134 On the Liquefaction of Gases. [1824, 



manner, a liquid has been observed to deposit from it. It is 

 not, however, a result of the liquefaction of the gas, but the 

 deposition of a vapour (using the terms gas and vapour in their 

 common acceptation) from it, and when taken out of the vessel 

 it remains a liquid at common temperatures and pressures, 

 may be purified by distillation in the ordinary way, and will 

 even bear a temperature of 170 F. before it boils at ordinary 

 pressure. It is the substance referred to by Dr. Henry in the 

 'Philosophical Transactions,' 1821, p. 159. 



There is no reason for believing that oil-gas, or olefiant gas, 

 has as yet been condensed into a liquid, or that it will take 

 that form at common temperatures under a pressure of five, or 

 ten, or even twenty atmospheres. If it were possible, a small, 

 safe, and portable gas-lamp would immediately offer itself to 

 us, which might 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 Fahr. at a pressure under four atmo- 

 spheres, 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 preclude its applica- 

 tion. But we may, perhaps, without being considered extra- 

 vagant, be allowed to search in the products of oil, resins, coal, 

 &c., 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 

 results 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 in- 

 teresting, and is the only additional one on the subject I am 

 acquainted with, I am desirous of doing so, as well also to point 



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

 Gas," Annals of Philosophy, N. S. iii. 3/. 



