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common air, in a few minutes (by which time the 

 effervefcence will be over, and the mixture will have 

 recovered its transparency) there will want about one 

 ninth of the original two meafures. I hardly know 

 any experiment that is more adapted to amaze and 

 furprize than this is, which exhibits a quantity of 

 air, which, as it were, devours a quantity of another 

 kind of air half as large as itfelf, and yet is fo far from 

 gaining any addition to its bulk, that it is diminifhed 

 by it. If, after this full faturation of common air with 

 nitrous air, more nitrous air be put to it, it makes an 

 addition equal to its own bulk, without producing 

 the leaft rednefs, or any other vifible effect. 



That this diminution is chiefly in the quantity of 

 common air, is evident from this obfervation, that if 

 the fmallefl quantity of common air be put to any 

 larger quantity of nitrous air, though the two toge- 

 ther will not occupy fo much fpace as they did fepa- 

 rately, yet the quantity will be ftill larger than that 

 of the nitrous air only. One ounce meafure of com- 

 mon air being put to near twenty ounce meafures of 

 ii'trous air, made an addition to it of about half an 

 ounce meafure. This, however, being a much greater 

 proportion than the diminution of common air, in the 

 former experiment, feems to prove that part of the 

 diminution in the former cafe is in the nitrous air. 

 Befides, it will prefently appear, that nitrous air is 

 fubjecl: to a moft remarkable diminution ; and as 

 common air, in a variety of other cafes, fuffers a di- 

 minution from one fifth to one fourth, 1 conclude, 

 that in this cafe alfo it does not exceed that propor- 

 tion, and therefore that the remainder of the dimU 

 nution refpects the nitrous air. 



In 



