Pagina-afbeeldingen
PDF
ePub

ingenious method of expressing the proportions in which bodies combine, can be applied with certainty and precision.*

D. Experiments on the Combination of the Sulphuret of Carbon,

with the Alkalies, the Earths, and the metallic Oxyds. The following experiments will shew in an unequivocal manner, that the sulphuret of carbon is capable of combining with saline bases. These combinations constitute a new class of bodies, for which there is no name in our present chemical nomenclature. I shall propose to call them carbosulphurets, a name quite consonant with the principles of the received chemical nomenclature.

The unavoidable presence of water, in either caustic potash or soda, induced me to try, in the first instance, the action of ammoniacal gas on the sulphuret of carbon.

Carbosulphuret of Ammonia. Some ammoniacal gas, and some liquid sulphuret of carbon were successively introduced into a receiver filled with mercury, the sulphuret being enclosed in a small glass bulb having an open orifice. The first effect of this contact was a dilatation of the gas; the surface of the sulphuret soon covered itself with a pulverulent strawcoloured substance, as if a portion of sulphur had been precipitated. After a few hours, the gaseous mixture had sensibly

It appears to me that the best way to form a system of definite proportions, and to make it harmonize with the general views of chemistry, would be to take oxygen as the base of the scale, because most chemical combinations turn upon the

propor: tion of that ingredient; and as gaseous bodies unite in equal or multiple volumes, I would consider as the atom of any other gas, the proportional weight of an equal measure of that gas.

diminished in bulk, and as this diminution proceeded, the gas gradually deposited on the surface of the glass a saline yellowish substance, which did not exhibit, even with the aid of a microscope, the least appearance of crystallization. The mercury having at last filled the receiver, an additional portion of ammoniacal gas was introduced, and this was repeated till no further absorption took place. The whole of the sulphuret of carbon was then found converted into the yellowish uncrystallized matter just described. This substance had a strong smell of ammonia, and was so deliquescent that it could not be transferred from one vessel into another, without undergoing an obvious alteration. The solution of this substance in water is first red, but it very soon passes to a deep orange colour, shewing that it undergoes a partial decomposition; and if it be distilled in its solid, though humid state, it sublimes and deposits small shining crystals of hydrosulphuret of ammonia; whilst, on the contrary, if it be heated in the same vessel in which it is formed, that is, without any access of air or moisture, the carbosulphuret of ammonia sublimes unchanged, from one part of the vessel to the other, and no vestige of hydrosulphuret is perceived. It appears therefore, , that the sulphuret of carbon can enter into combination with pure ammonia without depositing its carbon; but if moisture or air be admitted, an alkaline hydrosulphuret, or sulphuret is formed, and carbonic acid is generated.

Carbosulphuret of lime. If some pure quick lime be heated in a glass tube, by means of a lamp, and some sulphuret of carbon in vapour be made to pass through the heated earth, the latter becomes ignited at the moment the vapour comes into contact with it, and this ignition continues till the earth is

saturated. During this process, none of the sulphuret of carbon escapes, the whole of it being absorbed by the lime. The earth, at its surface, is found yellowish, owing to the formation of a little sulphuret of lime, but this appearance ceases on removing the surface, shewing that it arises from the contact of air. The earthy mass is tasteless, when first applied to the tongue, but a bitter taste, with a smell of sulphuretted hydrogen are soon perceived. It is no longer susceptible of being heated or dissolved by water. If digested with water in close vessels, a solution of hydrosulphuret of lime is obtained, and the undissolved portion is mostly found to be carbonate of lime,

Carbosulphurets of barytes and strontian may be produced in a similar manner, and are found to possess analogous properties.

There can be no doubt but that the two fixed alkalies, in a state of perfect dryness, would form, with the sulphuret of carbon, carbosulphurets of potash and soda, quite analogous to those just described; but as these alkalies cannot be obtained in an anhydral state, I could only examine their action on the sulphuret of carbon when in a state of solution. The general result of these trials was, that if a quantity of the sulphuret of carbon be long digested, at a very gentle heat, with a solution of caustic potash, the sulphuret of carbon is decomposed, and the mixture resolves itself into a hydrosulphuret, and carbosulphuret, and a carbonate of potash.

In the same manner, if sulphuret of carbon be long digested with liquid caustic ammonia, it dissolves very slowly, forming an orange coloured solution analogous to that in caustic potash just described.

I tried also to produce carbosulphurets of metallic oxyds. The process simply consisted in precipitating metallic solutions, by solutions of the sulphuret of carbon in caustic potash. The precipitates which were thus obtained, had characters sufficiently distinct to shew that they were chiefly metallic carbosulphurets; but as the presence of a hydrosulphuret, and of carbonate of potash, in the solutions used for these precipitations, necessarily interfered with the distinctness of the results, I shall not trouble the Society with a detail of these experi

ments.

E. Experiments to determine the nature of a particular Substance,

produced by the action of nitro-muriatic Acid, on the Sulphuret of Carbon.

We have already alluded, Dr. Marcet and myself, in the course of our paper, to a new and singular substance, which we produced by the long continued action of nitro-muriatic acid on the sulphuret of carbon. This compound was discovered in the following manner.

A portion of sulphuret of carbon was exposed to the action of a mixture of fuming nitric acid with concentrated muriatic acid. The acid instantly acquired a peculiar odour resembling that of muriated sulphur. Upon trying to promote the combination by applying heat, the sulphuret of carbon was expelled in the form of vapour, which obliged us to leave the mixture to its own spontaneous action, under the temperature of the atmosphere, which was then at least 70°.* The sulphuret of carbon soon passed to a reddish orange colour, which it communicated to the acid; and during this change,

* In August, 1812.

Dd

MDCCCXIII.

nitrous gas, with a strong smell of muriated sulphur, was slowly evolved. After the space of a week, the liquor began to cover itself with a white crystalline substance, losing at the same time its colour. On stirring the mixture, these crystals fell to the bottom, where they were immediately dissolved by the remaining sulphuret of carbon. This, however, in proportion as it saturated itself with the new formed substance, gradually lost its colour, acquired a greater consistence, and at last, at the end of three weeks, it was entirely converted into a solid white crystalline body, having the appearance of camphor.

This substance being separated from the acid, and washed with cold water, presented the following characters: it was colourless; its smell resembled both that of muriated sulphur and of oxyd of osmium ; its taste was both acrid and acid; it was very volatile, melted at a gentle heat, and sublimed without residue. In fact, this body very closely resembles camphor in its external properties. It is insoluble in water, but readily dissolves in alcohol and ether, from which it is precipitated by water; it is also soluble in the oils, whether fixed or volatile, with which it forms transparent solutions. The spirituous solution of this substance has a peculiar, disagreeable, and very acid taste.

acid taste. It reddens litmus paper, and dissolves zinc with the disengagement of an extremely fetid this solution, a spirituous liquor is obtained by distillation, which possesses the same smell, and leaves a residue of muriate and sulphate of zinc. When a pure solution of the peculiar substance in alcohol is submitted to distillation, the products are, first, some culphureous acid gas, and then alcohol strongly impregnated with muriatic ether; after which the air of the

gas. From

« VorigeDoorgaan »