210 ACIDIFIABLE COMBUSTIBLES, 



phurous acid, sulphurous acid, and sulphuric acid. 

 Let us, in the first place, determine the atomic 

 weight of sulphuric acid, which is the most im- 

 portant of these compounds. 



^* *' Sulphate of potash is a salt which usu- 

 acid huri a ^ crystallizes in pyramidal dodecahedrons, 

 though its primary form is an oblique four sided 

 prism ; and it contains no water of crystalliza- 

 tion. 11 grains of sulphate of potash, and 13-25 

 grains of chloride of barium, were dissolved in 

 separate portions of distilled water : the two solu- 

 tions being mixed, a double decomposition took 

 place ; and sulphate of barytes, being insoluble, 

 immediately precipitated to the bottom. The 

 residual liquid, which was transparent and co- 

 lourless, was tested with sulphate of soda, and 

 with muriate of barytes ; but by neither of these 

 reagents was it in the least affected showing 

 that it contained no sensible quantity either of 

 barytes or sulphuric acid. 



From this experiment it follows, that the sul- 

 phuric acid in 11 grains Of sulphate of potash 

 just saturates the barytes from 13*25 grains of 

 chloride of barium ; but the barytes from that 

 quantity of chloride is just 9*7^ grains, which is 

 equivalent to the atomic weight of barytes. 

 When the sulphate of barytes formed in the pre- 

 ceding experiment was washed, dried, and ex- 

 posed to a red heat, its weight was exactly 

 14*75 grains; and of this weight, 9'75 grains 



