Liquefaction of Gases 193 



air-pump. The lower end of the cylinder is joined by a 

 narrow copper tube to a little stopcock, through which the 

 oxygen, liquefied in the cylinder, can be poured down into 

 an open glass vessel kept cool by the surrounding air. Owing 

 to this isolation, liquid oxygen contained in the open vessel 

 evaporates but very slowly ; and when after some time its 

 quantity has considerably decreased, a new portion which has 

 been liquefied in the meantime can be led down into the 

 vessel by turning the cock. This may be continued until 

 the store of ethylene serving to cool the cylinder and the 

 amount of oxygen in the iron flask are exhausted. 240 g. 

 of liquid ethylene suffice to keep the oxygen liquid at the 

 atmospheric pressure for half an hour. 



By connecting the glass vessel which contains the liquid 

 oxygen with a good air-pump, its temperature can easily be 

 lowered to —211° C. Thus was solved the problem of lique- 

 fying considerable quantities of oxygen without the slightest 

 danger. This decides me to resume my former experiments 

 concerning the liquefaction of hydrogen ; and I hope thereby 

 to obtain more successful results. 



To this description, which I have given in a literal trans- 

 lation from the above-mentioned Bulletin International, I 

 subjoin a diagram (fig. 1) representing a section of my appa- 

 ratus, which I shall shortly explain. But I must remark that 

 in the same year (1890), when proceeding to my experiments 

 on the liquefaction of hydrogen, I doubled the dimensions of 

 the apparatus without changing anything in its construction. 

 The dimensions that I shall afterwards give refer to the enlarged 

 apparatus. 



The steel cylinder a, of a capacity of 200 cub. centim., has 

 its upper end connected by means of a thin copper tube 

 with a metallic manometer b, and an iron bottle c 10 litres 

 in capacity, containing dry oxygen or air under a pressure of 

 100 atm., the lower aperture of the cylinder a being con- 

 nected by a very thin copper tube with the little cock d, 

 which serves to let out the liquefied oxygen or air. The 

 cylinder a is placed in a glass vessel m with double or treble 

 walls, which serves to receive the liquid ethylene, of which 

 the iron flask/is the reservoir. This flask (3 litres in capacity) 

 is shaped like a siphon, and contains about 1 kilog. of liquid 

 ethylene. The ethylene, liquefied and cooled in the flask/ by 

 means of ice and salt, passes, after the cock is turned, into 

 the condenser g filled w T ith a mixture of ether and solid carbon 

 dioxide. To lower the temperature of this mixture —78° C.) 



Phil. Mag. S. 5. Vol. 39. No. 237. Feb. 1895. O 



