•^QQ ON THE COMPOUNDS OF SULPHUR AND OXYGEN. 



fulphite of barytes ; for the greater part of it was foluble in 

 fulphurous acid. 

 Nitric acid and When fulphite of potalh is thrown into concentrated nitric 

 f^phiteofpot- ^^j^^ ^ violent effervefcence takes place, and much heat is 

 (evolved, the lofs of weight is 44.5 ; the liquid treated with 

 nitrate of barjtes, gives a precipitate, which indicates the pre- 

 fence of 39.6 of fulphuric acid. Hence we fee that the lofs 

 of weight during the effervefcence was owing chiefly to the 

 efcape of nitrous gas. 



When the acid is diluted, the effervefcence is violent, but 

 no heat is evolved, and the fmell of fulphurous acid gas mak- 

 ing its efcape is very perceptible. The lofs of weight is only 

 12 per cent, the refiduum, treated with nitrate of barytes, gave 

 a precipitate indicating the prefence of 43.2 per cent, of ful- 

 phuric acid. Here we fee that moft of the lofs of weight was 

 owing to the efcape of fulphurous acid ; yet the greater part 

 was converted into fulphuric acid. 

 Compofition of 8. During the courfe of thefe experiments I had occafion to 

 fi^phiteof pot- examine the compofition of fulphate of potafh ; and as my re- 

 fults differ a little from thofe (lated by others, it will be pro- 

 per to notice fome of them in this place. 



When fulphite of potafh is heated to rednefs in a pla- 

 tinum crucible, the refiduum polfeffes the properties of fulphate 

 of potafh. It may be fufed without any lofs of weight, and 

 when diffolved and cryflallized again, we obtain the fame fait 

 as at firfl : 100 parts of this fait precipitated by muriate of 

 barytes, yields a precipitate which, after being heated to red- 

 nefs, weighs, at a medium, 96 parts, indicating about 23 per 

 cent, of fulphuric acid. Hence this fulphate is compofed of 

 23 acid 

 67 potafh 



100 

 When fulphuric acid is fuperfaturated by means of carbonate 

 of potafh, we obtain by evaporation the common fulphate of 

 potaQi of chemifts : the fame fait feparates in cryflals during 

 the purification of the potafh of commerce. When the fait is 

 reddened in a platinum crucible, it lofes 1,4 per cent, of its 

 weight, and no more, though it be kept in fufion. Diffolved 

 in water, and treated with muriate of barytes, it yields a pre- 

 cipitate which weighs 128,5 j the mean of three experiments 

 " differing 



