g^ ON THE COMPOUNDS OF SULPHUR AND OXYGEN. 



had loft 15.2 grains of weight. The fulphur being carefullj 

 colle6led, was found to weigh 5.1 grains. When burnt, it 

 left 0.1 of refiduum, which feemed to be fulphurate of Iron, 

 for it gave a jellow colour to muriatic acid ;* the water vola- 

 tili.'ed could not be weighed, but I eftimate it at 2 grains. 

 The experiment fliews us what the volatile matter is which is 

 drawn off when fulphate of potaQi is heated to rednefs. It is 

 compofed of 15.2 fulphurous acid 



5.1 fulphur 



2.0 water 



22.3 

 The fait which remained In the retort being diffolved, and 

 treated with muriate of barytes, gave a precipitate which in- 

 dicated the prefence of 23.2 of fulphuric acid. Hence ful- 

 phate of potafli is compofed of 



Component parts 23.2 fulpburic acid 



of fulphite of , ^ ^ r 1 t • T 



^otafix. ^-5.2 hilphurous acid 



5.1 fulplmr 



54-. 5 polafii 



2.0 water 



100.0 

 But it is obvious that, before tfie application of heat, the 

 firft three conftituents together contiituted fulphurous acid, 

 HeTice fulphite of potafii is compofed of 

 43.5 fulphurous acid 

 54.5 potadi 

 . 2.0 water 



100. 

 Explanation of This analyfis enables us to trace the changes produced upon 

 heatonrulphite fulphite of potafli by heat. A temperature of 300° feparates 

 of potafh. the water and a fmall portion of fulphurous acid, which 



feems more loofely combined ; for the fait, in confequence, 

 lofes its fmell ; an increafe of heat occafions a feparation of 

 a portion of the acid, unaltered ; the remainder divides itfelf 

 into two parts, namely, fulphuric acid, which remains com- 

 bined with the potath, and fulphur, which fublimes. Hence 



* I have never yet burned fulphur, without obferving traces of a 

 fimilar refiduum. 



