- From STRONriAN. 35 



" confifls of about half its weight of water-" From thefe ob- 

 fervations DrPKiPsiLEY inferS; that water enters into the com- 

 pofition of fixed air, nay, that it is this ingredient which is 

 eflential to the aeriform condition of the acid. He extends the 

 idea to all aerial fluids and hence draws a futile argument 

 againfl: Mr Cavendish's glorious difcovery of the compofition 

 of water. 



3. It is unneceflary to tranfcribe the words of Mr Watt 

 junior, who fpeaks on the authority of Mr [ostAH Wedgewood 

 junior, to nearly the fame purpofe or thofe of M. Sage, Four- 

 CKOY and Pelletier. who ftrangely allert, that this fubftance 

 is abfolutely unchangeable by heat. 



4. From this general opinion, however, I am obliged to dlf- 

 fent, having found, that the fixed air can be expelled from the 

 native aerated barytes by heat alone, if fufficiently intenfe ; a 

 circumftance that muft prove fatal to the theory founded on Its 

 fuppofed impracticability. The heat which anfwers this pur- 

 pofe is that of a fmith's forge, when the fire is fldlfully ma- 

 naged. By its affiftance, I have oftentimes deprived the bary- 

 tic fpar of its acid either entirely or nearly fo. 



5. I NEED not detail the particulars of more than of one expe- 

 riment. In feveral trials, however, it may not be improper to 

 remark, I was difappointed, in confequence of the barytes, vehe- 

 mently heated, acSing as a flux on the clay of the crucible, cor- 

 roding holes in it and making its efcape, leaving as its only ve- 

 ftige a green-coloured vitreous glazing on the infide of the cru- 

 cible. At firft I employed crucibles made of pure Stourbridge 

 clay, but was, from the circumfl;ance this moment mentioned, 

 obliged to have recourfe to thofe compofed of black lead, which 

 are able to refill and confine the heated fpar ; yet fometimes I 

 fucceeded even with thofe of clay. 



6. A SOLID and pure mafs of the fpar, weighing 338.4 

 grains, was put into a black lead crucible, having a hd of the 



E 2 fame 



