SULPHUROUS ACID GAS AND CARBONIC OXIDE. 481 



6. Carbonic acid and sulphurous acid gas. The two gases were 

 mixed in equal volumes, passed into a glass tube, which was then 

 sealed. After two hours and a half of strong sparks the author 

 observed 



Diminution of volume 19 vols. 



S0 2 31 



C0 2 30 



CO ... ... 20 



Each of the gases was decomposed for its own part. The 

 oxygen resulting from the dissociation of the carbonic acid was 

 condensed, uniting with the sulphurous acid under the form of 

 sulphuric acid. 



The sulphurous acid gas here seems more stable than the 

 carbonic acid gas, contrary to what might have been expected. 



7. Sulphurous acid gas and carbonic oxide. 1st. The mixture 

 made in equal volumes was slowly passed through a very small 

 porcelain tube at a clear red heat. There was collected 



Intermediate gas. Final gas. 



S0 2 47 vols. ... 37 vols. 



C0 2 9 ... 20 



CO ... ... 44 ... 43 



Sulphur was formed. Neither carbon oxysulphide nor carbon 

 disulphide was present in any considerable proportion. 



Thus the carbonic oxide reduced the sulphurous acid gas 



2CO + S0 2 = 2C0 2 + S. 



But the reduction remained incomplete, as the experiment 

 made with carbonic acid permitted of foreseeing. 



2nd. Two vols. of carbonic oxide and one vol. of sulphurous 

 acid gas were mixed and passed into a glass tube provided with 

 platinum electrodes, the tube being then closed. A series of 

 sparks was passed through it. The following are the results 

 of both trials : 



After After 



half an hour. two hours. 



Diminution 14 vols. ... 28 vols. 



S0 2 20 ... 6 



C0 2 18 ... 9 



CO 48 ... 57 



No sulphur nor carbon oxysulphide. Here again we see the 

 reduction of the sulphurous acid by the carbonic oxide. But, 

 and it is a remarkable circumstance, a considerable portion of the 

 former gas is destroyed for its own part without yielding its 

 oxygen to the carbonic oxide, and giving the same compound of 

 sulphur, sulphurous acid, and sulphuric acid already described, 

 and which condenses on the walls of the tube. 



3rd. The same experiment, repeated over mercury, with 

 strong sparks, in the space of four hours caused the total 



2 I 



