748 



NATURE 



[August 12, 1920 



from the mineral uraninite, which from chemical 

 and spectroscopic tests he concluded was nitrogfen. 

 This gas, we now know, was, in fact, helium. 



Finally, in 1895, Sir William Ramsay {Chem. 

 News, 1895, vol. Ixxi., p. 151) discovered that a 

 gas could be obtained from the mineral cleveite. 

 This gas he purified, and, on examining its 

 spectrum, he found it to be the long-sought-for 

 element helium. From 1895 up to the present, 

 investigation has shown that helium is widely 

 diffused throughout the earth. It can be obtained 

 from many types of rocks, minerals, and earths, 

 and it is present in varying amounts in practically 

 all natural gases and spring waters. It is present, 

 too, in the atmosphere of the earth to the extent 

 of about four parts in one million by volume. 



The gases from some springs in France have 

 been shown to contain as much as 5 per cent, of 

 hehum. In the Western States of America, 

 jespecially in Texas, natural gases exist which 

 ■contain from i to 2 per cent, of helium, but within 

 the British Empire no natural gases which have 

 been examined show a helium content as high as 

 05 per cent. 



Until the spring of 1918 not more than 3 or 4 

 cubic metres of helium had, in the aggregate, 

 been collected, and its market price, though 

 variable, was about 300!!. per cubic foot. 



The principal characteristics of helium are : 



(i) Its extreme lightness. It is only twice as 

 heavy as hydrogen, the lightest element as yet 

 isolated. 



(2) Its absolute inertness. All attempts to 

 effect combinations of helium and the rare gases, 

 neon, argon, krypton, and xenon, as well, with 

 other elements have as yet failed. 



{3) Its close approximation to an ideal or 

 perfect gas. It is monatomic, and is liquefiable 

 at a temperature below that of liquid hydrogen. 

 By causing liquid helium to evaporate in a 

 vacuum, Onnes (Proc. K. Akad. Wetensch. 

 Amsterdam, 191 5, vol. xviii., p. 493) has suc- 

 ceeded in reaching a temperature within 1° or 2° 

 of the absolute zero. 



(4) Its low sparking potential. Electric dis- 

 charges can be passed through helium more easily 

 than through most other gases. 



No element has had a more romantic history 

 than helium, and none is of greater interest to 

 men of science than is this gas at the present 

 time. Its formation as a disintegration product 

 of the radio-active elements, and the identity of 

 the nuclei of helium atoms with o-rays, give it a 

 unique position among the elements. 



Intense interest has been aroused by Sir Ernest 

 Rutherford's recent discovery that in the nuclei 

 of helium atoms in the form of a-rays we have a 

 powerful and effective agent for disintegrating and 

 simplifying the nuclei of atoms generally. This 

 discovery points the way to still further progress. 

 In the past helium has been considered a rare 

 and precious gas. To-day it is being produced 

 in large quaritities, and in view of the proposal 

 now being put forward to use this gas in place 

 of hydrogen as a filling for airships, one is apt 

 NO. 2650, VOL. 105] 



to consider it to be not so precious as heretofore. 

 It may be, however, that such vast and vitally 

 important directions will suddenly be opened up 

 in which helium can be utilised that the conserva- 

 tion of the gas, while it is still available to us, 

 will become a matter of the first importance. 



Shortly after the commencement of the war in 

 1914, it became evident that if helium were avail- 

 able in sufficient quantities to replace hydrogen 

 in naval and military airships, losses in life and 

 equipment would be very greatly lessened. 



The fact that helium is both non-inflammable and 

 non-explosive, and possesses 92 per cent, of the 

 lifting power of hydrogen, makes it a most suit- 

 able filling for airship envelopes. By the use of 

 helium the engines of airships can be placed 

 within the envelope if desired. A further advan- 

 tage possessed by helium over hydrogen is that 

 the buoyancy may be increased or decreased at 

 will by heating or cooling the gas by electric or 

 other means, which fact may possibly lead to con- 

 siderable modifications in the technique of airship 

 manoeuvring and navigation. Moreover, the loss 

 of gas from diffusion through the envelope is less 

 with helium than with hydrogen to the extent of 

 about 30 per cent. 



Although there are indications that proposals 

 had been put forward during the war by men of 

 science in Allied. and enemy countries, as well as 

 in the British Empire, regarding the development 

 of supplies of helium for aeronautical purposes, it 

 should be stated that the movement that led up to 

 the investigation which it was my privilege to 

 undertake was initiated by Sir Richard Threlfall. 

 The existence in America of supplies of natural 

 gas containing helium in varying amounts was 

 known to him and others, and preliminary calcu- 

 lations as to the cost of production, transporta- 

 tion, etc., which he made led him to believe that 

 there was substantial ground for thinking that 

 helium could be obtained in large quantities at a 

 cost which would not be prohibitive. 



Sir Richard's proposals were laid before the 

 Board of Invention and Research of the British 

 Admiralty, and in the autumn of 191 5 the author 

 was asked by that Board to determine the helium 

 content of the supplies of natural gas in Canada, 

 and later on of those within the Empire, to carry 

 out a series of experiments on a semi-commercial 

 scale with the helium supplies which were avail- 

 able, and also to work out all technical details in 

 connection with the production of helium in quan- 

 tity, as well as those relating to the re-purification, 

 on a large scale, of such supplies as might be 

 delivered and become contaminated with air in 

 service. The present paper aims at giving a brief 

 account of this investigation. 



Composition of the Natural Gases Investigated. 



In commencing the investigation, a survey was 

 made of all the natural gases available in larger 

 or smaller quantities within the Empire with the 

 view of ascertaining their helium content. Natural 

 gases from Ontario and Alberta, Canada, were 

 found to be the richest in helium, and these 



