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cluded that the deceased had not taken any dose of either of these poisons for at least three weeks before her death. In his opinion, therefore, her death could not have arisen from poison. The symptoms mentioned by Dr. Barclay were just such as antimony or arsenic would cause; but the result of the analysis showed that those poisons were not administered. Death could only be attributed to those poisons when traces of them were found. Dr. Barclay said that, after hearing the result of the analysis, he could only attribute the deceased's death to natural causes. Dr. Taylor, in answer to the coroner, said that Professor Rudersdorf, of Holland, took part in the analysis, and he was of the same opinion as witness-that no arsenic or antimony could have been taken by her for weeks before her death, and therefore they could not have caused death. The coroner having summed up, the jury returned a verdict of 'Death from natural causes."

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The Case of Reputed Poisoning by Atropine. -The trial of Mr. Sprague took place at Exeter on the first of this month. We give only Mr. Herapath's evidence. He said: I am a professor of chemistry, residing at Bristol. On the 19th July I received a wooden box, corded and sealed. The seals were intact. In the box was a pie-dish, which I produce, with its contents. There is in it the fore leg of a rabbit and a small piece of beef. The meat when I received it was not putrid. When meat is cooked it decomposes in a different way. While the albumen is in a soluble state you get sulphuretted hydrogen and ammonia liberated; when the albumen becomes solid by cooking, the meat dries like a mummy and becomes covered with mould, which is not poisonous. In the box was also a jar with vomit and a parcel of flour. I first wrote for the symptoms to give me some clue as to the mode I should pursue; but before I had the answer I received a letter stating that it was right I should know that a mustard emetic had been given to one party, and sulphate of zinc and ipecacuanha to the others. Before I received that I had intended to begin with the vomit. I received letters from Dr. Gervis and Mr. Caunter, clerk to the magistrates, dated July 18, in which the former said he believed the parties had suffered from some vegetable narcotic poison, such as atropine or morphine. Witness then stated in great detail the course he pursued in his analysis of the matter which he had obtained by introducing the leg of the rabbit into dilute hydrochloric acid, and allowing it to soak therein, in order that any narcotic poison in the rabbit might be dissolved out. The tests he had used, he said, he had applied also to a solution of atropine which he himself made, and with precisely similar results. Herapath continued-I have no doubt whatever that there was atropine in the contents of the pie. I have also examined the vomit, and though the indications were not so good, I have no moral doubt there was atropine there. There was none in the flour; but I obtained some from the scrapings of the surface of the leg of the rabbit. If a rabbit had died from taking atropine I should not expect to find the poison in the surface of the leg, but in the liver and stomach. In the present case I should expect to find it in the brain and the sheath of the spinal marrow. Cross-examined: If the rabbit had eaten of belladonna I should have expected to find the poison in the liver and the brain. I have found both metallic and vegetable poisons in the livers of animals. All parts of the belladonna plant, I believe, are poisonous. I have heard of dogs eating grass, but never belladonna. I have never heard of any animals but goats eating hemlock, and I do not know what the effect on them is. I received the matters on the Wednesday, but I did not find the atropine until the Sunday; I had twenty or thirty experiments to go through. I had to satisfy myself that I was right, and the first thing to do was to separate all foreign matters from the poison. The first object of a toxicologist is to

Mr.

eliminate the poison. I had first of all to find what substances were with the poison, and then to take the proper solvents to remove those matters. I wrote to be supplied with the symptoms-as I always do-immediately I received the box. If I had not had the symptoms I should have had a great deal more difficulty in finding the poison. Perhaps I should not have found it at all. The poisons are divided into several classes, and the symptoms would show me which of these classes I should test for. It would be useless for me, as there are at least 200 poisons, to commence a series of experiments which might exhaust the material long before I had finished the tests. In the interval between the Wednesday and the Sunday my tests gave me indications of one of the three cerebro-spinal poisons-atropine, daturia, and aconitina but the matter was not sufficiently clear of foreign mixture to be quite certain. Atropine and daturia, though prepared from different plants, are the same poison. I believe atropine has never been eliminated from an animal substance before. It has never been communicated before to the scientific world, but it is now through my evidence, and I shall be put on my trial quite as much as the prisoner. The poison, I think. must have been put in the pie while making, or on something that was put in the pie. I cannot say whether it was put in before or after the pie was cooking. The crust might have been lifted while it was hot, and the atropine put in; but my idea is that it was put in before the pie was cooked, and dissolved in the cooking.

The cross-examination of Professor Herapath was protracted to a great length, but without eliciting anything more of a material character, or shaking the learned gentleman's positive testimony that there was atropine in the pie. The prisoner was acquitted. In reference to this case Dr. Ogle has written to the Times mentioning some experiments of Runge, who found that rabbits could feed on belladonna leaves without being poisoned.

To Prevent Oaken Barrels from Colouring Spirit.-Dissolve one part of ammonia alum and two parts of sulphate of iron in 100 parts. Well wash the casks with this solution boiling hot, and allow them to stand for 24 hours. Then rinse out the casks well, dry them, and finally give them a washing with a thin solution of silicate of soda.-Chem. Cent. Blatt., No. 25, P. 400.

Mercurialised Collodion.—The following application is recommended for venereal warts :-Bichloride of bichloride, in fine powder, is shaken up with the collodion, mercury, 25 centigrammes; collodion, 52 grammes. The and the mixture is applied with a camel's hair brush. One or two applications will effect a complete cure.

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Vol. XI. of the CHEMICAL NEWS, containing a copious Index, is now ready, price 118. od., by post, 118. 6d., handsomely bound in cloth, gold-lettered. The cases for binding may be obtained at our Office, price 1s. 6d. Subscribers may have their copies bound for 2s. 6d. if sent to our Office, or, if accompanied by a cloth case, for Is. Vols. I. and II. are out of print. All the others are kept in stock. Vol. XII. commenced on July 7, 1865, and will be complete in 26 numbers.

Greville Williams' "Chemical Manipulations."
W. J. Grey.-A table for making the calculations is given in Mr.

T. C. (Bury).-Sulphate of lime is generally obtained in that form from acid solutions. J. H.-Common salt is often used for the purpose, and, we believe,

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SCIENTIFIC AND ANALYTICAL CHEMISTRY.

Experiments on the Precipitation of Phosphoric Acid as Phosphomolybdate of Ammonia, by Dr. R. FRESENIUS.

THE author has studied the influence of various reagents on the estimation of phosphoric acid by precipitation as phosphomolybdate of ammonia, and has come to the following conclusions:-His experiments were made with the same solution of phosphate of soda, 10 c.c. of which precipitated and weighed as pyrophosphate of magnesia gave as a mean o'0209 of phosphoric acid. The determinations with the molybdenic solution were controlled by a re-determination of the phosphoric acid in the precipitate as pyrophosphate of magnesia.

Ten c.c. of the phosphate of soda solution precipitated by the molybdenic solution gave o'0206 phosphoric acid, or 99 per cent. of the amount really present.

Nitric acid, even when in very large excess, the author found not to interfere with the result.

Hydrochloric acid, when in large excess, partially or even completely hinders the precipitation. When the amount of the acid is as low as 33 per cent. of the liquid, the result comes near the truth, but is always too low.

The simultaneous presence of much nitric and hydrochloric acid completely prevents the precipitation.

Sulphuric acid, perchloride of iron, and chloride of aluminium, have but little influence on the amount of precipitate. Thus the 10 c.c. of phosphate of soda solution, as above, gave, in the presence of sulphuric acid, 0.0208 of phosphoric acid, and in a second experiment o'ozo5. With perchloride of iron the same amount of phosphate of soda solution gave o'0207 phosphoric acid. The pyrophosphate of magnesia solution obtained from this precipitate showed a trace of iron with sulphocyanide of potassium.

In the presence of a considerable proportion of salammoniac the amount of precipitate was always a little too low; as was the case when the solution was much

diluted.

The author made another series of experiments. A solution in which the amounts of iron and aluminium greatly exceeded the proportion of phosphoric acid, as when the acid is estimated in a hydrochloric extract of a soil. He prepared a solution that contained in a litre 20 grammes of iron, as chloride, 2 grammes of aluminium, as chloride, and oor gramme of phosphoric acid. By the direct precipitation of 100 c.c. of this solution with the molybdenic solution, o'00991 of phosphoric acid was obtained. 100 c.c. of the same solution evaporated to dryness on a water-bath, and the residue dissolved in the smallest amount of nitric acid, also gave 0.00991 of phosphoric acid. 100 c.c. evaporated, and the residue dissolved in the least possible amount of hydrochloric acid, gave only o'00972 phosphoric acid.

The above results will serve to guide analysts in the use of the process mentioned for determining phosphoric acid. We ought perhaps to state that the author prepares his molybdic solution by dissolving one part of molybdic acid in four parts of ammonia, sp. gr. o.96, and adding to the solution fifteen parts of pure nitric acid, sp. gr. 12. In making the determinations, the phosphoric and molybdic solutions are mixed hot, and are

* Abstract from Zeitschrift für Analyt. Chem., No. 4, 1864, p. 447. VOL, XII. No. 298.-AUGUST 18, 1865.

kept at 65° C. for six hours, and then allowed to stand for twenty-four hours. The precipitate is then collected on a filter and washed with equal parts of the molybdic solution and water.

Reactions of Gelatine, by M. CAREY LEA, Philadelphia I HAVE been occupied at times for some years past with. here to describe a new reaction which I have observed, the study of this very interesting substance, and propose and which constitutes, I believe, the first coloured reaction described as produced between pure gelatine and a perfectly colourless reagent. It is true that the precipitate produced in gelatine solutions by gallotannic acid is much deeper in colour than the precipitant. But the straw yellow colour of gallotannic acid naturally leads to the expectation of coloured combinations, whereas in the case I am about to mention, the precipitant is colourless, and the production of a marked colour seems to point to a more complete action than that of simple combination.

When a piece of gelatine is dropped into an acid solu. tion of pernitrate of mercury, it gradually assumes a strong red colouration, and after a time dissolves in it completely, at ordinary temperatures, to a fine red solution. This solution deepens a little if boiled for some

minutes.

By chlorate of potash the hot solution is quickly decolourised, and passes to a pale dirty yellow.

of time for its production, which cannot be replaced by This red colouration seems to require a certain amount heat. If a piece of gelatine be immersed in the solution of protonitrate and boiled for some minutes it is dissolved, but the solution thus obtained is not red, but yellowish.

is not more delicate. It is only striking when tolerably It is to be regretted that the reaction here described strong solutions of gelatine are employed. When the solution is very weak, as, for example, if the gelatine constitutes only one-half of 1 per cent. of the mixed liquids, the limit of the delicacy of the test is reached. Such a solution by standing twenty-four hours exhibits a light but distinct pink colour. Although this delicacy is not what may be desired, still colloid organic substances are so comparatively difficult of qualitative devalue. tection as a general thing, that the method is not without

A neutral meta-gelatine was prepared in the following The experiment was next extended to meta-gelatine.

manner :

Gelatine was set to swell in cold saturated solution of oxalic acid, and then a moderate heat was applied for a sufficiently long time for the mass to remain quite fluid when cold. It was then agitated with precipitated carbonate of lime until the whole of the oxalic acid was got rid of. Meta-gelatine prepared in this way was kept for months in a corked phial, in a warm room, without fluid as water; perfectly neutral, and almost insipid to showing any disposition to putrefy. It was almost as the taste.

With this meta-gelatine, the red colouration was produced even more decidedly than with ordinary gelatine. The addition of the acid solution of pernitrate of mercury produced at first a whitish flocculent precipitate, which, by standing, acquired a strong red colour, as did the supernatant liquid.-American Journal of Science and Arts, vol, xi., No, 118, *.

On the Supposed Nature of Air prior to the Discovery of Oxygen, by GEORGE F. RODWELL, F.C.S.

(Continued from page 64.)

In the 17th experiment Boyle describes the way he adopted to determine the degree of exhaustion of a receiver. In his first attempts he placed a securely closed bladder containing a small quantity of air in the receiver to be exhausted, and considered the exhaustion good when the bladder was fully inflated. He afterwards measured the exhaustion by a small U tube, closed at one end, which was filled with mercury, and a small bubble of air then passed into the closed end. The tube was placed in the vessel to be exhausted, and the rarefaction judged of by the expansion of the bubble of air. Experiment 18. "About au easie way to make the pressure of the air sensible to the touch of those who doubt it." In order to effect this, Boyle constructed a small brass receiver of the form of a truncated cone, open above and below; the upper orifice was 14 inch diameter, and the lower, which stood on the air pump plate, 24 inches. "The person," he writes, "that would not believe the pressure of the air to be near so considerable as was represented was bidden to lay the palm of his hand upon the upper orifice, and being ordered to lean a little it, that so the lower part of his hand might prove a close cover to the receiver, one exsuction of the air was made by help of the pump; and then upon the withdrawing of the greatest part of the pressure of the internal air, that before counterbalanced that of the external, the hand being left alone to support the weight of the ambient air, would be pressed inwards so forcibly that, though the stronger sort of men were able (though not without much adoe) to take off their hands, yet the weaker sort of tryers could not do it (especially if by a second suck the little receiver were better exhausted), but were fain to stay for the return of the air into the receiver to assist them."

upon

Experiment 31. A magnet was loaded with the utmost weight it could carry. It was then introduced into a receiver. On exhausting, the weight still continued to be supported.

Experiment 32. A small brass syringe was taken, and the piston forced to the bottom of it, the orifice of the syring was then closed securely; when the piston was raised, great resistance was felt, and on releasing it the pressure of the air of course caused it to return to its former position. It was now placed in a receiver, and the piston handle placed in communication with the stopper of the receiver by a piece of string, so that by turning the stopper the string was shortened, and the piston consequently raised; when the receiver was exhausted, the piston was casily raised to the top of the syringe, when it was kept in that position, and air admitted, the piston was immediately impelled to the bottom of the syringe, and the string which held it was broken. The above experiment was varied by suspending a closed syringe in the air pump receiver by its piston rod, and attaching a weight to the barrel not sufficient to draw it down-in other words, not sufficient to overcome the pressure of the air on the area of the piston. On exhausting, the barrel immediately descended, and when air was admitted it rose to its former position, dragging up the weight with it.

Experiment 34. A syringe was placed in a receiver in such a manner that its piston could be raised when the receiver was exhausted; a glass tube was fitted to its nozzle, and its lower orifice caused to dip into mercury; on exhausting, and raising the piston, the mercury was

observed not to follow it, but when air was admitted it immediately rose to the piston.

Experiment 35. A cupping glass was attached to the palm of a person's hand by the usual method; the hand was then made to act as a cover to a small receiver; on exhausting, the cupping glass fell down.

Experiment 40. Some small feathers were detached from the top of a tall receiver; before exhaustion they fell slowly, and wavered in their course; after exhausting the receiver, they fell "like a dead weight."

Experiment 43. Sugar was submitted to friction in an exhausted receiver, and was found to emit light as readily as in air.

Experiment 45. In order to ascertain whether heat could be produced by friction in an exhausted receiver, a concave piece of brass was fixed to the air pump plate, a convex piece of the same metal was connected with a rod which passed air-tight through the cover of the receiver, and could be turned by a handle, when the two surfaces were rubbed together in vacuo, a considerable amount of heat was found to be produced.

Experiment 46. Quicklime was slaked in an exhausted receiver, and heat was found to be produced as readily as when it was slaked in air.

With this experiment we conclude our notice of Boyle's second pneumatical treatise; there are altogether fifty experiments, of these we have noticed the most important, omitting those which are only slightly modified forms of experiments described in the former treatise.

PHARMACY, TOXICOLOGY, &c.

On Tobacco, by FERDINAND F. MAYER, of New York. NUMEROUS as have been the essays published both on the chemical and the therapeutical relations of Nicotiana Tabacum and its narcotic principle, they refer for the greater part to the leaf of the usual brown colour and well-known irritating ammoniacal odour, which is the form officinal in all Pharmacopoeias; for, though universally cultivated, the plant is never prepared specially for application in medicine like other narcotics, partly because of the commercial article being still more readily obtainable, but in yet greater measure, because the fresh and the dried green leaves have very generally been considered, if not devoid, to be at least of very feeble developed medicinal virtues. Only those of another species, N. rustica, are occasionally used fresh as an external application, and are, or were formerly officinal in some European Pharmacopoeias.

There is so striking a difference in many of the outer properties of the officinal plant, in the green and the cured condition, as to offer in itself some grounds, for what was formerly universally and is even now very generally believed, that the volatile alkaloid on which the activity of brown tobacco is supposed to depend was not present as such in the living plant, but that it is a posthumous product formed entirely or partly during that incomplete fermentation which it undergoes in the hands of the cultivator, the "bulking" of tobacco. For, the fresh plant possesses none of the peculiar heavy odour of the other narcotics. Nor is the dried leaf much more pungent than a common herb. Its infusion, like the fresh juice, has an acid reaction, and contains no ammonia. Its colour is pale green, with here and there some brownish patches; but the taste is decidedly acrid. and certainly only differs from that of the commercial article by the absence of free ammonia. It also contains a large proportion of nicotina in combination.

This had been pointed out as early as 1809 by Vauquelin, in the report made by him with Robiquet and U.S. Consul Warden. It was again shown to be present by Posselt and Reimann, in 1831, in plants of several species grown near Heidelberg, and again in 1836 by Henry and Boutron-Charlard; and in 1831 A. Buchner, sen., prepared some nicotina from the seeds. Lastly, our excellent Proctor, in 1858, proved without doubt the presence of the alkaloid at least in the fresh leaves; and the authority on whose credit the origin by fermentation had been maintained, corrected the statement made there as early as 1844, upon the occasion of a paper on tobacco smoke by A. Melsens, in a note to which (Annalen der Chemie und Pharmacie, vol. 49, p. 359) Liebig mentions that "at the Giessen Laboratory not inconsiderable quantities of the alkaloid had been obtained from the fresh plant."

the matter, especially in regard to the seed, be again made the subject of research, and since this investigation has been undertaken by me, fresh interest has been imparted to it by the publication of a paper on the same subject in the Vierteljahresschrift für Pharmacie of April last. The author of this essay found a volatile principle, which on the strength of its odour he assumes to be trimethylina (pseudo-propylamin,) said to have originated from a fermentable substance contained in the sced, and he believes that Buchner mistook a mixture of ammonia and trimethylina for nicotina.

In order to avoid, if possible, errors arising from 1cliance upon such deceptive characteristics as odour, and because in the examination of the plant at least two bases are met with possessing a pungent and somewhat similar odour, I have made use, besides the usual distinction resting on the percentages of platinum in the double salts of the volatile bases, of the following table founded on previous and new observations of Nessler, Winckler, Proctor, myself, and others:-Principal Reactions of the Medicinal Volatile Bases. (w. watery solution; s. = salts, or acid solutions)

With such evidence the presence of nicotina in the plant, through its various stages, may be accepted as satisfactorily proved. Yet Mr. Proctor suggested that

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ish-red precipi red precipitate. tate.

e. and 8. Orange- Brown solution; w. and 8. Brownish w.ands. Pale brown. and s. Brownish
coloured precipi- afterwards a pre- red precipitate.
tate.
cipitate, or none.
Neutral and alka No precipitate.

s. No change.

Potassium

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line solutions;

tannin if concen-
trated.

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precipi. White precipi No precipitate.

8. No precipitate; s.
with caustic KO
orange to brown
precipitate.

. White to yellow
precipitate, solu-
ble in excess.

tate.

A loose mass of pale yellow crystal, very soluble in excess of iodide" of potassium, and caustic KO; decomposed by shaking with

water.

w. Precipitatewhich
re-dissolves in ex-

cess.

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w. Solution; white w. and s. Yellowish w. and s. Same as w. and s. Pale yellow

precipitate, solu-
ble in excess and
in KI, reproduced
by KO, but re-
dissolved by ex-
cess of the sime.

precipitate, some-
what soluble in
excessofre-agent,
and readily solu
ble in caustic KO.

nicotiua.

precipitate, little soluble in excess of re-agent or of caustic KO.

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w. Reddish-yellow w. Greyish-yellow, a. No precipitate. w. Yellowish, curdy, w. Whitish, insolu. Pale yellow, inprecipitate.

insoluble in by
drochloric acid.

Very soluble; mixes Very soluble; mixes. Scarcely soluble;
with water.

floats.

* In the watery solution, except of anilina, à white precipitate. Course of Proceeding.—The volatile alkaline substance having been obtained in form of a concentrated solution in water, and in part as solution in hydrochloric acid, a drop of a solution of iodide of potassium saturated with iodide of mercury is added to part of the acidulated solution. Either,

I. It produces no precipitate.-Absence of trimethylina, nicotina, lobelina, conia. To a portion of the unchanged solution add caustic potassa in slight excess, which causes a precipitate. It is

Whitish and pulverulent: anilina.

Reddish to brown and flocculent: ammonia.

II. A precipitate is produced.—Add excess of the solution of mercury.

1. The precipitate re-dissolves very readily trimethylina.

insoluble in HCI.

ble in HCl.

Little soluble;
sinks.

Little soluble;
floats.

soluble in HCI.

Little soluble; floats.

† Distinct precipitate only from nicotina, which dissolves on heating.

2. The precipitate is scarcely soluble in excess of mercury, but readily, while fresh, in caustic potassa: nicotina, conia. Apply the specific tests.

3. The precipitate is scarcely soluble in either: lobelina.

Ammonia.-Its reactions, as, for instance, that with cobalt, aro rendered indistinct by the presence of carbonic acid.

Commercial trimethylina (the medicinal propylamin) is probably never free from ammonia, which is readily ascertained in an acid solution by the test with iodohydrargyrate and caustic potassa. It should be perfectly colourless and clear, of a faint odour of ergot rather than of herring, and must burn like alcohol.

Conia, when quite pure, is colourless, and has a peculiarly sweet, but rancid or somewhat musty odour. Lobelina resembles it in any respects; has an herbaceous odour, recalling that of Prussic acid. The alkaloids tested were freshly prepared for the experiments by the method described further on for nicotina.

(To be continued.)

PROCEEDINGS OF SOCIETIES.

COLLEGE OF PHYSICIANS.

Wednesday, May 3, 1865.

-that acetic acid C,HO, for instance, was associated with the less oxidised bodies, olefiant gas C,H,, alcohol C2HO, and aldehyde C,H,O, as well as with the more highly oxidised glycolic and oxalic acids, C,H,O, and C2H2O respectively-to such an extent, indeed, they might all be regarded as varieties of one and the same primitive

"On Animal Chemistry." A course of Six Lectures by molecule. I further went on to say that the complex WILLIAM ODLING, M.B., F.R.S., F.R.C.P.

LECTURE 3.

Recapitulation-Statical and dynamical aspects of organic chemistry-Destruction and construction of constituent aplone molecules-Tendency of oxidation to produce molecules with fewer and fewer carbon and hydrogen atomsFinal production of carbonic anhydride CO2, and water HO-Destructive or analytic phase of organic chemistry -Natural synthesis of organic compounds attended by deoxidation-Liberation of oxygen by growing vegetables -Tendency of deoxidation to combine separate carbon and hydrogen atoms into complex molecules-Vegetable tissue and secretion formed by deoxidation of carbonic anhydride and water-Imperfect knowledge of intermediate products -Formation of nitrogenised tissues - Ammonia in its relations to plant-life-Correlations of ammonia, nitrous acid, and nitrogen-Deoxidation of nitrous acid by plants -Manurial equivalency of nitrous acid and ammoniaExistence of nitrogen in natural organic products as a residue of ammonia-Artificial synthesis of organic bodies -Combination of constituent molecules with one another -Elementary formation of constituent molecules-Historical remarks on organic synthesis-Alleged incompetency of chemical, and necessity for vital action-Artificial production of all organic compounds by purely chemical means-Kolbe's indirect formation of acetic acid from carbon, hydrogen, and oxygen, in 1845 Subsequent advances by Berthelot and others- Oxidation of hydrogen into water, and of carbon into carbonic anhydride-Evolution of light and heat-Deoxidation of water and carbonic anhydride into hydrogen and carbon-Similar separations of carbon and hydrogen effected by living plant and by artificial processes-Comparison of deoxidising vegetal and oxidising animal functions-Nature of forces concerned in respective actions.

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The acids of these two series presented, I told you, a marked parallelism in their constitution, seriation, and properties; and, moreover, when submitted to the action of the same chemical reagents, underwent precisely similar metamorphoses. I dwelt still more upon the mutual resemblance manifested by consecutive members of the same series, and pointed out that even the most remote members were distinguished from one another by gradational differences only. I observed, also that each one of these primary monobasic acids, fatty or aromatic, was associated with a more or less complete set of congeners, which differed from it in constitution and properties, but were correlated with it by the circumstance of their containing the same number of carbon atoms, and still more markedly by their derivation from, and convertibility into it and one another

tissue products of the animal and vegetable kingdoms were built up of the residues of these fatty and aromatic acids, and of their respective congeners; so that upon breaking up such tissue products into their constituent molecules, we were, in the great majority of instances, able, even at the present time, to refer the constituent molecules to their appropriate positions in certain definite series and groups, and had every reason to believe that with increasing knowledge we should be able to make the assignment in every instance. Again, in my first lecture, I pointed out to you that organic chemistry had a statical aspect which related to the composition of bodies, and a dynamical aspect which related to their changes of composition.

Now, in all that I have hitherto observed, I have had regard principally to the statical aspect of the question. I have, indeed, glanced at the mutual metamorphosis by oxidation and deoxidation of compounds belonging to the same natural group, and have referred more fully to the combination of different residues with one another in forming complex tissue products, and to the separation of the completed residues from one another in the breaking up of these products; but I have not considered the mode in which the primary constituent molecules are themselves produced, or yet the mode in which, when once produced, it is possible for us to destroy them, and to these points I will now direct your attention.

If we treat the more complex members of our series of fatty acids, for instance, with powerful oxydising agents, we obtain bodies in which the number of the constituent atoms of carbon and hydrogen becomes progressively less and less, until we arrive at bodies containing only two, and finally at bodies containing only one atom of carbon. In some cases these successive oxidation products are found to contain the same number of atoms of oxygen as the bodies from which they were produced, though in the majority of instances they contain a greater number, and, whether they contain the same or a greater number of consequently belong to more oxygenised series. But oxygen atoms, we find that the number of atoms of carbon and hydrogen becomes gradually less and less, or that the molecules pertain to simpler and simpler groupings. For example, the following intermediate compounds, among many others, have been successively obtained by oxidising stearic acid C17H3402, with nitric acid of moderate strength :

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The tendency of oxidation, then, is to separate the constituent carbon and hydrogen atoms from one another until at last there is left only the most stable mono-carbon compound known to chemists, namely, carbonic anhydride, or, as it is frequently called, carbonic acid. No matter what the complexity of the original molecule, the chemist eventually succeeds in transforming it by oxidation, through a series of less and less complex molecules, into carbonic anhydride, or oxide of carbon, on the one hand, and water, or oxide of hydrogen, on the other-the identical bodies out of which the vegetable organism directly, and the animal organism indirectly, constructs

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