contained in Sulphuric Acid. T13 



next, to the proportions of the latter, announced in the fy'- 

 iioptic lables oF Fourcroy, as entering into the compofition 

 of fulphate of barytes. According lo the former of thofe 

 chennfis, 100 parts of fulphuric acid contain 71 of fulphur 

 and 29 of oxygen; and again, in adopting the propor- 

 tions of the latter, we have 33 per cent, of acid in ftilphate 

 of ban-tes. But if 100 contain 71 of iulphur, ■^'^ nuifl; con- 

 tain 23.43. Confequentlv, for every lo^" parts of fulphate 

 of barvtes, I was to allow 33.43 of fulphLir, But, by the 

 rcfiilts of my analyfes, I had inch quantities of liilphate of 

 barytes as induced me to doubt the accuracy of one or other 

 of the ftatemcnts by which I eftiniated the quantity of real 

 Iulphur contained in the ore. 



No perfon is belter acquainted than our celebrated prefi- 

 dent with the many difficulties that occur in the analvfis of 

 falts in srencral, particularly with rciiard to the quaniity of 

 real acicl thev nuiv contain. It has been a work of trouble 

 to the aiiloll chemifts, and they have not always agreed in 

 their refults. The proportions announced by Fourcroy mav 

 therefore be doubted, in common with thofe of the other 

 learned operators to whom I have alluded. 



Tiie real quantity of acid produced by the combuflion of 

 any acidifiable bafis, can be determined by one or other of 

 the following methods only : bv diredl combination in fome 

 fait, the proportions of which are already known ; or by ob- 

 taining, in a ftate perfciSlIy free from water, the acid rcfult- 

 ing from fuch combuflion. To the former method, the ge- 

 neral objedions againft all analyl'cs of falts mull apply. 'I'he 

 latter is ftill move defeoiive. It is by no means certain that 

 we have fi^er yet obtained any acid in a ftate of perfect (ic- 

 city, nnlefs we except the phofphoric and thearfenic; for 

 even the cryliailized vegetable acids retain a portion of water 

 in their crvftallization. It is not that I abfolutely deny our 

 having obtained them f o ; but I fav nierelv that we have no 

 proof. It would indeed be fetting narrow bounds to the per- 

 fedion of nature to allert, that no combuitible body could, 

 when faturated with oxygen, airume of itfelf the ftate of li- 

 quidity ; or that the oxide of the parlicalar fubilance called 

 hydrogen muft be prefent to confer that property. Doubtlefs 

 fulphuric acid may, as well as water, contain in itfelf lb jutt 

 a proportion of fpecilic heat, as to remain liquid at the tem- 

 perature of our globe, and under the prellure of our atuio- 

 fphere. But both water and fulphuric acid being eafily vola- 

 tilized, and having a powerful aftinity for each other, it is 

 not eafv, if even^poHible, by diftillation, to feparate them 

 with lufficient accuracy in experiments of delicate inquiry.' 



Vol. XI. ' 11 Afecond 



