560 Prof. Sir J Dewar on Problems of Hydrogen [Jan. 22, 1915 



curves intersect at lower temperatures. When the indiambber 

 membrane is immersed in hquid air, the diffusion is too small to 

 be seen on the oil manometer ; the actual rate as determined on tlie 

 McLeod gauge l)eing only about 002 or • 003 c.c. per daj through 

 each square centimetre. These observations all refer to a difference 

 of pressure of one atmosphere on the two sides of the membrane. 

 The discussion of the results got by the action of varying pressures 

 and temperatures must be deferred to a future occasion. 



[J. I).] 



Mr. W. J. Green, B.Sc, of the Davv Faraday Laboratory, has 

 given valuable assistance in the conduct of the Investigation ; and 

 Mr. J. W. Heath, F.C.S., in the Lecture arrangements. 



