Hefcrjption of an Apparatus fir l)!/f!Iling. 34^ 



which proportions arc as near to what I had found as can be expe£ied ; for fulphate of 

 barytes docs not contain more than 3 per cent, of water of cryftallization, and they niuft 

 be dedudted from the quintal. 



Having determined with accuracy the proportion of acid in any infoluble fulphate, it is 

 cafy to proceed to the determination of that contained in any other fulphate. The doci- 

 maftic arc or analytic chymiftry, in general, cannot however expefl: to derive fuch advan- 

 tages froth the knowledge of foluble falts, as of thofe, which, from their infolubility, may 

 be ufed with accuracy in delicate experiments to determine the proportions of the confti* 

 tucnt parts of bodies. But if, with this mode of operating, we compare the quantities of 

 real acid, faid (in thofe excellent tables with which Mr. Kirwan has enriched the fcience) 

 to be contained in fulphuric acid of different fpecific gravities, each will ferve as a proof of 

 the validity of the other ; and perhaps demonftrate, that fulphuric acid, without the inter- 

 vention of water, may enjoy liquidity, at the temperature and preflure which aft upon 

 our globe. 



VII. 



Defcriptkn of an Apparatus fir Di/lilling, in which the EffeEis of Ahforption are prevented 

 without admitting the external Air. In a Letter from Mr. A. S, MvKKITT. 



To Mr. NICHOLSON. 

 SIR, 



A HAVE taten the liberty of inclofing a drawing of an apparatus, to prevent the ab- 

 forption which fo frequently happens in diftiiling acids, in particular the nitrous ; for 

 vhich I have moftly ufed it with the defired effeft. , 



Should it prove original, and meet your attention, you will confer a favour by giving it 

 a place in your valuable Journal. 



I am, SIR, 



Your moft obedient humble Servant, 

 Fket Street. Nov. 20, iZoi. A. S. BURKITT. 



Plate XVII. reprefents the apparatus; where A is a retort, B, the ufual receiver, having 

 a neck to receive the retort, and another from which the recurved tube F proceeds to the 

 bottom of a fecond receiver C ; and from this lafl veflel a communication is made in the 

 well known manner with the apparatus of Woulfe D. The principal fingularity and ad» 

 vantage of my apparatus confifts in the valve E, conftrudted by placing a plate, or'piano- 

 convex lens up«n the tnouth of a fmalkr tube, inferted by grinding within F like the valve 

 3 in 



