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From confidering the affinity which this vapour 

 has with phlogifton, I was induced to try the effect 

 of a mixture of it with nitrous air. Accordingly, to 

 two parts of this vapour, I put one part of nitrous 

 air, and, in about twenty-four hours, the whole was 

 diminifhed to fomething lefs than the original quan- 

 tity of the vapour, and was no farther diminifhed by 

 the admiffion of water. Holding the flame of a 

 candle over this air, the lower part of it burned green, 

 but there was no fenfible explofion. At different 

 times I collected 2| ounce meafures of this mixture 

 of air; but, upon agitating it in rain-water, it was 

 prefently diminifhed to i| ounce meafures. In this 

 ftate it effervefced with nitrous air, and was confi- 

 derably diminifhed by it, but not fo much as com- 

 mon air. Some allowance, no doubt, muft be made 

 for the fmall quantities of common air, which lodged 

 on the top of my phials, when I raifed the fume from 

 the fpirit of fait ; but, from the precautions that I 

 made ufe of, I think that very little is to be allowed 

 to this circumflance ; and, upon the whole, I am of 

 opinion, that this experiment is an approach to the 

 generation of common air, or air fit for refpiration. 



I had alfo imagined, that if air diminifhed by the 

 procefTes above-mentioned was affected in this man- 

 ner, in confequence of its being faturated with phlo- 

 jrifton, a mixture of this vapour might imbibe that 

 phlogifton, and render it whoiefome again ; but I put 

 about one fourth of this vapour to a quantity of air 

 in which metals had been calcined, without making 

 any feniible alteration in it. I do not, however, in- 

 fer from this, that air is not diminifhed by means of 

 phlogifton, fince the air, like fome other fub(lances ? 



I i 2 -may 



