Low-Temperature Research at the Royal Insiitution 735 



HODGKINS TRUST. 



E.ssAY BY Professor Henry E. AR:\isTROxa. 

 Low-Temperature Research at the Royal institution, 1903-1916. 



This third instalment of the record, under the terins of the Hodgkins 

 Trust, of the original inquiries pursued at the Royal Institution 

 follows in natural sequence of subject the two earlier notices,* the 

 work being for the most part the direct outcome and an integration 

 of that done during the previous periods. 



In my former account, I have termed the first septennate the 

 Hydrogen Period but have pointed out that the Dewar vacuum 

 vessel was first brought into use during the period. The second 

 septennate was termed the Charcocd Vacuum Period. In the interval, 

 not only has the Coming of Age of the Vacuum Vessel been celebrated 

 bat the Charcoal Vacuum process has been quietly appropriated, the 

 world over, by scientific and industrial workers, as affording an 

 otherwise unapproachable means of producing the highest vacua Ijy 

 effecting the all but complete removal of its gaseous contents from 

 any vessel. 



Although the liquefaction of most of the least coercible gases was 

 achieved without the aid of the vacuum vessel, that of Hydrogen 

 was not realized until a vessel of special type was made use of : 

 probably the critical importance of the device is not recognized ; it 

 is doubtful whether the liquefaction of Helium could ever have been 

 effected without the combined use of the vacuum vessel and the 

 charcoal vacuum. The manipulation of liquid air and of liquid 

 hydrogen and their use as refrigerating agents in experimental 

 inquiries and on a large scale would have been impossible without it. 

 The value of the vacuum or Thermos flask is now fully known to 

 the public through usage, though probably, as a rule, without any 

 appreciation either of the principle upon which it is founded or of the 

 history of its development. 



The use made of high vacua in the recent transcendental inquiries 

 into the constitution of the atom is known only to the few and 

 cannot be generally appreciated ; the advance made is already so 



* Summaries of the work carried on with the aid of the Hodgkins Trust 

 are, by the authority of the Managers, incorporated in the " Proceedings of the 

 Royal Institution " every seven years. 



Low Temperature Research at the Royal Institution, 1893-1900. Miss 

 Agnes M. Gierke. •' Proceedings," xvi. p. 699. 



Ditto, 1900-1907. Prof. Henry E. Armstrong. " Proceedings," xix. p. 354. 



