ON THE COMPOUNDS OF SULPHUR AND OXYGEN. |01 



differing from each other not more than 3.5 per cent.* 

 Hence it contains 30.84- fulphuric acid. This fiilphate, then, 

 is compofed of 



30.84 acid 



67.76 potafli 

 1.40 water 



100.00 

 When fulphite of potafli is left for fonie months expofed to 

 the air, and then healed to rednefs, it yields with muriate of 

 barytes a precipitate indicating about 3S per cent, of ful- 

 phuric acid. 



The fuperfulphate of potafh lofes 26 per cent, in a red 

 heat, and the remaining 74 parts diffolved in water, and 

 treated with muriate of barytes, yield a precipitate indicating 

 the prefence of 30.4 fulphuric acid, whereas 100 parts of the 

 fuperfulphate diflblved in water, without being previoufly 

 heated, yield, with muriate of barytes, a precipitate indicat- 

 ing the prefence of 38.4 fulphuric acid. Hence it follows 

 that the fait is compofed of 

 38. 4 acid 

 43.6 alkali 

 18.0 water 



100.0; 

 or, abftradting the water, of 46.4 acid 

 53.6 alkali 



100.0 



III. Oxide of Sulphur. 



Sulphur ufually occurs in one or other of three flates ; External charac- 

 namely, 1. A whitifh powder, formerly diftinguiflied by thei^^soffulphur. 

 name of lac fulphuris. 2. In rolls or flowers of a greenifli 

 yellow colour. This is the fulphur of commerce. 3. In the 

 fiate of a reddifi] yellow, pitchy lubflance. This is commonly 

 employed for forming the calls of medals, &c. known by the 

 name of fulphurs. 



* Mr. Vauquelin affirms, in his Diflertation oh the Potafh of 

 Commerce, that this fait yields with muriate of barytes a precipi- 

 tate amounting to 22°, the weight of the fait. My experiment 

 differs very much from this ftatement. 



1. It 



