On thi ^tantiiy of Sulphur in Sulphuric Ac'ul. 34$ 



Having therefore, in the ufual manner, afcertained what quantity of that ingredient re- 

 mained untouched, I was forced to feck the reft of it in the liquor, which had waflied the 

 Various precipitates. To obtain it, I poured a folution of nitrate of barytes into thofe 

 wafliings, when all the other fubftances had been carefully feparated, and was thereby 

 enabled to precipitate, 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 quan- 

 tity of fulphate of barytes, I had recourfe, in the firft inftance, to the quantity of fulphur, 

 faid by Lavoifier to be contained in fulphuric acid, and, in the next, to the proportions of 

 the latter, annourtced in the fynoptic tables of Fourcroy, as entering into the compofition 

 of fulphate of barytes. According to the former of thofe chymifts, 100 parts of fulphuric 

 acid contain 7 1 of fulphur and 29 of oxigen ; and again, in adopting the proportions of 

 the ktter, we have 33 pet cent, of acid, on fulphate of barytes. But if 100 contain 7 1 of 

 fulphur, 33 muft contain 23.43. Confequently, for every 100 parts of fulphate of barytCs, 

 I was to allow 23.43 of fulphur. But, by the refults of my analyfcs, I had fuch quantities 

 of fulphate of barytes, as induced me to doubt the accuracy of one or other of the ftatc« 

 ments, by which I eftimated the quantity of real fulphur-contained in the ore. 



No pcrfon is better acquainted than our celebrated Preftdent, with the many difficulties 

 that occur in the analyfis of falts in general ; particularly with regard to the quantity of 

 real acid they may contain. It has been a work of trouble to the ableft chymifts, and they 

 have hot' always agreed lit their refults. The proportions, announced by Fourcroy, nray 

 thereftjfe be doubted, in cotrtmori Swith thofe of the other learned operators, to whom I 

 have alluded. 



Tlie real quantity of acid, produced by the combuftion of imy acidifiablt baffs, can be 

 determined by one or other 6f the following methods only : by direfl: combination, in fome^ 

 felt, the proportions of which are are already known ; or by obtaining, in a ftate perfe£):Iy- 

 free from water, the acid refuhing from fuch combuftion. To the former method, the 

 general objeftions againft all analyfes of falts muft apply. The latter is ftill more defeftivc^ 

 It is by no means certain, that we have ever y«t obtained any acid, in a ftate of perfcft 

 Cecity, unltfs we except the phofphoric ami the arfenic ; for even the cryftallized vege- 

 table acids retain a portion of water in their cryftallization. It is not that I abfolutely 

 deny our having obtained them ft> ; but I fay merely, that we have no proof. It would 

 indeed -be fettihg narrow bounds to the perfe<fli6n of nature, to aflert, that no cOmbuftibic 

 body could, when faturated with oxigen, aflume of itfelf, the ftate of liquidity ; or that the 

 oxide of the particular fubftance, called hidrogen, muft be prefent to confer that property. 

 Doubtlefs, fulphuric acid may, as well as water, contain, in itfelf, fo juft a proportion of 

 fpecific heat, as to remain liquid at the temperature of our globe, and under the preffoTt 

 of our titmofphere. But, both water and fulphnnc acid being eafily volatilized, and having 

 a powerful affinity For each other, it is not eafy, if even poflibk, by diftillation, to ftpa- 

 Tate them with fufficient accuracy, in experiments of delicate inqmry. A feco*»d fottrce 



Vol- V. — December. i8ou . Y y of 



