ATTAINMENT OF VERY LOW TEMPERATURES. 



17 



with later (Part 11). The regenerator coil and the lower part of the 

 chamber C were enclosed within the vacuum vessel H, which was 

 secured to the metallic part of the apparatus by means of a gland p (fig. 

 4) which compressed a rubber ring into the space between the outer wall 



Fig. 3.— Hydrogen liquefier. 



of the vacuum vessel and the inner wall of the tube m, making a gas- 

 tio-ht junction. The apparatus rested on a brass flange, soldered to the 

 tu'be m, in a round hole in a wooden shelf fixed to the wall of the com- 

 pressor room. The upper part was surrounded with a thick layer of 



natural wool. u a u 



The hydrogen expanding at the valve E, which was controlled by 

 the lever a, became further cooled, and passing upward through the 

 interstices of the coil, cooling it and the gas passing through it, so that 

 after a short time liquid began to separate in the vacuum vessel, l^rom 

 the top of the regenerator coil the gas passed through the annular 

 space F, surrounding the chambers B and C, and returned through the 

 tuge G to the compressor. 



