514 PHILOSOPHICAL TRANSACTIONS. [ANN0 1784. 



only produced by the decomposition of the impurities in the tilings, yet it cer- 

 tainly ought to be repeated in a more accurate manner. 



Before concluding this paper, it may be proper to sum up the state of the ar- 

 gument on this subject. There are 5 methods of phlogistication considered by 

 me in my paper on air, namely, 1st, the calcination of metals, either by them- 

 selves or when amalgamated with quicksilver; 2dly, the burning sulphur or phos- 

 phorus; 3dly, the mixture of nitrous air; 4thly, the explosion of inflammable 

 air; and, 5thly, the electric spark; and Mr. Kirwan has not pointed out any 

 other which he considers as unexceptionable. Now the last of these I by no 

 means consider as unexceptionable, as it seems much more likely, that the phlo- 

 gistication of the air in that experiment is owing to the burning or calcination of 

 some substance contained in the apparatus.* It is true, that I have no proof of 

 it; but there is so much probability in the opinion, that till it is proved to be 

 erroneous, no conclusion can be drawn from such experiments in favour of the 

 generation of fixed air. As to the first method, or the calcination of metals, 

 there is not the least proof that any fixed air is generated, though we certainly 

 have no direct proof of the contrary; nor did I in my paper insinuate that we 

 had. The same thing may be said of the burning of sulphur and phosphorus. 

 As to the mixture of nitrous air, and the combustion of inflammable air, it is 

 proved, that if any fixed air is generated, it is so small as to elude the nicest test 

 we have. It is certain too, that if it had been so much as -J^ of the bulk of the 

 common air employed, it would have been perceived in the first of these methods, 

 and would have been sensible in the second, though still less. So that out of 

 the 5 methods enumerated, it has been shown, that in '2 no sensible quantity is 

 generated, and not the least proof has been assigned that any is in 1 of the 

 others; and as to the last, good reasons have been assigned for thinking it in- 

 conclusive; and therefore the conclusion drawn by me in the above-mentioned 

 paper seems sufficiently justified; namely, that though it is not impossible that 

 fixed air may be generated in some chemical processes, yet it seems certain, that 

 it is not the general effect of phlogisticating air, and that the diminution of 

 common air by phlogistication is by no means owing to the generation or sepa- 

 ration of fixed air from it. 



XVI. Mr. Kirwan s Reply to Mr. Cavendish's Answer, p. 178. 



Mr. Cavendish says, that in Mr. Lassone's experiments the effervescence pro- 

 ceeded not from any fixed air in the alkali, but from the further action of the 

 acid on the zinc from which inflammable air was disengaged. But this could 



* In the experiment with the litmus I attribute the fixed air to the burning of the litmus, not de- 

 composition, as Mr. Kirwan represents it, which is a sufficient reason why no fixed air should be 

 found when the experiment is tried with air in which bodies will not burn. — Orig. 



