LIQUEFACTION OF TEE ELEMENTARY GASES. 249 

 LIQUEFACTION OF THE ELEMENTAEY GASES. 



By JULES JAMIN, of the Institute of Feakce. 



THE earlier experiments of MM. Cailletet and Raoul Pictet in 

 the liquefaction of gases, and the apparatus by means of which 

 they performed the process, were described in " The Popular Science 

 Monthly," March and May, 1878. The experiments have since been 

 continued and improved upon by MM. Cailletet and Pictet, and 

 others, with more complete results than had been attained at the time 

 the first reports were published, and with the elucidation of some 

 novel properties of gases, and the disclosure of relations, previously 

 not well understood, between the gaseous and the liquid condition. 

 The experiments of Faraday, in the compression of gases by the 

 combined agency of pressure and extreme cold, left six gases, which 

 still refused to enter into the liquid state. They were the two ele- 

 ments of the atmosphere (oxygen and nitrogen), nitric oxide, marsh- 

 gas, carbonic oxide, and hydrogen. Many new experiments were tried 

 before the principle that governs the change from the gaseous to the 

 liquid, or from the liquid to the gaseous form, was discovered. Aime 

 sank manometers filled with air into the sea till the pressure upon them 

 was equal to that of four hundred atmospheres ; Berthelot, by the ex- 

 pansion of mercury in a thermometer-tube, succeeded in exerting a 

 pressure of seven hundred and eighty atmospheres upon oxygen. Both 

 series of experiments were without result. M. Cailletet, having fruit- 

 lessly subjected air and hydrogen to a pressure of one thousand atmos- 

 pheres, came to the conclusion that it was impossible to liquefy those 

 gases at the ordinary temperature by pressure alone. Previously it 

 had been thought that the obstacle to condensing gases by pressure 

 alone lay in the difficulty of obtaining sufficient pressure, or in that of 

 finding a vessel suitable for manipulation that would be capable of 

 resisting it. M. Cailletet's thought led to the discovery of another 

 fundamental property of gases. 



The experiments of Despretz and Regnault had shown that the 

 scope of Mariotte's law (that the volume of gases increases or dimin- 

 ishes inversely as the pressure upon them) was limited, and that its 

 limits were different with different substances. Andrews confirmed 

 the observations of these investigators, and extended them. Com- 

 pressing carbonic acid at 13° C. (55° Fahr.), he found that the rate of 

 diminution in volume increased more rapidly than Mariotte's law 

 demanded, and at a progressive rate. At fifty atmospheres the gas 

 all at once assumed the liquid form, became very dense, and fell to 

 the bottom of the vessel, where it remained separated from its vapor 

 by a clearly defined surface, like that which distinguishes water in the 

 air. Experimenting in the same way with the gas at a higher tern- 



