480 POWDERS WITH A NITRATE BASE. 



beforehand for several hours at a white heat, in a current of dry 

 chlorine, then cooled in a current of nitrogen). Operating in a 

 porcelain tube at a clear red heat, a gas was collected, formed of 

 carbonic oxide, carbon oxysulphide, and disulphide in the 

 following proportions : 



4S0 2 + 90 = 600 + 2COS + CS 2 , 



a small quantity of sulphur being sublimed at the same time. 

 All this is intelligible, on the supposition that the carbon took 

 the oxygen, 



S0 2 + 20 = 200 + S 2 , 



and that the gaseous sulphur, being set free, combined for its 

 own part partly with the carbon and partly with the carbonic 

 oxide. 



In these experiments the carbon contained in the tube 

 becomes covered with a sort of sooty coating, and undergoes a 

 remarkable disaggregation, which divides it into small frag- 

 ments, according to three rectangular planes ; phenomena which 

 appear to be due to the state of dissociation peculiar to 

 disulphide, which is partly destroyed at the same temperatures 

 at which it is formed according to former observations. 1 



5. Carbonic add and sulphur. The experiment was carried 

 out at two different temperatures. 



1st. The sulphur is raised to the boiling point in a glass 

 retort, and a slow current of dry carbonic gas is passed through 

 it. This reaction has been given as producing carbon oxysul- 

 phide. This is not the case, as the author has assured himself 

 by most careful tests. What may have occasioned the error 

 are the traces of sulphuretted hydrogen, which even the best 

 purified sulphur always liberates when heated. 



In reality, sulphur in a state of ebullition is without action 

 on dry carbonic gas. 



2nd. If carbonic gas mingled with sulphur vapour be passed 

 through a porcelain tube at a clear red heat, a reaction, very 

 slight it is true, but unquestionable, may, on the contrary, be 

 observed. 



Thus the gas liberated contained, out of 100 volumes, 2'5 vols. 

 of gases other than carbonic acid, viz. 



1 vol. COS; 1 vol. CO ; 0-5 vol. S0 2 . 



These small quantities seem to be attributable not to the action 

 proper of sulphur on carbonic acid, but to the previous dissocia- 

 tion of the latter into carbonic oxide and oxygen ; a dissociation 

 which, moreover, is but slight under these conditions, but which 

 the presence of sulphur, which unites at one and the same time 

 with the oxygen and carbonic oxide, tends to render manifest. 



1 " Annales de Chimie et de Physique," 4" srie, torn, xviii. p. 169. 



