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to feek the reft of it in the liquor, which had waftied the va- 

 rious precipitates. To obtain it, I poured a fohition of nitrate 

 of Barytes into thofe wafhings, when all the other fubftances 

 had been carefully feparated, and was thereby enabled to pre- 

 cipitate, in a ftate of purity, the fulphate of Barytes, formed 

 by that earth, and by the portion of fulphur originally acidified, 

 in the firft treatment of the ore by nitric acid. To come at the 

 knowledge of the proportion of fulphur, contained in a given 

 quantity of fulphate of Barytes, I had recourfe, in the firft in- 

 ftance, to the quantity of fulphur, faid by Lavoifier to be con- 

 tained in fulphuric acid, and, in the next, to the proportions 

 of the latter, announced in the fynoptic tables of Fourcroy, 

 as entering into the compofition of fulphate of Barytes. Ac- 

 cording to the former of thofe chymifls, loo parts of fulphuric 

 acid contain 71 of fulphur and 29 of oxygen ; and again, in 

 adopting the proportions of the latter, we have 33 per cent, 

 of acid, on fulphate of Barytes. But if ico contain 71 of 

 fulphur 33 muft contain 23.43. Confequently, for every 100 

 parts of fulphate of Barytes, I was to allow 23.43 of fulphur. 

 But, by the refults of my analyfes, I had fuch quantities of 

 fulphate of Barytes, as induced me to doubt the acjuracy of 

 one or other of the ftatements, by which I eftimated the quan- 

 tity of real fulphur contained in the ore. 



No 



