1911] 



on Chemical Change at Low Temperatures. 



!5y 



at D by means of a vaselined ground-glass joint to a tube E. The 

 luminous bacteria, cultivated on a thin surface layer in a tin cup 

 F, is placed in the bottom of the tube E, the end of which is immersed 

 in liquid air. The united tubes are then sufficiently exhausted to 

 allow the discharge to pass, and the cathode rays from B strike 

 directly on the surface of the bacterial culture. Experiments have 

 shown that hours of the cathode discharge will not kill the bacteria. 



Solidification of Gases. 



With regard to the liquefaction and solidification of gases, all have 

 been liquefied and solidified except helium, which still resists solidi- 

 fication, although its temperature has been reduced to below 3° abs. 



Hydrogen Nitrogen Oxygen 



Fig. 3. 



The solidification of oxygen has been finally accomplished by the 

 aid of a charcoal vacuum and of thermal isolation, such as can be 

 obtained with silvered vacuum vessels. The difference as regards 

 solidification of the three liquids — nitrogen, hydrogen, and oxygen — 



S 2 



