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flammable air is the very fame, as far as I am able to 

 perceive^ from whatever; fubftance of the fame 

 kingdom it be extracted. Thus it makes no differ- 

 ence whether it be got from iron, zinc,, or tin, from < 

 any kind of wood, or, as was obferved before, from 

 any part of an animaL 



If a quantity of inflammable air be contained in a 

 glafs veffel ftanding in water,, and have been gene- 

 rated very faft, it will fmell even through the water,, 

 and this water will alfo foon become covered with a 

 thin film, afluming all the different colours. If the 

 inflammable air have been generated from iron, this 

 matter will appear to be a red okre, or the earth of 

 iron, as I have found by collecting a considerable 

 quantity of it j and if it have been generated from 

 zinc, it is a whitifh fubftance, which I fuppofe to be 

 the calx of the metal. It likewife fettles to the 

 bottom of the veffel, and when the water is ftirrcd, , 

 it has very much the appearance of wool. When 

 water is once impregnated in this manner, it will 

 continue to yield this fcum for a confiderable time 

 after the air is removed from it. This I have often 

 obferved with refpecl to iron. 



Inflammable air, made by a violent effervefcence, I 

 have obferved to be much more inflammable than 

 ,that which is made by a weak efrervefcence, whe- 

 ther the water or the oil of vitriol prevailed in the 

 mixture. Alio the offenfive fmell was much 

 ftronger in the former cafe than in the latter. The 

 greater degree of inflammability appeared . by the 

 greater number of fuccefiive explofions,when a candle 

 was prefented to the neck of a phial filled with it. 

 It is poflible, however, that this diminution of in- 

 flammability 



