacy of this chloride in purifying air loaded with putrescent exhalations. Chloride of soda may be employed in bleach- ing and for all purposes, to which chlorine gas, or its solutions, was for- merly applied."—Turner. 573. Sodium unites with iodine and bromine ; and among the combustible bodies, with sulphur, phosphorus and selenium. It forms alloys with many of the metals. Its salts are numerous and important. Silliman remarks, " the great prerogative of sodium is to attract oxygen, in which function it is only inferior to potassium. Both these remarkable bodies are endowed with such a degree of activity, and their chemical re- lations are so numerous, as almost to realize the brilliant suggestion of their illustrious discoverer, that they approach to the character of the im- aginary alkahest of the ancient alchemists. Nothing can be more unex- pected than that common salt and sea weed should contain each a metal, oi wood ashes another. In the present state of our knowledge we must regard potassium and sodium as elements. As they exist abundantly in minerals, we can understand how in the processes of vegetable life, they should become constituent parts of plants." 574. Lithium.—Equiv. 10. This mineral is the base of a new alkali called lithia, discovered in 1818, by M. Arfwedson, then a young student in the laboratory of Berzelius. Its name is from the Greek, lithos, a stone. It has hitherto only been found in minerals, as the petalite, spodumene, tourmaline, in some va- rieties of mica, and in certain waters of Bohemia. 572. Chloride of soda. 573. Combinations of sodium with other simple elements, . This metal, sometimes called spelter, is obtained either from calamine (native carbonate of zinc) or from zinc blende, the native sulphuret. As it is a volatile metal, it is always obtained by distillation. The zinc of commerce was formerly brought from China. It is now extensively manufactured in Europe. It is found in some parts of the United States, as in the Southampton, Mass. lead mines, with granite and gneiss; also in crystals in lime rock, near the Genesee river. It resembles lead but is of a lighter color. It melts at about 700°, and crystalizes when slowly cooled. When heated without being exposed to the air, it sublimes, without any change of properties. If heated in the air, it absorbs oxy- gen rapidly, exhibiting a beautiful flame of a brilliant greenish color, and the newly formed oxide flies upward, in the form of white flowers, formerly called flowers of zinc, or philosophical wool. When heated to a white heat, in a covered crucible placed in a furnace, on suddenly removing the cover, it bursts into flame and burns with a brilliant white light. The metal may be stirred with an iron rod to expose other portions of it to the. air; and then if held aloft, and poured slowly upon a brick or stone floor, it descends in a burning sheet, and is dashed about in a fiery spray. This metal is little affected by the air or moisture, and is therefore not liable to rust by exposure to them. On this account, it has been applied in the manufacture of kitchen utensils, and water pipes. But it is found to be attacked by fat substances, especially when aided by heat; and also by the weakest acids; its use is, therefore, become very limited, except in the laboratory. 615. Sir H. Davy, on observing the peculiar property of zinc to resist corrosion, was led to make trial of it for the sheathing of vessels. Copper, 614. From what mineral, and how is zinc obtained ? Zinc of commerce, where now manufactured ? Localities in the United States. Properties. Action of heat upon this metal. Why is zinc not liable to rust? What property of zinc prevents its extensive use for common purposes ? 615. Effect of protecting the copper sheathing of ships from corrosion, by means of zinc. Objections to the use of zinc for the sheathing of ships. 20* 234 ZINC which had hitherto been in use for that purpose, oxidizes so rapidly in water, as to become, in a short time, unfit for service. The copper was found to derive its oxygen from atmospheric air dissolved in water, while the oxide of copper thus formed, uniting with the muriatic acid of the sea water, produced a sub-muriate of the oxide of copper. If, by any means, the cop- per could be secured against oxidation, it would not form a salt with mu- riatic acid—and according to Davy's electro-chemical theory, it only com- bines with oxygen because, by contact with that body, it is rendered electro- positive. By rendering the copper negative, it would then be in the same electrical state as oxygen, and the two would have no tendency to combine. Davy accomplished his object of rendering copper permanently negative, by bringing in contact with it, zinc, which when the two metals were in this state of contact, was positive, and the copper, consequently, of the opposite, or negative electricity. Thus the oxidation of the copper sheathing, was found to be prevented by a small piece of zinc, no larger than the head of a nail, affixed to a sheet of 40 or 50 inches of copper. The copper was found, after many weeks of exposure to the action of sea-water, to be perfectly bright, whilst the zinc appeared to be slowly corroding. Triumphant as the success of this experiment at first appeared, it was found, on the appli- cation of it to practical purposes, to be attended with an unexpected embar- rassment, and that, unless a certain degree of corrosion took place on the copper bottom of the ship, its surface became foul from the adhesion of sea- weeds, and shell-fish. The salts of copper had in fact, served a useful pur- pose, in preventing these organic substances from fixing themselves in so poisonous a bed. Zinc plates have been substituted in the place of copper ; but they are found to be liable to an accumulation of organic substances. A merchant in New York, sheathed the bottom of a ship with zinc plates, fastened with zinc nails ; but she returned from her voyage so exceedingly foul, that he was obliged to remove the zinc, and substitute copper. Ma- rine vegetables and even large oysters were found adhering to the zinc. Thus, in the wise economy of the Almighty, that which cannot be decom- posed for the purpose of entering into new combinations, is used as a matrix to multiply and support organic existence. 616. The protoxide of zinc is very rare in nature. It is ob- tained by the combustion of the metal in the open air. Thenard supposed that he obtained a deutoxide, and Berzelius describes a peroxide, but the former was admitted by its discoverer, to have had but an ephemeral existence, and the latter is consider- ed a form of the protoxide. Chloride of zinc, from its soft consistence, called butter of zinc, is formed by the combustion of zinc filings in chlorine gas. It is of an oily appearance, very volatile and deliquescent. Wa- ter changes it to the muriate of zinc. The natural sulphuret, called zinc blende, exists extensively in masses, and in crystals, which are sometimes semi-transpa- rent and afford beautiful gems. The white vitriol of commerce, is the sulphate of zinc. Its most important alloy is with copper, constituting brass; and in other proportions, pinch-beck, Dutch gold, &c. Its amalgam with mercury,- is used for exciting electrical machines. 61 6. Protoxide of zinc. Other supposed oxides. Chloride of zinc. Sul- phur et of zinc. White vitriol. Alloys of zinc. Amalgam. LEAD. 235 617. Cadmium.—Equiv. 56. This was discovered by Stro- meyer, in 1818. During the reduction of zinc ore by charcoal the cadmium, which is very volatile, flies off in vapor. Oxygen has no action upon it at the ordinary temperature, but when heated in the air, it burns with a yellow flame, forming an orange colored oxide. It is also oxidated by nitric acid, in which it is more easily dissolved than in any other acid. Oxide of cadmium, exists in nature, combined with carbonic acid and silica, in calamine, and other zinc ores. It may be obtained by heating the metal in contact with atmospheric air. Sulphuret of cadmium occurs native in some of the ores of zinc. M. Stromeyer obtained it by heating sulphur and cadmium. It was of a beautiful orange color, and on a careful evaporation, crystalized in transparent, gold colored lamina?. It is thought by mineral- ogists that the Missouri lead mines may afford abundance of both zinc and cadmium. 618. Cerium.—Equiv. 56. It is found in a rare Swedish mineral, called cerite. It has also been found with yttria in the yttro-cerite. Its qualities are little known. There are two ox- ides of cerium ; the protoxide is a white powder. When heated in open vessels, it absorbs oxygen, and becomes the peroxide, which is of a fawn-red color. CHAPTER XXVI. METALS OF THE FOURTH CLASS CONTINUED. 619. Lead.—Equiv. 104. This metal has been known from the earliest periods of history. It was called by the alchemists, Saturn; because, as this deity, (according to mythological fable,) devoured his children ; so lead, in the process of cupel- lation* absorbs, or devours most of the metals. The Latin name for lead is plumbum. Properties. Lead is of a bluish white color, and gives a dis- agreeable odor on rubbing ; its specific gravity is 11.352. It is * The oxides of lead have the property of combining with most of the metals, except gold, silver, and platinum, and on this account are used for purifiers, by a process called cupellation, a term derived from cupel, the name of a peculiar kind of vessel used in the operation. In this process, the lead melts first, and carries with it, in fusion, all the baser metals. 617. Discovery of cadmium. Oxide. Sulphuret. 618. Cerium and its oxides. 619. Alchemistical name of lead. Latin name. Properties. Action with heat, dry air and oxygen. Effect of moisture, combined with air or oxygen. Efl'ects of fusing and heating in open vessels. Various uses. Ac- tion of acids upon lead. 236 LEAD. soft and flexible, and has a strong metallic lustre, when recently cut; but soon tarnishes, on exposure to the air. It is one of the most fusible of the metals; melting much below red heat; it crystalizes on cooling. Atmospheric air, and dry oxygen gas, have no action upon it; but when moist, they soon cover it with a gray coat of the protoxide of lead. When fused in open ves- sels, a gray film is formed on its surface, which is a mixture of metallic lead and the protoxide ; and when strongly heated, it volatilizes in fumes of the yellow oxide of lead. On account of its abundance, and the facility with which it is wrought, lead is much employed in the arts. It is extensively used for aqueducts, reservoirs, chambers for the manufacture of sulphuric acid, printing types, and covering and sheathing gutters, and roofs of buildings. It is employed in medicine. Many of its compounds are poisonous to the human system. It has been asserted that leaden pipes for conducting water are unsafe, on account of the supposed danger of the water becoming impregnated with the metal and thus operating as a poison. Dr. Turner considers that the salts in spring-water, by gradually forming an insoluble film on the metallic surface of leaden pipes, effectually secure it against any change which would cause it to re-act upon the water. Lead is acted upon by acids, which promote its absorption of oxygen and carbonic acid from the atmosphere. Vinegar contains acetic acid ; and pickles should not, therefore, be kept in pots of earthen ware glazed with lead, as the acid corrodes the lead and forms poisonous salts. 620. Protoxide of lead, exists in nature only in combination with acids forming salts. It is prepared in laboratories, by de- composing any salt of lead by potassa or soda. When first precipitated, it is white because it contains water or is hydra- ted, but'when dried by heat and air it becomes yellow. This, in commerce, is called massicot. When the protoxide is partly fused in the air, it unites with about 4 per cent of carbon, and is called litharge; The protoxide forms with acids all the salts of lead, most of which are white. It readily unites with earthy bodies when fused with them, forming the lead-glazing for pot- tery, flint-glass, and pastes for artificial gems. The protoxide of lead in- creases the refractive and dispersive power of glass more than any substance, so that the gems made with it resemble the diamond, but may easily be dis- tinguished by their inferior brilliancy and hardness. 621. Deutoxide of lead is formed by heating the protoxide in open vessels with free access of air. This is known in com- merce as minium or red lead. It is used in potteries for glazing, m the manufacture of flint glass, and as a paint for oil colors. It is also used for the coloring of red wafers which are consequently poisonous. Peroxide or tritoxide of lead is obtain- 620. Protoxide of lead. Massicot. Litharge. Union of the protoxide with acids, and with earths. Use of the protoxide of lead in glass artificial gems. 621. Deutoxide of lead. Red lead. Its uses. Peroxide of lead. Dry- ing oil. LEAD. 237 ed by digesting the deutoxide in nitric acid, which dissolves one part, leaving the other combined with a large portion of oxygen. This oxide is of a brown color, called puce or pea- colored. It is not used in the arts, or in medicine. Fixed vegetable oils, if heated with the oxides of lead, dissolve a portion of them, and are converted into what is called drying-oil. 622. Chloride of Lead may be obtained by the action of chlo- rine gas on thin plates of lead. It is soluble in hot water, and is then considered a muriate of lead. A compound of the chlo- ride and protoxide of lead forms the paint called patent-yellow. The sulphuret of lead exists abundantly as a natural ore, called galena. This is the only ore which is wrought for the purpose of extracting lead. Galena is called potter's lead-ore, because it is used in pottery for glazing. This ore is abundant in the United States. The Missouri lead-mines are remarkable for their richness. There is a lead mine of considerable extent in Southampton, Mass. From specimens of galena found in that locality, we should infer that it might hereafter prove valuable, when improved pro- cesses for carrying on mining operations, and reducing metals, shall be bet- ter understood in this country* The proportion of silver in lead ore is judged of by cupellahon; a small piece of metallic lead is heated under a muffle, upon a cup of ashes made by burning bones. The lead oxidizes, the oxide is absorbed by the ashes, and a button of silver remains. 623. Lead forms vari- Fig. 101. ous alloys; among the most important, is that with antimony for printing types. With tin, lead forms alloys of different kinds, as pewter, in which tin constitutes more than half the compound, organ- pipes, tin foil, and nails used for some purposes in ship-building, because they do not rust in salt water. The solder of the tinner is composed of lead and tin. A compound of lead, tin and bismuth, melts below 212°, so that spoons made from it melt in boiling water. * In 1821, the author received from Charles Bates, Esq. some remarkably fine specimens of galena from the Southampton lead mine, and was inform- ed thaUne working of the mine had been attempted, but afterwards relin- quished on account of the difficulty and expense attending it.___________ --^^CUoMToJl^Tm^^of lead. "Patent yellow. Sulphuret of lead or galena. Lead mines of the United States, bilver obtained from ^^i^^S' ^dtree. How formed. Theory of the lead tree. 238 COPPER. Lead is precipitated from its acid solutions both by iron and zinc. The lead tree (or arbor saturni) * exhibits a beautiful arborescent crystalization of pure metallic lead, precipitated by means of zinc. A small lump of clean zinc (Fig. 101,) is suspended by a thread from the stopper of a transparent glass bottle, containing an ounce of the acetate of lead (sugar of lead,) dis- solved in a pint and a half of water. The lead is gradually precipitated upon the zinc, shooting forth into brilliant crystaline branches. The tree will continue to increase during several days, if the solution be suffered to stand undisturbed, and forms a beautiful and scientific ornament for a mantel piece. The precipitation of the lead, is at first, a chemical phenomenon. The zinc attracts the acetic acid from the solution of acetate of lead, and the lead is set free. The precipitation of the lead upon the zinc is supposed to be caused by galvanic influence. The two metals represent the two poles of the voltaic apparatus, and as the presence of diluted acid developes elec- trical agencies, a mutual attraction between the metals ensues. 624. Copper.—Equiv. 64. This is said to have been dis- covered in the isle of Cyprus and dedicated in heathen mytho- logy, to the worship of Venus; hence the alchemists termed this metal, Venus. The Latin name, copper or cuprum, is de- rived from Cyprus. The implements of war, and domestic utensils of the ancients were mostly made of bronze, or some other alloy of copper and tin. Copper is found pure in native masses and crystals, it is the only metal, except titanium, which is of a red color; it is very malleable, ductile, and elastic, and is the most sonorous of the metals. When rubbed, it emits a peculiar, nauseous odor. The pure metal and its compounds are all poisonous. It fuses at a white heat, and if the heat is urged further, it volatilizes in visi- ble fumes. On cooling slowly, it crystalizes in quadrano^ular pyramids. Copper filings thrown into a strong fire, burn with a green flame. It does not strike fire with flints, and is there- fore used for the nails, hammers and other implements used in the manufacture of gunpowder. But when exposed to the com- pound blow-pipe it burns with a green flame, and light too in- tense for the eye. On account of the color of its flame the salts of copper are sometimes used in artificial fire-works. Copper is little changed by a dry atmosphere ; but when exposed to air and moisture, it becomes thinly coated with a green sub-carbonate. As this metal is poisonous, culinary vessels of copper should never be used except when perfectly clean, or well tinned. When heated to redness, copper oxidizes, and becomes covered with brown scales. 625. The red protoxide of copper may be obtained by igniting * Tree of Saturn. 624. Origin of the name copper. This metal known to the ancients. How found in nature ? Color and other properties of copper. Action with heat. Why copper nails and hammers used in operations connected with the manufacture of gun powder. Combustion of copper. Color of the flame. Formation of sub-carbonate of copper. Copper vessels for culinary purposes. Oxidation of copper. 625. Protoxide of copper. How obtained ? COPPER. 239 in a close vessels 64 parts metallic copper with 80 parts of the peroxide, the metal takes from the peroxide 1 portion of oxygen, and the latter is thus reduced to the protoxide, of which, as 64 added to 80=144, there are 144 parts. 626. The protoxide of copper is dissolved by some of the acids, as also by ammonia; in solution with the latter it is colorless : but, on exposure to the air, it becomes blue, owing to the formation of the peroxide. The salts of the protoxide rapidly absorbs oxygen from the air, and become per- salts; that is, the base of the salt changes from the protoxide to the perox- ide, and the salt is, in consequence, changed from a proto-salt to a per-salt. The protoxide exists in nature; beautiful crystals of it are found in the mines of Cornwall, and in Connecticut and New Jersey. 627. Peroxide, or black oxide of copper, is formed by expos- ing the metal, for some time, to red heat, in the open air. The peroxide of copper is insoluble in water: it does not give the alkaline test with blue vegetable color, but unites acids to form salts; these salts are either green or blue. With ammonia, it forms a deep blue solution, a property which is peculiar to the peroxide of copper, and which affords a valuable test. It is pre- cipitated of a yellowish white color, by albumen, so that the white of eggs, and other substances containing albumen, are an antidote to the poison of this salt of copper. 628. The proto-chloride of copper may be prepared by heating copper filings with twice their weight of per-chloride of mercury, (corrosive subli- mate.) The perchloride may be obtained by digesting the proto-chloride in muriatic acid, and exposing the permuriate of copper, which is thus formed to a temperature of about 400° F. It is deliquescent in the open air, and becomes again the permuriate, by absorbing moisture, thus changing from white to green. Sulphuret of copper is a constituent of variegated copper ore. It may be prepared by fusing copper and sulphur together. Bi-sulphuret is of a yellow color, and more common as a native produc- tion, than the sulphuret. It exists in copper pyrites combined with proto- sulphuret of iron. The alloys of copper are numerous ; that with zinc, forming brass* is perhaps the most important. With tin, copper forms bronze, cannon-metal, bell-metal, and coating for the interior of copper vessels, and metallic mirrors. With gold or silver, it * The manufacture of brass has been practised from remote ages. The ancients confounded copper, brass, and bronze. Brass was, in their view, only a more valuable kind of copper, and they often used the word 24 Molybdenum. 48 Llthlum' 10 Tellurium. 32 Tungsten. 96 order ii. Metals whose oxides are alkaline Vanadium. earth*' . Uranium. 208 Barium. ^jq Manganese. 28 Strontium. 44 Cobalt. 26 Calcium. 20 12 Tin. 58 Magnesium. 663. Origin of the name osmium. Osmium obtained in a metallic state Its oxidation. Oxides of osmium. Chlorides, and other compounds of os- mium. Tests of osmium. 664. Latanium. 665. What metals of the 1st class ? 2d Class, 1st Oraer 2d Class 2d Order. 3d Class. 4th Class. REMARKS. 253 CLASS III. Cadmium. 56 Metals whose oxides are earths. Cerium. 50 ,, Equiv. Lead. 104 Aluminum. 10 Copper. 64 Zirconium. Bismuth. 72 Glucinum. Mercury. 200 Yttrium.* Si]ver# 110 Thorium. Go]d. 200 CLASS IV. Platinum. 96 Metals whose oxides are neither acids, alka- Palladium of- lies, nor earths. _.. ,. .. Equiv. Rhodium. 44 Iron. 28 Iridium. Nickel. 26 Osmium. Zink. 36 Latanium. 666. We have now completed a brief examination of the me- tals. In an elementary course little more can be expected, than that the pupil will gain a knowledge of general principles, and become familiar with a sufficient number of applications to illus- trate these, and impress them upon his memory. But such knowledge is of inestimable value. It furnishes the master-key which will enable him, hereafter, to enter into nature's labora- tory and examine for himself the wonderful operations which are there going on. He has learned to avail himself of the aids which the labors of others afford him ; and may consider him- self as standing at that point where the greatest chemists, who have preceded him, once stood. There was a time when they, too, were beginning to learn ; when observation of the power of chemistry to effect the most simple change in the elements around them caused their bosoms to dilate with emotions of de- light ; and the thought to spring up in their minds, " If science can do this, what can it not perform 1" A glorious future of discovery and invention dawned upon their fancy, and they fol- lowed with untiring steps through labors and difficulties, until success and honor crowned their efforts. Let not the American student fold his arms beneath the mantle of indolence, imagining that Lavoisier and Davy, Vauquelin and Berzelius have discov- ered all that is to be learned in this department of human know- ledge. He should rather consider, that their discoveries and in- ventions have put into h's hands important instruments, for the development of new facts, and the discovery of new principles. The God of Nature, who has placed no limits to man's desire of knowledge, renders also, the field of inquiry equally illimita- ble. One newly discovered region in science opens a pathway to many others, and thus there is, and ever must be, an infinite progression in knowledge, suited to the capacities of the im- mortal mind, and corresponding with the character and dignity of an infinite Creator. ____________^___ 666. Remarks. 22 254 CRYSTALIZATION. SALTS. CHAPTER XXVIII. CRYSTALIZATION. CLASSIFICATION OF SALTS. SALTS OF THB OXACIDS. CRYSTALIZATION. 667. Having now examined the elementary substances with their union with each other, called binary compounds, we shall proceed to describe the secondary compounds formed by the union of three or more simple bodies. These compounds are called salts. As salts under certain circumstances assume crystaline form's, the subject of crystalization may properly precede the description of them. Crystals are formed of similar particles of matter, which, ac- cording to some wonderful and unknown law of nature, arrange themselves into regular, geometrical forms. There is nothing in organic nature more admirable than that process of inorganic matter in which each particle takes its proper place, in order to form, by aggregation, that kind of figure which is peculiar to its own species of matter. The law of molecular attraction may account for the aggregation of particles, but it does not explain why, under certain circumstances they always arrange them selves in perfect symmetry ; nor can any satisfactory reason bb given for this phenomenon. 668. Solid bodies appear under a variety of forms. In the vegetable and animal kingdoms, figure is the result of organiza- tion. The plant bursting from the seed, puts forth roots, stem, leaves, and flowers ; and the animal, exhibits its head, limbs, and peculiar features. In both, organic laws prevail, and a liv- ing principle converts inorganic matter into nourishment, as- similating it to the substance with which it incorporates. In the mineral kingdom, solids are either irregular, amorphous* masses, in which the particles cohere without regular order, or exhibit a crystaline structure. 669. Exp. 1st. Dissolve crystals of alum, (a double salt of alumine and * From the Greek a, destitute of and morphe, regular shape. 667. Substances which have been examined, compounds to be described, &c. Formation of crystals. 668. Forms of organic bodies. Forms of minerals. 669. Effects of slow and sudden evaporation. Exp. 1st. Exp. 2dy and Exp. 3d. Crystals with truncated angles and edges. CRYSTALIZATION. 255 potash) and suffer the solution to evaporate slowly, you will have the same octahedral (eight sided) crystals as those dissolved. But if the liquid be expelled by a sudden and strong heat, you will find the salt in a shapeless mass, or in confused and irregular crystals. Exp. 2d. Plunge a lump of alum into a tumbler of cold water, let it re- main undisturbed a few days and you will find the surface of the salt eaten, and carved out into a variety of regular forms. (See fig. 103.) Exp. 3d. Let a few drops of a solution of alum, be put upon a glass plate ; in a few days, the particles of alum when examined with a microscope, will be found to have arranged themselves in small octahedra (eight sided figures,) (see fig. 104.) Crystals are liable to certain modifications ; thus in octahedral figures we may find some whose angles are truncated, or ap pear as if they were cut off or replaced by secondary surfaces ; sometimes the edges are also similarly modified ; at A, (fig. 105,) angles only of the oc- tahedron are truncated, at B, the edges only, at C, both the angles and edges. 670. As the soluble salts when thus evaporated, usually assume distinct figures, crystalization gives to the chemist and mineralogist a valuable me- thod of determining the composition and nature of different bodies. The smallest crystals obtained from a drop of solution, are equally perfect in figure as the largest ones, formed in greater quantities of the fluid; and, when viewed through a microscope, furnish evidence, equally satisfactory, of the nature, of the crystalized salt. Fig. 103. Fig. 104. 671. Different salts may be thus conveniently evaporated in separate small glasses, and their different crystals compared. Exp. Take common salt, (chloride of sodium,) Glauber's salt, (sulphate of soda,) Epsom salts, (sulphate of magnesia,) and nitre, (nitrate of potash,) of each a teaspoonful, and put them into separate wine glasses with water; 670. Advantages afforded by crystalization to the chemist and mineralo- gist. Small crystals equally perfect in form as larger ones. Comparison of the crystals of different salts. 256 CRYSTALIZATION. occasionally stir the mixture, to facilitate their solution, and when the salts are entirely dissolved, put a drop of each solution upon- a clean watch glass placed in the sun. As the liquid evaporates, crystals peculiar to each kind of salt, may be seen with a microscope ; common salt will appear in cubes ; Glauber's salt in irregular six sided prisms; Epsom salts in four sided prisms ; nitre in six sided prisms; (see fig. 106.) Glauber's salt and nitre, though resembling each other in the form of their crystals, exhibit a marked differ- ence when exposed to the air; ciystals of the former effloresce, that is they lose their transparency, and crumble to powder, while those of the latter are not changed by the atmosphere. Nitre is anhydrous salt, that is, it contains no water of crystalization. Fig. 106. Crystals of Epsom salts. Crystals of common salt Crystals of Glauber's Salt. Crystals of Nitre. 671. Crystals of various salts. 672. Division of crystals in respect to forms. 673. Most common primitive forms. Four sided prism. Cube. Rhom- CRYSTALIZATION. 257 Rhomboid. Tetrahedron. Fig- 108. The rhomboid (Fig 108,) haq its opposite sides equal and par- allel, but none of these are square, each having two acute and two obtuse angles, while each side of the cube has four right angles. The tetrahedron (Fig. 108,) is included within four, equilateral triangular planes. The octahedron, or eight sided figure has all its planes equal, and similai triangles. It may be considered a compound of the tetrahedron. The cut (Fig. 109,) represents a crystal of this form shaded, and the same in outline. The hexangular, or six sided prism; in this, the six sides are similar par allelograms, not square, but oblong ; it has six edges and six angles ; thai is, it is hexahedral and hexagonal. The rhombic dodecahedron : has twelve sides ; each plane being a rhomboid having two acute, and two obtuse angles. The dodecahedron with triangular faces has twelve, equal, triangular sides, a b Fig. 109. \— Hexangular Prisms. Rhombic dodecahedron. Dodecahedron with triangular faces. Fig. 110. mrniiTiinih. The primitive forms of crystals might be considered under the three general classes; the triangular or most simple prism, the tetrahedron or most simple solid, and the parallelopiped. (Fig. 110.) 674. To some one of these varie- ties of forms, all crystals, by me- chanical division may be reduced. Triangular Prism. Parallelopiped. Discoveries in crystalography, as boid. Tetrahedron. Octahedron. Hexangular prism. Rhombic dodeca- hedron. Dodecahedron with trangular faces. Triangular prism. Tetrahe- dron. Parallelopiped. 674. Circumstances which have led to discoveries in crystalography. The Abbe Hauy led to examine the structure of crystals. Planes, edges and angles. 22* 258 CRYSTALIZATION. in other departments of science, have been, in part, the result of accident. Gahn, a Swedish professor of mineralogy accident- ally broke a piece of dog-tooth-spar,* and found it was an ag- gregate of rhomboidal crystals. The Abbe Hauy, a celebrated French philosopher, when examining an expensive collection of minerals, let fall a beautiful crystal, which separated into many pieces; struck with the smooth and brilliant surfaces of these fragments, the Abbe was led to an examination of the structure of crystals. He found that all crystals are easily divided in certain directions, leaving smooth and regular surfaces; that the smaller crystals thus obtained, may again be divided into other minute crystals; but the same form is observed in all. Thus calcareous-spar, crystalizes in rhomboids, fluor-spar, in cubes, and quartz in six-sided pyramids. The surface of a crystal is called its plane or face. The lines made by the meeting ot two planes are called edges ; the meet- ing of three planes forms what is called a solid angle. Fig. 111. Fig. Ill, shows a cube in which a, a, a, are planes, 6, b, are edges and c c, solid angles. Thus the cube has six planes or faces, twelve edges, and eight solid angles. 675. The primary cubic form may be modified by va- rious circumstances. The three primary forms (see § 673,) were by Hauy considered as belonging to the inte- grant molecules of all crystaline bodies. " But it is not difficult, as Dr. Wollaston suggests, to conceive that these primitive forms may, themselves, be procured by c b c certain arrangements of spherical particles. Thus, four balls arranged as at a, (Fig. 112,) give the element of the te- trahedron. Six balls, arranged as at b, that of the octahedron, &c. Fig. 113, represents a number of spherical particles aggregated to form the tetrahedron and triangular prism. Fig. 114, represents the rhomboid and cube. Fig. 115, the octahedron and four sided prism formed in a similar manner. Instead, therefore, of assuming several distinct geometrical solids as primi- tive forms, some philosophers refer to the sphere, or spheroid, as the source of all, and assume it as the figure of the ultimate, mechanical particles of matter." Fig. 112. Fig. 113. a b * Crystaline carbonate of lime. 675. Modifications of the primary form. Hauy's opinion respecting the primary forms. Dr. Wollaston's suggestion. Opinion of some with respect to the figure of ultimate atoms. CRYSTALS. 251) Fig. 114. 676. The secondary forms of crys- tals are supposed to grow out of the integrant molecules and primi- tive forms, as follows. The mole- cules first unite, to produce the primitive form, and from this pro- ceeds the secondary form by the application of successive layers of the integrant molecules, parallel to its planes and faces. (Fig. 116.) If a cube be increased by layers of particles applied to all its sides, the edges of the layers being parallel to those of the cube and each layer being made less than that immediately preceeding it, by one row of particles on each of its edges, a dodecahedron, or twelve sided solid, with rhombic faces will be produced, (Fig. 116.) Fig. 116. Rhombic Dodecahedron. 677. Crystals not only differ one from another, in form, but those of similar form differ in the angles made by the inclination of the faces. Thus in the rhomboid, which is characterized by having one of its adjacent angles smaller than a right angle and the other larger, it is evident that the one angle may consist of almost any number of degrees less than 90, and the other of any number below 180, though this must be the amount of the two angles taken collectively; because the four angles of the crystal, must, together, be equal to four right angles, thus 90x4=360, which is the num- ber of degrees of a circle, by which angles are measured. Thus the primi- tive form of calcareous spar is a rhomboid whose faces are inclined at an- gles of 105° 5', which is more than a right angle, and 74° 5', which is less than a right angle, these numbers added together make 180°, which is the 6um of two right angles. The primitive form of the mineral called tourma- line, is an obtuse rhomboid, the largest angle of which is 113° 10'. 678. An instrument (Fig. 117,) called a goniometer* has been invented for measuring the angles of crystals. Its operation is founded upon the mathematical proposition! that " the opposite angles made by any two lines * From the Greek gon an angle, and metron measure. t Euclid, B. I. prop. 15.____________________________________________ 676. Manner in which the s«condary forms proceed from the primary. 677. Crystals of similar form may differ in the size of their angles. 678. Goniometer. Reflective, goniometer. 260 CRYSTALS. Fig. 117. in crossing each other are equal." Thus the angle made by the arms B B, B C B, of this instrument, above and be- low the pivot on which they re- volve, are equal to each other. Therefore if the angle of a crystal be placed at C, and the arms of the goniometer made to close upon its planes, a similar angle will be made by the arms on the opposite side, and this angle may be known by examining the semicircle, A A, which is graduated into 180°. An instrument called the reflective goniometer has Goniometer, or instrument for measuring the angles ^ ^^ £y Dj. WoUag_ ton, which measures with great accuracy the angles of the most minute crystals; here instead of the crystal itself being employed as a radius, rays of light reflected from the brilliant angles are made subservient to this purpose. 679. In order to obtain large and well formed crystals, three things are necessary, time, space and repose. 680. We have considered the subject of crystalization chiefly in respect to salts; but metals often assume very beautiful, and regular crystaline forms. This may take place either by liquefy- ing them by fusion, or by converting them into vapor ; and as the liquid be- comes solid by cooling, or the vapor by condensing, the particles arrange them- selves in crystals of greater or less re- gularity. Tin, lead, antimony, and bis- muth, all afford crystals. For this pur- pose they may be melted in a crucible; when the surface cools it should be ■H§fe pierced, and the liquid metal within poured out; when the hollow mass has become quite hard, it may be broken and the interior of the cavity will be found lined with crystals. Fig. 118, represents the crystalization of bismuth effected in this manner. 681. Crystals are to the mineralogist, what flowers are to the botanist. He reads the chemical constitution of minerals in the mechanical figure which they present, as the botanist decides by the organs of the plant, the class or group to which it be- longs. But as various accidental circumstances, to which flowers are not exposed, affect the forms of crystals,, it is often 679. To obtain perfect crystals. 680. Crystalization of metals. 681. Value of crystals to the mineralogist. SALTS. 261 necessary that the inquirer should examine the constituent parts; and this can only be done by the aid of chemical analysis. Classification of Salts. 682. To facilitate the study of the salts, they have, very pro- perly, been arranged in groups, or genera. As every acid, with few exceptions, unites with every alkaline base, the different kinds of salts thus formed are very numerous, amounting to more than 2.000, though not more than thirty were known a hundred years ago. The names given to the salts were, often, merely arbitrary ; but in the present nomenclature, the name of a salt expresses its composition, and the knowledge of its composi- tion recals its name. The name of the genus is derived from the acid, that of the species, from the base; thus sulphate is a generic term, including various species, as sulphate of soda, sulphate of lime, &c. 683. The acids are divided into two classes ; 1st Oxacids, or those acids in which oxygen is united to a combustible body ; 2nd Hydracids, or acids composed of hydrogen and some other substance. Until the great revolution in chemical science, which took place about the year 1775, it was supposed that oxy- gen was the only acidifying principle. Berthollet was the first to suggest doubts on this subject, by affirming that sulphuretted hydrogen ought to be regarded as an acid, though composed of hydrogen and sulphur. The discovery of iodine and chlorine, furnished new and convincing proofs that the acidifying pro- perty is not confined to oxygen, but exists in other bodies. The number of the binary oxacids amounts to more than twenty, while that of the hydracids is much less. 684. There are four orders of salts viz :— Order I, Salts of the oxacids. Order II, Salts of the hydracids. Order III, Haloid Salts. Order IV, Sulpho Salts. Every acid is capable of forming a salt with a base ; and such salt may be considered as a distinct genus; but as one element often forms with oxygen several acids, which though they possess individuality, are very similar, Ave shall consider the various salts formed by such acids as con- 682. Importance of some mode of classifying salts. Difference between the old names of the salts and those- which are founded on the chemical nomenclature. 683. Two classes of acids. 684. Orders of salts. What constitutes a general character in respect to salts ? Subgenera of salts. 262 SULPHATES. stituting divisions of a genus; thus the nitrites and hyponitrites will be classed as subgenera, of the genus nitrate. ORDER I. SALTS OF THE OXACIDS. GENUS I.--SULPHATES. 85. Of all the acids, none has a more decided tendency to combine with salifiable bases, than the sulphuric. The number of sulphates is of course very great. Properties. They have mostly a brittle taste; and are decomposed by baryta, which has a stronger affinity for sulphuric acid, than any other base. All the sulphates may be decomposed by carbon, at a high tempera- ture. The acid and oxide are both decomposed, the oxygen forming with the carbon, carbonic acid, and the sulphur forming with the metal, a sul- phuret. At common temperatures, the sulphates neither effervesce with acids nor give off vapors; but the sulphuric acid, by a high heat, may be displaced by boracic, phosphoric, and arsenic acids. Those which contain no water of crystalization, as the sulphate of iron, when exposed to great heat, yield a portion of anhydrous, sulphuric acid. Six of the sulphates are insoluble in water, viz : the sulphates of baryta, tin, antimony, bismuth, lead, and mercury; the sulphates of lime, strontia, silver, and a few others are sparingly soluble; all the others are soluble in water. The soluble sul- phates form with hydrochlorate of baryta, a dense white precipitate, which is the sulphate of barytas, and is insoluble. Among native sulphates, those of lime and baryta are most abundant. Those which are employed in the arts, are usually extracted from native minerals. Some are prepared directly by art, and many by double decomposition. 686. Sulphate of potassa, is a white salt, of an acrid and bitter taste; it was formerly much valued in medicine and is known in commerce, as vitriolated tartar. It is of use in the manufac- ture of alum, glass, and salt petre. It is not found native among mineral substances, but exists in the ashes of tobacco and some other vegetables. The bi-sulphate contains twice as much acid as the sulphate. 687. Sulphate of soda was discovered by Glauber, a German chemist in the process for obtaining muriatic acid, by decompo- sing common salt with sulphuric acid. A precipitate of soda was obtained which has been named Glauber's salt in honor of its discoverer. It is contained in the waters of some mineral 685. Why is the number of sulphates great ? General properties of this ge- nus of salts. Decomposition, &c. Insoluble sulphates. Soluble sulphates with muriate of baryta. Native sulphates, &c. 686. Properties of sulphate of potassa. Uses. Where found. 687. Discovery of sulphate of soda. Common name. Where it exists in nature. Properties. Crystals. Degree of temperature at which water most readily dissolves it. Effect of the effervescence of this salt. Uses. Bisulphate of soda. SULPHATE OF LIME. 263 springs, in sea water, in the ashes of sea weed, and sometimes effloresces at the surface of the earth, and upon the walls of cel- lars, and other excavations. It exists in a mineral found in Spain, called Glauberite. It is a colorless, and very bitter salt, capable of forming very large crys- tals, and containing 58-100th of the water of crystalization. According to Berzelius, the crystals are composed of 72 parts, or one equivalent of sul- phate of soda, and 90 parts, or ten equivalents of water. They undergo the watery fusion on exposure to heat. This salt readily effloresces in the air. It is one of the essential medicines of the family dispensatory. It is used in the arts for the preparation of carbonate of soda, and manufacture of glass. Bisulphate of soda is formed by adding sulphuric acid to a solution of sulphate of soda. 688. Sulphate of ammonia exists in small quantities in nature ; in the neighborhood of volcanoes, and in the waters of the Tuscan lakes. It is usually prepared by the direct combination of ammonia with sulphuric acid. 689. Sulphate of Baryta, called heavy spar is an abundant pro- duct of nature usually found in veins, with metals, sometimes in fibrous masses. It is wholly insoluble in water, and bears the most intense heat without fusion, or decomposition. The affinity of pure baryta for sulphuric acid, is so great, that when they are brought in contact, ignition is produced. This affinity enables baryta to separate sulphuric acid from all its combinations, giving a white precipi- tate, in a solution containing no more than one millionth part of baryta. All the salts of baryta, except the sulphate, are poisonous; and this excep- tion is owing to the perfect insolubility of the salt, in the juices of the sto- mach. If, therefore, any of the poisonous salts of baryta be swallowed, diluted sulphuric acid, a solution of sulphate of soda, or any other alkaline sulphate, would be the proper antidote. The sulphuric acid would unite with the baryta of the poisonous salt, and form the harmless sulphate of baryta. 690. Sulphate of Lime is abundant, existing in the form of gypsum, (plaster of Paris,) alabaster, and silky crystals, called selenite. It is found in the ashes of plants, and the water of springs, causing what is called the hardness of the latter. Hard water, or that which contains salts, and consequently acids in solu- tion, decomposes soap, while the oil combining with the earthy base of the *alt, floats on the surface of the water; thus it is impossible to form, what the laundress calls suds, with hard water. Add soap to a solution of sul- phate of lime, and the soap will immediately be decomposed. Sulphate of lime may be formed by adding sulphuric acid to any carbonate of lime, or lime water. When pure it is perfectly white, as in alabaster. Exposed to intense heat, it loses its water of crystalization, and fuses into a white powder; in this state it forms plaster of Paris. 688. Sulphate of ammonia. 689. Sulphate of baryta. Why not poisonous. 690. Existence of sulphate of lime in nature. Hardness of water. Pre- paration of sulphate of lime. Plaster of Paris. Composition of anhydrous sulphate of lime. Of the crystalized sulphate, Anhydrite. Uses of sul- phate of lime. Plaster casts. 264 SULPHATE OF ALUMINA. Anhydrous sulphate of lime consists of one proportion of acid=40, one proportion of lime=28. The compound equiv. is, therefore=68. The crys- talized sulphate contains, in addition, two proportions of water, -18, ma king its equivalent 68 added to 18=86. The uses of sulphate of lime are various. It is employed as a manure for soils ; and with lime plaster to give it a greater durability, firmness, and smoothness; this composition for walls and ceilings is called hard finish. This is a srreat improvement upon the old method of plastering, as it will bear washing with soap and water. Sulphate of lime is much used for statuary. Plaster casts are often taken from persons after death, but with the faithful preservation of their lineaments, there is also, in such busts, but too accurate a delineation of that last repose, which, however sanctified by religious hopes, humanity yet shudders to contemplate. 691. Sulphate of Magnesia was first obtained from a mineral spring, at Epsom, England ; hence its common name, Epsom salts. It is less bitter than the sulphate of soda, which it resem- bles in taste and medicinal properties. It is sometimes called Seidlitz salts, from a village in Bohemia which contains mineral springs strongly impregnated with this salt. It exists in sea- water, from which it may be obtained by evaporation. It is also manufactured from magnesian lime-stones. It is found crystal- ized in large quantities, in lime-stone caverns in Kentucky, and several other of the Western States. 692. Sulphate of Alumina exists in nature in a mineral called aluminate. It may be formed by mixing alumina with sulphu- ric acid. The pure sulphate is of little importance ; but com- bined with sulphate of potassa it forms a double salt of alumine and potash; which is the common alum of commerce. This salt has an astringent taste, is soluble in water ; reddens in- fusions of purple cabbage slightly ; changes blue infusions from the petals of flowers to a green color. Exp. Suspend a frame work of siring, or wires in a vessel filled with a hot, solution of alum, large and beautiful crystals will collect upon the frame, and thus may be formed a variety of pretty ornaments, as baskets, vases, and flowers. Alum crystals contain half their weight of the water of crystalization. When heated, they melt in this water, swelling and froth- ing, while the water passes off, leaving anhydrous alum in a white, light, and spongy mass. When heated with sugar, alum forms a compound which in- flames spontaneously ; it is known as Homberg's pyrophorus. Native soda alum is found in South America and in Greece. The chemical equivalent of pure sulphate of alumina is stated at 58 ; and the composition of alum is as follows ; Sulphate of potassa, 1 equivalent, =88 Sulphate of alum, 3 equivalents, (58x3)=174 Water, 25 equivalents, (9x25) 225 Chemical equiv. of Sul. alumina and pot.=487. 691. Sulphate of magnesia. 692. Sulphate of alumina. Alum. Exp. Anhydrous alum. Homberg's pyrophorus &c. Composition of sulphate of alumina. Law of chemical combination illustrated by this salt. Uses of alum, &c. SULPHATE OF IRON. 265 The composition of this salt illustrates an important law of chemical com- bination, viz ; that, in the double sulphates, the quantity of oxygen in one of the bases, will be proportioned to the quantity of oxygen in the other base. Now the oxygen in potassa is, in proportion to the oxygen of alumina, as 1 to 3 ; therefore, there are 3 equivalents of alumina to 1 of potash in alum j thus each base furnishes to the common stock, an equal amount of oxygen. Alum is an important article of commerce, and is employed in medicine and the arts ; it is used in dyeing, calico printing, in paper manufactories and by tallow chandlers to render their tallow more solid. It is not common in nature, but its elements are abundant. Where it is already formed, as at Solfaterra near Naples, it is sufficient to lixiviate* the earths, which con- tain it, and crystalize the liquor. 693. General remarks. The sulphates which are formed by the union of sulphuric acid with the fixed alkalies and alkaline earths, are the most important species of this genus. Those sulphates which are formed with oxides having neither earthy nor alkaline properties, and therefore commonly called metallic oxides, are scarcely less numerous than these oxides themselves, since all have some affinity, more or less, for sulphuric acid. But it should be remembered, that, in principle, there is no distinction between alkaline, earthy, and metallic salts, since all salts (with the exception of those of ammonia and the vegetable bases, which we shall hereafter consider,) are composed of acids and metallic oxides. Thus potassa and soda are now known to be oxides of metals, no less than the oxides of iron and copper ; though the two former are usually, called alkalies, and the two latter me- tallic oxides. 694. Sulphate of Iron. Sulphuric acid combines with three oxides of iron; but according to Berzelius there are but the proto and the joersulphate. He regards the deutosulphate as a compound of the two others. The protosulphate, or sulphate of the protoxide of iron commonly called copperas, green vitriol, &c. may be formed by the action of dilute sulphuric acid on metallic iron. Water is decomposed and furnishes oxygen, which uniting with the metal forms the protoxide; hydrogen escapes with effervescence, and sulphuric acid unites with the newly formed oxide. This sulphate is seldom found in nature in a solid state; but is often found, in solution, in water flow- ing in the neighborhood of mines. This salt crystalizes in rhombic prisms, is of a beautiful green color, and inky taste. Its color is owing to its water of crystalization of which it contains 45 parts in 100 of its weight. When deprived of this water by • To leach them, or to form a ley of them. 693. Most important species in this genus of salts. Salts which are not based on metallic oxides. 694. Number of combinations of sulphuric acid with oxides of Iron. Pro- tosulphate of iron, or copperas, &.c. 23 266 SULPHATE OF COPPER. heat, it becomes of a dirty white color. This salt is useful in the arts, par- ticularly in that of dyeing. In combination with nut galls it forms ink. Persulphate of iron is formed by the action of nitric acid with the proto- sulphate, or by the action of sulphuric acid upon the red oxide of iron, slightly moistened with water. It is not crystalizable. 695. The persulphate (or sulphate of the peroxide of iron) has 1£ an equivalent, or 60 parts of sulphuric acid, with 1 equivalent of peroxide of iron. This furnishes a striking instance of the acid of a salt being in pro- portion to the oxvgen of the base; the more remarkable as the peroxide of iron has its half equivalent of oxygen, and we find it requiring an additional half equivalent of the acid for its saturation. 696. Sulphate of manganese appears in transparent crystals of a slight rose tint. Sulphate of zinc or white vitriol reddens blue vegetable colors, though in its composition it is a neutral salt, consisting of one equivalent of acid and one of oxide. It is obtained in granular masses, resembling sugar ; but by evaporation may be crystal- ized in quadrangular prisms. It is employed in medicine, as an astringent, and in certain cases as an emetic. 697. Sulphate of Copper. There is no sulphate of the protoxide of copper; for, according to Proust, when this protoxide is heated with sulphuric acid, the result is, a solution of the deutoxide of copper, and a precipitate of metallic copper, which appears as a red powder.—Thenard. The bisulphate of copper (sulphate of the deutoxide) is the blue vitriol of commerce. It crystalizes in prisms with an oblique base ; its crystals contain in large quantities the water of crystalization, which renders them transparent, and gives them a beautiful blue color. Exposed to the air they become slightly efflorescent, and are covered with a whitish crust. They fuse easily, in their water of crystalization, and become white. This salt has a strong metallic taste, is used in medicine as a caustic, and when taken into the stomach excites nausea. It is soluble in water, but not in alcohol. It is seldom found crystalized in nature; but, by evaporating the water of cop- per mines,* in which this salt exists in solution, the crystalized blue vitriol of commerce is obtained. The same substance is also prepared by roasting copper pyrites with aceess of air and moisture, the sulphur is acidified, the copper oxidized, and Ihe deuto-sulphate which is formed, is extracted by solution and crystalization. Anhydrous sulphate of copper consists of Peroxide of copper, 1 equiv. =80 Sulphuric acid, 2 do. =80 Compound equivalent, =160. The crystalized sulphate contains in addition 10 equivalents of water, =90 The equiv. of the crystalized sulphate is =250. • Copper ore usually contains some sulphur; copper pyrites is the sul phuret of copper.____________________________________________________ 695. Persulphate of iron. 696. Sulphates of manganese and zink. 697. Why is there no sulphate of copper? Bi-sulphate of copper. Blue SALTS. 267 The sulphate of copper reddens vegetable blue colors ; it is therefore called a suyer-sulphate, and sometimes a bi-persulphate. Silliman justly re- marks,! " The refinements of a significant nomenclature are sometimes embarrassing, requiring frequent changes with the progress of discovery, and presenting names which are inconveniently Ions; they also compel us to return occasionally to the old proper names, such as alum, common salt, white, green, and blue vitriol." To this remark we would add, that our Chemists have undoubtedly gone too far in attempting to introduce technical names into common language. Our respect for science would scarcely pre- vent a smile should we hear one call for the protoxide of hydrogen combined with hydrocarbonous oxide, instead of water and sugar. When ammonia is added to a solution of blue vitriol, a pre- cipitate appears, of a greenish blue color ; on adding an excess of ammonia, this precipitate is dissolved and forms a liquid of a beautiful blue color, called celestial blue ; it is the ammoniaret of copper. Ammonia affords a valuable test of copper. The sulphate of copper is used in the arts to prepare blue cinders used in coloring paper, and Scheele1 s green. 698. Sulphites. Salts of this sub-genus are formed by the union of sulphurous acid with salifiable bases. They are dis- tinguished by a disagreeable taste, and an odor like that of burning sulphur. When exposed to air and moisture they absorb oxygen, and pass to the state of sulphates. They are decomposed by the stronger acids, such as the sulphuric, hydro- chloric, &c, effervescence takes place, owing to the escape of sulphurous acid, and a sulphate is formed. Nitric acid, by yielding oxygen, changes the sulphites into sulphates. CHAPTER XXIX. SALTS OF THE OXACIDS CONTINUED. , GENUS II.--NITRATES. 699. The nitrates may be formed by the action of nitric acid on metals, or their oxides. In the former case, according to the theory of the formation of salts, the metal must first oxidize, before it will become a salt. The nitrates are acted upon by sulphuric acid, which disengages nitric acid in the form of dense, f Elements, Vol. II. p. 282.____________________________ vitriol. Composition of the anhydrous sulphate of copper, and the crystal- ized copper. Properties. Chemical names not adapted to common lan- guage. Blue vitriol with ammonia. Uses of sulphate of copper in the arts. 698. Sulphites. ' • 699. Nitrates. Which are most readily decomposed ? 268 NITRATE OF POTASSA. white, acid vapors, having the peculiar odor of nitric acid. They are all decomposed by heat, giving out oxygen and be- coming nitrites. By a strong heat they lose all their acid. They deflagrate when heated with charcoal or other combustible substances. Most of the nitrates are composed of one equivalent of acid, and one of a protoxide; the oxygen of the oxide and acid is, in these cases, in the ratio of 1 to 5, because the proportion of oxygen in the protoxide is 1, and in the nitric acid 5. The oxides of those metals which have the least affi- nity for oxygen, as gold, palladium, &c. part with their oxygen at a low temperature, and the nitrates formed with them are easily decomposed, while the nitrate of lead and some others, require a red heat for their de- composition. 700. Jfitrate of Potassa* nitre, salt petre, &c. exists in great quantities, in nature. It is not found in large masses, but dif- fused on the surface of the earth, usually in connection with the nitrates of lime and magnesia, in places where animal substances have suffered decomposition. Efflorescences of this salt, resem- bling mould, are found upon the damp walls of old cellars and subterranean buildings, especially when these walls are covered with lime mortar. Nitre is manufactured by lixiviating the substances in which it is contained, and evaporating the solution. In the East Indies it is abundant as a natural production ; and large quantities are imported from thence into Great Britain and the United States. In Italy and Spain it is found in the dust of the roads; and it is common in the grounds near Lima in South America. It exists in some plants, as the hemlock, sunflower, tobacco, &c. 701. Properties. It is a white substance with a cool and sharp taste, and deflagrates when thrown upon burning charcoal. With heat it suffers the ignecris fusion, as it contains no water of crystalization, though its crystals are not quite free from some water of interposition, or water lodged mechani- cally in their interstices, instead of being chemically combined with their particles. Nitre is used in chemistry as a deoxidizing agent, and to obtain oxygen,f and nitric and sulphuric acids. It is useful in medicine on account of its cooling properties. It is an antiseptic, and is used in the salting of meat, to which it imparts a fine color, rendering the fibre both tender and * The nitre of the scriptures is the carbonate of soda, called in Greek, natron, and in Latin nitrum. Thus in Prov. 25 : 20, " as vinegar upon nitre, so is he that singeth songs to a heavy heart." Here the effervescence or disturbance caused by: the action of the acid vinegar upon the carbonate is evidently alluded to. In Jeremiah 11 : 22, we read of washing with nitre ; the cleansing or detergent property of the carbonate of soda must be referred to. t Oxygen being driven from nitre by heat, may be collected over the pneumatic cistern. 700. Nitrate of potassa as found in nature. Manufacture of nitre. In what countries most abundant. Exists in plants. 701. Properties. Action with heat. Uses. Tests. Action with water, NITRATE OF SILVER. 269 compact. It can be known by its deflagrating on burning coals, and by the disengagement of the fumes of nitric acid, when tested with sulphuric acid. Owing to its rapid combination with water, it forms with ice a valuable freezing mixture. 702. Its action with combustibles constitutes its efficacy as an ingredient in gunpowder, which is a mixture of 75 parts of nitre, 10 of sulphur, and 15 of charcoal. These are the usual proportions,"but they are sometimes varied. The composition of gun powder was discovered by Roger Bacon, a friar, in the fourteenth century. It is supposed that the Chinese were previously acquainted with it. It was first used by the English at the battle of Agin- court in 1415. Gun powder is merely a mechanical mixture, as at common temperatures no chemical action takes place among its parts. But when heated, the oxygen which the nitre yields so readily and abundantly, acts on the carbon and sulphur, producing with the latter a rapid and violent combustion, while the former yields a large proportion of elastic vapor. The volume ofj*as produced from powder at the moment of explosion, is said to be 1000 times greater than that of the solid powder. As each additional volume of gas exerts a force equal to that of the atmosphere, which is 15 pounds to the square inch, the force of this elastic vapor will be 1000X15 = 15,000 pounds on a square inch ; this according to calculation will project a bullet with a speed of 2000 feet in a second. The products of the detona- tion of gunpowder, are both gaseous and solid ; the former consisting of mix- tures of nitrogen, nitric oxide, carbonic acid, sulphuretted and carburetted hydrogen and ammonia. The solid products are some sulphate, and sulphu- ret of potassa, carbonate of potassa and charcoal. Various fulminating powders are made with nitre, some of which produce a more powerful detonation than gun powder. 703. JVitrate of Silver is obtained by dissolving silver in nitric acid. Cast in small moulds, it forms the lunar caustic* or lapis infernalis of medicine. It is highly corrosive, and changes the skin, first yellow, and then black on exposure to the air, (owing to the decomposition of the oxide of silver.) In a very dilute state it is used, with other ingredients, for staining the hair black, and for indelible ink, used in marking linen. An imposition has heretofore been practiced by the venders of the mark- ing ink, by selling at a great price, a vial of what they call solution; which is merely a solution of pearlash and water. The article to be marked, is wet with this solution, and then dried. The ink is, a colorless liquid, (unless it contains a small portion of India ink;) but the alkali of the pearlash, seizes the nitric acid, and forms nitrate of potash ; the oxide of silver being liberated, is precipitated among the fibres of the linen. Exposure to light, partially decomposes the oxide of silver, and the letters become black. When a white garment has been accidently stained with this ink, the spot may be removed by steeping in diluted nitric acid. * Lunar is derived from the ancient name of silver, caustic, from its agency in destroying animal texture. The name lapis infernalis, or infernal stone, was given in allusion to its strong burning property. 702. Gunpowder. Its composition. Discovery. Cause of its combusti- ble nature. Cause of its explosive property. Force. Products of its de- tonation. Fulminating powders. ,,,.., ■ , 703. Nitrate of silver, how formed ? Lunar caustic. Indelible ink. Mode of marking with this ink. Exposure to light. 23* 270 CHLORATES. 704. Nitrites and Hyponitrites. When nitrous acid is brought in contact with a salifiable base, the result is a nitrite, and under certain circumstances a hypo- nitrite. Nitrous acid does not appear to be susceptible of a permanent union with salifiable bases. By exposing the nitrates to a red heat, oxygen is given off and nitrites are formed; but by exposure to the air, the latter absorb oxygen, and again be- come nitrates. The hyponitrites, contain a less portion of oxygen than the nitrites. They are decomposed by water even at the ordinary temperature. GENUS III.--CHLORATES. 705. These salts (formerly called Hyper oxymuriates,) are form- ed by the combination of bases with chloric acid. They defla- grate with even greater violence than the nitrates, yielding oxygen so readily, that the slightest agitation will produce their explosion. They are soluble in water, and decomposed by heat, giving off oxygen, and becoming metallic chlorides. Most of the chlorates are composed of one equivalent of chloric acid, and one of a pro- toxide, it follows, therefore, that the oxygen of the latter, to that of the former, is in the ratio of 1 to 5, (chloric acid having 5 pro- portions of oxygen.) None of the chlorates are found native. They were discovered by Berthollet, in 1786. 706. Chlorate of potassa, (hyperoxymuriate of potash) is the most important species of the chlorates. Exp. It may be formed by passing a stream of chlorine gas, (Fig. 119,) Fig. 119. 704. Nitrites. Hyponitrites. 705. Former name of chlorates. Formation and character. Decompo- sition. 706. Chlorate of potassa. How formed ? Exp. Rationale of the process. CHLORATE OF POTASSA. 271 through a solution of caustic potash in Woulfe's bottles, or by saturating the gas with a solution of potash. A, represents the outer one of three jars, containing solution of the sulphate of potash ; peroxide of manganese being put into a retort C, and some hydrochloric acid added to it, chlorine gas is disengaged, and passes to the globe B, from whence it proceeds into the inner jar. If it be not all absorbed by the liquid in this jar, the superfluous gas will escape into the next jar, and so on, until all the liquid is saturated ; any gas which remains in excess, is conducted off by the pipe P, and receiv- ed in an inverted bell glass. E is a pipe which, when extended, may still further serve for conducting off the superfluous gas, into a suitable receiver. In this operation, it is supposed that one part of the potassa is deoxidized, and the reduced metal uniting with chlorine forms the chloride of the po- tassium, which is in solution; and that the oxygen of the potash unites to another portion of the chlorine, producing chloric acid, which, combining with the undecomposed potassa, forms the chlorate of potassa. 707. Dr. Hare contrived the ap- paratus here represented (Fig. 120,) for the purpose of separating the solution of chlorate of potassa from potassa and siliceous earth. A large vessel of sheet tin was fitted to a tin funnel, to support a glass filter- ing funnel, and furnished with an aperture which serves the purpose of a chimney, by conducting off'the smoke of the Argand lamp below. This lamp keeps the water hot, with which the tin vessel is filled. The hot water thus surrounding the so- lution as it filters, prevents its cool- ing. A coarse fibrous paper for a filter, is placed within the funnel; the filtering solution of chlorate of potassa, is received in the decanting jar beneath. On being kept undis- turbed, the salt crystalizes in beau- tiful white, rhomboidal scales, re- sembling mother of pearl. Their taste is cool, but bitter and nauseous. The crystals are anhydrous, and suffer the igneous fusion, below red heat; at a higher temperature they give off oxygen, with boiling and effervescence, and become chloride ofpo- 708. Properties. Chlorate of potassa yields a large propor- tion of pure oxygen gas. For this reason it acts powerfully on combustibles, readily inflaming them and producing violent detonation. Two parts of chlorate of potassa mixed with one of sulphur, and put into a paper, will explode with great violence on bein«r struck with a hammer. When rubbed in a mortar with phosphorus or charcoal, a loud detonation and jets of fire are produced. 707 Dr Hare's apparatus for purifying chlorate of soda, &c. of chlorate of potassa. Action of heat upon the crystals. 708. Properties. Exp. Crystals 272 BROMATES. Exp. If a small portion of phosphorus covered by chlorate of potassa (Fig. 121,) be placed in a glass which is then fill- ed with water and sulphuric or nitric acid, poured in through a long glass funnel, the mixture is inflamed, and burns with great brilliancy, with a series of detonations. Sugar mixed with chlorate of potash, deflagrates with the addition of a small quantity of sulphuric acid. 709. Chlorate of potassa is used in the arts, for fire- matches, and attempts have been made to introduce it as an ingredient in gun-powder ; but, though it produces a powder of greater impelling force than that which is commonly used, it inflames so easily by slight friction, or shocks, that its manufacture and use are very dangerous, and prevent its being employed for this purpose. It is composed of Chloric acid 1 equivalent=76 Oxide of pot. 1 do. =48 = 124 of oxygen, 5 in the acid and =48 =36 =40 Compound chemical equiv. =124 710. Perchlorates or oxygenated chlorates, are formed by the union of perchloric acid with salifiable bases. These salts dis- covered by Count Stadion, are little known. GENUS IV.--IODATES. 711. The iodates are produced, either by combining iodic acid directly with bases, or by double decomposition. The composition of iodic acid being similar to chloric acid, in re- spect to the quantity of oxygen, the iodates, like the chlorates, contain oxygen in the oxide and acid in the proportion of 1 to 5. Like the chlorates, they form deflagrating mixtures with sulphur, and other inflammables. Most of the acids decompose the iodates, by attracting the oxygen from iodic acid. The iodate of potassa is the most important species of this genus. GENUS V.--BROMATES. 712. Like chlorates and iodates, the proportion of the oxide to the acid in the bromates, is in the ratio of 1 to 5, bromic acid 709. Uses of chlorate of potassa. Cause which prevents its being used in gun-powder. Composition. 710. perchlorates. 711. Remarks on the genus, iodates. 712. Bromates. Fig. 121. Chemical equiv., therefore: Its ultimate compounds being 6 proportionals 1 in the alkali, 6x8 1 proportion of chlorine 1 do potassium CHUOMATES. 273 containing 5 proportions of oxygen. The properties of bromates appear to be analogous to those of chlorates, and iodates. GENUS VI.--PHOSPHATES. 713. These salts are not decomposable by heat, but melt at a high temperature. They are extensively diffused in nature. The phosphate of lime is most abundant, often forming an impor- tant constituent of mountain masses, and existing largely in animal bones. There are phosphates with excess of base called alkaline phosphates, neutral phosphates, acidulated phosphates and acid phosphates. 714. Phosphites are a combination of phosphorus acid with salifiable bases. When exposed to heat, they disengage phos- phuretted hydrogen, and a little phosphorus, while a phosphate colored by the oxide of phosphorus remains. When thrown upon burning coals, they produce a yellow flame. Hypophos- phites are combinations of hypophosphorus acid with bases. They are too soluble to be crystalized. GENUS VII.--ARSENIATES. 715. Salts composed of arsenic acid with bases are called arseniates. Arsenites are combinations of arsenious acid with bases. They are distinguished from the arseniates by a green precipi- tate with sulphate of copper, while the arseniates form with the same compound a bluish white precipitate. The arsenite of cop- per is Scheele's green. The arsenite of potassa is known in medicine as Fowler's solution. GENUS VIII.--CHROMATES. 716. The salts which result from the union of chromic acid with salifiable bases, are all colored ; yellow and red are the prevailing colors, the latter appearing when there is an excess of acid °The chromate of lead is a brilliant yellow, known in the arts as chrome yellow, it is of a beautiful pink in the state of a subsalt; chromate of lime is yellow, and chromate of potassa lemon color ; potassa combines with an excess of chromic acid in which case the salt is of intense orange color ; chromate of silver is of a rich crimson color ; chromate of copper, apple green. 713. Phosphates. 714 Phosphites. Hypophosphites. Vll ^a«?ter'ofttrch™».te.. Chromate of lead. Chromate of lime. Chromate of potassa, tc. Chromates of silver and copper. 274 CARBONATES. GENUS IX.--BORATES. 717. Boracic acid is reckoned among the weak acids ; its salts are therefore readily decomposed by the greater attraction of other acids for their bases. The Borates dissolve in alcohol, and burn with a green flame. Biborate of soda is imported from the East Indies in a crude state under the name of tincal. This is purified in the substance known in the arts- as borax. When exposed to heat its crystals lose their water of crystalization, •md become fused, forming a vitreous substance called glass of borax. It is used in chemistry for the preparation of boracic acid; and in glass making and pottery, as a flux. GENUS X.--CARBONATES. 718. Properties. These salts effervesce with most acids, owing to the rapid disengagement of carbonic acid, for which the bases have but a feeble affinity. The carbonates of the alkalies have an alkaline taste, and change to green the vegetable blue colors ; those of the earths are insoluble but become soluble with an excess of carbonic acid. Many of the carbonates are found in nature. 719. Carbonate of potassa is not found in nature, but is ob- tained by lixiviating vegetable ashes, and evaporating the solu- tion to dryness. Pearlash or saleratus differs from the crude carbonate of potash, only in being freed from impure matter It is an article much used in domestic operations. Its action with flour in raising bread, biscuits, &c. depends on the readi- ness with which it disengages carbonic acid, which becoming entangled among the glutinous particles of the paste, tends to make a light and spongy mass. On its alkaline properties depends its utility in neutralizing the sour- ness produced by suffering the dough to remain unbaked, until the vinous fermentation changes to the acetous. Some housewives prefer to let their dough thus sour, as, by adding pearlash, bread and biscuit are rendered more spongy and tender, while the acidity may be wholly corrected. But this process, unless carefully conducted, will give to the bread a darker hue, and the peculiar taste of pearlash. With a little attention, however, very delicate and palatable biscuit may be made without yeast, simply by the ac- tion of pearlash and sour cream, or milk mixed and kneaded with the flour, and baked immediately. The common pearlash is uncrystalized, and anhy- drous. It exists in white porous masses, potash is harder and of a darker color. 717. Character of the borates. Biborate of soda. Crystals. Glass oi borax. 718. Character of the carbonates. 719. Carbonate of potassa, how formed ? Pearlash. Its use in domestic economy. CARBONATES. 275 720. Carbonate of soda, is obtained by lixiviating the ashes of marine plants. The soda of commerce is an impure carbonate, which may be purified by heat. Though alkaline, it is not highly caustic. Its solution forms beautiful crystals composed of two quadrilateral pyramids. They contain 10 equivalents of of water, with 1 of carbonic acid and 1 of soda ; or acid 1 equiv. =22 added to do. soda, 32, added to 10 do. water, 90=144 which is the equivalent of crystalized carbonate of soda. Bicarbonate of soda is, in its composition analogous to the bicarbonate of potassa. A sesqui carbonate is said to exist native on the banks of soda lakes in Africa ; this in commerce is called trona. The best variety of the carbo- nate of soda which is known in commerce is called barilla ; an inferior kind is called kelp. These substances are much used in the manufacture of glass, soap, in dyeing, bleaching, and in the preparation of artificial soda water. 721. Carbonate of ammonia, commonly called volatile salts of hartshorn ; is considered as a sesqui* carbonate, consisting of 1 equivalent of ammonia, with 1£ carbonic acid. It is prepared by heating hydrochlorate of ammonia with carbonate of lime ; double decomposition ensues, hydrochlorate of lime remains in the retort, and the sesqui carbonate of ammonia sublimes. This salt is the white substance contained in the hartshorn smelling bot- tles. Its odor is volatile, pungent and stimulating lo the nerves. It pro- duces the alkaline effects on blue vegetable colors; alkaline earths attract its acid and liberate ammonia, while the acids attract ammonia and liberate the carbonic acid gas with effervescence. The proper carbonate of ammonia or that with 1 equivalent of acid and 1 of the base, is formed by mingling carbonic acid gas over mercury, with twice its volume of ammonia. Bicarbonate of Ammonia is prepared by saturating a solution, of the carbonate with carbonic acid gas. The common hartshorn or sesqui carbonate, when exposed to the air, loses ammonia and gains carbonic acid, and appears to be converted into a bi- carbonate, becoming almost inodorous and tasteless. This salt is composed wholly of gases in a condensed state ; the acid con- sisting of carbon and oxygen, the base of hydrogen and nitrogen ; or Acid, 1 equiv. carbon 6 added to 2 equiv. oxygen 16=22 Base, 1 equiv. nitrogen 14 added to 3 equiv. hydrogen 3=17 The chemical equivalent of this salt is, therefore, 39 As there are two equivalents of acid and one of base, the proportions are, carbonic acid 44 added to ammonia 17=61. The carbonate of ammonia is a most valuable medicine. It is much used in chemistry as a re-agent, and, diluted with water, has its useful applications in domestic economy, in re- moving spots of oil or grease from cloth, &c. * The term sesqui signifies one and a half. 720. From what plants is the carbonate of soda obtained ? Soda of com* merce. Crystals. Composition of the crystals. Bicarbonate. Sesqui-car- bonate. Barilla and kelp. Their uses. 721. Carbonate of ammonia. Composition. Preparation, Smelling bot- tles. Properties. The proper carbonate. Bicarbonate, Composition, Uses of carbonate of ammonia, 276 CARBONATES. 722. Carbonate of baryta may be prepared by double decompo- sition, by mixing a soluble salt of baryta with any of the alka- line carbonates. It is found native: is an insoluble salt, and of great use in chemistry for preparing the other salts of baryta. It is not readily dissolved by heat. 723. Carbonate of lime is an insoluble compound of lime, ex- isting abundantly in nature, in the form of lime-stone, marble, chalk, stalagmites, spar, &c. It is decomposible by fire, and by most of the acids, with effervescence. It is used in chemistry for obtaining pure lime, and carbonic acid, and in the arts for building and statuary. It is much used as a manure for soils, both in the form of lime and carbonate of lime. The advantage of burning it for this purpose appears to be of no other use than to destroy cohesion, so that it may be easily scattered among the soil; for quick lime soon becomes a carbonate by absorbing carbonic acid from the atmosphere. It was discovered by Dr. Black, in 1756, that lime acquired its caustic properties by the loss of carbonic acid. Though insolu- ble in water, carbonate of lime dissolves by an excess of carbonic acid : for this reason the spring water of lime stone countries is impregnated with this salt which is found deposited upon the bottom and sides of tea kettles, in which such water is boiled. 724. Carbonate of magnesia is prepared by decomposing sul- phate of magnesia with carbonate of potassa. It is not found pure in nature, being mixed with lime, silex, &c. Calcined magnesia is the carbonate deprived of its magnesia by heat. Carbonate of iron exists in nature in masses and veins. It is contained in most mineral springs, being held in solution by percarbonic acid. It may be prepared by decomposing the sulphate of iron by a solution of carbonate of soda or potassa. The precipitate of carbonate of iron readily attracts oxygen from the atmosphere, and the protoxide of iron, becoming a peroxide, parts with carbonic acid, which does not form with it a definite compound. Thus the carbonate of iron known in medicine, is chiefly the peroxide, distinguished by its red color. Carbonate of copper exists in nature as a beautiful light green mineral, called malachite, which is a carbonate of the peroxide of copper. It may be prepared by adding carbonate of potassa to nitrate or sulphate of copper. In an impure state it constitutes the blue pigment known as verditer. Carbonate of lead, whitelead, or ceruse. This substance, so much used in the arts, is rarely found in nature. It is manufactured by introducing a current of carbonic acid gas into a solution of the acetate of lead. Another method is to expose thin plates of sheet lead to the vapor of vinegar, which, by its acid fumes, first oxidizes the lead, and then changes it to a carbonate. 722. Carbonate of baryta. 723. Carbonate of lime, as found in nature. Decomposition. Uses. The utility of burning it for manure. Dr Black's discovery. Solution of car- bonate of lime. 724. Carbonate of magnesia. Of iron, lime, copper and lead. HYDROCHLORATES. 277 CHAPTER XXX. ORDER II.--SALTS OF THE HYDRACIDS OR HYDROSALTS. 725. The term hydracid is somewhat exceptionable, as it may lead to the error that hydrogen- performs the same office in the hydracid, as oxygen does in the oxacid ; whereas, it is the element with which hydrogen is united in these acids, that is in reality, the acidifying principle, and analogous to oxygen ; thus chlorine and iodine, like oxygen, are supporters of com- bustion, while hydrogen is a combustible body. Like oxygen, chlorine and iodine on the decomposition of hydrochloric and iodic acids by galvanism go to the positive pole, being, like ox- ygen, negative in relation to hydrogen. The acids in which hydrogen is a constituent element, and which form distinct genera of salts with different bases, are the following : Hydrochloric, (muriatic acid) Hydriodic, Hydrobromic, Hydrofluoric, Hydrosulphuric, (sulphuretted hydrogen,) Hydro- cyanic, (prussic acid.) GENUS I.--HYDROCHLORATES. 726. These salts are composed of hydrochloric acid, and me- tallic oxides. The name, muriatic acid, was first given to the hydrochloric, on the supposition that it was composed of oxygen, and a base called muriatum ; after the discovery of chlorine, and the consequent change of opinion with respect to the nature of muriatic acid, the name hydrochloric, was given in conformity with the principles, of the new nomenclature. Yet the name muriatic acid, had become so well established, and its com- pounds, the muriates and oxymuriates, so well known by these names, that custom has, in a measure, prevailed over the man- dates of science, even among chemists themselves. But expla- nations respecting the nature of these compounds and their changes according to theories now established, are more intel- ligible by the new nomenclature. For instance, when hydrogen or chlorine are said to be disengaged by the decomposition of a muriate, the nature of the process will not so readily be compre- hended as if the term hydrochlorate had been used. ~725. Difference in the nature of the office performed by the hydrogen and oxygen of these respective acids in the formation of salts. Number of hy- dracids. . . ., x , ^ _, , .. 726. Cause of the change of the name muriatic acid, to that of hydrochlo- ric. Why may chemical changes be better understood by using the proper chemical terms ? 24 278 HYDRIODATES. 727. Hydrochlorates are intimately related to the chlorides, as in desic- cation, (drying) and crystalization the hydrogen of the hydrochloric acia unites with the oxygen of the oxide forming water, and leaving the chlorine united to the metallic base of the oxygen, in other words, the hydrochlorate has become a chloride. On the other hand, when the chlorides are dissolv- ed in water, the chlorine unites with the hydrogen, and the metal with the oxygen of the water, aud the newly formed hydrochloric acid, and metallic oxide combine to form a hydrochlorate. Thus dry common salt is chloride of sodium, but, dissolved in water, it is chlorate of soda. Dry hydrochlo- rates or muriates, except that of ammonia, are mostly considered as chlo- rides. Properties. The hydrochlorates differ from all other salts by forming the white insoluble chloride of silver, when mixed with the nitrate of silver, and by being decomposed at the common temperature by sulphuric acid, with effervescence, and disengagement of white pungent fumes, characteristic oi hydrochloric acid. They differ greatly from the nitrates in being little af- fected by charcoal, sulphur and other combustibles. They melt and volati- lize by heat. They are soluble in water. The hydrochlorates which are found in nature are, ammonia, soda, lime, potassa and magnesia. 728. Hydrochlorate of ammonia, (the salammoniac of commerce) may be prepared by decomposing sulphate of ammonia, with the hydrochlorate of soda. The two gases ammonia and hydro- chloric acid exchange bases, and unite, forming the solid hydro- chlorate of ammonia, which is obtained pure by sublimation. Hydrochlorate of soda, is the chief constituent of sea-water; it exists only in solution, for when evaporated it becomes chlo- ride of sodium. Hydrochlorate of potassa exists in solution in mineral springs. Hydrochlorate of baryta is an important re- agent in chemistry. Hydrochlorate, of lime exists in mineral springs, and often gives common spring water the property called hardness, which is indicated by its not combining well with soap. Hydrochlorate of magnesia is abundant in sea-water, and often exists in mineral springs. When hydrochlorate of soda is separated from sea-water by crystalization, a liquid remains called bittern, consisting mostly of hydrochlorate of magnesia. GENUS II.---HYDRIODATES. 729. They are formed by the action of hydriodic acid with alkaline earths and metallic oxides ; and are supposed to exist only in solution. In drying, the hydrogen of the acid, unites with the oxygen of the oxide forming water ; iodic acid then unites with the metal, and an iodide remains. Hydriodic acid 727. Connection of the hydrochlorates and chlorides. Peculiar proper- ties of the hydrochlorates. 728. Hydrochlorate of ammonia. Hydrochlorates of soda, potassa, baryta, lime, and magnesia. 729. Remarks upon the hydriodates. HYDROSULPHURETS. 279 does not unite with all the metallic oxides; it forms salts with the alkalies and alkaline earths, and with the oxides of zinc, iron, and manganese. The hydriodates of potassa and soda are the only salts of this genus which are known to exist in nature. They are formed in the water of mineral and salt springs, in sea-water, sea-weed, the sponge and oyster, and in some other mineral, vegetable and animal, substances. 730. Hydriodate of potassa is more known than any of the salts of this genus. It may be prepared by adding hydriodic acid to potassa. On being crystalized, the oxygen of the potassa unites with the hydrogen of the acid to form water which evaporates, while the iodic acid unites with the po- tassium and a solid iodide remains. GENUS III.--HYDROFLUATES. 731. They are formed of hydrofluoric acid united with bases. The nature of the acid, (see § 298,) is somewhat doubtful. It was formerly supposed to consist of oxygen and fluorine ; but is now considered as a hydracid. The analogies of this acid with the hydrochloric, are in some respects remarkable; and these analogies extend to the salts of the two acids. Thus when the hydrofluates are evaporated to dryness, they become fluorides, when the latter dissolve in water, they are hydrofluates. Though the hydrofluates give the alkaline test with vegetable colors, they are, according to Berzelius and Thenard, neutral salts ; that is, composed of one equivalent of the acid with one of the base. It is not certain that they exist in nature, though the topaz has been called a double hydrofluate of silica and alumina; and some other rare minerals have been considered as composed of hydrofluoric acids united to metallic oxides. But these com- pounds are now regarded as fluorides. Fluor spar was known in chemistry as fluate of lime, when its acid was supposed to consist, in part, of oxygen ; but it is now regarded as a fluoride of calcium. 732. Hydrofluate of potassa. Two definite compounds of hydrofluoric acid and potassa may be formed. The neutral hydrofluate, consisting of one equivalent, and the bihydrofluate, consisting of two equivalents of the acid to one of the base. The neutral hydrofluate seems improperly named, since it possesses alkaline properties ; the bihydrofluate gives the acid test with vegetable colors. The hydrofluoric acid forms also, with soda and ammonia, both neutral and acid salts. GENUS IV.--HYDROSULPHURETS OR HYDROSULPHATES. 733. The term hydrosulphuric acid, which is generally used by 731.' RlmrtTuwn^Wnte1***- °Pinion °f Berzelius and Thenard' Fluor Spar. ?33 K^VoflKi%ric acid. Name of the salts of this acid. Properties of the salts. Result of this decomposition. 280 HYDROSULPH-ATER. the French Chemists to designate the acid composed of hydrogen and sulphur, is more expressive of its composition than the name sulphuretted hydrogen. In the one case, the salts formed with the acid would be properly called, hydrosulphates ; in the other hydro- sulphurets. This acid seems not capable of combining with the oxides of many of the proper metals, but forms with the alkaline earths, soluble salts, which have an acid and bitter taste, and disagreeable odor. The composition of the hydrosulphates is such that if the hydrosulphuric acid and the oxide mutually decompose each other, the result is, water and a metallic sulphuret corresponding to the degree of oxygen contained in the oxide ; thus a protoxide will produce a protosulphuret, and a deutoxide, a deutosulphuret. 734. Hydrosulphuret of ammonia is formed in nature by the decomposition of animal substances. It is obtained in the laboratory by combining am moniacal gas with sulphuretted hydrogen gas at a very low temperature ; for this purpose, the gases are often mixed in a glass globe surrounded by ice; the salt will be deposited in the form of white scales. 735. The hydrosulphates of potassa, soda, baryta, strontia, lime and magne- sia may be obtained directly, by causing a current of hydrogen gas to pass into solutions of these bases in water. For this purpose, an apparatus like that represented in figure 122 is used. Fig. 122. The matrass (Fig. 122,) placed over a furnace contains sulphuret if anti- mony, the first flask water, to wash the gas, and the third flask contains a solution of soda ; more flasks may be added, containing solutions of other alkalies or earths. Hydrochloric acid is poured through the branching tube upon the sulphuret of antimony, and a gentle heat applied ; hydrochlorate of the protoxide of antimony is formed in the matrass, while the hydrosul- phuric acid is disengaged.* * Thenard " Traite de Chimie." 734. Hydrosulphuret of ammonia. 735. Hydrosulphates of potassa, soda, &c. Process for preparing these salts by means of a current of hydrogen. HYDROFERROCYANATES. 281 736. Bisulphuretted hydrogen, unites with alkalies and alkaline earths forming salts, called sulphuretted hydrosulphurets. They absorb oxygen rapidly from the air and are used in eudiometry. Figure 123, re- presents the eudiometer of Dr. Hope. It consists of a graduated glass tube, sealed at one end, and at the other fitted, into the month of a tubulated glass bot- tle, so as to be air-tight. The tube is filled with air, the bottle, with the liquid sulphuretted hydro- sulphuret. The tube being inverted the air is made to pass into the bottle; the mixture is agitated, and time allowed for the absorption to be completed. The oxygen gas absorbed is replaced by water. The graduation being inspected, the deficit produced by the absorption of oxygen is thus ascertained. GENUS V.---HYDROCYANATES OR PRUSSIATES, 737. Are formed by combining hydro cyanic acid (prussic acid) with bases. They are distinguished by the formation of a deep- blue precipitate with salts of the peroxide of iron. With salts of the protpxide they give an orange colored precipitate, chang- ing in the air to green and blue. Hydrocyanate of potassa may be formed directly, by the union of hydro- cyanic acid with potassa; or by the decomposition of water by cyanuret of potassium ; in the latter case the oxygen of the water forms an oxide with potassium, the hydrogen forming hydrocyanic acid with cyanogen. The acid and oxide combined form the salt. Thus the cyanuret of potassium can only exist in the dry state, as when dissolved in water it becomes a hydro- cyanate. The cyanurets of the other alkaline and earthy bases also become hydro- cyanates when in solution ; the phenomenon being analogous to that attend- ing similar changes in the chlorides, iodides, bromides and fluorides. On the other hand, the hydrocyanates, when evaporated become cyanurets, parting with hydrogen from the acids, and oxygen from the oxides which unite to form water. GENUS VI.---HYDROFERROCYANATES, 738. Are sometimes called triple prussiates, ferroprussiates, hndferrocyanates. Hydroferrocyanic acid, consists of hydrogen, iron and cyanogen. It unites with oxides in the same manner as the other hydracids, the hydrogen of the acid being in the exact proportion to form water with the oxygen of the oxide. 736. Bisulphuretted hydrogen. Dr. Hope's eudiometer. 737. Characteristics of the hydrocyanates. Hydrocyanate of potassa. Change of cyanurets by solution. Evaporation of hydrocyanates. 738. Characteristics of the hydroferrocvanates. 2-i* OQO HALOID SALTS. It forms soluble salts with the alkalies and alkaline compounds. When evaporated by heat, the hydrogen of the acid goes off with the oxygen of the oxide in aqueous vapor, and a ferrocyan- uret remains. 739. Hydroferrocyanate of potassa (triple prussiate of po- tassa) is prepared by digesting potassa with pure ferrocyanate of the peroxide of iron, (prussian blue,) which last parts with its acid, and thereby neutralizes the potassa. It is also formed in the manufacture of prussian blue, when the blood, hoofs and horns of animals are calcined with potassa and iron. It appears in the forms of large, transparent, lemon colored crystals. The crystalized salts consist of cyan. 3. potassium 2. iron 1. Hyd., 3. and Ox., 3 equivalents of each. % 740. Hydroferrocyanate of the peroxide of iron is the basis of prussian-blue. It is formed by mixing the hydroferro cyanate of potassa, with the peroxide of iron ; the precipitate is of a deep blue color. The prussian blue is pre- pared by heating animal substances, with potassa and a salt of iron in a large iron crucible. Carbon and nitrogen arising from the decomposition of the animal matter form cyanogen, which, uniting with disengaged hydro- gen and a portion of iron, forms hydroferrocyanic acid. The acid now com- bining with iron and potassa forms a salt with a double base, which may be called a hydroferrocyanate of iron and potassa. ORDER III.---HALOID SALTS. Some late chemists have introduced an order of salts having for one or both of its constituents a compound analogous to sea-salt; the haloid* acids generally belong to electro-negative elements, and the haloid bases to the electro-positive metals. For example, the bichloride of mercury is called a haloid acid; its combination with metals forms salts, called Hydrargo^—chlorides. The perchloride of gold forms with metals aurochlorides. SULPHOSALTS. These are double salts as the oxy-saltsare double oxides, they are often called double sulphurets, among the genera of this order as the Hydrosulphurets, Hydrosulphocyanurets, Carbo- sulphurets, &c. * From hale, sea-salt, and eidos, appearance. f From the Latin name of mercury hydrargyrum. 739. Hydroferrocyanate of potassa. 740. Hydroferrocyanate of the peroxide of iron. Prussian blue. Haloid salts. Sulpho salts. CONCLUDING REMARKS. 283 CONCLUDING REMARKS. 741. We have now completed an outline of inorganic Chemistry. In a subject embracing such a vast variety of combinations, and susceptible of so much amplification, we have found it difficult to keep within the boun- dary of a simple elementary course of instruction. Yet believing that a few principles well understood are of more advantage to the student, than a mass of unconnected facts, we have endeavored to bring into bold relief the general laws of chemical science, and our choice of facts has often been di- rected by this view, rather than by their individual importance. For the same reason we have been more careful to explain the rationale of the changes described, than to enter into minute details of manipulations.* We have not attempted to follow the elementary substances through all their metamorphoses in the various arts and manufactures, but have sought ex- amples from the most common and familiar facts to illustrate principles, and on the other hand have endeavored to explain similar facts by a recurrence to principles previously established. * For a knowledge of these the student is referred to the author's Dic- tionary of Chemistry, Farraday's " Chemical Manipulations," Gray's " Ope- rative Chemist," Silliman's Elements, Hare's Compendium, Thenard's Traite de Chemie, &c. 741. Concluding remarks. PART III. ORGANIC CHEMISTRY CHAPTER XXXI. CONSIDERATIONS ON THE SUBJECT OF ORGANIC CHEMISTRY.--VEGE- TABLE CHEMISTRY.--PROXIMATE PRINCIPLES AND ULTIMATE ELE- MENTS.--VEGETABLE ACIDS. 742. Organic Chemistry treats of animal and vegetable substances, the elements which enter into their composition, and their modes of combination and arrangement. Though organic substances differ greatly from inorganic, they present us with no new ele- ments,but the vital power produces, in plants and animals, changes unlike any of the effects of mere mechanical action. Inorganic substances generally possess some peculiar principle, which distinguishes one from another ; as in the acids, where one contains nitrogen, another sulphur, another phosphorus, &c. But organic products, with few exceptions are composed of the same elementary principles, varying only in their proportions. These principles are mostly carbon, oxygen, and hydrogen; nitrogen is less abundant in plants than in animals. Lime,po- tassa, iron, phosphorus, and some other substances usually exist in organic matter, though but in small proportions. 743. It is beyond the power of science to explain in what manner the living principle operates in plants and animals, pro- ducing in the former, secretions of sap, gum, resin, oil, &c, and in the latter, secretions of a very different nature, as blood, bile, &c. Neither is the chemist able, inorganic chemistry, to prove the results of his analysis by synthesis. Although analysis 742. What is Organic Chemistry ? Cause of the difference between or- ganic and inorganic substances. 743. Effects of the living principle. Organic compounds cannot be re- composed. Transmutation of matter exhibited in organic substances. ORGANIC CHEMISTRY. 285 enables him to ascertain the simple elements which exist in gum or sugar, he cannot, by the union of hydrogen, oxygen, and carbon, in the same proportions in which they constitute these apparently simple compounds, form similar ones; but water and carbonic acid, only, result from his combination. If the simplest products of vegetable organization cannot be imitated by man, much less can he produce any action which bears the remotest analogy to that of the mysterious principle of life. Every plant and animal may be considered as a laboratory, in which a presiding ge- nius is carrying on a process of transmutation wholly unintelligible to those who behold the result. Out of the dust of the earth springs a beautiful plant, which drinking in the most offensive vapors, exhales the sweetest fragrance, and glowing with bright, or delicate tints, forms a strong contrast with the dark unsight- ly soil which gave it birth. The same elements moreover goto form the calyx, petals and pollen of the flower, with its stem, leaves and roots. Where is the chemist who can explain the cause of the various colors, texture and odor of these different organs, all resulting from the same elements, placed in the same circumstances of air, moisture, light and heat 1 In the young infant, how rapidly does milk become changed into fleshy fibres, and cellular membranes, giving roundness and beauty of outline to the limbs, while at the same time it is adding hardness to the incipient bones, and firmness to the un- strung muscles ! 744. Animal and vegetable substances are all decomposed by a red heat, and most of them at a temperature much below this. When heated in the open air, or with substances which yield oxygen freely, as the oxide of copper, for example, they burn, and are converted into water and carbonic acid ; but if exposed to heat in vessels from which atmospheric air is excluded, very complicated products ensue. A compound consisting only of carbon, hydrogen, and oxygen, yields water, carbonic acid, car- bonic oxide, carburetted hydrogen of various kinds, and proba- bly pure hydrogen. Besides these products, some acetic acid is commonly generated, together with a volatile oil which has a dark color and burnt odor, and is hence called empyreumatic oil. A substance containing nitrogen only in addition to carbon, ox- ygen and hydrogen, yields ammonia, cyanogen, and probably free nitrogen. 745. Organic products are distinguished by the following characteristics : 744. Decomposition of animal and vegetable substances. 745. Characteristics of organic products. 286 ORGANIC CHEMISTRY. 1. They are composed of the same elements. 2. They readily undergo spontaneous decomposition. 3. They cannot be formed by a direct union of these prin- ciples. 4. They are all decomposed at a red heat.* 746. Every distinct compound which exists ready formed in organic bodies is called a proximate or immediate principle, in distinction from the ultimate elements,which remain when these principles are reduced to their simplest parts. Thus gum and turpentine are among the proximate principles of plants, gelatin and albumen among those of animals. Carbon, oxygen, &c. are the ultimate elements. VEGETABLE CHEMISTRY. 747. The proximate principles of plants are either confined to a particular part, or distributed over the whole, thus pollenin is found only in the pollen of flowers, while sugar exists in the juices diffused throughout the whole body of many plants. There are various methods of procuring these proximate prin- ciples. The sap of the sugar maple, cane and beet yield sugar on being concentrated and evaporated by boiling. Starch is made by mechanical division of the potatoe, corn, and some other leguminous plants, and then washing the particles in which it exists,in pure water. On letting the water stand, the starch subsides. Volatile Oils are obtained by distillation. More than forty vegetable proximate principles have been discovered. 748. There are still many difficulties in the way of an accurate analysis of vegetable principles, though this subject has within a few years received much attention. The observations of Gay Lussac and Thenard, led them to form the following general conclusions with respect to the constitution of vegetable substances. 1. A vegetable substance is always acid, when the oxygen, in relation to hydrogen is in greater proportion than to form water, or in other words when oxygen is in excess. 2. When hydrogen is in excess, or when the oxygen is in relation to it, in a less proportion than is necessary to form water, the body is resinous, oily, or alcoholic. 3. When the oxygen and hydrogen are in the proportions to form water, or neither in excess, the body is neither acid, resinous, oily, &c, but sac- charine, as sugar; mucilaginous, as gum, &c. * Turner. 746. Distinction between proximate principles and ultimate elements. 747. Situation of the proximate principles of plants. Number of vegeta- ble proximate principles. 748. Conclusions of Gay Lussac and Thenard respecting the constitution of vegetable substances. VEGETABLE ACIDS. 2S7 749. In conformity with these views of the French chemists, a classifica- tion of proximate principles has been made by Turner. " These laws," he remarks, " are not rigidly exact, nor do they include the vegetable products CKnitiaifn!fg mtro-en> but f°r want of a better principle of classification I shall follow M. Thenard in making them to a certain extent the basis of my arrangement." Division of proximate principles. 1. Vegetable acids. 2. Vegetable alkalies. 3. Oils, resins, alcohol; substances with an excess of hy- drogen. 4. Sugar, starch, gum, &c, when hydrogen and oxygen are m proportions to form water. 5. Compounds which are not known to belong to the other divisions, as coloring matter, tannin, &c. VEGETABLE ACIDS. 750. The vegetable acids are composed of oxygen, hydrogen and carbon ; they redden blue vegetable colors, have mostly a sharp taste, and neutralize salifiable bases, forming salts. The names of these acids are generally derived from the vegetables in which they exist in the greatest quantity. They are decomposed by heat, or by hot nitric acid. The products of their decomposition are carbonic acid and water. 751. Acetic Acid. Of all the vegetable acids this is the most extensively used. It exists ready formed in the fruit of the Phus typhinus (sumach,) Sambucus nigra (elder,) and the sap of many plants, either free or combined with lime, or potassa. It is one of the principal products of the acid fermentation. It gives to vinegar its sourness. Besides acetic acid vinegar contains more or less water, mucilaginous matter, alcohol, and various salts in solution. In France, vinegar is made by exposing wine to the acid fermentation, in England, malt liquors are used for this purpose, and in the United States, most of the vinegar is made from cider. As oxygen is here the acidi- fying principle, the cider should be placed where the sun and air may have access, and be furnished with some of the mother of vinegar, a mucila- ginous, whitish, ropy substance which is usually found at the bottom of strong vinegar. This substance seems equally necessary in hastening the acetous fermentation of cider, as yeast is in promoting the vinous fermentation of bread. The vinegar from wine contains a certain portion of the bitartrate of potassa which may be obtained by evaporation. Vinegar as obtained 749. Turner's classification of proximate principles. 750. General characteristics of vegetable acids. Number. Derivation of the name of these acids. Decomposition, &c. 751. Acetic acid. Vinegar. Making vinegar. Wine vinegar. Dist'Ua- tion. Freezing, &c. 288 OXALIC ACID. pure by distillation, forms acetic acid. When vinegar is exposed to severe cold, some of its water freezes, and it becomes stronger, or more like pure acetic acid. 752. Acetic acid is also obtained by purifying the pyroligneous or empyreumaticacid, which is procured from the carbonization of wood in close vessels. On being distilled, a brown transpa- rent liquid is obtained, having a strong smell of smoke. This pyroligneous acid is beneficial in the preservation of meat, to which it imparts a flavor like that obtained in the common pro- cess of smoking. Pure acetic acid is obtained from the binacetate of copper, (crystalized verdigris,) and from the acetates of potassa and soda. The acetate is dis- tilled with sulphuric acid, which, uniting with the base, disengages acetic acid. 753. Properties. Acetic acid is very volatile, has a sour taste, and other acid properties ; its odor is refreshing, and hence vinegar is often burnt in sick rooms. Its crystals con- tain one equivalent of acid with one of water. The strongest acid is a hydrate; it cannot be obtained without a portion of water. According to the late analysis of Leibig, acetic acid is composed of the following elements, Car. 4, Hyd. 4, Ox. 4.* 754. Acetic acid acts readily on ammonia and most of the metallic oxides, forming salts called acetates. Acetate of ammonia is used in medicine under the name of spirit of min- derus; it is obtained by saturating carbonate of ammonia with acetic acid. The acetates of soda and potassa, are employed for obtaining acetic acid. They may be prepared by neutralizing potassa and soda with distilled vine- gar. The acetate of potassa exists in the sap of many plants. The acetate of alumina is used by dyers and calico printers ; that of baryta as a re-agent in Chemistry. Acetate of Copper furnishes the green paint known as verdigris ; this may be obtained by exposing metallic copper to the vapor of vinegar ; the metal first oxidizes by the action upon it of the oxygen of the air, and the oxide then unites with the acid. There are several definite compounds of copper and acetic acid. Acetate of lead is made by distilling the carbonate of lead, or litharge in distilled vinegar. It has a sweetish taste, and is known as sugar of lead. It is much used in medicine, and in the arts. OXALIC ACID. 755. So named from the Oxalis acetosella, or wood-sorrel, • The numbers denote equivalents. 752. Pyroligneous acid. Acetic acid obtained by the distillation of ace- tates. 753. Properties of acetic acid. Its constituent elements. 754. Acetates. Acetate of copper. Acetate of lead. TARTARIC ACID. 289 where it was first discovered by Scheele combined with potassa, forming the salt called oxalate of potassa. Oxalic acid may be obtained by heating nitric acid in a retort with sugar, starch, alcohol or most vegetable acids. It is much used to remove colors occasioned by the oxides or salts of iron. The strong sour taste of this acid is apparent in the different species of sorrel; the bruised green leaves of these plants, on account of the presence of this acid, are efficacious in removing stains, and iron rust from linen. In combination with lime, oxalic acid exists in the leaves of the garden rhubarb. It acts as a poison on the animal system. Its crystals contain 4 equivalents of water (9x4=36) with one equivalent of acid 36, their equivalent number is therefore 72. " It is singular," says Silliman, " that this powerful acid in firm crystals should be midway between the two gases carbonic acid and carbonic oxide, and it may even be regarded as composed of 1 equivalent of carbonic acid, 22, and one of carbonic oxide, 14=36. It has the composition of a mineral acid, and it has been proposed to call it the carbonous acid which its composition would fully justify." The combination of oxalic acid with salifiable bases forms salts called oxalates, and sold under the name of salts of sorrel and salts of lemon ; the latter name however belongs to the nitrates, which we have yet to notice. The binoxalate of po- tassa, called salt of sorrel is used to remove stains of iron and ink. One equivalent of the acid gives to the iron forming a soluble oxalate of iron, and leaving a soluble oxalate of potassa. The quadroxalate of potassa is obtained by digesting the bin- oxalate with nitric acid, which, uniting with half the base, leaves the other half combined with the whole of the oxalic acid, of which there are now four proportions with one of potassa. If, of 4 parts of this salt, 3 are decomposed, the disengaged potassa can be exactly saturated with the acid which may be obtained by the decomposition of the 1 remaining part. The nature of the oxalates of potassa beautifully illustrates the law of multiple proportions. Their composition is as follows. Equiv. Equiv. Base. Acid. Equiv. oi base, of acid. Oxalate contains 1 -f 1 = 48 + 36 = 84. Binoxalates " 1 + 2 = 48 + 72 = 120. Quadroxalates" 1 + 4 = 48 + 144 = 192. TARTARIC ACID. 756. Was first obtained from cream of tartar, (bitartrate ofpo tassa,) from whence it received its name. It exists in the tama- 755. Name, discovery, &c. of oxalic acid. Method of obtaining it. Uses, &c. Composition of its'crystals. Oxalates. Binoxalate of potassa. Qua- droxalate of potassa. Composition of the oxalates of potassa. 756. Tartaric acid, derivation of its name, plants in which it exists, &c Mode of obtaining it. Properties. Pyrotartaric acid. Double salts. 25 290 MALIO ACID. rind, pine apple and many other acidulous fruits, also in balm, sage, and probably sumach. It is obtained by decomposing the bitartrate of potassa by carbonate ol lime. Carbonic acid goes off with effervescence, and one equivalent of the insoluble tartrate of lime is precipitated, while one equivalent of the neutral tartrate remains in solution. The precipitate is washed and then mixed with water containing some sulphuric acid; the latter by uniting with the base of the tartrate, disengages tartaric acid, which when filtered and eva- porated is obtained in prismatic crystals. Tartaric acid possesses strong acid properties. It is used in fevers as a cooling drink. With soda, it forms an effervescing mixture, the tartrate of soda. This acid is remarkable for its tendency to form double salts among which are the tartrate of antimony and potassa, or the tartar emetic of medicine; and the tartrate of potassa and soda, or Rochelle salt. Pyrotartaric acid is the re- sult of destructive distillation of tartaric acid. 757. Bitartrate of potassa, cream of tartar exists in the juice of the grape, and is found lining the sides and bottom of wine casks. Owing to the insolubility of this salt in alcohol, it is gradually deposited during the vinous fermentation, especially of the red wines. In a crude state, it is called wine stone. This crude tartar is purified by dissolving, filtering, and crystali- zing. White crystals are skimmed off the surface of the solution, these are called cream of tartar. Its peculiar sour taste is well known, and it has other acid properties. It is valuable in me- dicine, and is composed of 2 equiv. of acid and 1 of base. 758. Tartrate of potassa or soluble tartar, was formerly used in medicine, under the name of vegetable salt. 759. Citric acid is named from the genus of plants, Citrus containing the orange and lemon. It may be obtained by pouring lemon juice upon chalk, and decomposing the citrate of lime thus formed, by sulphuric acid. The sulphate of lime be- ing insoluble, is separated from the liquid citric acid by filtering. Large transparent crystals are obtained by evaporating the liquid. It is used as a substitute for lemon juice, and for effervescing draughts with the carbonates of soda; the effervescence is caused by the escape of carbonic acid gas, and the liquid is then a solution of citrate of soda. Spots caused by iron and ink are removed by citric acid. Its crystals are remar- kable for not being affected by the air. When heated, they suffer the watery fusion, the acid decomposes and a peculiar compound called hydro- citric acid sublimes. Scheele first ascertained that the sourness of the lemon and lime were owing to the presence of the peculiar acid, now called the citric. This is often combined with malic acid in red fruits. The only citrate known to exist in nature is that of lime, which is found in very small quantities in fruits containing citric acid. 760. Malic acid is contained in the apple, Pyrus malus. It 757. Bitartrate of potassa. 758. Tartrate of potassa. 759. Citric acid, how obtained. Uses. Crystals, &c. Citrate of lime. 760. Malic acid. Malates. Cause of the specific flavor of fruits. GALLIC ACID. 291 exists in the juices of the cherry, strawberry <&c It may also be obtained by digesting sugar with three times its weight of nitric acid. Its salts are called malates. When sheet lead is steeped in apple juice, malate of lead is formed. The malates are usually distinguished from the citrates in being more soluble. Malic, citric and tartaric acids, together with sugar, mucilage and some other principles, give their flavor to fruits, and according as one or the other acids, or sugar prevails, is their specific flavor. In the lemon, citric acid is greatly in excess ; in the orange, it is generally neutralized by sugar. In sour apples, malic acid is in excess ; in the whortleberry and strawberry malic and citric acids exist in nearly equal quantities, with a large proportion of sugar. In the grape the tartaric acid is in excess. As fruits ripen, they usually contain a larger propor- tion of sugar. 761. Benzoic acid is obtained from benzoin, the gum of the Styrax benzoe, a plant of the East Indies. It is also found in castor, cinnamon, in some volatile oils, in the flowers of the Trifolium melilotus, and other vegetables as well as some animal substances. Its taste is rather sweetish, but it is deci- dedly acid in its effect on vegetable colors, and with alkalies. Its crystals are white with a silky lustre. It gives to the paregoric elixir its taste and peculiar aromatic odor. It burns with a yellow flame. Its salts are called benzoates. 762. Gallic acid was first discovered by Scheele, in 1786, in gall-nuts, or the excrescences found upon the leaves of a species of oak, supposed to be occasioned by the puncture of an insect whose egg is often found in the center of the nut. The nuts are about the size of a pigeon's egg, of a brown color and un- even surface. They are known in commerce as nut-galls, and are used in domestic coloring to produce slate color and black. Gallic acid, at first supposed to be peculiar to the gall nut, is now known to be associated with tannin in the barks of most trees, and in astringent vegetables. It is an important test with the metals. It precipitates iron deep black, and with tannin forms the basis of ink and black dyes. Ink is a mixture of the gallate and tannate of iron, and is soluble in the acid which is always present in this fluid; thus, when ink becomes thick, we dissolve it by adding weak 761. Plants which contain benzoic acid. Properties. Salts. Benzoates. 762. Discovery of Gallic acid. Gall nuts. Substances containing gallic acid. Scheele's method of obtaining this acid. Crystals and properties of gallic acid. Ink. Cause of the stains made by tea on knives, &c. Dis- tinction between gallic acid and tannin. Gallates. 292 CARBAZOTIC ACID. vinegar. The black stains caused by tea, on knives and other iron or steel utensils, are owing to the action of gallic acid and tannin, upon iron. Gallic acid is distinguished from tannin by giving no precipitate in a solution of gelatine. The salts of this acid are called gallates. The pergallate of iron is blue, the gallates of potassa and soda are colorless. 763. Ellagic (ellagique) acid was so named by the French Chemist Bea- connot, by an invasion of the word galle (gall.) Thenard supposes that it forms salts with the alkalies, which he terms ellagates; he considers that there is a nentral ellagate of potassa, which is soluble and greens vegetable blues; and an acid ellagate which is white and insoluble. He suggests that the ellagic acid does not exist in the gall-nut, but is formed during the pre- paration of gallic acid when tannin decomposes by contact with the air. 764. We have now described the most important of the vegetable acids, many of which are indispensable in manufactures and the arts. There are others which are less known; as, Mucic or saccholactic acid (so called from mucus, gum) which was obtained by Scheele, by the action of nitric acid on gum, sugar or milk,* &c. The precipitate is in the form of a white, gritty powder, with feeble acid properties. When decomposed by heat, it yields, besides the usual vegetable products, a white sublimate called pyromucic acid. The saccholactaies have been little studied. This acid belongs both to animal and vegetable compounds. 765. Pectic acid derives its name from the Greek pedis, coagulum, being remarkable for its tendency to coagulate or to exist in a gelatinous form. It was first obtained by Beaconnot from the pulp of carrots, boiled with po- tassa ; the alkali unites with the pectic acid and forms a gelatinous mass which is the pectate of potassa. On adding an acid, the pectate decomposes, giving up its base to the new acid, and disengaging pectic acid in the form of jelly, which is insoluble in cold water. 766. Indigotic and carbazotic acids are obtained by the action of nitric acid on indigo. When indigo is boiled in diluted nitric acid, carbonic, prussic and nitrous acids are evolved, and in the liquid, besides carbazotic acid, resinous matter, p, and may be collected for the perfumer. Palm oil is used in warm countries for food, and exported for medicinal purposes, and to form the finer kinds of soap. Cocoa butter is not liquid at the common temperature, it has the flavor of chocolate. Castor oil from the Ricinus communis is very valuable in medicine. It does not congeal, but at a temperature much below zero. 782. The volatile oils are the aromatic principles of plants which sometimes are confined to the flower, leaves, bark, or root, and sometimes diffused through the whole: but seldom contained in the cotyledons of seeds which furnish most of the essential oils. These oils may be obtained by distilling the plant with water. The operation of distilling plants is as simple as that of making fruit preserves, and might furnish an agreeable and feminine employment. Every lady may manufacture rose-water of a much better quality than that which is generally sold. A small distilling apparatus may be placed over a por- table furnace, with a quantity of water and rose petals in the boiler ; the aromatic principle of the rose passes over with the distilled water into the recipient. This product should be returned to the boiler and a new portion of the rose petals added, and a stronger product is next obtained. The oper- ation must be repeated, several times, before the water will become strongly impregnated with aromatic properties. The essential oil of the rose will ap- pear when the water is cool, in very minute quantities on the surface. But the proportion of oil in this flower is so small that great quantities of its petals are requisite for obtaining a very little oil. As the rose petals drop off, they may be collected and dried, or preserved by putting them into a jarge vessel and sprinkling them with salt. The salt will not come over with the product of distillation, nor disengage its elements. Other aroma- tic plants may be distilled in a similar manner. In India the oil, or attar of roses, is obtained by filling large casks with rose petals, covering them with water, and placing them in the sun, after a few days, particles of oil appear floating on the surface. These are collected and put into the small bottles, which are sold in the shops. In some cases, as in the rose, jessamine and lily of the valley, the water which passes into the recipient in distillation will be strongly impregnated with the aroma of the plant, while no oil may appear on its surface when cold. Thus, rose-water, though not visibly con- taining any oil„owes its aromatic property to a very small portion of essen- tail oil, dissolved by the water, in the distilling process. 783. Essential oils much diluted with alcohol, are called essences ; twenty or thirty drops of essence do not usually con- tain more than two or three drops of the essential oil; in me- dicine, therefore, it is important to distinguish between the two, as over-doses of the volatile or essential oils will produce con- vulsions, and even death. The strong odor of flowers in a con- lined room is unhealthy, on account of exhalation of volatile oils. Properties. These oils are generally more energetic than the fixed oils; they are odoriferous, with a hot aromatic taste. 782. Situation of the volatile oils in plants. How obtained ? Manufac- ture of rose-water. Attar of roses. 783. Essences. Properties of volatile oils. Principal volatile oils, &c. RESINS. 299 They are colorless, yellow, green or blue, very volatile and in- flammable ; they readily absorb oxygen from the air, and be- come thick. They do not easily combine with salifiable bases. With nitric acid they often inflame and burn brilliantly. The most important of the volatile oils are those of turpentine, cloves, nutmeg, lavender, cinnamon, peppermint, annise, and chamomile. 784. The oil of turpentine is procured by distilling turpentine. When pu- rified it is called spirits of turpentine. Camphor may properly be ranked with the essential oils, as it is odorous, inflammable and volatile. The camphor of commerce is chiefly extracted from the Laurus camphora, which grows in Japan and the East Indies. The camphor is obtained in the form of green, porous masses. Crude camphor is purified by sublimation. Its odor is strong, but agreeable and refreshing, and its taste acid and pungent. Il is soluble in alcohol and ether. It burns brilliantly in oxygen gas, producing camphoric and carbonic acids. It is lighter than water, its specific gravity being 0.980. It is insoluble in water. When a few drops of a solution of camphor in spirits is put into a tumbler of water, the water and spirits unite and camphor is precipitated. Proust obtained a crystaline product from thyme, and some other labiate flowers, which he supposes differs little from camphor. Camphoric acid which results from the action of nitric acid on camphor, unites with salifiable bases forming salts called camphorates. Cou- marin is a peculiar, odoriferous, volatile principle derived from the Couma- rouna odorata or Tonka bean. RESINS, 785. Are the thick juices of certain plants, and are often found combined with essential oils, which give them their peculiar taste and odor, and render them soft. The resins are non-con- ducters of electricity, but become negatively electrified, on being rubbed. Exposed to the action of fire, they burn with a yellow flame and much smoke. They are insoluble in water, but solu- ble in alcohol, oils, and solutions of potassa and soda. With the two latter they form a kind of soap. They are not decom- posed by air. Nitric acid rapidly decomposes them, much gas is disengaged, and a compound results which resembles tannin. 786. The resin of pine has been analyzed by Gay Lussac and Thenard, 100 parts of which were found to contain Carbon, 75.944; Hydrogen, 10. 719; Oxygen, 13.337. The juice of the different kinds of pine, called turpentine, consists chiefly of resin combined with the volatile oil of turpentine. The resinous products of the different species of cone-bearing trees are distinguished by various names. Common turpentine is obtained by making incisions in the pine trees, and hardening the juice which flows out by exposure to the air and sun. Burgundy pitch is from the Norway spruce and larch. Tar is melted out from the resinous trees by a smothered fire resembling a coalpit. Lac is a 784. Oil of turpentine. Camphor. Coumarin. 785. Cause of the peculiar taste of the resins. Properties of resins. Com- position. 786. Resinous products of the pine. Lac. Copal. Amber. 300 WAX. red concretion caused by the puncture of an insect upon the branches oi the banyan, fig, and Rhamnus jugaba of the East Indies. It consists mostly of resin with coloring matter and wax. Shell lac contains more resin and less coloring matter than Stick lac. Shell-lac, in India, is cast into beads, and other ornaments ; it is used for red sealing wax. Stick-lac is used in dyeing. Copal is a brilliant, transparent resin which is chiefly used for varnishing. It is brought from South America and the East Indies. It is susceptible of becoming highly electrified by friction. Amber resembles copal in appearance ; it is supposed to be of vegetable origin, though found in sand. It is sometimes found in beds of bituminous coal, and enveloping vegetable substances. It often contains insects in good preservation. It was in this substance that electrical phenomena were first observed ; its an- cient Greek name was electron. It consists of a volatile oil, succinic acid, resin, and a bituminous principle. 787. Balsams are resins containing so much essential oil as to render them fluid, or nearly so. They are not proximate principles, but rather consist of several of these principles united ; as resin, benzoic acid, essential oil. They are divided into liquid, of which the balsam of copaiba and styrax are examples, and solid, as benzoin and dragon's blood; the latter is used in making red varnish. 788. Gum resins contain gum, resin, wax, volatile oil, and ex- tractive matter. They are not therefore distinct proximate principles. The gum-resins are valuable in medicine. Among the most important are myrrh, aloes, assafoetida, gamboge andguiacum. 789. Caoutchouc, Indian rubber, or gum elastic is the concrete juice of the Urceola elastica, and Jatropha elastica, plants of South America. It is said to have been prepared from the dried juice of the milk weed, (asclepias.) It is white, when not blackened by smoke as is common in its preparation; it is soft, flexible, very tenacious and elastic. It melts readily and burns with a bright flame, leaving little residuum. It is insoluble in water, alco- hol, alkalies and acids. The volatile oils are its proper solvents. The pu- rified Naphtha from coal tar dissolves it, and being a cheap article may be profitably employed in Indian rubber manufactories. It must contain some nitrogen since by destructive distillation it yields ammonia. Creosote exists in tar and pyroligneous acid ; it is an oily fluid, with an odor of smoke. 790. Wax is extensively diffused in nature. It is found as a varnish on the surface of the leaves of plants, in the pollen of flowers, and in many trees. The wax of bees appears not to be wholly of vegetable origin, being composed also of some animal secretion. Huher found that bees which were fed solely on sugar, produced wax in as great quantities, as those which had access to flowers. The berries of the Myrica cerifera or bayberry contain large portions of wax; it is aromatic, of a pale green color, and is sometimes mixed with tallow to render candles more firm ; it has been call- ed bayberry tallow. Wax is usually more or less colored, and may be bleach- ed by exposure to the sun and air, and by the action of chlorine. Thus 787. Balsams. 788. Gum resins. 789. Caoutchouc or Indian rubber. 790. Wax. Wax of the myrica cerifera, &c. Properties of wax. Con, etituent principles of wax, composition, ALCOHOL. 301 bees wax which is yellow and has an aromatic smell, becomes, by bleaching very white and destitute of odor. Wax melts at 154° F., it is insoluble in water, dissolves in warm ether and alcohol, but precipitates when cold. It is easily dissolved by the fixed and volatile oils. It has been found to consist of two principles, one of which called cerin is soluble, the other called myricin is insoluble in alcohol. The composition of bees' wax ac- cording to Gay Lussac and Thenard, is in 100 parts ; Car. 81.784. Nit. 12.672. Ox. 5.544. According to Liebig, Car. 20, Hyd. 20, O. CHAPTER XXXIII. ALCOHOL, ETHER, &C ALCOHOL, 791. Is a colorless, volatile liquid, of a strong odor and a burning taste. It is the intoxicating ingredient in all kinds of spirits, wine, cider and beer. It does not exist ready formed in plants, but is the product of vinous fermentation. Fermented liquids have been known from the remotest periods of history-; distilled liquors were first prepared by an Arabian alchemist in the 10th century, though they were little known, until several hundred years after. 792. On account of its volatile nature, alcohol is readily obtained by dis- tilling fermented liquors. Pure alcohol is called rectified spirit, and when supposed to be entirely free from water, absolute alcohol. The purity of al- cohol is in an inverse proportion to its density. Common alcohol has a specific gravity of about 86, but when freed from water of 82. Thus the specific gravity of spirits is a test of their purity, which is determined by the hydrometer.* Alcohol boils at a temperature as low as 176° F. It pro- duces cold during evaporation. No degree of cold has yet been known, with certainty, to freeze alcohol. When half water it freezes at 60° below zero. On account of the property of alcohol to remain liquid at the extreme degree of cold where mercury freezes, it is used in thermometers designed to measure intense cold. 793. As alcohol burns without smoke or residuum, the spirit lamp is much used in laboratories. Attempts have been made to introduce alcohol into common use, in the place of oil, for lamps, but its use has been found dan- gerous, owing to its great inflammability; if accidently spilled when burn- ing, its whole surface wilPburst forth into instant flame. The products of • See the author's Familiar Lectures on Natural Philosophy, page 165. 791. Physical properties of alcohol, &c. Distilled liquors first known. 792. Mode of obtaining alcohol. Rectified spirit and absolute alcohol. Specific gravity. Its boiling point. Effect of its evaporation on surround- ing bodies. Freezing point of alcohol. How useful in thermometers ? 793. Spirit lamp. Products of the combustion of alcohol. Its use in light-houses, &c. 26 302 ALCOHOL. its combustion are water and carbonic acid. The flame of alcohol directed upon lime or chalk produces a most vivid light, and is therefore much used in light-houses. It may be inflamed by the electric spark. 794. Alcohol dissolves most of the vegetable principles, as the essential oils, resins, balsams, and most of the vegetable alkalies and acids, but not many of the animal oils. It dissolves potassa, soda, and ammonia, but not the earths or metallic oxides. Phosphorus, sulphur, and iodine are spar- ingly soluble in Alcohol. Chlorine produces with it an oily substance, ac- companied with hydrochloric and carbonic acids. This oily matter seems to be a combination of chlorine and percarburetted hydrogen. When equal parts of alcohol and water are mixed, there is an elevation of temperature, and consequent expansion of the liquids; this mixture constitutes proof spirit. 795. When alcohol is heated in a porcelain tube, the products of the de- composition are carburetted hydrogen, carbonic oxide and water. Accord- ing to the analysis of the younger De Saussure, the ultimate elements of al- cohol are Carbon 2 Equiv.=12 parts in 100 52.17 Oxygen 1 " = 8 " " 34.79 Hydrogen 3 « = 3 " " 13.04 Equiv. of alcohol 23 100.00 These elements are in the proportion to form olefiant gas and water; there are 2 equivalents of carbon, 1 of oxygen and 3 of hydrogen. Olefiant gas requires 2 eq uivalents of carbon+2 of hydrogen. Water requires 1 equivalent of oxygen-)-l of hydrogen. According to Liebig's formula the constituents of alcohol are Car. 4, Hyd. 5, Ox.+ Hyd. Ox.=46. 796. It was formerly asserted that alcohol did not exist ready formed in wine, but was generated by heat, during the distilling process. Mr. Brande determined this question by obtaining alcohol from wine without the aid of heat. He precipitated the acid, and extracted coloring matter by the sub-acetate of lead, and then absorbed the water from the alcohol by dry carbonate of potassa. Pure alcohol rose on the surface. The strong wines, Maderia, Sherry, Port, &c. contain from 18 to 25 per cent of alcohol, and cider, ale and porter from 4 to 10 per cent. 797. The action of the acids on alcohol produces ether. Al- cohol also, like water, forms with certain bodies, definite crystal- ine compounds, called alcoates* When the anhydrous chlorides of calcium, manganese and zinc, or the nitrates of lime and magnesia are heated with anhydrous alcohol, the com- pound on cooling will assume a crystaline form. A very small quantity of water would prevent the crystalization. The crystals are deliquescent, soluble both in water, and alcohol, and readily £ise in their water of crys- talization. * As crystals containing water are called hydrates. 794. Solvent powers of alcohol. Use of Spirit. 795. Products of the decomposition of alcohol. The elements composing alcohol are in the proportion to form olefiant gas and water. 796. The question settled with respect to the existence of alcohol ready formed in wine. 797. Action of acids with alcohol. Alcoates. How formed ? ETHER. 303 798. Alcohol, on account of its great solvent power, and other peculiar properties, is an agent of great importance in medicine and the arts; but however indispensible, when taken in any considerable quantities into the animal system it has a poison- ous and fatal tendency ; and this, under whatever disguises it may be presented. ETHER, 799. Is an inflammable,volatile liquid, formed by the action of alcohol with various acids. The ethers are composed of three classes, the 1st containing those which are composed of oxygen, carbon and hydrogen ; 2d those whose acids contain hydrogen instead of oxygen, and 3d when the oxacid is united with alcohol. 800. Sulphuric ether was long the only ether known. It is much used in medicine and the laboratory. It is formed by heating strong sulphuric acid with an equal weight of rectified alcohol in a glass retort; ether rises in a recipient surrounded by ice-cold water. The operation is continued until white vapors appear in the retort; after this, sulphurous acid gas, with a peculiar yellowish liquid, called ethereal oil, and the sweet oil of wine (sulphovinic acid,) begin to pass over ; longer continuance of the heat produces olefiant gas. The ether thus obtained is impure ; it is rectified by adding potassa, which absorbs the sul- phurous acid and the ethereal oil. 801. Theory. It was long believed that sulphuric acid transformed alco- hol into ether, by taking from it a certain quantity of water; and the com- position of ether seemed to favor the theory. At present, the decomposition of sulphuric acid during the process for obtaining ether is admitted, and also that alcohol consists of 1 part of olefiant gas and 1 of water ; and ether of 2 of olefiant gas and 1 of water. 802. Physical Properties. Sulphuric ether is without color, has a strong and fragrant odor, and a hot and sharp taste. Ac- cording to Gay Lussac it does not transmit the electric fluid. It reflects light strongly, is perfectly limpid and fluid. Its specific gravity when purest is about 0.70 ; It is very volatile, boiling at 96° F. under atmospheric pressure; and at 20° below zero in a vacuum absorbs caloric so rapidly from surrounding bodies as to freeze water, and even mercury. It freezes at—46°. Its vapor has a density of about 2.58, air being 100. It flows through a capillary tube nearly four times as fast as water, and eight times as fast as alcohol, but does not rise so high by capillary attraction as either of the other two fluids. It is 798. Use of alcohol, and its efl'ects on the animal system. 799. Ether. 800. Sulphuric ether. Preparation. 801. Theory. 802. Physical properties. 304 ETHER. highly inflammable, burning with a blue flame ; its vapor forrns a mixture with the oxygen gas, which explodes by an electric spark or on the approach of flame. 803. " When a coil of platinum wire is heated to redness, and then sus- pended above the surface of ether contained in an open vessel, the wire in- stantly begins to glow and continues in this state until all the ether is con- sumed. During this slow combustion, pungent acid fumes are emitted, which, if received in a separate vessel, condense into a colorless liquid pos- sessed of acid properties. Mr. Daniell, who prepared a large quantity of it, was at first inclined to regard it as a sour acid which, in reference to the mode of obtaining it, he called lampic acid; but he has since ascertained that the acidity is owing to the acetic acid, which is combined with some compound of carbon and hydrogen different both from ether and alcohol. Alcohol when similarly burned likewise yields acetic acid."—Davy. 804. Chemical properties. Ether is somewhat less powerful as a solvent than alcohol, though most of the substances which dissolve in the latter, are dissolved in the former. It has no action upon the fixed alkalies, but unites with ammonia. It dissolves Indian rubber with great facility. When exposed to the light it gradually absorbs oxygen, and becomes sour, which is supposed to be occasioned by the formation of acetic acid. Ether is very inflammable, burning with a blue flame ; a lump of sugar filled with ether thrown into a vessel of boiling water, forms a burning fountain, by lighting it with a taper. Chlorine with ether produces spontaneous combustion and explosion. 805. Hydrochloric ether is obtained by distilling a mixture of equal parts of hydrochloric acid and alcohol in a glass retort connected with Woulfe's apparatus. The first flask contains water, the others are empty and sur- rounded with ice. This ether is composed of equal volumes of hydrochloric acid and olefiant gas, united without condensation, as its specific gravity is equal to the sum of the specific gravity of the two gases ; viz. hydrochloric acid having the specific gravity of 1.278X to alcohol having the specific gravity of 972=2.250, which is very near the specific gravity of hydrochlo- ric ether, when compared with atmospheric air. It is even more volatile than sulphuric ether : boils by the heat of the hand, producing by its eva- poration a sensation of coldness. It burns with a green flame, disengaging hydrochloric acid gas. From its composition it is apparent that it contains no oxygen gas. 806. Hydriodic ether is obtained by distilling hydriodic acid and alcohol. When poured on hot charcoal it gives off the purple vapors peculiar to iodine. 807. Nitric ether is made by distilling equal weights of alcohol and nitric acid : but the mutual action of the two substances is so violent as to render the process dangerous. The alcohol must be added in small quantities. 803. Substance named by M. Daniell lampic acid. 804. Chemical properties. 805. Hydrochloric ether. 806. Hydriodic ether. 807. Nitric ether. Properties. Sweet spirit of nitre. Ultimate elements. Acetic ether, &c. SUGAR. 305 Pig. 124. A, (Fig. 124,) represents a Woulfe's bottle; B, a receiver; c, c, glass funnels ground to their necks, and glass rods ground to the funnels; the acid being in one funnel and the alcohol in the other. Nitrous ether is of a yellowish color, has a strong odor, and burning taste. It is more vola- tile than sulphuric ether. With alcohol k forms the sweet spirit of nitre, which is valuable in medicine. Its ultimate elements are Car. 4, Hyd. 5, Ox-j-Nit. Ox. 3. Acetic ether is formed in a manner analogous to the ether already describ- ed. It inflames on the approach of a burning substance, reproducing acetic acid. It has an agreeable odor, dissolves in alcohol, and forms a stimula- ting medicine. Oconanthic ether gives to wines their peculiar odor; it is obtained by the decomposition of wine and produces intoxication when inspired. Pyroxylic spirit is a kind of ether formed by heating wood. There are other ethers formed with alcohol and the vegetable acids ; or the benzoic, citric, oxalic, &c. CHAPTER XXXIV. SUGAR, STARCH, GUM, &C SUGAR. 808. Under the head of sugar are included those substances which have a sweet taste, and when brought in contact with water, and a very small proportion of yeast, produce alcohol, by means of the vinous fermentation. This proximate principle is extensively diffused throughout the vegetable kingdom. Plants which contain it are called saccharine. Sugar is crystalizable either more or less perfectly, sweet, inodorous and very soluble in water, alcohol and other liquids. Pure sugar is hard, firm, and not acted upon by the air. Sugar, by friction, is phosphor- escent in the dark. Sulphuric acid decomposes it and disen- gaging charcoal, forms water, and acetic, or some other vegetable acid. When nitric acid is mixed with sugar, both substances decompose, and oxalic acid is formed. Owing to the quantity of carbon in sugar it is very inflammable, and gives off a peculiar odor in burning.* It forms but feeble * The carbonaceous, acetic and other vapors which exhale from burning sugar, possess medicinal powers ; and the practice of sprinkling sugar in the domestic warming pan, when used for warming the beds of those who are suffering under rheumatic affections or sudden colds, is founded on more substantial reasons than " old wives' whims." 808. General properties of sugar as produced from various substances. 26* 306 SUGAR. combinations with metallic oxides; lime, baryta or strontia boiled with sugar make it bitter, astringent, and uncrystaliza- ble. By adding a sufficient quantity of an acid to neutralize the oxide, the sugar resumes its properties. 809. The results in the decomposition of sugar being found to vary, it was at length discovered that its constituent principles varied in some degree in different vegetables; thus the sugar of the cane affords more carbon than that of the grape. According to Gay Lussac the sugar of the cane is, in weight, composed of Carbon . 42.47 Oxygen 50.63 Hydrogen 6.90 100.00 According to Liebig; Car. 12, Hyd. 11, Ox. 12=179 Sugar of the grape was found to consist of Carbon 36.71 Oxygen 56.51 Hydrogen 6.78 100.00 The specific gravity of sugar is about 1.6. 810. The sugar cane is the arundo saccharifera of botanists. This plant furnishes the greater part of the sugar of commerce. Although sugar was manufactured in India in the days of Alex- ander the Great, who is said to have brought the knowledge of it to Macedon, yet it was scarcely used in Europe, except in medicine, until the discovery of the West Indies, where the most extensive sugar manufactories now exist. Sugar is obtained from the expressed juice of the sugar cane, by slow boiling, during which process the aqueous particles evaporate. Lime water is then added to the liquor when boiling, to neutralize the oxalic, and other vegetable acids, and to separate extractive matters and other impurities, which, uniting with the lime, rise and form a thick scum on the surface ; the liquor below, is drawn off, by means of a syphon, into large shallow vessels, where an imperfect crystalization takes place. 811. From the sap of the sugar-maple tree Acer saccharinum, is manufactured, to a considerable extent, a valuable domestic sugar in many of the northern United States. Incisions are made in the trees at that season of the year when the sap runs most abundantly ; this is in early spring, with the first warm beams of the sun. The sap of the maple is about one sixth as rich as the juice of the cane; four pounds of maple sap yielding one pound of sugar. When suita- bly evaporated, by boiling in large kettles, and permitted to cool, it forms a granular solid mass. This may be purified so as to resemble loaf sugar, in whiteness and fineness ; but is generally used in a less refined state. The maple juice boiled down to a consistence somewhat less than common West 809. Constituent principles of sugar, &c. Gay Lussac's and Liebig's analysis. 810. Sugar cane. Manufacture of sugar. 811. Maple Sugar. Manufacture of Maple Sugar. SUGAR. 307 India molasses is used for similar purposes ; and when evaporated to a thick syrup, resembling liquid honey, it is sometimes used for the table, as a sub- stitute for sweetmeats. 812. The beet root is found to be rich in sugar. In France, are many large manufactories of this article. Count Chaptal, a peer of France, a theoretical, and practical Chemist, and farmer, says, " from twelve years experience I have learned in the first place that the sugar extracted from beets differs from that of the sugar cane neither in color, taste, nor crys- talization ; and in the second place that the manufacture of this kind of sugar can compete, advantageously with that of the sugar cane.* 813. Many other succulent roots, besides the beet, furnish sugar, as the onion, parsnip and carrot. Sugar of grapes, of figs and other ripe fruits contains more or less of the peculiar flavor of the fruit derived from other prin- ciples. It does not crystalize in regular forms, and it is less sweet than the sugar from the cane. Sugar of mushrooms crys- talizes in four-sided prisms ; its taste is not pleasant. Sugar of starch is made by forming a paste with starch and water and allowing it to stand for some time. Sulphuric acid converts starch into sugar. De Saussure found the weight of sugar formed was considerably more than that of the starch employed, from whence he inferred that a portion of the water becomes solidified, that the sugar of starch was consequently only a combination of sugar with hydrogen and oxygen in the neces- sary proportions to form water, and that the sulphuric acid had no other influence than to increase the fluidity of the aqueous solution of starch. 814. Manna (from a Syrian word mono a gift, being the food given by God to the Israelites), exists in the sap of the ash, Fraxinus ornus, in the celery and beet plant. It is sweet and crystalizable like sugar, but it owes its sweetness to a distinct principle called mannite. This princip e differs from sugar in not fomenting with water and yeast, of course it produces no alco- °Honey is composed of two kinds of sugar, the one liquid and uncrystaliza- ble, the other analogous to the sugar of grapes and crystalizable; these, with mucilage, and an aromatic principle, constitute all the varieties of honey. By mixing honey with alcohol, the liquid sugar may be obtained by pressing the solution through a strainer, wh.le the crystalizable principle femains solid. Honey is prepared in the stomach of the bee from the vw- cous juice and sugar which this insect collects from the nectaries of flow- ers arte remaining a time in this laboratory it is deposited in the cavities of the honey comb! Honey varies in quality according to the different * Se* Chaptal's « agricultural Chemistry," for a detailed account of the mode of cultivating the beet root, and conducting the beet sugar manufac- ture. ________________________. 812. Sugar of be^ts. Chaptal's opinions upon the manufacture of beet STl3. Other roots which furnish sugar. Sugar of grapes, figs, &c. Sugar of mushrooms. Sugar of starch. 814. Manna. Honey. Sugar of liquorice. 308 STARCH. plants which furnish the materials. That which is obtained from the flow- ers of the tobacco, stramonium, and others of the same natural family, is poisonous. The honey of Mount Hymettus and Mount Ida in Greece was celebrated in ancient times for its beauty and excellence. The honey fur- nished by labiate plants, as the thyme, balm, &c, is of the best kind. Honey is used as food and medicine. When united with the vinegar it forms oxy- mel. Thus the common preparation of squills is called the oxymel of squills.* Dissolved in water, honey ferments, and forms a liquor called hydromel or metheglen, a pleasant but intoxicating beverage. Sugar of liquorice. The substance called liquorice is from the root of a plant, the Glycirrhiza glabra; its sweet principle seems to be of a peculiar kind. It resembles amber in its appearance and inflammability. 815. Starch, is one of the most abundant proximate principles in nature, existing in the stems, leaves, roots and seeds of plants. When pure it is a white powder, insipid, inodorous, insoluble in cold water, alcohol and ether, but soluble in boiling water. This solution on cooling takes the form of a jelly, in which state it is used by the laundress for starching linen. Hot sulphuric acid transforms starch into sugar, capable of yielding alcohol by fer- mentation. Nitric acid changes it into malic and oxalic acids. Iodine furnishes the best test for starch, forming with it com- pounds of a blue color. The principle deduced from this fact is applied in the arts to discover whether goods owe their fine- ness to the texture of the material or to a finish of starch; in the latter case, a drop of the solution of iodine produces a blue spot. 816. According to Gay Lussac and Thenard, starch is composed of 43.55 parts of Carbon. 49.68 " " Oxygen. 6.77 " " Hydrogen. Starch is usually obtained by grating or bruising the substances which contain it, and washing the product with pure water. Its specific gravity being greater than that of water, the starch is soon deposited in the form of a white mass, which, when dry, is a soft powder. If a piece of dough or wheat flour be enclosed in a linen bag, and pressed with the hand while a current of cold water is poured on, the starch or farina will be washed out mechanically and subside at the bottom of the vessel, while the gluten of the flour is left pure in the bag, and saccharine matter and mucilage are in solu- tion. Heat produces with starch peculiar effects ; thus, when dry starch is heated a little above 112°, it becomes soluble in cold water, and its odor resembles that of baked bread. The action of boiling water on starch, as prepared for starching muslin, produces a similar change of properties. By continued heat, and careful evaporation a transparent mass is obtained, so- * That is, oxymel combined with the juices of a bulbous plant, the SciUa maratima or squills. 815. Abundance of starch in vegetables. Properties. Action of other bodies upon it. 816. Constituent elements of starch. Modes of obtaining starch. Action of heat and of boiling water upon starch. GUM. 309 sable in cold water, and resembling horn, this is called amidine*. Starch tfhen exposed to a greater heat than sufficient to produce amidine is con- certed into a substance called gum, and in this state is used by calico prin- .ers. 817. We have seen that the constitution of starch differs lit- tle from that of sugar, and that the former may be easily con- creted into the latter. This change takes place in the germina- tion of seeds, in the process of malting barley, and in vegeta- Dles that have been frozen under certain circumstances: thus apples,which have been exposed to the air during severe frosts, acquire a peculiar sweetish taste. 818. Of the various kinds of starch, those which are obtained from the flour of different kinds of grain, from the potato, and green Indian corn are used in the laundrey for starching linen and muslin. The Indian arrow- root, (Maranta arundinaeca,) Sago (from the pith of the Cycas circinalis,") Tapioca, and Cassava (from the root of a plant,) have the properties of pure starch. They are all highly nutritious and valuable as food for the sick. GUM AND MUCILAGE. 819. Gum is an aDundant product of vegetables. It is un- crystalizable, colorless, inodorous, insoluble in alcohol, and so- luble in water with which it forms a gelatinous compound called mucilage. It cannot be made to pass through the vinous fermen- tation. Nitric acid changes it to mucic acid. Gum or mucilage is found in all the parts of herbaceous plants, in many roots, and in all fruits. Many trees, particularly those whose fruit is of the drupef kind, secrete large portions of gum. 820. The principal gums are. 1. Common gum, obtained from the peach, plumb, cherry tree, &c. 2. Gum Arabic, which flows naturally from the acacia or mimosa of Egypt, Arabia and other warm countries ; this, with water, forms a clear, transparent mucilage. 3. Gum Senegal resembles Gum Arabic except that it is exported in much larger pieces. 4. Gum tragacanth, from the Astragalus traga- cantha, a shrub of Syria, and of the islands of the Levant. These are all useful in medicine and the arts; and in some countries they are used as food. * So called by the French Chemists from amidon, the French name for starch. t Having a kernel enclosed within a pulpy substance, as the cherry, plum, and peach. 817. Conversion of starch into sugar. 818. Uses of starch. 819. General properties of gum, &c. 820. The principal gums. Uses of these gums. 310 WOOD, LIGNIA, &C 821. Flax-seed, the fruit and seeds of the quince, the bark ot the slippery elm, and the different species of mallows, all afford mucilage when boiled in water. When evaporated to the thick- ness of syrup the gum is precipitated by alcohol. Mucilage may be considered as an aqueous solution of gum, existing naturally in ripe fruits, and the leaves and roots of some plants, and formed by dissolving gum in water. Mucilage soon be- comes sour on exposure to the air, owing to the formation of acetic acid; and in time this change takes place without access of air, which must be owing to the new arrangement of its con- stituent principles. 100 parts of gum arabic have been found to consist of. 42.23 parts of Carbon. 50.84 " " Oxygen. 6.93 " " Hydrogen. 100.00. Vegetable jelly, such as is obtained from the currant, quince grape, &c, is mucilage combined with different vegetable acids. WOOD, LIGNIA, OR WOODY FIBRE. 822. This is the basis or skeleton of vegetable substances, and' the most abundant of all the proximate or vegetable princi- ples forming about 96 per cent of the different kinds of wood. The woody or hard substance of plants contains, in its inter- stices the sap, and other peculiar principles, as the volatile oils, gums, resins, sugar, &c. This substance is found in every part of the plant, the root, the stem, leaf, fruit and even the flower. In the dry state it may be seen in the shells of almonds and many other nuts, even the soft petals of the rose, when deprived of their essential oils, mucilage and other extractive matter, will be found reduced to this hard insoluble substance. Lignia,for chemical purposes, fs usually obtained from saw-dust, because wood thus minutely divided, is in a favorable state to be acted upon by the agents which are required to purify it of all foreign matter. Saw-dust is first digested in alcohol, to dissolve the resinous part, afterwards in water which dissolves some salts and extractive matter, then with weak muriatic acid, which attacks salts that are insoluble in water, particularly the carbo- nate and phosphate of lime. Lignia is white, insipid, inodorous, and speci- fically heavier than water. Sulphuric acid decomposes lignia ; changing it first into a gum-like sub- stance, which, on being boiled, becomes sugar. According to Beaconnot all substances which contain lignia, as saw-dust, straw, bark, and linen, 821. Mucilage. Composition of gum arabic. Vegetable jelly. 822. Abundance of woody fibre, &c. Lignia for chemical purposes, host obtained ? Properties, &c. Products of the decomposition of wood, by heating in close vessels. Bread made from saw-dust, &c. COLORING MATTER, &C. 311 may be converted to sugar. In heating wood in close vessels, acetic (pyro- ligneous) acid and volatile products are obtained. Among these, ispyroxy- lic spirit. It is found that bread may be made from saw-dust, bark, rags, Sic, by converting these substances into lignia. The latter, when heated in an oven, smells like meal or flour of Indian corn. It ferments with leaven, and affords a spongy, nutricious bread. The same flour of wood, when boiled, affords a jelly like that of starch. COMPOUNDS WHICH ARE NOT CONSIDERED AS BELONGING TO THE PRECEDING DIVISIONS OF VEGETABLE PRINCIPLES J AS COLORING MATTER, TANNIN, GLUTEN, &C. 823. Coloring matter. Vegetable coloring matter is found at- tached to some proximate principle, as mucilage, farina, resin or extractive matter ; and its solubility depends on the nature of the principle with which it is associated. Coloring matter cannot, therefore, be considered as itself a proximate principle. Color is a secondary property, dependant on the peculiar ar- rangement of atoms, and of course affected by chemical changes. Thus, we have seen in the course of our experiments, color of bodies changing with new combinations ; a colorless acid trans- forming the blue infusions of flowers to a brilliant red, and a colorless alkali changing the same blue infusion, to a green color. The process of dyeing, depends on chemical principles, but the details of the subject belong to the arts rather than to science. The coloring matter resides in various parts of plants. In some, it is in the flower, in others, in the bark, or the leaves, wood, or root. It is soluble by various agents according to the nature of the proximate principle with which it is associated; thus some colors are obtained by means of alcohol, others by water, others by acids, and others by the essential oils. Most vegetable colors are decomposed by exposing to the sun, and all by the agency of chlorine. 824. Several of the metallic oxides, and especially alumina and the oxides of iron and tin form with coloring matter insoluble compounds, to which the name of lakes is applied. Lakes are commonly obtained by mixing alum or pure muriate of tin with a colored solution, and thus, by means of an alkali, precipjtating the oxide, which unites with the color at the moment of separa- tion. In this property is founded many of the processes in dyeing and calico- printing. The art of the dyer consists in giving a uniform and permanent color to cloth. ^_________ 823. Coloring matter not a proximate principle, &c. Situation of the coloring matter in plants. Means of obtaining these colors. Decomposi- tion of vegetable colors. 824. Compounds with coloring matter, called lakes, &c. betting of colors. The use of a mordant. Substantive and adjective colors. Sub- stances which change the hue of coloring matter, &c. 312 BLUE. The setting of colors depends on a chemical affinity between the dye, and the material with which it unites. To produce this affinity the agency of a third substance is often required, which is called a basis or mordant* This unites the coloring matter to the cloth by means of an affinity for both. The most important bases or mordants used in dyeing, are alumina, and the oxides of tin and iron ; but many others are useful, as alum, copperas, sugar of lead, muriate of tin, blue vitriol, &c. Colors that adhere to the cloth without the intervention of bases are call- ed substantive colors, while those which only form a transient union with cloth, unless fixed by a third substance, are called adjective colors. Besides bases to fix the coloring matter, various chemical agents are em- ployed to alter the shade or hue of colors; thus the hydrochlorate of tin changes the crimson of cochineal to a brilliant scarlet. Alum changes the dull red of madder to a bright crimson. The attraction both of coloring matter and mordants for wool and silk, is much greater than for cotton; thus we find the most brilliant and permanent hues in woolen and silken stuffs. All the hues obtained in dyeing, may be produced by four primary colors, blue, red, yellow, and black. 825. Blue. The only vegetable substance used for dyeing blue is indigo. This is obtained from several species of the In- digofera, and has been found in small quantities, in some other plants. The indigo plant is a product of warm climates. The leaves are fermented with water in large tubs ; the liquor becomes acid, and covered with irised pellicles. It is then drained, and .mixed with lime water. A deposit is formed, which when washed, and dried, is the indigo of commerce. In order to obtain perfectly pure indigo, it should be heated in a closely covered silver crucible. It soon volatilizes and deposits purple crystals. Pure indigo has neither taste nor odor; its color is a rich blue, with a shade of purple. It does not dissolve in water, al- cohol, or ether. Strong sulpuric acid dissolves it, forming a sulphate of indigo, which is employed for giving the color called Saxony blue. Where indigo is deoxygenated it loses its fine color, becomes yellow, and is easily dissolved in slightly alkaline water; if this solution be agitated in contact with the atmos- phere, the indigo acquires oxygen, and becomes blue. The dyer's blue-vat is made by mixing indigo with an equal weight of green sulphate of iron, twice its weight of lime, and boiling the mixture in waterf. The protoxide of iron precipitated by lime, gradually deoxydizes the indigo, and a yellow solution is obtained. Cloth wet in this liquid, and exposed to the air, becomes green, and then blue by the union of the deoxy- dized indigo with the oxygen of the air; and the blue indigo being now chemically united with the fibre of the cloth, a permanent color is obtained. A white substance called indogene has been obtained by depriving indigo of its oxygen ; it rapidly changes to blue on exposure to the oxygen of the air. * From mordeo to bite, corrode or fasten upon. t In the domestic blue dye the ammonia of urine is the solvent of indigo. 825. Indigo, how obtained from the plant? Properties of indigo. Effects of deoxygenating indigo. Blue-vat of the dyer, &c. Effect of air upon cloth wet in a solution of deoxydized indigo. YELLOW. 313 826. Red. Among the red coloring matters are Madder, Cochineal, Archil or Litmus, Logwood, Brazil Wood and Safflower. Madder is the root of the Rubia tinctorum. It is used in dyeing the Turkey-red, and by the aid of proper mordants, may produce not only the various hues of red; but purple and black. This is seen when calico stamped with different mordants is wet in the madder dye. The coloring matter of madder is supposed to have been obtained in a pure state by some of the French chemists in the form of brilliant red, needle-shaped crystals. Cochineal, though found on the leaves and branches of the cactus plant, is an animal substance, deposited by an insect which feeds upon it It is a fugitive dye when mixed with water only ; but becomes fixed by alumina, or the oxide of tin. Its natural crimson color is changed to scarlet by the permuriate of tin, or the bitartrate of potassa, (cream of tartar.) Carmine is made of cochineal and alumina. Litmus, archil, or turnsol is prepared from the Lichen roccella, a plant which grows in the Canary, and Cape de Verd islands. The color of the linchen is red; but in preparing litmus by means of fermentation with an alkaline substance, it receives a blue tint. This preparation is affected by the weakest acids, and is, therefore much used as a chemical test. Paper tinted with litmus is called litmus paper, and furnishes a convenient mode of using this as a chemical test. Litmus paper, when reddened with an acid,becomes blue in an alkaline solution. Logwood is a heavy compact wood from the Haematoxylum* campechianum, a plant which grows in South America. Its coloring matter has been ob- tained in crystals called hematine. Logwood affords a red, fugitive color, but is chiefly used for black dyes, which are fixed or set with iron ; copperas (sulphate of iron) is chiefly used for this purpose. Brazil Wood is from the Caesalpina echinata a large tree of Brazil. Safflower is the dried flower of the Carthamus tinctorius, an unusual plant of the countries bordering on the Mediterranean. This is the exotic com- pound flower of our gardens, known by the name, Saffron, although the crocus is the true Saffron. The flowers of the Carthamus or false saffron are yellow; but according to Thenard, repeated washing dissolves the yel- low coloring matter, leaving the red which was combined with it. This article gives.a variety of shades of red, from that of the damask rose to the cherry. They are fugitive colors though very brilliant. Rouge is prepared from this substance. 827. Yellow. Of yellow dyes the principal are the American walnut, tumeric, fustic, saffron, sumach, and quercitron. These like the red dyes are all adjective colors. The bark of the walnut, and the butternut afford a yellow dye, which, with iron becomes brown. Turmeric is the root of an East Indian plant, the Cucurma longa. Paper stained with an infusion of this dye is called turmeric or cucurma paper; it is stained brown by an alkali, for which reason it is used as a chemical test. Fustic is obtained from the West In- dies ; it is the wood of the Morus tinctoria. Saffron is from the Crocus sati- vus. With water and alcohol it forms'a bright yellow, which sulphuric * This name is from the Greek haima, blood, in reference to the red color of the wood. 826. Red Colors. Madder. Cochineal. Carmine. Litmus. Logwood. Brazil Wood. Safflower. Rouge. 827. Yellow dyes. 27 314 TANNIN. acid changes blue, then lilac, and nitric acid gives it a green shade. Su- mach. The bark of the different species of the Rhus, furnishes a yellow dye. This was formerly exported in large quantities from America to England. Quercitron is the bark of the common black oak of this country. A decoc- tion of this bark, gives a bright yellow dye with a basis of alumina ; with oxide of tin all the shades of yellow from pale brown to deep orange. With indigo it forms a green color, and with oxide of iron a drab color. Annotta, improperly called otter, is obtained from the seeds of a plant of Cayenne, the Bixa orellana ; it is sometimes used to heighten the color of cheese, and is much used in domestic dyeing. Carthamus tinctorius so common in our gardens furnishes a fine though fading straw color. It is probable* that the foreign species of carthamus from which saffron is obtained, differs from the saffron of our gardens. 828. Black dyes, as writing ink, &c. consist of the salts of iron with gallic acid and tannin; astringent barks, such as maple, oak, &c. afford these two substances; secretions of such barks with copperas (sulphate of iron,) will therefore color black. Gall-nuts are often used instead of bark to furnish gallic acid and tannin. There are various mineral dyes as orpiment, the chromates, and Prussian blue; the latter is partly mineral, and partly, an animal compound. There are various modes of applying the colors in dyeing cloth of different kinds. In general, the cloth is passed through a decoction of the coloring matter, and then of the mordant; the latter seems to perform the same office in preserving a union between the coloring matter and the texture of the cloth, as the alkali which affects a combination between oil and water. In calico printing " The mordant thickened with gum or flour, is applied to the cloth by means of blocks or engraved copper cylinders. The cloth is then passed through a decoction of the color which adheres only to the spots impregna- ted with the mordant, and is easily discharged, by washing. To preserve certain parts white, they are occasionally covered with wax, tallow or pipe clay, and sometimes the color is discharged from particular parts by chlo- rine."—Sitf. TANNIN. 829. To the proximate principle called tannin, vegetables owe their astringent properties. This principle exists in large pro- portions in the bark of certain trees, in the gall-nut, and in the leaves of the tea-plant. The most remarkable property of tannin is that of forming with many animal substances, particularly gelatine, a tough insoluble and imputrescent compound. Thus the skins of animals, which are mostly composed of gelatine, by being soaked in the tan-vat, (a decoction of astringent bark,) are con- verted into leather, which is not only necessary to the comfort, and health of man, but in various ways contributes to his con 828. Mineral dyes. "Various modes of applying colors, &c. 829. Cause of the astringent properties of plants, &c. Action of tannin with gelatine. Leather. Action of tannin on the salts of iron. GLUTEN. 315 venience, and is of extensive use in the arts of civilized life. Another important property of tannin is its action on the salts of iron, which it preciptates, producing in combination with gallic acid, ink and black dyes. 830. Pure tannin is obtained with difficulty owing to its tendency to form combinations with the principles with which it is associated. It may be precipitated from an infusion of nut-galls by various re-agents ; as sulphuric and muriatic acids, carbonate of potassa, and muriate of tin. The precipi- tate of tannin is combined with other matters, which are separated by va- rious complicated methods. Some gallic acid and extractive matter will often be found after the most careful preparation. Proust recommends pre- paring tannin by precipitating it from an infusion of nut-galls, by muriate of tin, washing the precipitate, and passing over it a current of sulphuric hydrogen, filtering and evaporating the liquor. Tannin tolerably pure may be obtained by precipitating it from an infusion of nut-galls, with lime-water. Pure tannin is without color, very soluble in water, but insoluble in per- fectly pure alcohol. The acids, except the acetic, precipitates it from its solution in water. Tannin is most abundant in the inner layers of the bark of hemlock, oak, chestnut and birch. 831. Artificial tannin, a substance resembling tannin may be produced by the action of difuted nitric acid on oil, or indigo ; or by the diluted sulphu- ric acid with the resins, or charcoal. A solution is thus obtained which, when evaporated to dryness, produces a brown, fusible substance, soluble in water, and insoluble in alcohol, and which exhibits, with a salt of iron, and a solution of gelatine the same changes as natural tannin. Lagrange asserts that tannin changes into gallic acid by the absorption of oxygen. GLUTEN, YEAST, VEGETABLE ALBUMEN. 32. Gluten is obtained in the process for the separating the fecula or starch from wheat flower by washing ; the albumen and sugar lodged in the interstices of the gluten are dissolved and carried off with the fecula; the gluten is pure when it no longer disturbs the transparency of water by washing. It is of a grayish white color, soft, viscous, very tenacious, and elastic. When dried it becomes brown, and has a glossy brittleness. Exposed to the moist air it swells, putrifies and diffuses an odor, like that of cheese. It does not dissolve in cold water or alcohol ; warm water destroys its tenacity and elasticity, but without dissolving it. It is soluble in most of the vegetable, and some of the mineral acids. Charcoal, sulphuric and nitric acids act upon it, as upon most animal substances. 833. Taddei, an Italian Chemist does not regard gluten as a proximate principle, but as formed of two such principles, which he calls gliadine,m * From the Greek glia, gluten. 830. Extraction of pure tannin. Properties of pure tannin. 831. Artificial tannin. 832. Manner of obtaining gluten. Its properties, &c. 833. Gliadine and zimome. Test for zimome and albumen in flour. 316 YEAST. and zimome.* Berzelius, however, supposes the gliadine to be modified gluten, and the zimome to be albumen. The Italian Chemist, in his re- searches, discovered that the powder of gum guaicum afforded a delicate test for the zimome ; as, when rubbed in a mortar with this substance in a moist state, it strikes a fine blue color. This test is found equally good to shew when flour contains the due proportion of albumen or gluten ; it is kneaded into the flour, which, if good, assumes a blue color. But if the flower be bad, owing to the spontaneous decomposition of gluten, the blue tint is scarcely visible. 834. Gluten appears to promote fermentation. The action of yeast has been ascribed to i£s presence. It is favorable to animal nutrition. Thus bread is emphatically called the "staff of life." The different kinds of grain contain a large proportion of gluten, but wheat more than any other. The gluten in wheat flour, on account of its elastic, and viscous nature,is favorable to the formation of light bread. The carbonic acid gas which is disengaged during the fermation, being detained by the gluten, expands it, and causes the pores which appear in light, wheaten bread. Rye bread can never be made so light as wheat, because rye contains little gluten ; and Indian meal without intermixture with some other substance can scarcely be raisedat all by yeast. 835. Potatoes contain no gluten, but much farina, and may be mixed with wheat flower in making bread; but, if added in too large proportion, the bread will be heavy, because, for want of sufficient gluten to retain the gas of fermentation, the latter passes off in the atmosphere ; and if, as supposed, gluten assists fermentation, there will be the less gas disengaged. This sub- stance was discovered by Beccaria an Italian chemist, who, from its analogy to glue, both in its viscid properties, and its tendency to putrefy, like animal substances,called it gluten. 836. Yeast is a viscous, frothy substance which rises to the surface of fermenting liquors.f When liquor is fermenting, the yeast rises to the surface, with the gas it generates; but, afterwards, becomes specifically heavier than the liquor, and sinks. The yeast of breweries, and distilleries is best for raising bread. But when this cannot be obtained yeast may be prepared by adding a small quan- tity of ferment to a decoction of hops, made of proper consistency with rye or wheat flour. Boiling wate«^ or heat, equivalent to it, destroys the fer- * From zume, a ferment or yeast. t Vulgarly called emptins, as when beer is drawn off, it is found at the bottom, or in the emptyings of the cask. 834. Gluten favorable to fermentation, &c. Rye flour and Indian meal contain little gluten. 835. Effect of mixing potatoes with wheat flour in making bread. Dis- covery of gluten and derivation of the name. 836. Yeast, &c. Domestic yeast. Dried yeast. Effect of heat on yeast. PIPERIN. 317 menting power of yeast. The cause of its action in producing fermentation has not been discovered. By distillation yeast affords carbon, hydrogen, and some nitrogen ; it resembles gluten in its composition. 837. Vegetable Albumen, a substance resembling animal albu- men, and especially in its property of coagulating with heat, has been discovered in the almond, and some other oily seeds. It contains nitrogen, and when exposed to the moist air, under- goes the putrefactive fermentation, emitting an offensive odor like that of old cheese, and disengaging ammonia. Vegetable albumen and gluten appear to form a connecting link between vegetable and animal substances. 838. There are many vegetable principles which have not yet received a classification, owing to their not having been sufficiently studied, or to some obscurity in the nature of their constitution. Asparagin has been discovered in the juice of the asparagus, with an acid called espartic ; which, by decomposition, affords ammonia, proving that it contains nitrogen ; it exhibits neither acid nor alkaline properties, it is found in the juice of liquorice, and the Althea officinalis or marsh-mallows. Fungin is that portion of the fleshy part of the mushroom which remains after removing every thing soluble, by digesting in alcohol and alkaline water; it is very nutritious, has a smell like bread, but appears to resemble animal matter, in its composition. Legumin is extracted from the pulp of peas ; its solution gives, with sulphate of lime, a dense coagulum, which is supposed to explain why peas boiled in hard water, or that containing a salt of lime, become hard ; peas and beans are found to consist of 18.40 per cent of le- gumin with 42.58 of starch, 8 of water, 4 of nitric acid, and 8 animalized matter, &c. Ulmin was discovered by Vauquelin in the brown matter which exudes from the elm, (Ulmus), Braconnot found it in turf and mould ; it has been regarded by some Chemists as an acid, and called ulmic acid ; ammo- nia and oxygen change gallic acid into alumina. Caffein is a white, crystaline matter extracted from coffee ; Pelletier re- garded it as a salifiable base, but it neither affects blue vegetable colors, nor combines with acids. Bassorin was first extracted from gum Bassora, a substance resembling gum tragacanth, and imported from Bassora in Asia ; it has been found in assafcetida, and some other resinous plants. Cathartm is a substance which has been obtained from senna and is supposed to con- tain the cathartic principle of that plant. Suberin is a name applied by Chevreul to the cellular tissue of the cork tree (Quercus Suber,) which he supposes to be a proximate principle ; the cells of this substance are filled with astringent, coloring, and resinous matter; the latter, Chevreul called cerine. By the action of nitric acid, suberin changes to suberic acid. Lu- pulin is obtained from the membraneous scales of the pistilate flower of the hop It is very bitter, and soluble in water and alcohol. Piperin is procured from black pepper (piper nigrum); it has some of the stimulating properties of pepper; these being found to reside in a vola- tile oil. Oliville extracted by Pelletier from the gum of the olive tree, has a bitter and aromatic taste. Rhubarbarin is a name given to an extract of 837. Vegetable albumen. . 838 A«paragin. Fungin. Legumin. Ulmin. Caffein. Bassorin. Ca- thartin Suberin. Lupulin. Piperin. Oliville. Rheubarbann and Rem. Sarcocoll- Pollenin and Medullin. Colocynthis. Polycroite. Nicotm. Dahline and Inulin. 27* 318 CHL0R0PHILE. the medicinal rhubarb, supposed to contain its active principle. Sarcocoll, from a plant of Ethiopia and Persia called the Penoza sarcocolla, is imported in small grains, resembling gum arabic. It forms mucilage with water ; it differs from gum in being soluble in alcohol, and by being precipitated by tannin from its aqueous solution. It has a sweetish taste, resembling that of liquorice. Pollenin. The pollen of tulips was found by Professor John, to constitute a peculiar principle, of a very insoluble nature, highly com- bustible, burning with a rapid darting flame. It has been used in theatres for artificial lightning. The same chemist discovered a peculiar substance in the pith or medulla of the Sunflower, which he called medullin. This substance yields ammonia by destructive distillation. C olocynthin, is aname given by Vauquelin, to a bitter, resinous extract from the colocynth in which the medicinal properties of the plant reside. Polycroite is obtained from the flowers of the saffron (Crocus sativus.) It is the coloring matter of the saffron; it is named from polus, many, and kroma color, on account of its producing different colors with acids. .Nitric acid gives it a green color, which disappears on diluting it with water. Sul- phuric acid, at first, changes it blue, which color gradually passes to violet. Nicotin is a peculiar principle obtained by Vauquelin from tobacco (Nico- tiana tabaccum.) It has the smell and taste of the plant, is volatile and poisonous. Professor Silliman says, " The empyreumatic oil of tobacco, disengaged in smoking, is doubtless nicotin modified and perhaps rendered more noxious by the heat."* Dahline exists in the tubercles of the Dahlia. It resembles starch in most of its properties. Dahline exists with inulin in the Jerusalem artichoke, both substances are varieties of fecula or starch, and are therefore nutritious. The Dahlia root, if as easily cultivated as the potatoe, might, therefore form a valuable aliment. 839. Chlorophile is a name given to the green coloring matter of plants, formerly called green fecula of plants; it is obtained by coagulating the green juice of plants with heat, and purifying the coagulum with water and alco- hol; it is a deep-green, resinous substance; from some late discoveries it appears that the resin may be removed by ether, after which, according to some chemists, the coloring matter will be left pure.t Bitter principle, a term formerly applied to a supposed peculiar substance which caused the bitterness of plants; but it is found that different principles in different plants produce this effect; thus the bitter principle of the hop is owing to lupulin, that of opium to morphia, &c. Extractive matter, a term formerly supposed to refer to a peculiar principle; but it is vague and indefinite, since no such distinct principle has ever been obtained. When vegetable substances are macerated in water, there usually remains, after removing the proximate principle, something which seems to belong to none of these principles; and this has been called extractive matter, a convenient term which expresses a mixture of different principles, or the residuum of vege- table infusions and decoctions. * " As a source of refreshment and pleasure to man, tobacco ou«ht to be universally proscribed ; it should be retained only as a means of destroying insects and vermin, and as a medicine, which, in its internal use is so vio- lent and dangerous, that the proper occasions for emyloyin^it must be " few and far between."—Sil. El. of Chem. Vol. 2. p. 509. t What can those chemists mean who talk about a pure coloring matter since color is itself a mere secondary property of matter, and cannot exist separate from a colored body ? Can they expect to obtain a substance of which they can say,' this is pure color ?' or, " pure coloring matter 1" 839. Chlorophile. Bitter principle. Extractive matter. FERMENTATION. 319 CHAPTER XXXV. FERMENTATION. 840. By fermentation is understood, a spontaneous change which takes place in substances; their elements disunite, com- bine in other proportions, and give rise to compounds, differing wholly from any which had originally existed in the fermenting mass. There are various kinds of fermentation; as the panary which produces bread, the saccharine which affords sugar, the vinous in which sugar is converted into alcohol, the acetous which results in vinegar, and the putrefactive which results in the entire dissolution of organic matter. 841. Panary* ox bread fermentation. It is evident that bread, or even raised dough, differs essentially from a mixture of flour and water which has not undergone a process of fermentation. Besides the porous and spongy texture which distinguishes the former, it has a peculiar pungent odor, so that on opening a mass of thoroughly raised dough, a peculiar effluvia issues, scarcely less penetrating than that of ammonia. Dough is not only enlarged in bulk by fermentation, but, when subjected to the heat of the oven, it swells to a still greater bulk, and ap- pears in the form of light bread ; while dough that has not pas- sed through the fermenting process does not rise in the oven, and would, if baked, present a compact, heavy, insipid and in- digestible mass. 842. It is to gluten that flour owes its property of forming a paste with water. Paste is merely a viscous and elastic tissue of gluten, the cells of which are filled with starch, mucilage, sugar, &c. This being understood, we can readily conceive, that to gluten, paste owes its property of becoming light when mixed with yeast. The yeast acting upon the farina or starch of the flour converts it into a gummy, sugar-like substance. This saccharine fermentation is the first stage in the process. The change of sugar into alcohol and carbonic acid next takes place, and this vinous fermentation is the second stage. If the process is suffered to go on, alcohol isconverted into active acid or vinegar, and this acetous fermentation works a third stage. * From the Latin panis, bread. 840 What is meant by fermentation ? Different kinds of fermentation. 841* Changes effected in flour by means of the panary fermentation. 842! Importance of gluten in flour. Stages in panary fermentation. Cause of the porous texture of bread. 320 FERMENTATION. At the second or vinous stage of fermentation, a large portion of carbonic acid is disengaged. This in seeking to escape be- comes fixed in the cellular tissue of the gluten, which being tenacious and elastic extends itself, forming a series of mem- branous partitions filled with gas, and thus swelling out the mass. When exposed to heat, as in baking, the gas expands still more, and the baked loaf becomes specifically much lighter than before. 843. It is very necessary in making bread to observe ; 1st. That the yeast should be mixed thoroughly with the dough; otherwise the bread will be heavy in certain portions. 2d. The dough will rise light in proportion to the quantity of gluten, contained in the flour ; for this reason wheat flour makes better bread than any other. 3d. Substances which contain no gluten cannot be raised with yeast. Thus the flour of Indian corn, cannot by itself make light bread, but may be advantageously mixed, in certain proportions with wheat or rye ; and potatoes though they are nutritious on account of the farina which they contain, can never be used for bread, except with the flour of the glutinous grains. When bread has been suffered to sour, or pass through the acetous fermentation, the acetous acid which is generated may be neutralized by a solution of pearlash, or some other carbonated al- kali ; in this case, the further disengagement of carbonic acid gas, by the union of its base with acetic acid will render the bread still lighter, though if the alkali is too freely used, it will acquire an alkaline taste, and a yellow- ish color. 844. Saccharine fermentation produces sugar in bodies where it did not previously exist. It accompanies the germination of many buds, is produced in heating starch with sulphuric acid, and in the action of yeast, or gluten uponfarina. When starch, which has been coagulated by boiling water, is kept moist, during some time, a spontaneous change takes place, and sugar is produced. The germination of the buds of barley, in the malting process is an example of the saccharine fermentation. Vinous or Alcoholic Fermentation. 845. Fermentation takes place when sugar, or farina, the latter being readily changed to sugar, together with water, and a small portion of yeast, is exposed to a temperature from 60° to 80° F. The liquor soon begins to exhibit marks of action ; bubbles of carbonic acid, attracting around them small portions of the yeast, form a froth on the surface ; the liquor, after a time, deposits the interposed substances, which disturbed it, and becomes clear. The sugar having disappeared, it is proba- 843. Considerations important in respect to the making of bread. 844. What is saccharine fermentation, and when does it take place ? 845. Production of the vinous fermentation. Phenomena attending this fermentation. Experiment to illustrate the process of vinous fermentation Change, of sugar to alcohol. FERMENTATION. 321 ble that it has been converted into alcohol and carbonic acid ; especially as the weight of the two latter is found to be about equal to the weight of the sugar. This process may be examined, by way of experiment, by placing about five parts of sugar, with twenty parts of water, and a very little yeast in a glass flask with a bent tube, the extremity of which opens under an in- verted jar, full of water or mercury, and exposing the whole to the prope" temperature. The carbonic acid gas which is. disengaged may thus be col- lected, and its weight, together with that of the alcohol which is now form- ed in the flask, may be readily ascertained. The quantity of yeast decom- posed is so small as not to be brought into the account; the only part the yeast performs is that of exciting the fermentation ; the agency of atmos- pheric air is of no importance, as the operation proceeds equally well with- out it. According to Gay Lussac sugar may be transformed into alcohol, by taking from the former 1 volume of oxygen gas and 1 volume of the vapor of car- bon, constituing, by their union, one volume of carbonic acid gas. 846. Many vegetable juices containing sugar, acids, mucilage and starch, undergo the vinous fermentation without yeast, owing to the presence of gluten, which seems, in many respects, analogous to it. Cider is thus obtained by the fermentation of the juice of the apple, wine from that of the grape, currant, gooseberry, &c. In the malting of barley, the grain, after being soaked, is spread upon a floor. When the fermentation begins, and the seed germinates, the process is interrupted by heat, and the barley remains in a saccharine state; it is now called malt. When malt is fermented with an infusion of hops, the liquid is called beer, ale, or porter, in all of which, alcohol is produced during the fermentation. Ale and beer are more liable to sour than wine, on account of the mucilage and other principles which the former derive from malt. Alcohol may be obtained by distilling both the liquors produced by the vinous fermentation of saccharine fruits, and those which result from the fermented decoction of hops and malt. Acetous Fermentation. 847. The vinous fermentation readily passes to the acetous, or that in which acetic acid is generated. The acid appears to result from a change in the constituent principles of the alcohol. That this change takes place, seems evident from the disappearance of the alcohol, and the simultaneous production of acetic acid in an equal proportion to the alcohol which had previously existed. Pure alcohol, mixed with yeast and exposed to a warm temperature, will undergo the acetous fermentation. The nature of the chemical action which thus changes alcohol 846. Vinous fermentation produced by gluten. Malt, &c. 847. Cause of the change from the vinous to the acetous fermentation. In what case pure alcohol may be made to undergo the acetous fermenta- tion. Distinction between the formation of acetic acid, and the acetous fermentation. 322 PUTREFACTIVE FERMENTATION. into acetic acid is yet considered doubtful. It is necessary to distinguish between the mere formation of acetic acid, and the acetous fermentation. Most vegetable substances yield acetic acid when they undergo spontaneous decomposition. Mucil- aginous substances, even when excluded from the air, gradually become sour. But these processes appear essentially different from the proper acetous fermentation, when there is a visible movement in the liquid) with absorption of oxygen, and disen- gagement of carbonic acid. 848. The acetous fermentation is attended by the following circumstances. When a vinous liquor is exposed to the atmosphere, at a certain tempera- ture, it yields a portion of its carbon to the oxygen of the air, from whence results carbonic acid gas, and a slight disengagement of caloric ; the liquid becomes turbid owing to the formation of a filamentous matter, which, after much agitation, subsides in a jelly-like mass ; the alcohol is decomposed, becomes transparent, and is found changed to vinegar or acetic acid. The alcohol has been supposed to pass to the state of acetic acid, by yielding a portion of its hydrogen and carbon to the oxygen of the air,forming carbonic acid and water, and leaving its remaining carbon, hydrogen and oxygen in the exact proportion for forming acetic acid. But according to the experi- ments of De Saussure, the volume of carbonic acid gas formed, is such as to show that all the oxygen absorbed from the air unites with the carbon of the alcohol, while the hydrogen must be disposed of in some other way than by combining with oxygen to form water, as is supposed upon the former theory. Putrefactive Fermentation. 849. While organized beings possess life, the elements of which they are composed, remain combined according to the laws of the vital principle, which are often contrary to those of affinity ; but when life is extinct, the laws of affinity prevail, and former combinations are broken up in the effort of the ele- ments to unite according to their chemical attractions. This movement of the particles of bodies is called putrefaction, or the putrid fermentation. It is more rapid in animals than in vegeta- bles ; and more rapid in vegetable substances, in proportion as their constitution resembles that of animal matter. A damp and stagnant air, and warm temperature, hasten the progress of this fermentation. When vegetables deprived of their living principle, are thus situated, they become converted into a black matter, called mould, disengaging at the same time a little oil, acetic acid, water, nitrogen, carburetted hydrogen, and carbonic acid. Animal matter under the same circumstances besides most of these products, gives ammonia, some nitric acid, and hydro-cyanic acid. All the gases which are disengaged carry with them a little decomposed animal matter, which gives them 848. Circumstances which attend the acetous fermentation. 849. Change which ensues in organic beings when life ceases, &c. Phe- nomena of the putrefactive fermentation. Products of this fermentation. Miasma of marshes, &c. ANIMAL CHEMISTRY 323 a very offensive odor. The noxious miasma of marshes are sup- posed to be a gaseous principle, arising from the putrefactions of vegetable matter, but they have never been obtained in an in- sulated state, and it is not even known that they are a distinct principle of matter. 850. Thfe dark mould arising from putrefactive fermentation enriches soils, and fits them for the production, and nourishment of new plants. Thus, in the vegetable kingdom, we everywhere behold decay followed by renewed life. Why then should man fear to commit his organic frame to the dissolution of the sepul- chre, and the watchful eye of that Omniscient Power to whom every atom is known, and who can as easily re-assemble the dispersed elements, as he could at first have made man of the dust of the earth 1 And why should infidel man speculate upon the ability of the Almighty to raise the dead, because the atoms which composed these bodies, have successively held a place in other material forms 1 Having seen the powers which chemistry developes, shall we dare restrict the power of The Great Chemist of the Universe, to preserve amid the " wreck of matter" one minute atom, one little germ which may constitute our personal identity, and to form from this, that " celestial body" which is to be fashioned like unto His glorious body, im- mortal and incorruptible !"* CHAPTER XXXVI." ANIMAL CHEMISTRY, OR ANIMAL ORGANIC BODIES. 851. Animals, like vegetables, are composed of different parts J these parts, of different animal substances ; and these substances, of differeni proximate principles. The object of animal chem- istry, is to examine into the nature of those proximate principles, and their associations in the various solids and liquids of animals. •We do not find in the analysis of the proximate, animal prin- ciples, any new ultimate elements. These proximate principles differ from the vegetable principles, in containing more nitrogen, in a stronger tendency towards putrefactive fermentation, and in giving off offensive odors during this process. * For an account of the chemical phenomena attending the germination, growth, respiration, &c. of plants, the student is referred to the author's " Familiar Lectures on Botany," where these subjects are discussed at large. 850. Reflections on the new life which results from putrefactive fermen- tation. 851. Composition of animals. The object of animal chemistry. Differ- ence between the proximate animal principles and the vegetable principles. 324 ANIMAL CHEMISTRY. 852. By destructive distillation, or exposing animal substances to heat in close vessels, we obtain their ultimate elements. These, in some cases, as in animal oil, are the same as we obtain in the destructive distillation of vegetable matter; but, in the former, nitrogen in greater quantity is generally obtained and sometimes a little phosphorus and sulphur. The ultimate elements of animal matter may be, in general terms, stated as nitrogen, hydrogen, carbon and oxygen. 853. Animal substances are formed by the various operations of a living principle, as respiration, circulation, nutrition, se- cretion, &c. The proximate animal principles are less numerous than the vegetable. They may be divided into, 1st. Neutral principles, or those that are neither fat nor acid ; 2d. Animal acids ; 3d. Animal substances which are fat, without being acid ; and 4 328 muriatic...................... J2" nitric......................... ]3& nitro-hodro-chloric............. 127 nitro-muriatic................. J2? nitrous....................... J3' ole ic........................• • 329 oxalic..................... 154,283 oxv-muriatic................... 100 1 ■ 000 pectic......................... ""-' per chloric...................•_ 105 phosphoric.................. "^> '90 phosphorous......•............ 181 29 ?38 INDEX. Acid, pruisic.................... 168, pyro-ligneous.................. pyro-mucic.................... pyro-phosphoric........«....... pyro-tartaric.................. rheumic....................... saccholactic, .............. 292, sebaeic....................... selenic....................•■•• lelenious.........•.....•...... silicic......................... silico-hy dro-fluorie............. stannic........................ stearic........................ suberic....................... succinic....................... sulpho-naphthalic.............. sulphuric...............»•..... sulphurous..................... tartaric...................... titanic........................ tungstic-.......-........ »..... ulmic...-.................... vanadic....................... sarnie.......................-• Adipocire..............-............ Aeriform bodies, effect af caloric on... Affinity, simple...-.................. elective, single............. double.............. disposing.................... quiescent and diveilent....... by what causes modified.... .. Aii, atmospheric.....-............... fixed........................... inflammable.....»............... non-respirarble.................. Albumen, animal..................*■ vegetable........-........ Alcoates ............................ Alcohol...........................-• Algaroth, powder of.................. Alkali, volatile...................... fixed......................... Alkalies, chemical properties of...... nature of.........-......•••• vegetable... -.............. Alleys of antimony................... copper..........■-.......-•■ gold....................... lead.......-............... mercury................... nickel..................— 9flver........... -......... sodium..................... 294 283 292 181 290 294 323 329 194 194 175 177 210 329 293 293 164 1S3 187 289 202 206 31"? 206 294 331 27 77 79 60 207 81 S2 130 149 114 130 323 317 302 301 209 142 218 61 211 293 201 239 247 237 tin. Almond oil............ Alum...............*■ Alumina.............. Aluminum............■ oxide of.--- chloride of. Amalgams............ Amber............... Amidine.............• Ammonia............ eobaltate of-. muriate of. • • nitrate of. •• sulphate of •• Ammoaiuret of copper. silver.. 243 233 243 217 211 297 265 224 224 225 226 243 300 309 HO 209 142 143 2fi3 267 245 Anatase..................-......... Anhydrous alum..................... Animal, acids....................... albumen.................... chemistry-........-......... heat........................ jei'y........................ oils......................... substances, analysis of........ Anions............................. Annotta............................. Antharcite................. ........ Antimoniates........................ Antimony........................... oxides of................. alloys of................... chlorides of................ sulphuret of................ argentine flowers of........ Apparatus, distilling.................. Aqua ammonia...................... fortis.......................... regia.......................... Arbor Diana........................ Saturn!....... ................ Archil.............................. Argand lamp........................ Argellite............................ Argentine flowers of antimony........ Arrow root.......................... Arseniates,....................... 200 Arsenic....................-........ eromide of................... chloride of-.................. iodide of.................... sulphuret of.................. Arsenites............................ Ashes............................... Asparagin........................... Assimilation......................... Atmospheric air..................... analysis of............ Atomic theory....................... Atropia............................. Attraction......-.................... Azote............................... B. Baldwin's phosphorus................ Balsams.........................•••• Bark, Peruvian...................... Barilla.............................. Barium............................. oxides of..................... Barometer.......................... Baryta, sulphate of................... Bass-orin.............-.............. Barberry tallow..................... Bill metal.......................... Benzoates........................... Berillia............................. Bile................................ Bismuth............................. oxide of..................... chloride of.................. nitrate of................... flowers of................... Bitartnte of potassa................. Bitter principle...................... Bittern.......................... 106 Bl^ck dye......-.................... 202 264 328 325 323 335 326 329 324 62 314 146 201 200 201 201 200 201 201 45 141 133 246 245 238 313 27 226 201 309 . 273 199 200 200 200 200 145 317 334 120 132 90 296 53 S00 295 275 213 2'9 130 263 317 300 239 291 332 240 '.M0 240 240 040 i90 313 273 314 INDEX 339 Black drop.......................... 295 wad.......................... 207 Black lead.......................... 231 Blacking........................... 102 powder..................... 103 Blende.............................. 233 Blood............................ 99, 333 Biowers............................. 158 Blowpipe, compound................. 117 Blue, Prussian....................... 232 celestial ..................... 267 dyes.......................... .312 vat........................... 312 Boiling point of liquids.............. 41 influence of pressure on 42 Bolognian phosphurus.............. . 63 Boracic acid..................... 112, 172 Borates............................. 274 Borax, glass of................•..... 274 Boron............................... 170 chloride of..... -.............. 173 fluoride of.................... 173 Brass............................... 239 Brazil wood......................... 313 Bromates........................... 272 Bromic acid......................... 107 Bromine............................ 105 chloride of.................. 107 properties of................ 106 Bronze.............................. 211 Brucia.............................. 295 Burgundy pitch...................... 299 Cadmium............................ oxide of................... sulphuret of................ Caffein............................. Calamine •......................... Calcareous earth..................... Calcium........................-••■ oxides of................ chloride of.................. Calcined magnesia................... Calions............................. Calomel............................• Caloric............................. absorption of................. conduction of................. expansion by, of solids........ of liquids....... of aeriform bodies of fluidity.................... latent.............•.......... radiation and reflection of..... specific...................... sources of..................... Calorific rays........................ Calorimeter, Lavoisier's............. Hare's................. dies, mercurial..................... Calx............................... Camphor............................ Camphorates........................ Cannon metal............•.......... Canton's phosphorus.................. Caoutchouc......................... Carbon.............................. crystallized................... chloride of................... phosphuret of................. 235 235 235 317 233 220 220 220 221 276 62 242 13 30 24 14 17 20 34 32 28 34 14 50 33 58 241 220 299 299 239 63 300 144 146 166 185 Carbon, properties of-................ sulphuret of.................. Carbonates....................... 153, of ammonia............ 156, Carbonic acid..................... 97, oxide........ ......... Carburetted hydrogen................ Carmine............................ Cassius, precipitate of................ Cassava............................ Castor oil........................... Cathartic........................... Caustic, lunar....................... Celestial blue............. ......... Cerin............................... Cerium............................. oxides of.................... Cerite.............................. Ceruse.............................. Cetine.............................. Chalcolite,.......................... Chalk............................... Chameleon, mineral................. Charcoal............................ Cheese............................. Chemical affinity.................... classification............... combination, laws of....... equivalents................. nomenclature.............. rays....................... Chemistry, animal.................. definition of.............. object of................. organic.................. vegetable................ Classification of chemicel substances... Chlorates........................... Chloric acid......................... ether........................ Chloride of boron.................... bromine................. carbon................... cyanogen...............• gold..................... lime.................. 103, lithicum.................. magnesium............... nitrogen................. phosphorus............... silicon................... silver.................... sodium............... 124, sulphur.................. Chlorine............................ chemical character of........ tests of...................... Chloriodic acid...................... Chloro-carbonic acid................. Chlorophyle......................... Chlorous acid........................ Chromium.......................... oxides of.................. phosphuret of.............. Chromates.......................... Chrome yellow...................... Chyle............................... Cinchonia.......................... Cinders, blue........................ Cinnabar............................ Citrates...................•........ 147 192 i74 -75 149 154 158 313 247 309 293 317 269 267 301 235 235 235 276 330 206 276 207 145 8.6 97 93 86 88 70 50 323 17 7 284 286 93 270 104 163 173 107 166 170 102 222 218 224 143 182 177 103 216 192 100 101 103 109 166 3 It) 104 203 203 204 273 273 332 296 267 241 390 ?A0 INDEX. Coal................................ 145 Cobalt.............................. 203 oxides of...................... 209 Cochineal........................... 313 Codeia............................. 296 Coke............................... 146 Colocynthin......................... 313 Co lorific rays........................ 49 Colors, substantive and adjective...... 312 Coloring matter...................... 311 Columbates......................... 202 Columbium.......................... 201 oxide of.................. 202 Combination, chemical..............• 1 IS Combustion of charcoal............... 148 oxygen................. 96 theories of............. 93 Common salt......................... 216 Compound blowpipe.................. 117 Conductors of caloric................ 24 Conia............................... 296 Copal............................... 300 Copper............................. 238 oxides of---................. 239 chlorides of................... 239 sulphurets of................. 239 hydrates of................... 240 alloys of...................... 239 pyrites of.................... 239 amminiuret of................ 267 Copperas............................ 265 Cork............................... 317 Corrosive sublimate.................. 242 Coumarin.......................... 289 Couronne des Tasses................. 57 Creosote........................... 300 Cream of tartar...................... 289 Crocus.............................. 213 Cruickshank's trough................. 57 Cryophorus, Wollaston's.............. 38 Crystallization..................... 84, 245 water of............... 122 Crystals, primitive................... 256 secondary................... 259 Currents of air, how produced........ 27 Curcuma paper...................... 313 Cyanogen........................... 166 chlorides of................ 170 bromide of................. 170 iodide of................... 170 Cyanic acid......................... 168 Cyanous acid........................ 167 D. Daguerreotype...................... 51 Dahline............................. 318 Davy's safety lamp................... 160 Decomposition of water.............. 121 Deflagration.......................59, 149 Deoxidizing rays..................... 51 Dephlogisticated air................. 94 marine acid......... 100 Detonating silver.................... 245 Dew, formation of................... 32 Diachylon plaster.................... 297 Diamond............................ 146 Differential thermometer............. 2] Digester, Papin's..................43, 327 Distillation.......................... 45 destructive............ 145,324 Distilling apparatus.................. 45 Dragon's blood...................... 30° Dyes............................... 3U black......................... 314 blue........................... 312 red............................ 313 yellow......................... 313 E. Earths.............................. 218 Ebullition........................... 40 Elaine.............................. 330 Elastic gum......................... 300 Elasticity, its effects on chemical affinity 84 Elective affinity, single............... 79 double.............. 80 Electricity......................... 54 animal.................... 55 Electrodos.......................... 62 Electro-magnetic telegraph........... 68 Electrolytes......................... 62 Electrography...................... 69 Electro-megnetism................... 64 Amperu's theory of 67 Electron........................... 300 Electro-negatives................... 63, 93 positives.................. 63, 114 Electrotype......................... 68 Emetia............................. 296 Emetic, tartar....................... 201 Empyreal air........................ 94 Empyreumatic oil.................... 285 Emulsion............................ 297 Epsom salts......................... 264 Equivalents, chemical................ 88 table of......... 195 Essences............................ 293 Essential oils........................ 298 Ethal............................... 330 Ether............................... 303 acetic......................... 305 auriferous...................... 247 chloric........................ 163 hydriodic....................... 304 hydro- chloric................... 304 nitric.......................... 304 oconanthic..................... 305 sulphuric....................... 303 Ethiop's mineral..................... 243 Euchlorine.......................... 164 Eudiometer......................... 132 Eudiometry......................... 132 Evaporation........................ 37, 84 Exhilarating gas..................... 134 Expansion of aeriform bodies........... 20 of solids.................. 14 of liquids.................. 17 exceptions to the law of.... 18 Expansive force of freezing water..... 19 of steam............. 47 Extractive matter.................... 313 F. Fahrenheit's thermometer............ 23 Fat of animals....................... 329 Fermentation,....................... 319 acetous................ 3-21 alcoholic............... 320 panary................. 319 putrefactive............ 322 saccharine............. 320 vinous................. 320 INDEX. 341 Ferrocyanates....................... 281 Fibre, woody........................ 310 Fibrin.............................. 3 04 Firedamp........................... 15g Fixed air............................ I49 oils........................... 296 Flame........................... 117, 159 Flint glass.......................... 236 Flints, liquor of..................... 176 Florentine glass..................... 20 Flour of sulphur..................... 84 Flowers of sulphur................... 186 Fluate of lime....................... Ill Fluoric acid......................... Ill Fluoboric acid....................... HI Pluoborates...................... 112, 174 Fluo-silicic acid gas.............. 113, 177 Fluorides........................... 279 Fluorine............................ 110 Fluorspar................... 110, 222, 279 Frigorific mixtures................... 34 table of............ 35 Frost bearer......................... 33 Fulminating gold.................... 247 mercury................. 167 silver................ 167,245 Fulminating powders................. 269 platinum................ 250 Fulminic acid....................... 167 Fuming liquor of Libavius............ 211 Fungin............................. 317 Fusing point of metals................ 34 Fustic.............................. 313 G. Galena............................. 237 Gallates............................. 292 Gall nuts............................ 291 Galvanic battery..................... 57 modifications of...... 58 Galvani............................. 64 Galvanic circle...................... 65 Galvanism, history of................. 64 effects of................. 69 theories of............... 69 Galvanometer....................... 6;> Gases............................... *6 Gas, coal and oil..................... 164 ammoniacal..................... 141 carbonic acid................... 149 carburetted hydrogen............ 158 chlorine........................ 100 fluo-silicic acid................. 113 hydrogen....................... 114 nitrogen........................ 128 elefiant......................... 163 oxygen......................... 94 sulphurous acid...... .......... 187 telluretted hydrogen............. 205 Gastric juice........................ 3 82 Gelatine............................ 326 Glass.............................. 176 antimony....................... 201 etching on..................... 101 flint........................... 263 Glauber's salt....................... 226 Glauberite.......................... 263 Gliadine............................ 315 Glucinum........................... 227 oxides of................... 227 Glue................................ W Gluten.............................. 315 Glycerine........................... 331 Gold................................ 246 alloys of...................... 24? carats of....................... 243 chlorides of..................... 247 fulminating..................... 247 oxides of....................... 246 stannates of..................... 247 sulphuret of.................... 247 Goniometer......................... 259 reflective................. 260 Graphite............................ 231 Gravity, effect on chemical union..... 86 specific..................... 74 of gases............ 76 of liquids............ 75 ofsolids............. 74 Gum............................... 309 elastic......................... 300 resins.......................... 300 Gunpowder.......................... 269 Gypsum............................. 263 H. Haloid bodies....................... 124 salts......................... 282 Hartshorne, spirits of.............. 77, 275 volatile salts of.......... 275 shavings................. 327 Haematite........................... 230 Hea , use of term.................... 13 animal........................ 335 Hematine........................... 313 Heavy spar.......................... 263 Homberg's pyrophorus............... 264 sedative salt.............. 172 Honey.............................. 307 Hydracids........................74, 123 Hydrate of baryta.................... 219 of lime...................... 221 of potash.................... 214 of strontia................... 220 Hydrates............................ 123 Hydriodates......................... 278 Hydriodic acid...................... 128 Hydro-bromic acid............... 106,127 Hydro-chlorates..................... 277 Hydro-chlorate of lime............... 222 Hydro-chloric acid................... 126 Hydro-chlorides..................... 277 H ydro-cyanates...................... 281 Hydro-ferro-cyanates................ 29 Hydro-fluates................... 111,279 Hydro-fluoric acid................... HO Hydrogen.......................... H4 arseniuretted............... 200 deutoxide of................ 123 bi-carburet of.............. 163 carburetted................. 168 Hydrogen, phosphuretted............. 184 properties of............... H6 seleniuretted.............. H4 mlphuretted.............. 190 telluretted.,............... 205 Hydrometer......................... 301 Hydrostatic balance.................. '5 Hydro-sulphuric acid................. 192 Hydro-sulphurous acid............... 192 Hydro-sulphurets.................... 279 Hypo-chlorous acid.... r...,......... 104 342 INDEX. Hypo-nitrous acid................... 137 Hyosciamia........................ 296 I. Iceland spar......................... 49 Igneous fluid........................ 13 Imponderables....................... 13 Incandescent bodies.................. 51 Indigo.............................. 312 Indigogene.......................... 312 Indigotic acid....................... 292 Inflammable air..................... 114 Ink, sympathetic..................... 209 indelible....................... 269 Iodates.............................. 272 Iodides............................. 108 Iodide of nitrogen................... 144 of starch...................... 108 of sulphur................... 192 Iodine....................."......... 107 bromide of.................... 110 chemical properties of.......... 110 chloride of.................... 110 discovery of................... 107 mode of obtaining.............. 109 natural history of............... 10S Iodous acid.......................... 110 Ions................................ 62 Iridium............................. 251 Iron................................ 228 carburets of.................... 231 cast............................ 232 chlorides of.................... 230 oxides of....................... 229 rust............................ 230 sulphuret of.................... 231 wrought ....................... 232 Isinglass............................ 327 Isomeric bodies.......•.......... 157, 180 Ivory black.......................... 145 J. Jargoon........, Jelly, animal... vegetable. 226 320 310 K. Kelp..... Kinic acid. 109, 275 ... 293 Lac................................ 300 Lakes.............................. 311 Lamp, flameless..................... 161 safety........................ 160 spirit........................ 301 black........................ 145 I atanium........................... 252 Latent caloric....................... 32 Li;ad................................ 235 alloys of........................ 237 chlorides of.................... 237 muriate of...................... 237 oxides of....................... 236 red............................ 236 sulphuret of............. ...... 237 Legumen............................ 317 Libavius, fuming liquor of. Light, decomposition of.... definition of........ monochromatic..... uature of.......... 211 49 48 49 48 223 Light, refraction of......... sources of........... Lignia..................... Lime-stone................. Lime-water................ Lime..................... hydrate of............. milk of................ quick................. salts of................ slacked............... sulphate of............ Liniment, volatile........... Liquefaction................ Liquids, expansion of........ conducting power of. Liquorice, sugar of.......... Litharge................... Lithia...................... Lithium.................... oxide of............ chloride of......... Litmus..................... Loadstone.................. Logwood................... Lunar caustic............... Lupulin.................... Lymph....................., M. Madder.................... Magnesia.................. calcined........... Magnesium................. chloride of............... oxide of.................. Magnetism, electro.................. Malachite........................... Malates............................. Manganese.......................... chloride of............... fluoride of................ oxides of................ sulphuret of.............. Manganesiate of potassa.............. Manganesic acid..................... Manna.............................. Marble............................. Marine acid......................... Massicot............................ Meconic acid........................ Medullin........................... Menstrum.......................... Mephitic gas........................ Mercurial calcs..................... Mercury............................ alloys of................... chloride of................. oxides of.......-........... precipitates of, red......... white....... yellow...... prussiate of................. sulphurets of................. Metallic oxides................... Metalloids......................... Metals............................. alkaline..................... conducting power of.......... classification of........... 193 electrical attraction of........' Metameric bodies................ 18 51 310 276 221 220 221 221 221 223 221 203 297 34 17 26 303 236 218 217 213 213 313 230 313 269 317 333 313 223 ,276 223 224 223 64 276 291 206 207 203 207 203 207 207 307 276 126 236 29j 313 b3 130 241 240 243 242 241 242 242 243 243 243 72 211 197 211 25 252 64 15S INDEX. 343 Melhegliu.......................... 308 Meteoric stones...................... 232 Milk of sulphur...................... lg6 sugar of........................ 328 Miuderus, spirit of................... 288 Mineral chamelion................... 207 Minium............................. 23-6 Molybdenum........................ 204 chloride of.............. 204 oxide of................. 204 sulphuret of............. 204 Mordant............................. 312 Morphia............................ 294 Mother of vinegar................... 287 Mucilage........................... 310 Muriate of lead...................... 237 Muriatic acid........................ 126 Mushrooms, sugar of................. 307 Myrica cerifera, wax from............ 300 Myricin............................. 301 N. Naphtea........................... 164 Naphthaline........................ 164 Natural history...................... 7 Natural philosophy................... 7 Narcotine........................... 295 Neutralization....................... S4 Nickel.............................. 232 alloys of..................... 233 Nicotin............................. 313 Nitrates......................... 139, 267 Nitrate of silver..................... 139 of ammonia............... 134, 143 Nitre.............................. 268 Nitric acid.......................... 138 Nitrogen............................ 128 bromide of................. 144 chloride of................. 143 discovery of..... .......... 130 iodide of................... 144 oxides of................... 134 properties of................ 130 Nitro-hydro-chloric acid.............. 127 Nitro-muriatic acid.................. 127 Nitrous acid......................... 137 Non metallics, division of............. 93 Non metallic elements, table of....... 19a Non respirable air................... 130 o. Ochres............................. 230 Oil, almond......................... 297 castor........................... 298 drying.......................... 237 linseed.......................... 297 olive............................ 297 palm............................ 298 train.......................;---- 3'^ varnish........................ • 297 of turpentine.................... 299 Oils, animal......................• • • 329 essential or volatile..........23b, 29H fi«d........................... f£ siccative...................... f Olefiant gas.......................... "£ Olive oil............................ ,,, Olivile.............................. 3^ Opaque bodies....................... * Organic chemistry.. •••••;;•—;;; ■ 'J 3 4 Orpiment............... ' Ozmazomc.......................... 323 Osmium............................. 252 Oxacids............................. 124 Oxalates............................ 289 Oxalic acid...................... 154, 238 Oxidation........................... 95 Oxide, carbonic...................... 154 of tellurium................... 205 Oxygen............................. 94 combustion of................ 96 discovery of.................. 94 mode of obtaining............ 94 properties of................. 75 Oxymel............................. 303 Oxymuriatic acid.................... 100 P. Palladium........................... 251 chlorides of............... 251 oxides of................. 251 Papin's digester................... 43, 327 Parilla.............................. 29G Patent yellow....................... 239 Pearl white......................... 240 Pearlash............................ 274 Pectate of potassa.................... 292 Pectic acid.......................... 292 Perchloric acid...................... 105 Percussion powder................... 167 Peruvian bark....................... 295 Pewter............................. 237 Philosopher's stone.................. 173 wool.................. 233 Phlogiston........................ 98, 114 Phosphates......................... 273 Phosphites.......................... 1S2 Phosphori solar...................... 52 Phosphorescence..................... 52 Phosphoret of carbon................. 186 Phosphoric acid................... 97, 180 Phosphorous acid..................... 181 Phosphorus.......................... 177 Baldwin's................ 53 Bolognian................ 53 Canton's................. 53 chlorides of........... 182, 1S3 hydrateof................ 182 oxide of.................. 182 Photometers......................... 53 Physical sciences.................... 7 Picromel............................ 332 Piperin............................. 317 Pit coal..........~................. 145 Pitch, Burgundy..................... 299 Plaster of Paris...................... 263 Platinum............................ 243 chlorides of................ 249 fulminating................. 250 oxides of................... 249 spongy. ................ 117,260 Plumbago....................... 146,231 Pollenin............................ 318 Polycroite........................... 318 Polymeric bodies.................... 168 Penderables......................... 209 Potassa............................. 214 Potassium........................... 212 bromide of................ 215 chloride of................ 215 cyanuret of................ 215 iodide of.................. 216 344 INDEX. Potassium, oxides of.................. 21.3 phosphuret of.............. 215 Precipitates......................... 80 Pressure, influence on boiling point.. • 42 Proteine............................ 325 Proximate principles.............. 287, 323 Prussian blue......................•. 282 Prussiates........................... 281 Prussic acid...................... 168, 294 Pulse glass.......................... 39 Putrefactive fermentation............. 322 Pyroligneous acid.................... 288 Pyrometer........................... 15 Pyromucic acid...................... 292 Pyrophorus of Homberg............. 264 Q. Quercitron.......................... 314 Quick lime.......................... 221 Quicksilver......................... 240 Quinia.............................. 295 R. Radiant caloric...................... 28 Rays, calorific....................... 60 chemical...................... 50 colorific..........•............ 49 deoxidizing.................... 61 Realger............................. 200 Rectified spirit...................... 301 Red dyes............................ 313 Refrigerator........................ 25 Resius.............................. 299 Respiration................... 99, 135, 336 Rheumic acid....................... 293 Rhodium............................ 251 chlorides of................ 251 oxides of................... 251 Rhubarbarin........................ 317 Rouge.............................. 313 Rutile.............................. 202 s. Saccharine fermentation.............. 320 Safety lamp......................... 160 Safflower............................ 313 Saffron.............................. 313 Sago................................ 309 Sal ammoniac.................... 142, 278 Salifiable bases....................72, 293 Saleratus............................ 274 Saliva.............................. 333 Salt petre........................... 263 Salt, definition of.................... 71 common.....................•• 216 spirit of........................ 126 ofsorrel....................... 289 Glauber's...................... 262 Salts, acidulous...................... 72 classification of................ 261 crystalization of............... 254 definition of................... 61 deflagrating................... 140 Epsom........................ 264 general remarks on............ 254 neutral........................ 72 of hydracids................... 279 of oxacids..................... 262 Seidletz....................... 264 sub........................... 72 super......................... 72 Sandarac............................ 199 Sand bath........................... 39 Sanguinaria......................... 29o Saponification....................... 331 Sarcocoll............................ 318 Scheele's green..................... 267 Science, effect on the mind.......... 8, 10 art and..................... 9 Seidletz salts........................ 264 Selenic acid......................... 194 Selenious acid,...................... 194 Selenium............................ 194 bromide of................. 194 chloride of................. 194 oxide of.................... 194 phosphuret of............... 195 sulphuret of................ 195 Separable helices.................... 67 Serum.............................. 333 Siccative oils........................ 297 Silicates............................ 176 Silicon.............................. 174 chloride of................... 177 sulphate of................... 177 Silicic acid.......................... 175 Silvering............................ 243 Silver............................... 244 alloys of...................... 245 ammoniuret of... ............. 245 chloretof..................... 245 detonating..................... 245 fulminating.................... 245 nitrate of...................... 269 oxides of...................... 244 Silver plate......................... 245 Slag................................ 233 Smalt............................... 209 Smoke.............................. H5 Soap, glass makers................... 208 portable....................... 327 Soda................................ 215 muriate of...................... 216 Sodium.............................. 215 alloys of..................... 217 chloride of.............•..... 2 lfi oxides of.................. 215, 216 Solar phosphori...................... 62 spectrum...................... 49 Solder.............................. 237 Solids, expansion of.................. 14 conducting power of........... 24 Solution.......................... 82, 269 Solubility, degrees of................ 83 Solvent............................. 82 Spar, fluor.................. 110, 222, 279 heavy......................... 263 Iceland....................... 43 Specific gravity...................... 74 caloric...................... 33 Spectrum, solar...................... 49 Spelter............................. 233 Spermaceti.......................... 330 Sphene............................. 202 Spirit lamp.......................... 301 of salt......................... 126 proof......................... 312 pyroxylic.................. ... 305 rectified....................... 301 Starch.............................. 308 Steam............................. 43 elasticity of................... 44 INDEX. 345 Stearin............................. 330 Strontium.......................... 219 carbonate of............... 220 nitrateof..............•••• 220 oxides of.................. 219 sulphurets of............... 220 Strychnia........................... 295 Suberin............................. 317 Sugar............................... 305 ofgrapes ..................... 307 of lead........................ 288 of liquorice................... 303 of milk........................ 323 of mushrooms.............. ... 307 of starch...................... 307 Sulphates........................... 262 Sulpho-naphthalic acid............... 164 Sulpho-salts......................... 232 Sulphur............................. 185 affinity for oxygen............ 182 alcoholof................... 192 bromide of.................. 192 chloride of.................. 192 flowers of................... 186 iodide of.................... 192 milkof...................... 186 Sulphurous acid...................... 137 Sulphuric acid....................... 188 ether...................... 303 Synovia............................. 333 Sympathetic ink..................... 209 T. Tannin.......................... 314,327 artificial..................... 315 Tantalum........................... 202 Tar................................. 299 Tartar-emetic....................... 201 vitriolated................... 262 Tellurium...............V.......... 205 oxides of.................. 2°6 Thermometer..........• ■........... 20 invention of............ -'1 differential, Howard's... 22 Leslie's.... 21 Fahrenheit's........... 23 Thermo-eleclrical phenomena......... 68 Thorinum.............••............ 227 carbonates of............. ■«*' oxides of................. 227 r,,- ................ 210 1 in......................... „., alloys of........................ 211 chlorides of..................... 2U sulphurets of.................... 210 Tinfoil............................. 21£ Tin plate........................... ™ Tincal.............................. *i£ Titanite............................ ..„ Titanium.......••.................. *" oxidesof................... 202 Tourmaline. • • •;.................... 48 Transparent bodies................... Trona................ ..... 205 Tungsten.................. b chloride of................. 206 oxide of..................... gl3 Tumeric.....................'!!."."."." 313 Turnsol.................... "'" 599 Turpentine.........................| 301 Type metal......................... u. Ulmin.............................. 317 Uranium............................ 206 oxidesof.................. 206 Ultimate elements................... 323 V. Vanadium........................... 206 Vauadiate of lead.................... 202 Vaporization........................ 36 Vapors............................. 46 elasticity and condensibility of 47 Vegetable acids..................... 287 albumen.................. 317 alkalies.................. 293 chemistry................. 286 jelly..................... 310 Vegetation.......................... 133 Vegeto alkalies...................... 72 Verafria............................ 296 Verdigris........................... 288 Verditer.........................240, 276 Vermilion........................... 243 Vinegar............................. 287 Vinous fermentation................. 320 Vital air............................ 94 Vitality............................. 334 Verifiable earth..................... 176 Vitriolated tartar.................... 262 Vitriol, blue........................ 266 green....................... 229 white....................234,266 Volatile liniment.................... 297 Volta............................... 66 Volta's electro induction.............. 66 Voltaic pile.....................• • • • 56 currents..................... 66 Volumic theory...................... 91 w. Water, analysis of................... 120 carbonated................... 151 decomposition of...........61, 115 of crystalization.............. 122 of interposition............... 268 of nitre...................... 140 Wax................................ 300 Whey.............................. 328 White lead......................... 276 Woody fibre......................... 310 Wolfram............................ 206 Yeast............................... 316 Yellow dyes......................... 313 patent....................... 239 Yttrium............................. 227 z. Zaffre ......... Zimome....... Zinc blende Zinc...........■ chloride of flowers of. muriate of. oxide of... 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