hïi 



*xj'ii 



used equally well as wires of eonstantin (the suitability of which 

 was shown oil a former occasion), as resistance thermoineter in 

 this region of temperatures. 



h. Pure cadmium rind pure tin. Pure cadmium (Kahi-baum) was 

 cast in a glass tube like mercury. From the tin (IvAiii.BArM) a thin 

 \\ ire was cut on the lathe. 



c. Copper and iron. The cojiper wii'c was made of commercial 

 electrolytic copper^). The iron was from Sweden (Kolswa II). It 



1) W. Meissner (Verli. D. Pliys. Gos. (10), 262, 1914) nseil much purer ropppr. 

 In Ills detorniinalion.': Ilie resistance at the boiling point of liquid hydrogen was 

 only 0.26 o/o of the resistance at 0° G. 



