[ *9 6 ] 



(which I had kept alive, that the experiment might 

 be made on both the kinds of air with the very- 

 fame animal) would have been fufficiently recruited, 

 luppofing it to have received any injury by the 

 former experiment, was put into the fame veffel of 

 air ; but though it was withdrawn again, after be- 

 ing in it hardly one fecond, it was recovered with 

 difficulty, not being able to ltir from the place for 

 near a minute. After two days, I put the fame 

 mouie into an equal quantity of common air, and 

 obferved that it continued feven minutes without 

 any fign of uneafinefs ; and being very uneafy after 

 three minutes longer, I took it out. Upon the 

 whole, I concluded that the reftored air wanted 

 about one fourth of being as wholefome as common 

 air. The fame thing alfo appeared when I applied 

 the teft of nitrous air. , 



In the feven days, in which the mint was grow- 

 ing in this jar of noxious air, three old fhoots had 

 extended themfelves about three inches, and feverai 

 new ones had made their appearance in the fame 

 time. Dr. Franklin and Sir John Pringle happened 

 to be with me, when the plant had been three or 

 four days in this ftate, and took notice of its vigorous 

 vegetation, and remarkably healthy appearance in 

 that confinement. 



On the 30th of the fame month, a moufe lived, 

 fourteen minutes, breathing naturally all the time, 

 and without appearing to be much uneafy, till the 

 laft two minutes, in air which had been rendered 

 noxious by mice breathing in it almoft a year before, 

 and which 1 had found to be moft highly noxious on 

 the 19th of this month, a plant having grown in it, 



but 



