Page:Experimental researches in chemistry and.djvu/181

166 one delineated in the sketch, fig. 1, containing a mercurial gauge at a, c, and the extremities being open. It was then cooled to 0° from a to b, and in that state made the receiver into which the first product from a portion of the original fluid was distilled. The part at b was then closed by a spirit-lamp;

and having raised enough vapour to make it issue at c, that was also closed. The apparatus now placed as at fig. 2, had a and d cooled to 0°, whilst the fluid collected in b was warmed by the hand or the air; and' when a portion had collected in dsufficient for the purpose, the whole instrument was immersed in water at 60°; and before the vapour had returned and been all dissolved by the liquid at b, the pressure upon the gauge within was noted. Sometimes the fluid at d was rectified by warming that part of the tube and cooling a only, the re absorption at b being prevented or rather retarded in consequence of' the superior levity of the fluid at d; so that the first portions which returned to b lay upon it in a stratum, and prevented sudden solution in the mass below. This difference in specific gravity was easily seen upon agitation, in consequence of the strim produced during the mixture.

Proceeding in this way, it was found, as before stated, that the highest elastic power that could be obtained from the substances in the tube was about four atmospheres at 60°; and as there seems no reason to doubt but that portions of the most volatile substances in oil-gas beneath olefiant gas were