98 



Mr. Faraday on new Compounds 



IVeth 



To ascertain this a tube was prepared, like the one delineated in 

 the sketch. Fig. 1, containing a mercurial guage 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 instru- 

 ment 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 guage within was noted. Sometimes the 

 fluid at d was rectified by warming that part of the tube, and 

 cooling a only, the reabsorption 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 striae 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 defiant gas were contained 

 in the fluid, inasmuch as even defiant gas itself is dissolved by 

 it in small proportions, it may be presumed that there is no sub- 

 stance in oil gas much more volatile than the one requiring a 

 pressure of four atmospheres at 60°, except the well-known 

 compounds ; or, in other words, that there is not a series of sub- 

 stances passing upwards from this body to defiant gas, and 

 possessing every intermediate degree of elasticity, as there 



Note. — The particular inclination of the parts of the tube one to another was given, 

 that th» fluid when required might be returned from a to d without passing on to i. 



