NEWS PHARMACY, TOXICOLOGY, &c. Preparation of Liquor Bismuthi. MR. T. P. BLUNT communicates the following process to the Pharmaceutical Journal as an improvement of that of Mr. Bartlett, which appeared in our pages (vol. xi., p. 29): Take of subcarbonate of bismuth, 2 oz.; citric acid, 1 oz.; nitric acid, 3 oz.; water; solution of potash; spirit of wine,-of each what is sufficient. Dissolve the bismuth in the nitric acid, add sufficient water to take up the nitrate precipitated (from two to three ounces); carefully avoiding excess. Dissolve the citric acid in the solution thus formed (which will not be perfectly clear), and add gradually solution of potash (liquor potass) until the mixture is only faintly acid, and gives, after filtration, but a slight cloud on the addition of more potash. Filter, collect the precipitate, wash slightly (the presence of a trace of nitrate of ammonia in the product is of no consequence), and transfer the precipitate to a dish; add solution of ammonia gradually, until the precipitate is dissolved (a little oxide will remain); filter. Measure 4 fluid drachms of the solution, add excess of sulphide of ammonium, collect the precipitate on a counterpoised filter, wash, dry, and weigh; 261 grains of the precipitate thus obtained represent 237 of oxide of bismuth. Dilute the whole of the sclution with water and spirit of wine, in such proportions that a mixture of part of spirit with 7 of water shall contain the required number of grains (I generally prefer 4) to the drachm of solution. In the above process, it is especially necessary to avoid the addition of an excess of potash, which appears to decompose the citrate formed, and precipitate an oxide insoluble in ammonia, and this appears, indeed, to take place to some extent previously to saturation; a slight waste is therefore incurred, by leaving the solution faintly acid, in order to avoid the formation of this insoluble precipitate. The chief points in which I am indebted to Mr. Bartlett, in addition to those mentioned previously, are the following: 1. The substitution of carbonate for nitrate of bismuth. The former is far more soluble than the latter, which was used by me in consequence of its supposed greater constancy of composition. 2. The solution of the precipitate in pure ammonia. Before the appearance of Mr. Bartlett's communication, a mixture of citrate of ammonia with frce ammonia was used, and heat was applied. 3. The highly important addition of a quantitative analysis. A margin was formerly left to allow for loss (which is not considerable) in the manufacture, and, as above stated, the nitrate of bismuth was used as a more uniform salt than the carbonate. The weak points in Mr. Bartlett's process appear to be the following: 1. The great acidity of the solution from which the citrate of bismuth is ultimately separated causes the precipitation to be extremely imperfect; there is consequently great waste of material and labour. 2. The extreme dilution of each portion of the acid bismuth solution, in the act of addition to the solution of citrate of potash, seems to determine the precipitation of basic uitrate, insoluble in ammonia, before the double decomposition necessary to the formation of the citrate can take place. PHYSICAL SCIENCE. The Expansion of the Diamond and of Crystallised Protoxide of Copper under the Influence of Heat,* by M. H. FIZEAU. IN pursuing my studies on the propagation of light through bodies at various temperature, I was led to make several new observations on the expansion of several bodies which have not yet been studied from this point of view. From the nature of the results obtained, as unforeseen, as varied, and singular, it will be seen that it would be scientifically interesting to multiply as much as possible such determinations, and especially to apply them to natural groups of bodies, well defined either by their chemical composition or their crystalline form, so as to follow, under the most.varied circumstances, the modifications to which this order of phenomena is susceptible, and to discover, if possible, by what law they are regulated. The field of these researches is evidently of great extent, and but a very limited portion has as yet been explored. However, there are already a certain number of amorphous or crystallised bodies, especially those which crystallise in the regular system, whose expansions have been determined by the method employed in these researches, and in which, by means of the length of the wave of light, the most minute changes of volume in bodies only a few millimetres thick may be estimated. I will not here enter into the details of the various important improvements suggested by experience, made in the apparatus, but will reserve them for another memoir containing the whole of the observations. In order accurately to ascertain the temperature of the body experimented upon, the small steel tripod supporting it was placed between two concentrical stoves of thick copper, by which means the heat was uniformly distributed, and the height of the temperature very accurately taken. Further, the displacement of the fringes or rings at the surface of the body, during the and thus very precisely estimated. changes of temperature, was watched with a small lens, Among the bodies of which I have determined the expansion, two present a remarkable phenomenon which has not hitherto been observed in any other body; this is, an expansion so slight at low temperature that great care and special observations were requisite to detect and exactly measure it. These two bodies are the diamond and protoxide of copper, both crystallising in the regular system, translucent, and with the highest indexes of refraction, but differing from each other in composition and in their chemical and physical properties. Moreover, not only is the expansion very slight in these two substances, but it very rapidly decreases as the temperature becomes lower, exactly as with water at about its maximum of density; so that it would, by the phenomenon of a maximum of density-that is to analogy, appear that these two solid bodies might present say, decreasing, would become nothing at a certain temperathat their co-efficient of expansion, first positive, and ture, and then negative. The determinations hitherto made agree well with this supposition, and render probable the existence of a maximum of density for the diamond and for oxide of copper. The following are the results of experiments:- * Comptes Rendus, lx., 1161. large plate of diamond 15 mm. thick, for which I am indebted to the kindness of M. Halpen; then on several stones variously cut, and among others on a beautiful brilliant procured for me by M. Mellerio. I thus observed the very slight expansion of this substance, and found that the co-efficient of expansion diminishes rapidly with the temperature; but to obtain precise measurements of these always very slight expansions it is necessary that the diamond should unite certain conditions of size, as well as of dimension and parallelism in the cut faces, conditions which are perfectly realised in one of the most valuable stones in the museum collection. This beautiful stone, which has a slightly yellow tint, weighs 1'94 gr., and is ·625 mm. thick. The administration of the Museum having entrusted it to me to determine its expansion, I took eleven series of measurements, each comprising eleven distinct observations made at different points of the stone, and at temperatures between 18° and 77°. From these experiments it would appear very probable that the diamond has a maximum density at about 38.8°. In the above only the linear expansion has been considered; now, the crystals of the regular system, as the diamond and oxide of copper expand equally in all directions (Mitscherlich); to ascertain the cubical expansion, the linear expansion must be multiplied by three. Crystallised Protoxide of Copper.-The crystals of this substance are sometimes remarkably transparent to red light. I cut a small crystal of this body into a prism, and found that it refracted the light much more than the diamond. For its refraction index with the most refrangible red ray which traversed the substance I found n = 2'8984; and with the simple red ray emitted by lithia vapour in a flame n = 2.8489. Two sufficiently pure crystals from Chessy (Rhône), one octahedral the other dodecahedral, being in some parts transparent to red light, were experimented upon; their thickness was 9'844 and 10.570 mm. Six series of measurements of twelve observations each gave concordant results, and showed decisively that the expansion of oxide of copper is, especially at low temperatures, much less than that of the diamond; and furthermore, that the value of the co-efficient also varies more rapidly, so that this co-efficient becomes rapidly smaller as the temperature decreases, and tends to become null at a higher temperature than the diamond, the increases of the co-efficient being always in propor tion to the increase of heat. Up to the present time we know only of water and some saline solutions-that is to say, of bodies in a liquid state, which present the phenomenon of the maximum of density; the existence of a phenomenon of this kind in solid bodies ought to introduce new data to the theories relative to heat, and throw a light on the molecular constitution of bodies. Encaustic.—Bocklin gives the following process :— Moist plaster of Paris is painted with water colours as usual. When the design is perfectly dry it is painted over with a hot solution of wax and resin, and this coating is burnt in with a strong heat. The wax sinking in fixes the colour, and gives together with its compound with resin a solid transparent surface which effectually protects the painting from injury by damp or dust, the colours at the same time being greatly heightened and improved. Chem. Cent. Blatt., 26, 415. THE July 21, 1865. DUBLIN INTERNATIONAL EXHIBITION. By CHAS. R. C. TICHBORNE, F.C.S., F.R.G.S.I., &c. (Specially Reported for the CHEMICAL NEWS.) (Continued from page 16.) Chemical, Pharmaceutical, and Other Ex. hibitors in the British Department not already noticed.-J. Barrington and Sons, Dublin, soap, candles, and chemicals used in the manufacturing of the same. Bewley and Draper, Dublin, mineral waters, perfumery, pharmaceutical preparations, and wines. British Seaweed Company, series illustrating Stanford's patent method of making iodine, &c. The specimens in this case have become disarranged. Bryant and May, London, patent safety matches without phosphorus. Cooney and Co., Dublin, starch, dextrine, laundry blues, and samples of the raw material. J. and C. Hare, Bristol, painters' colours. Hirst, Brook, and Tomlinson, Leeds, acetic acid and acetates, wood naphtha, artificial fruit essences, varnishes, &c. Johnson and Sons, Basinghall-street, London, a similar case to Johnson, Matthey, and Co., but upon a small scale. The specimens in this case are very fine; it contains refined antimony, bismuth, cadmium, and tin. Kane, Dublin, sulphate of sodium, sulphuric acid, and bleaching powder. Lewis, Dublin, perfumery, &c. McMaster and Hodgson, Dublin, rape oil, linseed oil; cakes, meals (?), and seeds from which they are manufactured. Mawson and Swan, photographic collodion and other preparations. Piesse and Lubin, London, perfumery, odoriferous gums, fragrant woods, and plants. Pulford and Co., London, magnetic paints. L. Simon, Nottingham, bronze powders. Taylor and Co., Leith, stearic acid, paraffine, candles, &c. S. and W. Tudor, London, white and red lead, litharge, and orange lead. J. and J. Colman, London, starch, coloured starch, mustard, and oil of mustard. Bewley, Hamilton, and Co., Dublin, some small but extremely fine specimens of chemical and pharmaceutical products. The aloine, granulated sulphate of iron, and a few others should have been left out; they do not add and evidently genuine collection. to the appearance of what is otherwise a very good Boileau and Boyd, a good general collection. British and Foreign Safety Fuse Company, patent safety fuse for blasting. patent, said to be manufactured from the Japan wax. Patent Wax Soap Factory, soap made under Kottula's In Section 3 we have : Glorney, Dublin, mustard oil, &c. Hart, London, isinglass. One quarter of a pound of isinglass is shown cut into 50,000 shreds, which would extend over seven and a-half miles if connected. Specimens of swimming bladders, &c. NEWS admitting oxygen and hydrogen to the burners of dis- hand in the course of the year. This shows a total of solving view lanterns. Ottewill, Collis, and Co., London, cameras. Solomon, London, cameras. Warner, London, camera stand. Section 28: India-rubber, Gutta-percha, and Telegraph Company, Essex, St. Denis, France, and Menin, Belgium, articles in india-rubber, &c., submarine cables, &c. Minerals and Metallurgical Operations. Ireland is essentially a mineral country, although this fact has only received credence within the last year or so. The Irish mining operations are well represented, as all the national mining companies have their cases. Thus there is the Connorrce Mining Company (limited), Avoca Company, Wicklow, native copper, copper pyrites, silver, lead ore, iron pyrites, ochre; the General Mining Company for Ireland (limited), raw and dressed calamine, arsenical pyrites, fire clay, ochre, lead and copper ores; Carysfort Mining Company, copper ores, gold, &c. There is always a great amount of speculation attached to mining operations, and many must suffer before the resources of a country are properly opened. One of the most successful companies, and most deservedly so, is the Mining Company of Ireland. It is immaterial whether we visit their mines or their factory at Bally corns, where the smelting operations are carried on, we find the same system carried out. No expense is spared that is likely to give a return, and perfect order is carried out in every department; whilst the wants and requirements of the employed are as much looked after as the working of the establishment. This Company has copper mines, coal mines, and lead mines in operation at the present time. The latter are situated in the valley of Glendalough, upon which Moore has written his celebrated poem,-— "By the lake whose gloomy shore Where the cliffs hang high and steep." This valley also contains the ruins known as the Seven Churches, described by Thackeray with such humour. These ruins are much frequented by tourists, who, however, seldom take the trouble to push up the ravine to visit these interesting mines. At the end of this ravine is a sloping amphitheatre upon a stupendous scale. If he is of a romantic turn of mind he may imagine that some Brobdignagian carter had been shooting down on every side into the said amphitheatre load after load of angular granite stones of immense proportions; not a vestige of verdure covers the rugged pile, and it would leave a gloom indeed if it were not for the busy scene which is going on in the little flat below. The mine comes out upon the surface about one-third of the way up the mountain, which mountain they have bored right through. The explorers go in at one side and come out in the other valley. In the lead mines, situated in flat countries, shafts have to be sunk; from the situation the working by shafts has but a limited application in the Wicklow mine. The mountain is penetrated in the corner of the vein by "levels." It is eighty fathoms deep (480 feet) from the apex of the mountain; the workings are carried on at a depth of more than 2000 feet. The large amount of material actually broken up in the Glendalough mine-indeed, in all mines-to get at the ore is something tremendous. There remains underground in broken stuff, which is called "deads," 22,000 tons; 10,000 rejected at the surface; treated upon the dressing floors, 14,000 tons; so that 46,000 tons of ore and rock pass through the miner's 46,000 tons broken to get at 1800 tons of ore dressed for the market in this one mine, and there are many where more ore is annually turned out. Thus A few rare minerals are found in this mine. Witherite, a very rare mineral in Ireland, has been found in very small quantities in the mines of Luganure, Another barium salt in the form of heavy spar is met with in this mine, beautifully crystallised carbonate of lead, and the black variety of carbonate of lead. But perhaps the most interesting of the collateral minerals which have been found with the lead in these mines is the native silver. Bright silver juts out of the rock in most fanciful convolutions, sometimes resembling vegetation. The native silver in this mine is generally found in direct contact with a friable and apparently disintegrated ore, which consists of sulphide of silver, also galena rich in sulphide of silver-large quantities of this ore have not been found. Blende is found in large quantities here, but is not worked; but the finer portions of this blende get ultimately carried down from the dressing floor into the lake, and getting into the gills of the fish, literally chokes them. It is a fact that no fish will live in the lake, and this has perhaps added weight to the line "By that lake whose gloomy shore." The circumstance that we have just mentioned has given rise to the fable that the water is poisoned by the lead; but this is not the case, as the waters have been analysed and found to be free from lead. This is a practical proof of the insolubility of sulphide of lead in water. The quantity of lead ore raised in the whole of Europe and North America is estimated at about 190,000 tons per annum. Great Britain gives 90,000, of which 2500 is raised in Ireland, or about 13 per cent. of the whole raised in the world. Ireland yields about 14,000 ounces, or 24 per cent. of the whole of the silver raised in the world; its valuc may be estimated at about 3850l. per annum. To give an idea of the value of any mine, the tons of ore raised may be multiplied by 7, which will give the quantity of lead. This Company shows lead ore dressed in various stages-lead in pig, sheet, pipe, shot, and red lead. A piece of silver valued 3050l., copper ore from Knockmahon, county Waterford, crystallised lead, coal and strata illustrative of the geological formation of the coalfields of Tipperary, specimens from Ballycorns, lead slags, &c. Other Mining and Quarrying Exhibitors.— Sir R. Griffith, Bart., geological map of Ireland, on a scale of four miles to an inch. Section from the eastern to the western coast of Ireland, showing the succession of the silurian, Devonian, and carboniferous rocks of the country. Section showing the coal series of the county of Antrim. Section showing the geological structure of the south-east of Ireland. Vertical section showing the tabular arrangement of the columnar and amorphous basalt and interlaced beds of red lithomarge of the Causeway range of the north coast of Antrim. Sectional view of M'Gillicuddy's Recks, Killarney. Austin, Glasgow, block coal. Carrick-Fife, cannel coal, and oil and grease manufactured from the same coal. J. Lisabe, Dublin, slates, ores of copper, lead, iron, baryta. F. Danchell, Dublin, peat and condensed peat. PROCEEDINGS OF SOCIETIES. COLLEGE OF PHYSICIANS. Wednesday, April 26, 1865. velopment and recognition is apparent even now; for we find that notwithstanding the continuous accumulation of recorded experiment, and the continuous discovery of new and complex bodies with a rapidity at which all must be amazed, chemistry is daily becoming less and less a science of detail, more and more a science of generality, to such "On Animal Chemistry." A course of Six Lectures by an extent, indeed, that in my opinion a student beginning WILLIAM ODLING, M.B., F.R.S., F.R.C.P. LECTURE 1. Introductory remarks on recently-established general principles in chemistry-Plants and animals made up of distinct parts or organs-These, again, of minute parts, differing from one another in structure and arrangement -Composition of various tissue-constituents definite and independent of their structure and arrangement— Statical chemistry concerned only with the composition of parts; with the different kinds of matter of which all tissues and fluids of the body are composed-Dynamical chemistry concerned with the changes of composition undergone by various parts from time to time-Physical changes, as of a piece of iron, contrasted with its chemical changes-Special reference of chemistry to past and future changes of bodies-Every action of living body attended by changes of chemical composition-Recent advances in chemistry of tissue-products-Leucine a result of the natural metamorphosis of glandular tissue -1ts artificial formation, destructively and constructively-Taurine a constituent of bile, &c.-Its artificial production from carbon, hydrogen, nitrogen, oxygen, and sulphur-Chemical types of construction and double decomposition-Compounds of hydrogen with other three gaseous elements-Establishment of molecular formulæ for hydrochloric acid HCl, water H20, and ammonia HN-Existence in two volumes of gaseous hydrochloric acid, water, and ammonia, of one, two, and three volumes of hydrogen respectively, in addition to one volume of chlorine, or oxygen, or nitrogen-Monhydrides, dihydrides, and trihydrides in general, and their derived chlorides- Existence of analogous mono-, di-, and trichlorides of metals deduced from specific heats of respective metals, &c.—Mutual relations of chlorides, hydrates, and amides, both of elements and groupings-Interchangeability of comparable residues (Cl from HCl, HO from H.HO, and H2N from H.H,N) in great variety of compounds Chlorinated, hydrated, and ammoniated forms of the same primitive bodies-Many complex nitrogenous tissue-products only the ammoniated forms of comparatively simple bodies-Urea, glycocine, and taurine the ammoniated forms of the carbonic, acetic or glycolic, and isethionic acids respectively. MR. PRESIDENT AND GENTLEMEN,—It has been, I believe, the traditional policy of this College, in its character of a learned body, to foster the cultivation of natural science for its own sake, irrespective of any immediate advantage accruing to medical practice, and regardless even of the ultimate advantage which, sooner or later, must acc: ue from every addition to our knowledge of the phenomena of life. I therefore make no apology, Sir, for directing your attention to topics of which the present interest, at any rate, is more scientific than practical, relying upon the favour -ever extended to pure science within these walls--relying still more confidently upon the prospective ability of science to repay your favour many fold. I feel, however, that I ought to apologise for venturing to discuss in this presence some of the more rudimentary principles of chemical philosophy; but the circumstance that these principles, despite their rudimentary character, are yet of very recent introduction must furnish my excuse. Indeed, it is only within the last fifteen years or so that chemical facts have been in any large measure subordinated to chemical principles, and only within a very few years past that these principles have been consistently developed and generally acknowledged. But the result of this de the study of chemistry now, with a view to make himself acquainted with the knowledge of his own day, has a far of twenty years ago, despite the then limited range of less difficult task before him than had his predecessor of chemical inquiry. To some extent, therefore, I am forced, more especially in this introductory lecture, to devote a considerable proportion of my allotted time to an enunciation of certain general truths of more or less recent estastandpoint, I must beg still further to trespass upon your blishment. But, in order that we may set out from the same attention by reminding you briefly of the special province of chemical science, and the special character of chemical phenomena. in it a great number of parts or organs-root and stem, and If we examine any ordinary plant or animal, we find bark and leaves, and flowers and fruit, or bones and ligaments, and muscles and viscera, and nerves and vessels. If we examine any one of these parts more minutely, we find that it also is made up of parts differing from one another, and so disposed towards one another as to present little further, we find that each of these parts has a definite evidence of arrangement or organisation. Proceeding a composition, and that the composition of the different parts is, to some extent, at any rate, independent both of their individual structure and mutual co-ordination. We find, for instance, very differently-characterised tissues composed mainly of fibrin or albumen, others of gelatine or chondrine, others of fat, and others, again, of phosphate of lime. Now, chemistry does not concern itself at all with the structure and arrangement of parts, but treats only of their composition. It distinguishes between the different kinds of matter of which all bodies whatsoever are commineral or organic. In particular, it teaches us as physiposed, whether living or dead, structural or structureless, cians the composition of every tissue and fluid of the human body, and of every external agent by which that the food by which we are nourished, the medicines by body is affected-the air we breathe, the water we drink, destroyed. But the knowledge of the composition of which we are healed, and the poisons by which we are bodies is, after all, only the statical or secondary object chemistry has primary reference to the changes which of chemical inquiry; for, in common with physics, not only as it now is, but as it has been, as it may take place in the state of bodies. We consider a body hereafter be, the changes it has undergone in time past, the changes which it may undergo in time to come. Confining our attention to a single object-this piece of iron, for instance-let us consider how varied have been the states of its existence at different times. We know that it has been at rest and in motion; it has been silent and sonorous; it has been luminous and obscure, hot and cold, liquid and solid, magnetic and non-magnetic, electrical and non-electric. But throughout all these changes of rest and motion, sound and silence, heat and cold, &c., the individual piece of metal has continued one and the same; it has been composed throughout of identically the same matter. Now, so long as a body continues to be one and the same body-so long, in fact, as its composition remains unaltered, so long do all the changes which it manifests belong to the province of physics, and not to the province of chemistry. For this piece of iron to undergo a chemical change, it must cease to be a piece of iron, and become some other body-rust of iron, or vitriol of iron, or tincture of iron, or Prussian blue, or clot of blood, or some one of many hundred different combinations. Looking, then, to the chemistry of this piece of iron, we have regard to NEWS the state of ironstone in which it existed before it became metallic iron, and to the many different non-metallic states in which it may hereafter exist. The dynamical interest of a body has reference to its existence in time, to its past and future variations of state, even more than to its present condition. I venture to impress this point particularly on your attention, that while chemistry treats of the composition of bodies, it has special reference to their changes in composition. Now, when we consider that every action of the living body, every growth, every waste, every secretion, every movement, and even every thought is attended by, and consequent upon, a change of chemical composition, we perceive, in an instant, how much the future of physiology must depend upon the progress of chemical research-how only the iatro-chemist, if I may so call him, can ever hope to understand the varied series of actions, healthy and morbid, which are continually taking place in the living organism. The chemistry, then, of any animal tissue-of a piece of muscle, for instance, no less than of a piece of iron, has reference to its origin and metamorphoses. The chemist looks equally to its past and its future to the pabulum from which it was formed, and to the products into which it is ever changing. Of late years the chemistry of animal products has made very great advances. In the table before you are written up the names and somewhat complicated formulæ of a few of those compounds, most of which occur in the animal body, as results of the natural metamorphosis of its several tissues. Now, despite the complexity of many of these bodies, the intimate constitution of even the most complicated of them is fairly well understood, and in many cases so well understood that the bodies themselves can | be actually built up by the chemist in his laboratory without having any recourse whatever to organic nature. Animal Products. Let me direct your attention to one or two of these more particularly. Here, for instance, is leucine, a white crystalline body, consisting of 6 atoms of carbon, 13 of hydrogen, of nitrogen, and 2 of oxygen. Now, leucine is a product of the use, and consequent waste or metamorphosis, of glandular tissue. It is found in decoctions of glandular tissue, more particularly of the spleen and pancreas. It also occurs occasionally as an abnormal constituent of urine. It may be made artificially in the flask or crucible by the breaking up of muscle, ligament, skin, horn, hair, feathers, and a variety of other animal substances; but so well is the constitution of this complex tissue-product understood that leucine can now be formed, not only destructively by the breaking up of more complex bodies, but constructively by a synthesis of less complex organic bodies quite independently of animal life. It may be produced, for example, by the combination. with one another of water, essential oil of valerian, and prussic acid, as shown in the table, and in several other H2O CH100 CH N ways. C6H13NO2 Water. Ol. valerian. Prussic acid. Leucine. The case of taurine, C2H,NSO, is even more striking. Taurine, like leucine, has been found in glandular tissue, more particularly of the lung; but its chief source is the bile, where it exists conjugated with cholic acid, to form what is known as tauro-cholic acid; though whether the constituent taurine of this acid is really formed by the liver, or merely extracted by the liver from the blood of the portal vein, is not, I believe, satisfactorily established. But the constitution of this highly complex organic body, containing, as you see, carbon, hydrogen, nitrogen, sulphur, and oxygen, is so well understood that it can easily be put together in the laboratory, and from such well-known bodies as sulphuric acid, alcohol, and ammonia, each of which again is capable of being produced from its constituent elements, so that we may actually form this most interesting organic product taurine out of sulphur, charcoal, oxygen, hydrogen, and nitrogen, by processes which I hope to bring under your notice more particularly in a subsequent lecture. I might make similar remarks with regard to the greater number of these other products included in the table. Instead, however, of entering at once upon the consideration of these and similar compounds, I propose to occupy the remainder of this lecture with an account of certain bodies of a much simpler character. I mean those fundamental combinations that serve as types to which the above class of bodies and the great majority of organic as well as mineral compounds are more or less directly referrible. The recognition of these types, with the establishment of their nature and mutual relationship, constitutes the great chemical advance of the last dozen years or so; and at the present time, the proper understanding of these types enables us to give at once a more or less satisfactory interpretation of even the most recondite discoveries of modern organic chemistry. I need scarcely remind you that among the infinite number of bodies known to chemists some of them, so far as as our present knowledge goes, appear to consist of one kind of matter only. For instance, while cinnabar may be proved to consists of two different kinds of matter, known as sulphur and mercury respectively, out of mercury we can obtain nothing but mercury, and out of sulphur nothing but sulphur. Bodies of this description, therefore, which the chemist has not succeeded in resolving into two or more different kinds of matter, are assumed to consist of one kind of matter only, and are accordingly termed simple bodies or elements. These elements amount to about sixty in number, and are possessed of very diverse properties. About four-fifths of them are metallic, as mercury, and silver, and gold, and copper, and lead, and iron. The remainder are non-metallic, as oxygen, and chlorine, and bromine, and sulphur, and phosphorus, and charcoal. The great majority of them exist naturally in the solid state. Only two are liquid, namely, bromine and mercury; while four of them are gaseous, namely, hydrogen, chlorine, oxygen, and nitrogen. Now it is the combinations of these four gaseous elements with one another, or rather, I should say, the combinations of hydrogen with the other three gaseous elements, which constitute our primary chemical types-chloride of hydrogen or hydrochloric acid, oxide of hydrogen or water, and nitride of hydrogen or am. monia-which we will now consider seriatim. If we expose a mixture of chlorine and hydrogen gases to diffused daylight, they gradually combine with one another to produce a compound gas called hydrochloric acid-the gas which we have in this tube, and which I daresay I shall be able to render evident to you by breaking off the point of tube under water. The presence of hydrochloric acid gas in the tube is now manifested to you by its solubility in water, and by its action upon colouring matter. But, if instead of allowing the two gases to act upon one another slowly in diffused daylight, we expose them to direct sunlight, or if we bring them into contact with flame, their combination then takes place, as you see, instantaneously and with explosion. Now, it has been shown over and over again, that when chlorine and hydrogen gases unite with one another to form hydrochloric acid, it is always in the ratio of equal volumes. If we take one volume of hydrogen and one volume and a quarter of chlorine, the one volume of hydrogen |