236 Mr. Faraday on the Liquefaction of Gases. 



knowledge of the strength of the vapour of chlorine will enable us 

 to construct them of a much more convenient and portable form 

 than has yet been given to them. 



Arsenhtretted Hydrogen. — This is a gas which it is said has 

 been condensed so long since as 1805. The experiment was 

 made by Stromeyer, and was communicated, with many other 

 results relating to the same gas, to the Gottingen Society, Oct. 

 12, 1805. See Nicholson's Journal, xix. 382 ; also, Thenar d 

 Traitc de Chimie, i. 373; Brando's Manual, ii. 212; and Annates 

 de Chimie, Ixiv. 303. None of these contain the original ex- 

 periment ; but the following quotation is from Nicholson's Journal. 

 The gas was obtained over the pneumatic apparatus, by digesting 

 an alloy of fifteen parts tin and one part arsenic, in strong muri- 

 atic acid. " Though the arsenicated hydrogen gas retains its 

 aeriform state under every known degree of atmospheric tem- 

 perature and pressure, Professor Stromeyer condensed it so far 

 as to reduce it in part to a liquid, by immersing it in a mixture 

 of snow and muriate of lime, in which several pounds of quick- 

 silver had been frozen in the course of a few minutes." From 

 the circumstance of its being reduced only in part to a liquid, we 

 may be led to suspect that it was rather the moisture of the gas 

 that was condensed than the gas itself ; a conjecture which is 

 strengthened in my mind from finding that a pressure of three atmo- 

 spheres was insufficient to liquefy the gas at a temperature of 0°F. 

 Chlorine. — The most remarkable and direct experiments I have 

 yet met with in the course of my search after such as were con- 

 nected with the condensation of gases into liquids, are a series 

 made by Mr. Northmore, in the years 1805-6. It was expected 

 by this gentleman " that the various affinities which take place 

 among the gases under the common pressure of the atmosphere, 

 would undergo considerable alteration by the influence of con- 

 densation ;" and it was with this in view that the experiments 

 were made and described. The results of liquefaction were there- 

 fore incidental, but at present it is only of them I wish to take 

 notice. Mr. Northmore's papers may be found in Nicholson's 

 Journal, xii. 368. xiii. 232. In the first is described his appa- 

 ratus, namely, a brass condensing pump ; pear-shaped glass re- 



