« VorigeDoorgaan »
contents upon the surface of the mercury, where the oily liquor continued to burn until it was all consumed. Water being then introduced, an absorption of gas took place, and the water became sulphureous. The unabsorbed portion of gas being introduced into lime water, rendered it turbid, and formed a quantity of carbonate of lime, which was sufficient to be carefully examined and accurately estimated.
3. We caused some alcohol of sulphur to dissolve in barytic water, in a well stoppered bottle. This solution proceeded very slowly, and was only completed at the end of three weeks. The barytic water had assumed a yellowish colour, and had deposited a white precipitate, which being well washed, and treated with liquid sulphureous acid, dissolved in it with effervescence. It was therefore carbonate of barytes.
4. A similar experiment being tried with lime water, an analogous result was obtained.
It follows from these experiments, that the alcohol of sulphur contains, carbon, and therefore that this body, the nature of which has been the subject of so much doubt and speculation, is a true SULPHURET OF CARBON, a name by which, in compliance to the received chemical nomenclature, we shall henceforth usually designate it in the course of this paper.
§ IV. Experiments to determine the Proportions of Sulphur and
Carbon, in the Sulphuret of Carbon. : In attempting to analyse, with accuracy, the sulphuret of carbon, considerable difficulties occur from the great volatility of that compound, and from the inconsiderable action which most chemical agents exert upon it.
1. We first tried to ascertain the proportion of its constitu
ent parts, by exploding it, in a state of vapour, with
oxygen gas, in Volta's eudiometer; but this method presented insurmountable obstacles, and in particular that of our not being able to determine, with accuracy, the quantity of the oily substance actually decomposed by that process.
2. On the other hand, on attempting simply to burn in oxygen gas the sulphuret of carbon in its liquid state, the necessity of previously kindling it in the air, in order to avoid explosions, prevented our being able to ascertain, with accuracy, the quantity of the oily substance submitted to the experiment.
3. We also attempted the oxydation of the sulphuret of carbɔn by nitro-muriatic acid; but we obtained by this method, as we shall see afterwards, results and combinations which were quite different from those which we had expected.* 4
We then had recourse to the action of alkaline substances on the sulphuret of carbon, with a view to produce an alkaline sulphuret, and afterwards to convert this into a sulphate by means of nitro-muriatic acid. The sulphuric acid, precipitated by a barytic salt, was ultimately expected to indicate the
quantity of sulphur contained in the oily compound. In order to try this method, we exposed portions of the sulphuret of carbon to the action of caustic potash, ammonia, barytic water, &c. and when the solutions appeared to be completed, we tried the effect of acids upon them; these separated from them a soft, reddish, glutinous substance, which, when exposed to distillation, yielded, first, a portion of the oily liquor undecomposed, and afterwards sulphur; thus shewing that the
• A new and singular compound was obtained from the long continued action of nitro-muriatic acid on the alcohol of sulphur, the history and composition of which will be detailed in the Appendix.
whole of the sulphuret of carbon had not been decomposed. A black powder remained in the retort, which was found to be charcoal, and afforded us a new and unequivocal proof of the presence of carbon in the oily substance.
This imperfect decomposition of the sulphuret of carbon in alkaline solutions, was found an insurmountable objection to this mode of analysis; and induced us to try the method of distilling the sulphuret through ignited metallic oxyds,
5. For this purpose, we introduced a glass tube (BC), in an inclined direction, through a small stove (fig. 1, A), the
tube being protected by lute, and filled with red oxyd of iron coarsely pulverized. The sulphuret of carbon, after being accurately weighed, was enclosed in a little retort (E), which we hermetically sealed to the upper extremity of the tube (B). To the other extremity (C), we adapted another glass tube
(CGI), terminating in a mercurial pneumatic apparatus (H), and having a bulb or expansion (in G), at about half way between its extremities, which bulb was cooled down to about 15° FAHRENHEIT, and kept at that temperature during the experiment by means of a mixture of ice and salt. The tube in the stove (BC) being now heated to redness, and an extremely gentle degree of heat applied to the retort, the oily liquor distilled slowly through the red hot oxyd of iron, and the whole of the experiment succeeded in a most satisfactory manner; for we found that the joints of the apparatus had remained, perfectly tight during the process, and every vestige of the sulphuret of carbon had been decomposed. * We could not perceive in the bulb the least appearance of moisture.
6. The oxyd of iron (the whole weight of which was about ten times that of the oil decomposed), was partly converted into sulphuret of iron, having a yellow colour and a brilliant metallic lustre. This sulphuret was dissolved by nitro-muriatic acid, and the oxyd of iron was separated by ammonia. The filtered liquid, being neutralized by muriatic acid, was precipitated by muriate of barytes, and the precipitate was well washed, and heated to redness.
7. During the process of decomposition above related, the mixture of sulphureous acid gas and carbonic acid gas had collected in the receiver (H) placed on the extremity of the
• The process was so slowly conducted, that it required six hours and a half for the decomposition of about fifteen grains of the oil. The heat applied to the retort was merely that which radiated from a small lamp (F); placed at some distance from it, a screen being interposed between the furnace and the retort. In several previous trials, we had failed from not being sufficiently cautious and gradual in the mode of warming the retort,
tube. In order to separate these two gases from each other, we made use of the brown oxyd of lead, a substance which one of us had often employed for the purpose of combining with, and separating from other bodies, liquid sulphureous acid, with which that oxyd forms a neutral sulphate. The same method, to our great satisfaction, succeeded perfectly with the gaseous sulphureous acid. After a contact of about one hour, between the brown oxyd of lead and our mixed gases, the whole of the sulphureous acid gas was so completely absorbed, that the carbonic acid gas which remained in the vessel, had not the least sulphureous smell, and yet the carbonic acid itself remained perfectly unaltered in its bulk, after continuing in contact with the oxyd of lead for the space of three days.*
8. The mode in which the respective weight of the two acids was ascertained was this; the oxyd of lead was placed in a small glass capsule (a, fig. 2), the orifice of which was carefully secured, by means of a thin piece of glove-leather, against the admission of quicksilver. A very thin flexible metallic wire was fastened to the capsule, so as to enable the operator to raise it through the mercury in the receiver containing the gases, as is expressed in the figure (fig. 2). After continuing the contact for several hours, and when the absorption had
* The brown oxyd of lead, used in our experiments, was recently prepared, and had been long digested in weak nitric acid. In wiping this oxyd, and pressing the moisture out of it, we found it expedient to reduce it to the state of small laminæ, as in this form it is more easily penetrated by the acid gas than in the state of powder. It may be proper to remark, that when, for the sake of trial, gaseous mixtures, consisting of sulphureous acid gas and sulphuret of carbon in vapour, were used, the latter, as the absorption of the acid gas proceeded, was deposited in its liquid state upon the oxyd of lead.