482 POWDERS WITH A NITRATE BASE. 



destruction of the sulphurous acid gas, producing a final mixture 

 containing 



CO, 24vols. 



CO 75 



1 



Under these conditions the mercury absorbs the anhydrous 

 sulphuric acid, and eliminates it, forming a sub-sulphate. 



8. Saline compounds. All the alkaline oxysalts of sulphur 

 being reduced to the state of sulphate and sulphide towards 

 a red heat, special attention was paid to these two salts, together 

 with potassium carbonate, and they were allowed to act at a red 

 heat on sulphur, carbon, and their gaseous oxides. The salts 

 were contained in elongated vessels arranged in a porcelain 

 tube. 



9. Potassium sulphate and carbonic acid. At a 'bright red 

 heat, no action took place. At a higher temperature it would 

 doubtless be important to take into account the dissociation of 

 the sulphates observed by Boussingault. 



10. Potassium sulphate and carbonic oxide. At a bright red 

 heat the sulphate was charged into sulphide, or rather into 

 poly sulphide, 1 containing some flakes of carbon, and a mixture 

 of carbonic acid and carbonic oxide was collected, the relative 

 proportion of the former gas varying between four-fifths and 

 the half, according to the speed of the current and the tempera- 

 ture. 



The principal reaction here is 



S0 4 K 2 + 400 a K 2 S + 4002. 



There is a trace of carbonate. 



11. The reducing action of carbon on potassium sulphate is 

 so well known that it was not deemed necessary to reproduce it. 



12. Potassium sulphate and sulphurous acid. There is no 

 action at a bright red heat. 



13. Potassium sulphate and sulphur. Sulphur may be evapo- 

 rated in presence of potassium sulphate, provided the tempera- 

 ture be carefully kept below a red heat. 



On the contrary, in a red-hot porcelain tube, sulphur vapour 

 reduces potassium sulphate, producing polysulphide and 

 sulphurous gas 



S0 4 K 2 + 4S = K 2 S 3 + 2S0 2 . 



This transformation was never total. It seems, moreover, to 

 represent the last term of a series of changes, in which the lower 



1 The constant formation of polysulphide in the actions caused by heat 

 which yield sulphur, has been remarked by Gay-Lussac, Berzilius, and Bauer. 

 It is connected with some imperfectly known reaction, such as the formation 

 of an oxy sulphide of potassium. 



