299 



cumstances, and I have uniformly obtained sulphurous and 

 sulphuric acids. I will not refer to any particular expe- 

 riments in which these acids were produced directly from 

 oxygen gas and sulphur in a dry state, as I am desirous of 

 repeating them at my first leisure, under more favourable 

 circumstances. 



" I have repeatedly found that by burning the vapour 

 of sulphur in flasks and retorts, under circumstances in which 

 it would be difficult to admit the presence of any appreciable 

 quantity of water, sulphuric acid as well as sulphurous acid 

 is copiously produced. 



" In the well-known method of making sulphurous acid 

 gas, by heating a mixture of sulphur and oxide of manganese, 

 it is supposed no sulphuric acid is formed. This is a mistake. 

 Sulphate of manganese is produced, together with a rich 

 brown pigment, probably the sesquioxide. This sulphate is 

 employed in dyeing and calico printing, and is now prepared 

 by more complicated processes. In experiments with the 

 Saxon and other varieties of manganese and sulphur, I have 

 obtained pure sulphates of manganese. And this method 

 seems to offer the chemist one of the readiest modes of obtain- 

 ing the compounds of manganese in a state of purity, and of 

 detecting it in analyses. 



" The application of the foregoing facts to the manufac- 

 ture of sulphuric acid seems obvious, but I hope in a subse- 

 quent communication to bring that subject before the Aca- 

 demy. 



" I cannot close this communication without acknowledg- 

 ing the assistance I received in my experiments from my in- 

 telligent young friend and pupil, Mr. George Keogh, and my 

 son, Edmund William Davy." 



Mr. Robert Mallet made the following observations on 

 Mr. Davy's paper : 



VOL. IV. 2 A 



