240 Mr. Faraday on the Liquefaction of Gases. 



be filled with liquid without being subject to any greater force than 

 the strength of its vapour, and would afford an abundant supply 

 of gas as long as any of the liquid remained. Immediately upon 

 the condensation of cyanogen, which takes place at 50° F. at a 

 pressure under four atmospheres, I made such a lamp with it. It 

 succeeded perfectly, but, of course, either the expense of the gas, 

 the faint light of its flame, or its poisonous qualities, would pre- 

 clude its application. But we may, perhaps, without being con- 

 sidered extravagant, be allowed to search in the products of oil, 

 resins, coal, fyc. distilled, or otherwise treated, with this object in 

 view, for a substance, which being a gas at common temperatures 

 and pressure, shall condense into a liquid, by a pressure of from 

 two to six or eight atmospheres, and which being combustible, shall 

 afford a lamp of the kind described*. 



Atmospheric Air. — As my object is to draw attention to the re- 

 sults obtained in the liquefaction of gases before the date of those 

 described in the Philosophical Transactions for 1823, I need not, 

 perhaps, refer to the notice given in the Annals of Philosophy, 

 N.S. vi. 66, of the supposed liquefaction of atmospheric air, by 

 Mr. Perkins, under a pressure of about 1100 atmospheres, but 

 as such a result would be highly interesting, and is the only addi- 

 tional one on the subject I am acquainted with, I am desirous of 

 doing so, as well also to point out the remarkable difference be- 

 tween that result and those which are the subject of this and the 

 other papers referred to. Mr. Perkins informed me that the air 

 upon compression disappeared, and in its place was a small 

 quantity of a fluid, which remained so when the pressure was 

 removed, which had little or no taste, and which did not act on 

 the skin. As far as I could by inquiry make out its nature, it 

 resembled water, but if upon repetition it be found really to be 

 the product of compressed common air, then its fixed nature shews 

 it to be a result of a very different kind to those mentioned above, 

 and necessarily attended by far more important consequences. 



* In reference to the probability of such results, see a paper " On 

 OlefiaiU Giis." Annals of Philosophy, N.S. iii. 37. 



