NEWS case. These, we believe, are used in glass staining more as delcolourisers than as anything else, except the chromate, which produces a fine bluish green glass. Some watch oils are exhibited in this section which were examined by one of the jurors; they consist of olein from olive oil, very neutral, and when subjected to the continuous action of a freezing mixture remained perfectly limpid, although at the same time they became viscid. Eau de Cologne is represented by no less than three firms; each of these firms states that he or she is the original. The woodstuffs prepared for paper makers are very good in this department, and superior to some exhibited in the Italian. They are made from the linden, aspen, Scotch fir, and pine, and excellent writing paper was shown containing 48 per cent. of woodstuff. A propos of paper, a starch manufacturer informed the writer that large quantities of starch are being manufactured now in England for paper makers. The starch is mixed cold with the pulp, and after making the paper is passed through pretty hot rollers. It will be seen that the starch granules being partially broken and converted into dextrine two objects are obtained-a saving of the expensive rag stuff, and a homogeneousness of texture. Other Foreign Exhibitors.-Loehnert, Bohemia, dextrine. Brasseur, Ghent, chemical products from the destructive distillation of wood. the fatty acids -Series of aromatic acids and hydrocarbons -Other groups and series-Possibility of referring every aplone molecule to a definite position in some homologous series and heterologous grouping-Hippuric acid formed of three constituent residues convertible into complete molecules by an absorption of water-Assignment of these molecules to their appropriate positions in groups and series -Possibility of obtaining any two residues in combination, by destruction or removal of third-Benzamide formed by destruction of glycolic residue, benzoglycolic acid by destruction of ammonia residue, and glycocine by removal of benzoic residue-Assumed pre-existence of benzamide, benzoglycolic acid, and glycocine in hippuric acid-Probable internal arrangement of the acid–Illustrative animal products formed of two constituent residues— Urea, glycocine, leucine-Spermaceti and myricin the analogues of acetic ether-The true fats-Illustrative animal products formed of more than two residues-Taurine, sarcosine, alloxan, and the biliary acids-Scheme of the constitution of kreatine. CHEMISTS have ascertained that the various tissues of plants and animals are composed of, or contain, a great number of distinct chemical compounds, capable, for the most part, of being separated from one another by what may be regarded as physical processes-that is to say, by processes dependent on differences of volatility, fusibility, soluhave either been built up in the living plant or animal, or bility in different menstrua, &c. These several compounds have been formed spontaneously in the dead plant or animal out of ancestral substances which were built up in the living plant or animal. Somehow or other these proximate animal and vegetable principles, as they are Rocques and Bougeois, Seine, chemical products. Antonio, Baron Cristofero Catania, essential oil of termed, have been produced through the agency of vitality. lemons, oranges, and orange flowers. Campisi, Alfio Militello, citric acid. Candiani, large collection of chemical products, acids (pure and commercial), ammonia, nitro-benzol, silicates, nitrate of silver, sulphate and borate of manganese, &c. Garofolletti, Ferdinand's crystals for making black ink. Parenti, Galgono, asparagine, caffeine, citrate of caffeine, &c., very fine. PROCEEDINGS OF SOCIETIES. COLLEGE OF PHYSICIANS. Friday, April 28, 1865. They have been formed through the intervention of a living organism, and are hence called organic compounds, in contradistinction to such substances as quartz and feldspar and hæmatite, which pre-exist in the mineral kingdom, and from such substances as copperas and alum and carbonate of soda, which are produced artificially by human ingenuity out of the pre-existing compounds of the mineral kingdom. When the chemist gets hold of these different tissue products and components he submits them to a variety of experiments, and subjects them to the most strange transformations; he performs a simple subtraction by taking away certain constituent atoms and leaving the remainder; or he performs a simple addition by introducing fresh constituent atoms, whether of a similar or a different nature; "On Animal Chemistry." A course of Six Lectures by or he performs a substitution, taking away certain conWILLIAM ODLING, M.B., F.R.S., F.R.C.P. LECTURE 2. Proximate animal and vegetable principles included in the class of organic compounds, together with the various bodies resulting from their natural and artificial metamorphoses-Carbon the characteristic element of organic compounds-Number, variety, and complexity of its combinations with hydrogen and oxygen-Highly complex organic bodies built up of less complex molecules-Salicine formed of saligenine and glucose; populine of benzoic acid, saligenine, and glucose-Occurrence of constituent molecules in an incomplete state-Doctrine of residues-Existence of minute residues of acetic acid and ammonia in acetonitrile, and of oxalic acid and ammonia in cyanogen-Residues of constituent molecules ever ready to regenerate complete and separate molecules by an absorption of water-Aplone molecules possessed of simple constitution, or associated with bodies of simple constitution as members of the same family-Distribution of aplone molecules into series of similarly constituted compounds-Their distribution also into groups of dissimilarly constituted compounds susceptible of mutual metamorphosis-Series of primary fatty acids Acetic, propionic, and butyric groups-Relations of alcohols and glycols to mono- and di-basic acids—Nature of homologous series-Differences and resemblances between stituent atoms and introducing fresh ones in their places; or he effects a more or less complete decomposition, by breaking up the substance into a variety of less complex bodies. Now, all these products into which the chemist transforms the proximate vegetable and animal principles, of which we have spoken, belong to the class of organic compounds. As a rule, they do not pre-exist in living organisms, they are not formed spontaneously in dead organisms, but they result from the skill of the chemist operating upon compounds which were formed at some time or other through the agency of living organisms. Just as the alum and carbonate of soda which the chemist manufactures out of native minerals belong to the class of mineral compounds, so do such substances as chloroform and aniline and cyanuric acid, which the chemist manufactures out of the proximate principles of plants and animals, belong to the class of organic compounds. It is found that all organic compounds, whether of natural or artificial production, contain carbon as an essential constituent, nearly all of them contain hydrogen also, while the great majority consist of carbon, hydrogen, and oxygen. In my last lecture I brought under your notice certain nitrogenous products of tissue metamorphosis, but confining our present attention to such organic bodies as consist of carbon, hydrogen, and oxygen, or of carbon and hydrogen only, I would speak to you, in the first place, of their immense number and variety. If we take any three elements whatsoever, exclusive of carbon, we shall find that by their mutual combinations they very rarely indeed form more than half-a-dozen definite and distinct compounds; but we are acquainted with some thousands of compounds composed solely of carbon, hydrogen, and oxygen united with one another in different quantities and proportions; which thousands of compounds differ most strikingly in their properties, but were all originally produced in living organisms, or made artificially by a transformation of the compounds originally produced in living organisms. In addition to their number and variety, organic or carbon compounds are characterised by the complexity of their constitution, or by the number of constituent atoms of which their respective molecules are composed. If we take any definite mineral substance containing only three different kinds of elementary matter corresponding to the carbon, hydrogen, and oxygen of the bodies now under consideration, we shall find that the number of constituent atoms in such mineral substance very rarely indeed exceeds ten or twelve, never perhaps exceeds twenty; whereas, among organic or carbon compounds, bodies containing hundreds of constituent atoms are not unfrequently met with, a few of which compounds, by way of illustration, are written up on the table before you. First of all we have starch, a compound consisting of 6 atoms of carbon, 10 of hydrogen, and 5 of oxygen, making altogether 21 atoms. Next we have mannite, the crystallisable principle of ordinary manna, of which it forms, I believe, as much as 60 or 70 per cent. It consists, as shown by its formula, of 6 atoms of carbon, 14 of hydrogen, and 6 of oxygen, making altogether 26 atoms. Next we come to the crystallisable bitter principle of willow bark-namely, salicine, which, I am informed by manufacturers, is still largely produced and used as a substitute for quinine. It is characterised, as you perceive, by the red colouration it experiences when acted upon by sulphuric acid, and contains, as shown by its formula, 38 constituent atoms. Next we come to populine, a similar crystallisable principle, much less generally known and less widely distributed. It is found in its leaves and bark of the poplar, and contains 50 constituent atoms; while tannin contains 66 atoms, and cholesterine 71. I may take this opportunity of observing that cholesterine, hitherto regarded as an exclusively animal product, is now known to enjoy an extensive distribution in the vegetable kingdom, having been extracted from peas, wheat, almond oil, olive oil, &c. We pass on to spermaceti, with its 98 atoms, and, lastly, to stearine, with its 173 atoms of carbon, hydrogen, and oxygen. Comparing tri-elementary bodies of this kind with tri-elementary mineral substances in which the number of atoms seldom exceeds ten or twelve, you will see that the compounds presented for our consideration are at first sight of a highly complicated nature. But in the majority of instances a minute chemical examination of these apparently complex organic bodies has led to the conclusion that they are formed, if I may so say, by the agglomeration of certain less complex mole. cules. Taking salicine and populine as illustrations, we find that salicine readily breaks up into the less complex molecules known as saligenine and glucose or grape sugar, while populine breaks up into a molecule of saligenine, a molecule of grape sugar, and a molecule of benzoic acid. I have here a specimen of saligenine or saligenic alcohol, a beautiful crystalline body, which even when in very weak solution is capable of being recognised by its action on perchloride of iron. Thus, on adding tincture of iron to a dilute solution of saligenine, we get a deep purple colour, developed by the mutual reaction of the two bodies, as you perceive. Salicine, then, by an absorption of water, breaks up into the less complex bodies saligenine and glucose, as shown in this equation Salicine. Water. Saligenine. Glucose. Populine. Water. while, under similar circumstances, populine, with its fifty in the molecule of salicine, as shown in the table. C-H2O2 1 Salicine CH12O61 Water. C13H2008 C13H1807 H2O C13H2008 Hence the necessity for the atom of water, which has to be incorporated by the salicine before it can split up into its constituents. We may say, then, that salicine does not contain either saligenine or glucose as such, but that it contains, in a state of combination, a residue of saligenin and a residue of glucose, which residues are, as it were, ever on the alert to take up water, and so produce the separate and distinct molecules saligenine and glucose respectively. If we attempted to represent the composition of salicine graphically, we should not place two complete circles in apposition side by side, thus :— Saligenine. Glucose. residues of three circles conjoined with one another, as in one or other of these figures: Populine. NEWS oxalic acid, and if from the resulting oxalate of ammonia we abstract water, we thereby obtain cyanogen gas, as shown in this table: Name. 1 Oxalic acid The constituent residues existing in salicine and populine form very considerable proportions of the original molecules; but in many instances these residues become extremely small. For instance, by combining acetic acid with ammonia we obtain acetate of ammonia, a salt formed by the direct union of the two complete molecules, acetic acid and ammonia. Under certain circumstances an atom of water may be eliminated from this acetate of ammonia, whereby it becomes converted into acetamide, which by the further loss of an atom of water becomes aceto-nitrile, as shown in these diagrams : In acetamide the residues of acetic acid and ammonia contain only 59 out of 77 parts, while in aceto-nitrile they amount to only 41 parts, or little more than half the weight of the original molecule. Nevertheless, in acetonitrile the two small residues stand apart from another as perfect representatives of, or proxies for, the entire molecules, ready without a moment's notice to regenerate them on the concurrence of suitable conditions. Under a variety of circumstances both acetamide and aceto-nitrile absorb the elements of water with reconversion with acetate of ammonia, a body containing the complete antagonistic molecules, to which the constituent residues of the amide and nitrile alike appertain. Let me give you one additional illustration of this doctrine of residues. Upon applying a gentle heat to certain metallic cyanides we obtain cyanogen gas, which is recognisable by the beautiful violet-coloured flame with which it burns, as you see, at the mouth of the tube. In this experiment the cyanogen gas is being made by heating a metallic cyanide, but it is capable of being produced in an entirely different manner. If, instead of combining ammonia with acetic acid, we combine it with 2 Ammonia (H2N) H&N2 34 Cyanogen (CN)2 C2 90. The formula for oxalic acid is C2H2O4, and its atomic weight is With this we combine two atoms of ammonia, HN, the atomic weight of which is 34. Adding these together, we get 124 for the atomic weight of oxalate of ammonia. When from this we subtract 4 atoms or 72 parts by weight of water, we have left only two atoms from the ammonia, which exist united with one another of carbon from the oxalic acid, and two atoms of nitrogen to form two atoms, or a single molecule, of cyanogen gas, and which amount to only 52 parts out of 124, or to considerably less than half the weight of the original compound. In cyanogen gas, then, the only evidence of the original oxalic acid is carbon, and the only evidence of the original ammonia is nitrogen. Nevertheless, the constituent carbon and nitrogen of this remarkable gas, which in so many of its properties resembles certain of the elementary bodies, are not incorporated with one another, but remain apart, in the same way as do the residues of saligenine and glucose in salicine, and the residues of acetic acid and ammonia in aceto-nitrile. Accordingly we find that cyanogen gas, when dissolved in water, gradually absorbs the water necessary to reform oxalic acid and ammonia, the entire molecules of which the small residues of carbon and nitrogen are but the representatives. In cyanogen gas, no matter how produced, there is a something, however small, pertaining to oxalic acid, a something, however small, pertaining to ammonia. The two residues are not intermingled promiscuously, but remain apart, ever mindful of their distinct individualities, ever anxious to reform the complete and separate molecules from which they sprung. Ac The progress of organic chemistry, then, has led to the conclusion that highly complex molecules are built up of the residues of less complex molecules, which constituent residues, by a direct or indirect absorption of water, are capable of separation from one another, and reproduction in their complete and perfect state. cordingly, we regard highly complex or polymerone bodies as compounds formed by the union of less complex or aplone bodies with one another, the union being attended by an elimination of water. Now, it appears that aplone molecules, of which our constituent residues represent greater or less portions, either have a very simple constitution, or are associated with bodies of a very simple constitution, as members of one and the same organic family. Despite their enormous number, the great majority of these molecules have been already referred to certain definite positions in certain very simple groups or series, and we have every reason to believe that, with increase of knowledge, they will all be referred in a similar manner to groups or series, such as those to which I am pointing. Organic chemistry, then, has achieved this great analytic success. The compounds so elaborately built up by living organisms it has taken to pieces, and the pieces themselves it has arranged into natural series or groups of associated bodies-into series of bodies of similar constitution and similar properties that are not susceptible of mutual metamorphosis, or into groups of bodies of dissimilar constitution and dissimilar properties that are susceptible of mutual metamorphosis. Here, for example, we have a series of bodies, namely, the primary monobasic fatty acids, beginning with formic But in the succeeding table we have three of our primary monobasic fatty acids-namely, the second or acetic acid, the third or propionic acid, and the fourth or butyric acid associated each with a set of bodies dissimilar to the acid, and dissimilar to one another; but all containing the same number of carbon atoms as the fatty acid, and correlated with it and with one another by a susceptibility of mutual metamorphosis, to such an extent indeed, that they may almost be looked upon as varieties of one and the same primitive body. your attention-are, 1st, the monatomic alcohol; 2nd, the monobasic acid corresponding thereto; 3rd, the diatomic alcohol or glycol; and 4th, the dibasic acid corresponding thereto. In the 2-carbon group, for instance, we haveC2HO Alcohol. C,H,O, Glycol. 2 CH,O, Oxalic acid. C2HO2 Acetic acid. The monobasic acid, you observe, differs in composition from its correlated alcohol by containing one additional atom of oxygen in place of two subtracted atoms of hydrogen; while the dibasic acid differs from its correlated glycol by containing two additional atoms of oxygen in place of four subtracted atoms of hydrogen. But even of these four principal members of every complete organic group, by far the most importance is attached to the monobasic acid, which is accordingly selected in preference to the alcohol, glycol, or dibasic acid as the characteristic term or pivot of the group. As a rule, the series of monobasic acids is more complete than that of the other terms; the bodies themselves enjoy an extensive natural distribution either in the isolated condition or in the form of constituent residues; they can be obtained in a comparatively pure state, many of them occurring as commercial products; and their properties, both as individuals and as a class, have been very carefully investigated. (To be continued.) ON LECTURE ILLUSTRATIONS. A Discourse Delivered to the Members of the Chemical (Reprinted by permission of the author from the Journal of the Chemical Society, Ser. 2, vol. iii., p. 156.) (Continued from page 45.) AMMONIA. The method of ascertaining the volume-ratio in which hydrogen and nitrogen combine to form ammonia is less simple than that which suffices for the corresponding study of hydrochloric acid and water. For this purpose we avail ourselves of chlorine, which enables us to withdraw the hydrogen from ammonia, and set free the nitrogen; the experiment has, of course, to be made under circumstances which permit the determination with accuracy of the volume of nitrogen thus separated from a known quantity of ammonia. A glass tube for holding chlorine, and a globe for receiving solution of ammonia, and admitting it, drop by drop, to the chlorine, constitute the requisite apparatus. The glass tube is from 1 to 15 metre long, sealed at one end, open at the other, and marked off by elastic caoutchouo rings slipped over it and clipping it firmly into three equal divisions. The globe (Fig. 8) has FIG. 8. a stoppered aperture above, and a dropping tube drawn out to a narrow orifice below. This tube is fitted with a stop-cock, and passes through a perforated cork, by means of which it can be tightly fixed into the open mouth of the chlorine-tube. The apparatus is thus employed. The long chlorine-tube having been filled with cold water and inverted over a pneumatic trough, with its mouth immersed below the water level, is filled with chlorine gas in the usual way. When full, it is still allowed to stand for about fifteen minutes over the chlorine-delivery-tube, that its interior surface may be quite freed from the chlorine-saturated water that else would remain adherent thereto. The globe, meanwhile, is filled with a strong solution of ammonia, and its stop-cock is turned so that its dropping-tube also may be filled to its very tip with this solution. The cock is then again closed and the globe stoppered; after which it is ready for connection with the chlorine-tube. To effect this connection without admission of air into the chlorine-tube requires some little care and dexterity. The globe has to be immersed in the pneumatic trough, with its dropping-tube upwards, and in this position to be brought beneath the mouth of the chlorine-tube, into which the globe-tube is inserted, and fixed firmly by means of the cork which it carries. In effecting this junction, great care must be taken not to introduce any water from the trough into the chlorine-tube. This tube, with its ammonia-globe joined to it, may now be removed from the trough, and supported in a vertical position, with the globe surmounting it. A single drop of the ammonia FIG. 9. FIG. 11. solution is now suffered to fall from the globe into the chlorine-tube, the stop-cock being opened for a moment for this purpose (Fig. 9). The entrance of this drop into the atmosphere of chlorine is marked by a small, lambent, yellowish-green flame at the drawn-out point of the dropping-tube. Drop by drop, at intervals of a few seconds, the ammonia solution is allowed to fall into the chlorine-tube, the ammonia of each drop being, at the instant of its contact with the chlorine, converted, with a flash of light and the formation of a dense white cloud, into hydrochloric acid and nitrogen. The addition of ammonia must be continued till the whole of FIG. 10. the chlorine present is supplied with hydrogen at the expense of ammonia. To ensure this, the ammoniacal solution is added in excess, a column of three or four centimetres being abundantly sufficient. After a few seconds the interior of the tube is lined with a deposit of chloride of ammonium; this being soluble is readily washed down and dissolved by agitating the liquid in the tube, which now contains the whole of the nitrogen separated, except a little which remains dissolved in the liquid. This small quantity of dissolved nitrogen is easily expelled from the liquid by heat. We are now sure of two points -viz., that the whole of the chlorine has been converted into hydrochloric acid at the expense of the ammonia; and, secondly, that we possess within our tube the whole of the nitrogen thus set free. It becomes our next object to withdraw the excess of ammonia. For this purpose dilute sulphuric acid, which fixes the ammonia, is introduced by means of the globe previously employed to admit ammonia. The nitrogen being thus freed from all intermixed gaseous bodies, has only now to be brought to mean atmospheric temperature and pressure in order to be ready for measurement. The temperature, which had been raised by the application of heat to the liquid, to expel the dissolved nitrogen therefrom, is readily reduced by plunging the tube into cold water. Water must now be admitted into the tube until the pressure inside and outside is brought to a state of equilibrium. This is effected by means of a bent syphon-tube plunging into a cup of water and fixed by a cork into the globe (Fig. 10). As soon as water ceases to flow through the syphon into the tube, all the requisite conditions are fulfilled for obtaining an exact knowledge of the volume of nitrogen; and this, on inspection, is found exactly to fill one of the three divisions marked off on our tube at the outset. Now, bearing in mind that we started with the three divisions full of chlorine, and that we have saturated this chlorine with hydrogen supplied by the ammonia; bearing in mind, moreover, that hydrogen combines with chlorine, bulk for bulk; it is evident that the one measure of nitrogen which remains in the tube has resulted from the decomposition of a quantity of ammonia containing three mea. sures of hydrogen. It is, therefore, clearly proved by thi |