( 185 ) 



about I to 11 at tin boiling-point. It points to a critical temperature 

 which is not much higher than 5° K., and a critical pressure which 

 is not much higher than 2,3 atms. 



But all the quantities mentioned will have to be subjected to 

 further measurements and calculations before they will be firmly 

 established, and before definite conclusions may be drawn from them. 



We may only still mention here a preliminary value of a, viz. 

 0.00005. When in 1873 van der Waals in his Dissertation 

 considered whether hydrogen would have an a, it was only after 

 a long deliberation that he arrived at the conclusion that this 

 must exist, even though it should be very small. It may be presumed 

 that matter will always have attraction, was his argument, and as 

 chance would have it these words were repeated by him in reference 

 to helium some days before the liquefaction of helium (These Proc. 

 June 1908). The a found now denotes the smallest degree of this 

 attraction of matter, which still manifests itself with remarkable 

 clearness also in helium in its liquefaction. 



Geology. — "The age of the layers of Sonde and Trinil on Java" , 

 By Prof. K. Martin. 



(This paper will not be published in this Proceedings). 



(September 8, 1908). 



