1824.] On the Liquefaction of Gases. 131 



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 atmospheres was insuffi- 

 cient to liquefy the gas at a temperature of F. 



Chlorine. The most remarkable and direct experiments I 

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

 connected 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 in- 

 fluence of condensation ;" and it was with this in view that the 

 experiments were made and described. The results of lique- 

 faction were therefore 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 apparatus, namely, a brass condensing pump ; 

 pear-shaped glass receivers, containing from three and a half 

 to five cubic inches, and a quarter of an inch thick; and occa- 

 sionally a siphon gauge. Sometimes as many as eighteen atmo- 

 spheres were supposed to have been compressed into the 

 vessel, but it is added,. that the quantity cannot be depended 

 on, as the tendency to escape even by the side of the piston, 

 rendered its confinement very difficult. 



Now that we know the pressure of the vapour of chlorine, 

 there can be no doubt that the following passage describes a 

 true liquefaction of that gas : " Upon the compression of 

 nearly two pints of oxygenated muriatic acid gas in a receiver, 

 two and a quarter cubic inches capacity, it speedily became 

 converted into a yellow fluid, of such extreme volatility, under 

 the common pressure of the atmosphere, that it instantly eva- 

 porated upon opening the screw of the receiver ; I need not 

 add that this fluid, so highly concentrated, is of a most in- 

 supportable pungency. . . . There was a trifling residue of a 

 yellowish substance left after the evaporation, which probably 

 arose from a small portion of the oil and grease used in the 

 machine," &c., xiii. 235. 



Muriatic Acid. Operating upon muriatic acid, Mr. North- 

 more obtained such results as induced him to state he coulc). 

 liquefy it in any quantity ; but as the pressure of its vapour at 



