January 26, 1922] 



NATURE 



"3 



under the direction of the late Sir William Ramsay, 

 and those of Canada were also examined, but in 

 both cases the efforts were unsuccessful. The dangers 

 attending hydrogen-filled aircraft were obvious from 

 the fate of many of the German Zeppelins, so that 

 the possibility of extracting sufficient quantities of 

 an incombustible gas such as helium (admirably 

 suited in every way to the peculiar requirements of 

 lighter-than-air machines) was too important to be 

 ignored. 



In the United States the help of certain com- 

 mercial firms, employing the Linde and Claude pro- 

 cesses of gas liquefaction for the treatment of air, 

 was solicited, and in 191 8 two plants were in opera- 

 tion at Fort Worth, Texas, ultimately giving an 

 average production of 5000 cb. ft. of gas per day, 

 yielding on purification up to 93 per cent, of helium. 

 Although the effect of the armistice was to check 

 military requirements, the development of com- 

 mercial aviation keeps this use of helium very much 

 in the foreground, and in view of this and also of 

 the far-reaching scientific problems involved the 

 United States Geological Survey has just published, 

 from the pen of G. Sherburne Rogers, a most valu- 

 able monograph on " Helium-bearing Natural Gas " 

 (Professional Paper 121, 1921). 



The chief region from which commercial supplies 

 of helium are obtained is that of the Mid-Continent 

 oilfields, more especially from two areas, one in 

 North Texas and the other in North Oklahoma and 

 South Kansas ; gas in both these areas yielded up 

 to 0-5 per cent, of helium, in some cases the amount 

 being as much as 2 per cent. One would naturally 

 expect helium-rich gas to show a high nitrogen con- 

 tent with consequent low calorific value ; generally 

 speaking this is found to be so, though in one 

 instance a gas with 14 per cent, of nitrogen yielded 

 0-35 per cent, of helium. On the other hand, a 

 high nitrogen content is not necessarily a criterion of 

 a high helium yield, and Rogers cites several ex- 

 amples of this. The nitrogen-helium ratio in natural 

 gas in thirteen samples quoted ranges from 114 to 

 20 ; the conclusion to be drawn from this, and also 

 from a careful study of several other available 

 analyses, is that a low (N2He) ratio implies a low 

 helium content. 



The richest helium-bearing gas in America is 

 obtained from comparatively shallow depths in the 

 Pennsylvanian beds, and it is interesting to note 

 that cas emanating from younger beds, such as the 



Cretaceous or Tertiary of Texas and Louisiana, is 

 low in helium content. Bearing in mind Czako's 

 contention that the radio-activity of a gas is an index 

 of its helium content, and also Holmes's work on 

 radio-activity as a measurement of geological time, 

 it is thus not difficult to appreciate the reason 

 of the low helium content of ii-uropean natural gas, 

 derived for the most part from Tertiary strata. 

 Evidence is not forthcoming as to the radio-activity . 

 of the gas from the Pennsylvanian beds, but 

 McLennan's researches in Ontario (Nature, vol. 70, 

 p. 151, 1904) demonstrated the tendency of de- 

 creased radio-activity with increased depth, and this 

 may reasonably be correlated with the marked 

 decrease in helium yield with increase in 

 depth from which the gas is obtained in the 

 present case. 



The origin of the helium in the gas affords a wide 

 ground for speculation, though in the present state 

 of our knowledge it would be very unsafe to dog- 

 matise. Rogers discusses this at some length, but 

 of the several possible theories he favours two, 

 more particularly the first — that the helium is gene 

 rated from uranium or thorium deposits disseminated 

 through the beds proximate to the natural gas 

 horizons, or that it is primordial and comes from 

 abyssal sources. His arguments in favour of the 

 former theory are very sound, though, as he admits, 

 it assumes the occurrence of radio-active deposits of 

 which we have no knowledge, more particularly in 

 the upper palaeozoic rocks of the Mid-Continent 

 region, or in some of the buried igneous masses 

 occurring as subterranean uplifts. 



It is interesting to note that in the case of the 

 three principal occurrences of natural gas in this 

 country, at Calvert, Buckinghamshire, at Middles- 

 brough, Durham, and at Heathfield, Sussex, the 

 nitrogen contents were 19-5 per cent., i6-8 per cent., 

 and 0-9 per cent, respectively ; in the first case the 

 source of the gas is doubtful, but it is presumably 

 from pre-Liassic beds ; in the second case it is 

 obtained from the Magnesian Limestone, and at 

 Heathfield it is unquestionably derived from the 

 Kimmeridge Clay. If the nitrogen evaluation is any 

 indication of helium-bearing gas, as it would seem 

 to be in the United States, it is extremely unlikely 

 that helium occurs in those gases in amount greater 

 than 0-5 per cent, (if as much as that) at Calvert 

 and Middlesbrough, while at Heathfield it is prob- 

 ably absent altogether. 



Obituary. 



Lord Bryce, O.M., F.R.S. 



IT can be but seldom, when a man's life has been 

 prolonged to well over eighty years, that his 

 death is generally felt as a serious public loss. Lord 

 Bryce's sudden, if happy, death on January 22, in 

 his eighty-fourth year, is a shock which will be felt 

 equally here and in the United States, where only 

 last summer he had been engaged both by lecturing 

 and in social intercourse in spreading a better under- 

 standing of the problems of Great Britain and 

 NO. 2726, VOL. 109] 



Europe. Years ago, by his great work on " The 

 American Commonwealth," and at a later date by 

 his tact and manifold activities while our Ambassa- 

 dor at Washington (he was reputed to have visited 

 every State in the Union), Lord Bryce had made 

 himself a living link between the two peoples. In 

 the United States he was not only trusted by states- 

 men and appreciated by the leading men in thought 

 and literature, but he was also an idol of the crowd. 

 When he came into a popular assembly the proceed- 



