5J9 



little from that given Comm. 112, June 1909. Our resists (yet of a 

 preliminary kind) were (see table IV p. 518). 



The density of tlie liquid was measured by a small hydrometer 

 for densities of 1,20 to 1.30, floating in the bath, which after a 

 preliminary trial was specially made for this purpose. 



4. Prclüiiinnri/ iiivestnintlcn of the behaviour of neon loith respect 

 to the IwD of corresjwnding states. 



The pieces of isothermals of low temperatures given in § 2 are 

 too short and have therefore too few characteristic features, to be 

 able to yield the critical constants of neon by the method of drawing 

 them in a logarithmic diagram and making this fit the logarithmic 

 diagram of another substance of known critical data, by parallel 

 motions in two directions. 



They are still insufficient for this purpose, if the improved method 



is used of taking as one of the coordinates in the diagram in which 



pv 

 the isothermals are drawn the expression — , which has the same 



value for all substances in corresponding states, so that now only 

 a motion in one direction is required. Definite results are to be 

 obtained, however, if in addition Ihe value of the critical pressure 

 (Con)m. 112 June 1909) is utilized, although it is only a preliminary 

 value. Following this plan we have placed the net of isothermals 



of neon in a -;: /<>(/ /^ diagram on top of that of hydrogen, oxygen 



and argon and by ascertaining what temperatures the isothermals 

 which coincide belong to for each of the substances, we have arrived 

 at a few estimates of Ihe critical temperature. 

 The results were as follows : 



1. Uyd'Ogen. (Kamekmngh Onnes and Braak). 



a. The isothermals — 200. "Tve and — 21 7. °41//j coincide and cover 

 each otiier completely o\cr a long distance. Taking for the critical 

 temperature of hydi'Ogeii the value found experimentally by Bullk 

 6/^7,= — 241. °1 4 C, we get 



öi...v, =-231.°2 C, TtA, .= 41.°9 K. 



h. The isothermals — 182.°6a'„ — 200.''6/^^ coincide. This gives: 



%Ae = — 233".2 C, 7\..,v, = 39.°9 K. 



In this case we used also o'tf/, = — 241.°14C., but, as this value 

 belongs to monatomic hydrogen and hydrogen at — 200° C. is certainly 



