[MCLENNAN & SHRUm] 



LIQUEFACTION OF HYDROGEN 



191 



MULIUM 



LiQUcrieFi 



Fig. 6 



reduced to this temperature it must then be expanded from a nozzle 

 with the application of the principle of regenerative cooling. In the 

 design of our helium liquéfier provision was made for these features. 

 The arrangement of parts is shown in Fig. 6. 



The gas enters at the intake indicated in the figure. It passes 

 successively through the coils -Di, Bi and Dz, 1)4 arranged in parallel. 

 It then enters Pi and Fi also in parallel and afterwards passes succes- 

 sively through P3, P4, P5. Di, D^, Pi and P3 are to be cooled by the 

 vapourized hydrogen that is drawn off by the hydrogen vacuum 

 pump. Di, Ds, Pi and P3 serve as exchangers for the expanded helium. 

 The coil D^ is to be partially immersed in liquid hydrogen boiling at a 

 pressure of 5 cms. of mercury. The trap T is to be kept immersed in 

 liquid air in order that the last traces of oil or water vapour coming 

 from the pump may be condensed out. B]_ and B^ are bombs to be 

 filled with charcoal and kept at the temperature of liquid air so that 



