obtained in the Decomposition of Oil. \Q\ 



turn, 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, tliat 

 the highest elastic power that could be obtained from the sub- 

 tances in the tube was about 4? 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- 

 tained in the fluid, inasmuch as even olefiant gas itself is dis- 

 solved by it in small proportions, it may be presumed that 

 there is no substance in oil gas much more volatile than the 

 one requiring a pressure of 4- atmospheres at 60°, except the 

 well knoAvn compounds ; or, in other words, that there is not 

 a series of substances passing upwards from this body to ole- 

 fiant gas, and possessing every intermediate degree of elasti- 

 city, as there seems to be from this body downwards, to com- 

 pounds requiring 250° or 300° for their ebullition. 



In reference to these more volatile products, I may state 

 that I have frequently observed a substance come over in small 

 quantity, rising with the vapour which boils off at 50° or 60°, 

 and crystallizing in spiculae in the I'eceiver at 0°. A tempera- 

 ture of 8° or 10° causes its fusion and disappearance. It is 

 doubtless a peculiar and definite body, but the quantity is ex- 

 tremely small, or else it is very soluble in the accompanying 

 fluids. I have not yet been able to separate it, or examine it 

 minutely. 



I ventured some time since upon the condensation of various 

 gases*, to suggest the possibility of forming a vapour lamp, 

 which, containing a brilliantly combustible substance (liquid at 

 a pressure of two, three, or four atmospheres at common 

 temperatures, but a vapour at less pressure), should fm'nish a 

 constant light for a length of time, without requiring high, or 

 involving inconstant, pressure. Such a lamp I have now 

 formed, feeding it with the substance just described; and 

 though at pi-esent it is only a matter of curiosity, and perhaps 

 may continue so, yet there is a possibility that processes may 

 be devised, by which the substance may be formed in larger 

 quantity, and render an application of this kind practically 

 useful. 



On the remaining Portions of the condensed Oil Gas Liquor. 

 It has been before mentioned, that by repeated distillations 

 various jjroducts were obtained, boiling within limits of tem- 

 perature which did not vary much, and which when distilled 

 were not resolved into other portions, differing far from each 



* Quarterly Journal of Science, xvi. 240. 



other 



