Page:The chemical history of a candle.djvu/89

and is cooled again without the access of air or water, it does not change in its weight; but after having had this current of steam passed over it, it then comes out heavier that it was before, having taken something out of the steam, and having allowed something else to pass forth, which we see here. And now, as we have another jar full, I will shew you something most interesting. It is a combustible gas; and I might at once take this jar and set fire to the contents, and shew you that it is combustible; but I intend to shew you more if I can. It is also a very light substance. Steam will condense: this body will rise in the air, and not condense. Suppose I take another Fig. 15. glass jar, empty of all but air: if I examine it with a taper, I shall find that it contains nothing