Experiments on Charcoal. 157 



heat it evaporates, and is condenfed in the water of theflaik; 

 it traverfes it in globules which in appearance do notdiflblve, 

 and which are collected at the bottom. 



The complete fuccefs of this experiment is very uncertain... 

 The regular manner in which fulphur a&s. when heated in clofe 

 veflels, is one of the principal obltacles. It is well known that 

 if fuddenly expofed to a great heat inttead of being volatilized, 

 it becomes fixed in fome meafure, and forms a kind of patle. 

 It often happens that fulphur expofed to a ilrong heat in a 

 porcelain tube is not volatilized, and that no carburated ful- 

 phur is formed. In that cafe more fulphur is introduced, to 

 bring the other to fuch a low temperature that the whole 

 may be volatilized; but it then . pafles too rapidly over the 

 charcoal to be united with it, and the fublimated fulphur, 

 by condenfmg in the adaptor, often makes it burft. It is 

 much better to urge the fulphur very (lowly, and, in parti- 

 cular, to incline the tube towards the adaptor to make the 

 fulphur run upon the charcoal. 



During the production of the carburated fulphur, no gas 

 is difengaged. The air in the vetlels only receives an ex- 

 panfion by its mixture with the carburated fulphur, which is 

 exceedingly volatile, and a little which has become inflam- 

 mable efcapes. 



Notwithstanding the difficulty of fucceeding in this expe- 

 riment, we made one in which ten grammes of charcoal en- 

 tirely vanifhed. It appeared to us that it formed nearly one- 

 third of the combination. When anv bits of charcoal re- 

 main they are viflblv corroded and of a paler black colour 

 than before, being fubje&ea to the a&ion of the fulphur. 



When more fulphur than is neceffary for the production 

 of liquid carburated fulphur pafles on the ignited charcoal, 

 the refult is a folid, which cryitaHizes in the adaptor. Thefe 

 cryflals feem to refemble thofe of fulphur, but they contain 

 charcoal, for they evidently leave fome of it after their com- 

 buition in the open air. This folid carburated fulphur may 

 contain a little of the liquid, and in that cafe it forms a pafle, 

 which in the air foon lofes its odour and its confidence. 



It appears that to produce a combination of fulphur and 

 charcoal they mud be both exceedingly warm ; for, by heat- 

 ing in a retort a mixture of fulphur and charcoal well united, 

 a little gas only is obtained of a bad odour, infoluble in 

 water, and which Scheele called injoluble hepahc gas. 



We burnt a gas nearly fimilar, which may be procured in 

 large quantity, by means we (hall defcribe hereafter; and we 

 had for product a great deal of carbonic acid and fulphurous 

 acid, but apparently no water. 



5 Whether 



