616 THE POPULAR SCIENCE MONTHLY. 



LIQUEFACTION OF GASES. 1 



By GASTON TISSANDIEK. 



EVERY one knows that the matter which constitutes the various 

 natural bodies occurs iu three different forms, namely, the solid, 

 the liquid, and the gaseous states. So, too, every one knows that 

 the state of a body is not at all immutable : a solid may be fused 

 and volatilized ; a liquid may become a solid, or be transformed into 

 vapor ; a gas may be changed into a liquid or a solid all these 

 changes occurring according to the conditions of temperature or of 

 pressure to which the solids, liquids, or gases, are subjected. Water 

 turns into ice under the action of cold ; into steam under the action 

 of heat. Sulphur, phosphorus, tJie metals, and most solid bodies, may 

 in like manner assume these three states. Chlorine, protoxide of ni- 

 trogen, carbonic acid, etc., may be liquefied or solidified. To this end 

 we have only to bring the molecules nearer to one another by com- 

 pressing them, or subjecting them to the action of cold. 



Faraday succeeded in liquefying a certain number of gases by 

 compression and refrigeration, but there still remained a number that 

 proved absolutely refractory to the most powerful agencies ; hence 

 these gases were called permanent. They are hydrogen, nitrogen, 

 oxygen, carbonic oxide, bioxide of nitrogen, and formene (marsh-gas). 

 Chemists, it is true, were quite confident that these gases, like all 

 others, were subject to the general laws of bodies ; it was held to be 

 certain that the gases just named would, like the others, yield to suffi- 

 ciently his;h pressure or refrigeration. But, nevertheless, they still 

 remained bodies sui generis, defying, so to speak, the powers of the 

 chemist, and their change of state presented itself as a weighty prob- 

 lem, the solution of which was all the more alluring in proportion to 

 the difficulties with which it was surrounded. Berthelot, as we know, 

 subjected them to the enormous pressure of 800 atmospheres, and to a 

 refrigeration of more than 100 below zero, Centigrade; but all was 

 in vain, and the permanent gases justified their name. 



This is so no longer. A retired manufacturer, who at the same 

 time is a distinguished man of science, M. Cailletet, has subdued the 

 permanent gases, having succeeded in liquefying and solidifying them. 

 This result, which is one of the most interesting achievements of our 

 time, must unquestionably be regarded as a new and a grand conquest 

 of matter by science. 



Nearly at the same moment, another ingenious investigator and 

 inventor, M. Raoul Pictet, reached the same result with regard to 

 oxygen gas. We will pass in review successively the experiments of 



1 Translated from the French by J. Fitzgerald, A. M. 



