[64]

XIII. Extract of a Memoir upon the Products which result from the Action of the Metallic Muriates, the Oxy-mu

riatic Acid, and the Acetic Acid, upon Alcohol. By M. THENARD *.

M. THENARD demonstrates in this memoir, that the metallic muriates form with alcohol only a very small quantity of ether; that this ether, which is at first dissolved in a great quantity of alcohol, may be separated from it by a gentle heat in the form of gas, particularly by means of warm water, which seizes upon the alcoholic part, and puts the etherated part at liberty to a certain point; that this ethereated gas has a very great analogy to that obtained with the muriatic acid and alcohol; that in both cases it has the same smell and taste, the same solubility in water, the same manner of burning with a green flame diffusing vapours of the muriatic acid, although before the combustion no reagent indicated the presence of the gases; in short, that they only differ from each other by the etherated muriatic gas not liquefying, except at a heat of 12.5 of the centigrade thermometer, while the other becomes liquid at + 165. This difference being very slight, M. Thenard thinks we can no longer hesitate to acknowledge the nature and mode of formation to be the same in both: thus in the metallic muriates, it is only the excess of acid which acts upon the alcohol, &c. that for this reason alcohol cannot be converted into ether except by a great quantity of metallic muriate, and that this conversion is the easier, the greater excess of acid the muriate contains, and the more it is soluble in alcohol: the muriate of tin therefore will succeed better in this operation than any other. In all cases the oxide of the muriate is not de-oxidated, and a portion only of this oxide is precipitated.

Proceeding to consider the action of the oxy-muriatic acid upon alcohol, he shows that in the re-action of these two bodies upon each other, which is very brisk, almost all the oxy-muriatic acid is decomposed, and that much water is produced, plenty of muriatic acid, undecomposed alcohol,

* From Ann. de Chimie, tom. Ixi. p. 308.

a great

a great quantity of oily matter thicker than water, having a cool taste like mint, and a peculiar smell completely diffe rent from that of ether: further, a small quantity of carbonic acid, a matter easily charred, and probably acetous acid, but no ether:-that the oxy-muriatic ether of Scheele is merely muriatic ether properly so called, when made of a mixture of alcohol, muriatic acid, and black oxide of manganese; or of muriatic ether and sulphuric ether, when made with the black oxide of manganese, sea-salt, alcohol, and sulphuric acid :-that Pelletier's is also of this nature, since he made it by using the foregoing mixture; and that the oxy-muriatic ether said to be obtained by passing the oxy-muriatic acid through alcohol, is nothing else than a solution in alcohol of a greater or less quantity of oily matter. We may even separate the oil from the latter by means of water, and we re-form it all at once by dissolving this oil in a determinate quantity of alcohol.

The novelty in this part of the author's labours does not consist in this formation of oily matter, water, acetous: acid, &c.; for Scheele, in his Memoires de Chimie, speaks of the oily matter; and M. Berthollet, in the Memoires de l'Academie for 1785, speaks of this matter, and besides of water, acetous acid, &c., as produced in this operation. M. Thenard's claim to novelty consists in his having proved* that the oxy-muriatic acid could not with alcohol form ether; and he has explained why Scheele and so many other chemists happened to obtain it.

In the last place, being anxious to examine the formation of the acetic ether, M. Thenard mixed together 120 grammes of highly concentrated alcohol, and 120 parts of acetic acid, of an acidity determined by the quantity of potash required by this acid for its saturation; he distilled this mixture, cohobated it twelve times, and thus sensibly decomposed the whole of the alcohol employed, and 66.16 grammes of acetic acid, representing 32 grammes of dry

* M. Berthollet, in the Memoires de l'Academie for 1785, has even an-, nounced that the muriatic acid and alcohol produce but very little ether; and we may perceive that he is inclined to regard this small quantity of ether as foreign to the re-action of these two bodies. 1

Vol. 30, No. 117. Feb. 1808.

E

acid,

acid, or as it exists in the acetite of potash well melted. About 120 grammes only of acetic ether were formed, however, although no gas was liberated; and the operation when terminated presented a loss of seven grammes only: from this M. Thenard is led to think that a portion of the oxygen of the acetic acid is combined with a portion of the hydrogen of the alcohol, while the other principles of the acid and those of the alcohol unite to constitute ether. Otherwise, if no water was formed, it would be necessary, in order to account for this operation, to admit that the best rectified alcohol contains nearly one-fifth of its weight of water, which is scarcely probable. This ether has a pleasant smell of ether and acetic acid, and yet it neither reddens turnsole tincture nor turnsole paper; it has a taste peculiar to itself, and very different from that of alcohol. Neither its specific gravity nor its tenuity, has been as yet exactly taken; all we know is, that it is lighter than water, as it floats above it, and more turbid than alcohol. Water seems to dissolve more of it than of the sulphuric ether. It burns with a yelłowish white flame, producing an acid, which is probably the acetic. Finally, in a sealed flask, it does not seem to alter upon standing for a length of time; at least M. Thenard had a six months experience on this point.

XIV. Upon a peculiar Property in Camphorated Water. By M. CADET*.

THREE years ago a surgeon in Madrid announced that the carbonic acid favoured the solution of camphor in water, and that the water had very remarkable medicinal properties in diseases of the bladder. Leaving it to physicians to judge of this matter, I was merely desirous of ascertaining the chemical, fact. I made a solution of camphor in distilled water, and another in water saturated with carbonic acid by Mr. Paul's method, in order to estimate the quantity of camphor dissolved. I weighed the camphor before and after the solution, and I found that the distilled water had absorbed 16 grains of it per pint, and the carbonic acid only * From Ann, de Chimie, tom. Ixii. p. 132.

15 grains.

15 grains. As I had been obliged to filter the liquors and to dry the filters, I thought that the camphor not dissolved must have lost its weight by evaporation, and that the ba lance did not give me the just quantity absorbed by the water: I therefore sought for a reagent, which evinced to me the presence of camphor in the water.

I found that potash precipitated the camphorated water, while soda or ammonia did not affect it; but the potash must be pure and caustic. If it contains carbonic acid, it does not precipitate the camphor; and if after having precipitated it we expose the vessel to the air, the liquor absorb ing carbonic acid resumes its transparency.

Here, therefore, is a new method of distinguishing potash from soda. Camphorated water is in this respect a more certain reagent than the nitro-muriate of platina, and more easily procured. But the metallic salt is more convenient, as it precipitates the carbonate of potash.

On trying by caustic potash camphorated water charged with carboni..cid, I obtained no precipitate, except by put ting in a great excess of alkali : this precipitate did not seem to be greater than that obtained in distilled water. I think, therefore, that carbonic acid does not sensibly favour the solution of camphor in water; but it at least results from these experiments, that the water does not merely charge itself with the aroma of the camphor, as some chemists think, and that this concrete volatile oil is dissolved in a proportion sufficient for the purposes to which it is applied. When the camphor is reduced very small by trituration with some drops of alcohol, water takes up more of it than 16 grains per pint, and some chemists have dissolved even 30 grains.

XV. Letter from GAVIN LOWE, Esq., on the Comet of 1807..

SIR,

To Mr. Tilloch.

THE Comet that made its appearance about the latter end of last September, and continued visible during the three succeeding months, has no doubt been carefully and assiduously observed by the astronomers, not only in this coun

that the elements of its orbit will be ascertained w precision.

I had an opportunity of observing it fourteen ti tween the 4th of October and the 12th of Novem none afterwards. The right ascensions and declinati corrected for refraction, and from them the geocentr tudes and latitudes were deduced. With these data puted the elements of the orbit according to the ru down in sir Henry Englefield's excellent Treatise up mets, and hope that, though not quite accurate, they be found to err much.

The drawing (see Fig.) represents the comet's orbit applied to, but not projected on the plane of the e The outer circle Y,,,, is drawn at pleasur any radius. A B C D is the earth's, and EV F part comet's orbit: X S V its axis: 88 the line of V the perihelion point, and S V the perihelion distan The elements of the orbit are nearly as follows: perihelion distance 0.64802; the distance of the from the sun S A or S B being = 1'00000.

The time of the comet's passing the perihelion at September 18th, 22 hours 10 minutes M. T.

The longitude of V on the orbit was 28° 41′in Scorp The longitude of the ascending node 26° 36′ in tarius.

The comet passed the ascending nodę September 18h 48m.

The longitude of the axis S X as seen from the sun, in 13° 11′ of Gemini; and its elevation or north lati 24° 43'.-The inclination of the orbit 63° 15′-thi easily conceived, by supposing the visible part of the from n to F to revolve upon the line of nodes g n till point in the orbit, as F, is elevated 634o above the plan the ecliptic.

The comet was seen here soon after it passed V; the ea at that time was nearly at A, moving from thence towards while at the same time the comet moved from V towa F; and consequently its motion was direct.

Owi