166 On some new Products [1825. 



one* delineated in the sketch, fig. 1, containing a mercurial 

 gauge at a, c, and the extremities being open. It was then 

 cooled to 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 ; 



Fig. 1, 



Fig. 2. 



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 d 

 sufficient 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 con- 

 sequence 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 conse- 

 quence of the striaB 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 sub- 

 stances 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 con- 



* The particular inclination of the parts of the tube one to another was 

 given, that the fluid, when required, might be returned from a to d without 

 passing on to b. . 



