[ ^19 3 



XV. Experiments and Obfervations relating to Air and Water » 

 By the Rev. Jofeph Prieflley, LL,D. F.R.S, 



Read February 24, 1785. 



EVER fince the difcovery of the diminution of refpirabic 

 air in thofe proceffes which are generally called phlogijiicy 

 it lias been a great objed with philofophers to find what be- 

 comes of the air which difappears in them. Among others, I 

 have made and publifhed a variety of experiments with that 

 view; but though by this means fome farther progrefs was 

 made in the philofophy of air, and confequently our know- 

 ledge of the principles, or conflituent parts, of natural fub- 

 fiances was extended, I did not by any means fucceed to my 

 fatisfadion with refpedt to the immediate obje6l of my re- 

 fearches. Others, however, were more fuccefsful, and their 

 fuccefs has at length enabled me to refume my experiments 

 with more advantage ; by which means I have been led both to 

 confirm their conclufions, and, by diverfifying the experi- 

 ments, to throw confiderable light upon various other chemical 

 procefies. The refult of thefe obfervations I fhall lay before 

 the Society, with as much brevity and diftindnefs as I can. 



In the experiments of which I fhall now give an account, 

 I was principally guided by a view to the opinions which have 

 lately been advanced by Mr. Cavendish, Mr. Watt, and 

 M. Lavoisier. Mr. Cavendish was of opinion, that when 

 ^/r is decompofed, water only is produced; and Mr. Watt 



concluded ■ 



