2?o Dr. Priestley's Experimetits andOhfervatlons 

 concluded from fome experiments, of which I gave an account 

 to the Society, and ahb from fome obfervations of his own, 

 that water confifts of dephlogifticated and inflammable air, 

 in which Mr. Cavendish and M. Lavoisier concur with 

 him; but Mr. Lavoisier is well known to maintain, that 

 there is no fuch tiling as what has been called phiogi/Io?i, affirm- 

 ing inflammable air to be nothing elfe but one of the elements 

 of condituent parts of water. In the following experiments I 

 alfo had a particular view to a conclufion which 1 had drawn 

 from thofe experiments, of which an account is given in my 

 laft communications to the Royal Society j vi%, that inflam- 

 mable air is pure phlogiilon in the form of air, at lead with 

 the element of heat ; and that fixed ah* confifls of dephlogifti- 

 cated and inflammable air; both which do6lrines had been firft 

 advanced by Mr. Kir wan, before I had made the experiments 

 which I then thought clearly proved them. 



^uch were the hypothefes to which I had a view when I 

 began the following courfe of experiments, which I hope will 

 be an admonition to myfelf, as w^U as to others, to adhere as 

 jigoroufly as poffible to aSlual obfervations, and to be extremely 

 careful not to overlook any circumftance that may poffibly con- 

 tribute to any particular refult. I fhall have occafion to notice 

 my own miilakes with refpe£l to co?icluJto?is, though all the 

 fiiBs were ftri6lly as I have reprefented them. But whilfl phi- 

 lofophers are faithful narrators of what they obferve, no perfoii 

 can juflly complain of being milled by them; for to reajon 

 from the fads with which they are fupplied is no more the 

 province of the perfon who discovers them, than of him to 

 whom they are difcovered. 



One of the moll: Ample of all phlogiftlc proceflfes is that in 



which metals are ignited in dephlogiflicated air. I therefore 



3 began 



