1907.] High Vacua and Helium. 747 



WEEKLY EYENINO MEETING, 



Friday, June 7, 1907. 



The Eight Hox. Loed Kelvin, O.M. G.C.Y.O. P.O. D.C.L. 

 LL.D. D.Sc. F.R.S., in the Chair. 



Professor Sir Ja^ies Dewar, M.A. LL.D. D.Sc. F.R.S. M.R.I., 

 Fullerian Professor of Chemistry, R.I, 



Studies in High Vacua and Helium at Low Temperatures. 



In a former lectm^e the production of very high vacua by means of 

 charcoal absorption at the temperatures of liquid air and liquid 

 hydrogen was discussed. With this new means of research, we shall 

 now follow its application in various directions. We live in an age 

 characterised by volume and rapidity of publication, in which scientific 

 literature takes its place, so that science is now burdened with much 

 that in former days would have been confided to the waste-paper 

 basket. There is a type of the modern scientist who needs to be 

 continually before the public, and the result is the appearance of 

 immatiu'e communications often loaded with needlessly endless details. 

 The foundations of scientific research in our time would seem to be 

 not a little undermined ; the tendency being to regard quantity and 

 not quality of output. In these pioneer studies we shall be content 

 to describe the general lines of this investigation, omitting for the 

 present any reference to refinement of details. 



High vacua and helitim might not appear to have much to do 

 with each other, but, as we shall see, they are intimately connected. 

 Immediately after the liquefaction of hydrogen by regenerative 

 expansion in 1896, I attacked the problem of the liquefaction 

 of helium, following by strict thermo-dynamic analogy the process 

 that had succeeded with hydrogen.* The hydrogen process was as 

 follows : hydrogen at a pressure of 180 atmospheres cooled down to 

 - 205' C, was made to issue, at the rate of about 15 cubic feet per 

 minute, from a nozzle terminating a long spiral coil of copper pipe 

 placed in a silvered glass vacuum vessel having a spiral tube con- 

 nected with the interior. After five minutes' circulation liquid hydro- 

 gen began to drop from the end of the spiral tube, and when the 

 liquid was evaporated under exhaustion, it froze into a white frothy 

 mass of solid hydrogen, presenting an appearance quite different from 

 the common belief that in this condition it would in all probabihty 



* For full description see Presidential Address, British Association, 1902. 



