6l4 PHILOSOPHICAL TRANSACTIONS. [aNNO J 7 10. 



larger than the small hollow wire, it was wedged into the same with pieces of 

 steel wire, till the cast brass was filled as full as it could contain. In this man- 

 ner it was put into a charcoal fire, where it lay till it was thoroughly red-hot. 

 The receiver being then exhausted of its air, the cock, on its upper part was 

 turned, which gave liberty for that air only which must necessarily pass through 

 the red-hot metals to succeed. This air first passing down through the small 

 ducts between the red-hot wires, before it could come to enter the red-hot hol- 

 low brass wire, must of necessity suffer or undergo such a change as fire or the 

 fumes of such red-hot metals would give it. When the receiver was filled with 

 this air, and had stood some little time, the brass cover was taken off, and a 

 pretty large cat immediately plunged into it; the cover being laid on again, the 

 cat immediately fell into convulsions, and in less than a minute appeared with- 

 out any sign of life. Then being taken out of the receiver, and laid on the 

 floor, she seemed as dead; but in less than a minute of time she began to dis- 

 cover life by motion in her eyes, and after two or three hideous squalls, she 

 began to recover apace, but was very fierce, and would spit and fly, as well as 

 her weakness would suffer her, at any one that offered to touch her, and it 

 seemed hazardous for any one then to attempt it. But after about half an 

 hour's time, as her strength and ease recovered, so her former temper increased 

 upon her, suffering herself to be handled without any sign of fierceness. 



The effect the same sort of factitious air had upon flame was as follows ; on 

 plunging a lighted candle into it, it was immediately extinguished; and this I 

 several times observed, that when the candle was slowly immersed, so much of 

 the wick, which before was lighted, as came but just within the verge of the 

 glass, died; and so the rest successively, as it descended to the same place; 

 and this, on several repetitions, answered much the same. But in some time, 

 as the common air came to mix with it, one might plunge the lighted candle 

 lower and lower before it would go out, till at last it would remain burning at 

 the bottom. As to the elasticity and specific gravity of the said medium, I have 

 made several accurate trials, but find it nowise differing from common air, in 

 respect to those properties. Hence it follows, that the foregoing effect, is 

 nowise owing to any imperfection or defect in the last mentioned properties: 

 therefore the following queries seem to offer themselves. Query 1 . Whether 

 air itself may so suffer in its own nature, by any sort of fire, as to be divested 

 of the power of subsisting life or flame?* or, 



♦ When atmospheric air is made to pass through red hot metallic tubes in the manner above- 

 mentioned, it is deprived of its oxygen, which combines with the heated metal, whose sur&ce is 

 thereby more or less oxydized. Hence tlie residual air (consisting of azote, with sometimes a small 

 proportion of carbonic acid gas) becomes unfit for the support of life and flame* 



