They first endeavoured to afcertain whether the fixed alkali would occafion any earthy precipitate in pure cyder, which, for this purpose, they made themfelves of apples procured from Normandy, according to the feveral modes there practised: fome they made from the juice of the apple alone; in fome, they had added to this the ufual proportion of rain, or of well water; for fome they had pounded the apples in wooden troughs; and for fome, in troughs made of a white calcareous tone, used in Normandy for this purpofe, and there called Pierre de Liais.

On trial with the alkali, they found that it caufed no precipitation in cyder, made either without water, or with the addition of rain water, when the apples had been pounded in a wooden trough; but, when one of ftone had been used for this purpose, a fmall degree of precipitation was obferved; this was very confiderable in cyder which had been made with well

water.

They next examined whether the addition of earthy or calcareous substances would prevent the detection of lead in the cyder by the hepar fulphuris, the vitriolic, or the marine acid; this, after very accurate experiments, they decided in the negative. To the question, whether these trials are fufficient to determine concerning the adulteration of the cyder by preparations of lead, they answer, that when a few drops of the vola. tile liver of fulphur caufes a black, or even a brown precipitate, it is highly probable, and almoft certain, that the liquor contains either lead, or fome other metal; but, as it has not yet been proved that fuch a precipitate may not be occafioned by other fubftances, in themfelves innoxious, and naturally occurring in the cyder, it will be prudent, in cafes where punishment might be inflicted, to proceed to further trial. The only certain mode of doing this, they think, would be to evaporate a confiderable quantity of the cyder; and, having incinerated the extract, to expofe it, combined with borax and fixed alkali, in an affaying crucible, to the action of fire, till it is in a ftate of fufion. By this operation, the lead, if there be any, will be dif covered in a metallic and malleable ftate. If the cyder fhould contain copper, it may be detected by immerging a small iron, bar in it, and leaving it there twenty-four hours, without ftirring the liquor: for the particles of copper, having less affinity with the acid than the iron has, will be depofed on the latter, and form a coating on it, which will give it the refemblance of a. bar of copper. They however oblerve that fuch an adulteration, though highly deleterious in its confequences, cannot arife from interefted views; as, fo far from improving, it gives a difagreeable flavour to the cyder. It muft, therefore, be accidental; and is probably owing to the ufe of copper utenfils for

warming

warming the juice of the apples, in order to quicken the fer

mentation.

On the Decompofition of Sal Ammoniac. By M. CORNETTE.

In decompofing this falt, the principal object is to extract all its volatile alkali; for which purpofe, inftead of mixing three parts of lime with one of fal ammoniac, M. CORNETTE advifes equal quantities of each.

Obfervations on Calomel. By the fame.

In order to avoid the inconvenience arifing from the tedious operation of triturating the corrofive fublimate with quickfilver, M. CORNETTE advises to fubftitute for the latter, mercury diffolved in the nitrous acid, and precipitated by volatile alkali.

Lemeri had afferted that corrofive fublimate might be obtained from a mixture of two parts of fea falt, with one of the precipitate of mercury; but M. CORNETTE, after various experiments, denies this; and fays that, if the fea falt be pure, no fublimate will be produced, nor will it form any combination with the calx of mercury.

Concerning a newly discovered Method of obtaining the Elaftic Fluid which is known by the Appellation of Atmospheric Mofette, and the Production of this Gas in Animals By M. DE FOURCROY.

This elaftic fluid (which the academician thinks is not fufficiently difcriminated by the name of phlogifticated air) was obtained in great purity from the air-bladders of carp: an hundred of thefe, which he broke under a receiver, yielded a volume of this air equal to two French pints: it retained its fishy fmell after paffing through mercury; but loft this entirely on being tranfmitted through water. M. DE FOUR CROY has not had an opportunity of examining the air-bladders of other kinds of fish; but obferves, there is great reafon to prefume, that they all contain the fame kind of gas; which he fuppofes to be generated in the ftomach by the fermentation of their aliments.

Reflections on the Decompofition of Water by Vegetable and Animal Subftances. By M. LAVOISIER.

Previously to his entering on the fubject, M, LAVOISIER reminds his readers of two facts, which he conceives he has already eftablished, and which form the bafis of his theory. Thefe are, firft, that fixed air is a compound of 28 parts of coal, and 72 of the oxygenous principle, or bafis of vital air. Secondly, that water refults from the combination of 15 parts of the hydrogenous principle, or bafis of inflammable gas, with 85 parts of the oxygenous.

Dr. Priestley difcovered that, by repeatedly calcining charcoal, provided it be expofed to the air after every calcination, it may be entirely decompofed into carbonic acid (fixed air) and hydrogenous gas (inflammable air); but there is one circumftance in this experiment, to which, fays M. LAVOISIER, philofophers

Rr 2

have

have not attended; and this is, that the weight of the two elaftic fluids, thus produced, is above three times that of the charcoal calcined. This additional weight muft refult from fome fubftance which the coal imbibes during its exposure to the air; and this fubftance, after fome experiments, which appear to have been made with great accuracy, is pronounced by M. LAVOISIER to be water; and he confiders this circumstance as a proof that, to coal, when heated red hot, the oxygenous principle has a greater affinity, than to the hydrogenous gas.

These phenomena induced M. LAVOISIER to repeat fome of the experiments related by Dr. Hales, in his Vegetable Statics. He diftilled woods and plants of various kinds, and always obtained from them a mixture of fixed and inflammable air. From moft vegetable fubftances, thefe elaftic fluids were produced in nearly the fame proportion to each other, as in the diftillation of water and charcoal; but, from those vegetables which contain oil, a much larger proportion of inflammable air was obtained. This difference is afcribed to the decompofition of the oil; and, f.om the whole of thefe experiments, M. LAVOISIER concludes that a great part of the fixed and inflammable air, produced by the diftillation of vegetables, is an effect of the decompofition of water: that, in vegetables, the coaly matter exifts fully formed; and that their decompofition by diftillation must be ascribed to the affinity of the coal to the oxygenous principle in the water, which, feparating from the hydrogenous, or bafis of inflammable air, unites with the coal, and forms the carbonic acid, or fixed air.

M. LAVOISIER illuftrates this theory by obfervations on the analyfis of fugar, which he here confiders as confifting of the oxygenous, the hydrogenous, and the carbonic principle, which appear to form a triple combination. This combination, effected by vegetation, and not yet imitated by art, is very common in the vegetable kingdom, and is generally known by the appellation of faccharine or mucous bodies. In this kind of combination, the carbonic principle is the moft abundant: the hydrogenous and oxygenous are nearly in the proportions requifite for the conftitution of water. Thus fugar, and vegetable fubftances in general, contain the principles of the carbonic acid, of oil, and of water; but not the fubftances themselves in their specific forms, because thefe principles are not combined by pairs, but form a triple combination.

By this theory, M. LAVOISIER obferves, it is easy to account for the alterations which fugar undergoes in different circumftances: thefe alterations may be effected either by partially, or entirely, fubtracting fome of its conftituent principles, or by addition. Thus, by diftillation, it may be deprived of its oxygenous and hydrogenous principles; but if any process

could

D

could be discovered, by which the oxygenous alone could be fubtracted, and the oil left, which confifts of the hydrogenous and carbonic principles, we should have a solution of one of the most interesting problems of vegetable analyfis,-which this ingenious chemift confiders as not unattainable.

But the eafieft way of effecting these alterations is by addition. If fugar be oxygenated by the nitrous, the oxygenated muriatic acid, or any other process whatever, it will be converted into an acid, the particular nature of which will vary according to the different proportions of the feveral principles of which it is compofed. This property, of being convertible into acids by oxygenation, is common to almost all vegetable and animal fubftances.

Toward the clofe of this Memoir, M. LAVOISIER propofes a new difcrimination of combuftion into ardent, and obfcure or latent, in imitation of Scheele's diftinction of heat. It may be useful to mention this, as it may render his future, memoirs more easily understood. He gives the name of combustion to every operation in which there is a combination of the carbonic and oxygenous principle; and obferves, that this general term may, perhaps, be made to comprise all operations that oxygenate, and that the particular kind of combuftion may be diftinguifhed by fpecifying the circumftances which attend it.

The memoir is terminated with the propofal of a new theory of vegetation, in which this philofopher conceives that nature operates by a double affinity. To this procefs, he obferves, water and the carbonic acid are abfolutely neceffary; these two fubftances decompofe each other in the act of vegetation: the hydrogenous principle feparates from the oxygenous, and unites with the coal, to form the oils and refins, and to constitute the vegetable; while the oxygenous principle, of the water and the carbonic acid, is let loose; and, combining with light, forms oxygenous gas.

On the Nature of that Acid and Saline Subftance, which is extracted from the Cherry, the Currant, the Peach, the Apricot, the Rafpberry, the Mulberry, the Apple, the Pear, the Barberry, and the Pomegranate. By Meffrs. DE LASSONE and CORNETTE.

This tubftance appears to be no other than cream of tartar. On the Carbonic Acid yielded by the Fermentation of Grapes, and the Acetous Acid produced by combining it with Water. By M. CHAPTAL.

From this memoir, which was fent to the Academy by the Royal Society of Sciences at Montpellier, we find that, if diftilled or rain water is impregnated with the carbonic acid, generated by the fermentation of grapes, and afterward expofed to the action of the atmosphere in a temperature not lower than 15 degrees (we fuppofe of Réaumur's fcale), it will, in the

Rr 3

courfe

course of fix or feven months, become very good vinegar. Oxygenous air, admitted to it, is found to accelerate the procefs.

ANATOMY.

Third and Fourth Memoirs on the Anatomical Hiftory of the Tendons, and their Mucous Capfula. By M. DE FOURCROY.

In the former of thefe memoirs, are described the mucous capfulæ of the tendons of the fore arm and hand; and, in the latter, those which belong to the tendons near the articulation of the os femoris with the os innominatum.

NATURAL HISTORY.

Defcription of a new Genus of Plants. By M. FOUGEROUX DE BONDAROY.

This plant, which is originally a native of Louisiana, refembles the Rudbeckia in some of its characters, and the Heliantus in others; in compliment to M. GAILLIARD, a botanift of Charentonneau, it is thus denominated: Gailliardia (pulchella) foliis alternis lanceolatis femi amplexantibus, floribus fubfolitariis ter minalibus purpureoflavis.

On a new Genus of Trees, the Ailanthus Glandulofa. By M. DESFONTAINES.

The tree here defcribed has generally been mistaken for the Rhus fuccedanea, which it refembles in its leaf, though its fructification is very different. It came originally from China; and, by Rhumphius, in his Hort. Amboin. is called arbor cæli. In France, it grows to the height of above 40 feet. Its flower is polygamous, and is thus defcribed: CALIX perfiftens, monophyllus, quinquedentatus. COROLLA petala quinque aperta, verfus bafim canaliculata. STAMINA decem longitudine coroliæ, filamentis tenuibus, compreffis; antheræ exigua, oblonga, verfatiles. STYLUS us, lateralis, ftigma patens, germina tria quinque, compressa, furfum attenuata. PERICARPIUM membranaceum, oblongum, acutum, planum, altero latere emarginatum. SEMEN unicum, lenticulart, ofeum, laterale. FOLIA alterna, impari pinnata.

ASTRONOMY.

On the firft Comet obferved in 1786. By M. MESSIER.

This comet was difcovered, at the Royal Obfervatory, by M. MECHAIN, January 17, at 6 35′ 38′′ mean time, in the left fhoulders of Aquarius, near the ftar 3. Its right afcenfion was 320° 52' 37" and its declination 5° 11' 11" fouth. On the 10th of January, it was obferved by M. MESSIER at 67' 44" true time, when its right afcenfion was 318° 45′ 28′′, and its fouthern declination, 6° 53′ 33′′. The nucleus appeared bright, and furrounded with a nebulous vapour, but without any tail. As we have hitherto only these two observations of it, its elements cannot be afcertained,

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