[ *9* ] 



Six ounce meafures of air not readily abforbed by 

 water, appeared to have been generated from one 

 moufe, which had been putrefying eleven days in con- 

 fined air, before it was pot into ajar which was quite 

 tilled with water, for the purpofe of this obfervation. 



Air thus generated from putrid mice {landing in 

 water, without any mixture of common air, ex- 

 tinguifhes flame, and is noxious to animals, but 

 not more fo than common air only tainted with pu- 

 trefaction. It is exceedingly difficult and tedious to 

 collect a quantity of this putrid air, not mifcible in 

 water, fo very great a proportion of what is collect- 

 ed being abforbed by the water, in which it is kept; 

 but what that proportion is, I have not endeavoured 

 to a (certain. 



Though a quantity of air be diminimed by any 

 :fubftance putrefying in it, I have not yet found the 

 fame effect to be produced by a mixture of putrid air 

 with common air; but, in the manner in which I 

 have hitherto made the experiment, I was obliged 

 to let the putrid air, pafs through a body of water ; 

 which might inflantly abforb whatever it was in the 

 putrid fubitance, that diminimed the common air. 



Infects of various kinds live perfectly well in 

 air tainted with animal or vegetable putrefaction, 

 when a tingle infpiration of it would have inflantly 

 killed any animal. I have frequently tried the ex- 

 periment with flies and butterflies. I have alfo 

 obferved, that the aphides will thrive as well upon 

 ; plants growing in this kind of air, as in the open 

 air. I have even been frequently obliged to take 

 plants out of the putrid air in which they were 

 growing, on purpofe to brum away the fwarms of 



5 thefe 



