[ 243 ] 



No. 96.) he ftates the proportions of fulphuric acid, obtained by 

 treating fulphur with nitric acid, to be 



Sulphur - - 55-56 



Oxygen - - ' 44.44 



100.00 



but in the extradt given by Guyton in that No. of the Annales 

 de Chimie, the mode of operation is not defcribed. Calcined 

 fulphate of Barytes is efti mated in the fame paper to contain 



Barytes - - 74.82 



Sulphuric acid - - 25.18 



100.00 



which proportions are as near to what I had found as can be 

 expefled ; for fulphate of Barytes does not contain more than 

 3 per cent, of water of cryftallization, and they muft be de- 

 ducted from the quintal. 



Having determined with accuracy the proportion of acid in 

 any infoluble fulphate, it is eafy to proced to the determina- 

 tion of that contained in any other fulphate. The docimaftic 

 art or analytic chymiftry, in general, cannot however exped to 

 -derive fuch advantages from the knowledge of foluble falts, as 



of 



