December 9, 1922J 



NA TURE 



791 



the sky is termed. The type developed by Abbot 

 and Aldrich is described in Smithsonian Misc. Collec- 

 tions, vol. 66, No. 7, 1916, but the name would be 

 suitable for Mr. Dines's instrument {Meteorological 

 Magazine, vol. 55, p. 189, 1920) ; by analogy the 

 Callendar radiograph, which gives a record of the 

 heat carried by the luminous rays from sun and sky 

 and received on a horizontal surface, should be a 

 pyranograph. 



Prof. Abbot measures the heat from the sun, 

 and also the heat from the sun plus the heat from 

 the sky within 15 of the sun with one of these 

 instruments, and by applying appropriate factors 

 obtains the " solar constant." Mr. Knox-Shaw has 



examined a series of observations made at Calama in 

 Chile and reduced by Prof. Abbot's staff by this 

 method. He finds that they show no correlation 

 between the computed values of the solar constant 

 and the transmission coefficient. It is to be hoped 

 that the validity of this new method will be confirmed, 

 as it will make the regular determination of the 

 strength of solar radiation practicable at many 

 stations where the more elaborate routine could not 

 be adopted. At Helwan the sun is to be observed 

 with the Angstrom apparatus once a day at a specified 

 altitude. For the application of Abbot's method 

 the Angstrom readings will have to be supplemented 

 by those of a pyranometer. 



Natural Gas Gasoline. 



The Production of Light Oils from Natural Gas. 

 Bv H. B. Milner. 



"NT ATURAL gas may be of two distinct types — dry 

 -L ' gas or wet gas. The former consists essen- 

 tially of methane, with practically no other members 

 of the paraffin series, the latter being composed of 

 methane with varying amounts of ethane, pentane, 

 hexane, and heptane, and certain dilutants such as 

 nitrogen, carbon dioxide, carbon monoxide, sul- 

 phuretted hydrogen, and sometimes helium. Dry gas 

 is normally associated with coal or decomposing 

 vegetable matter and is rarely met with in the presence 

 of petroleum ; wet gas, on the other hand, is essen- 

 tially the gas present in oil pools, either in the free 

 state or dissolved in the oil under pressure. 



The production of natural gas gasoline — as it is 

 called — constitutes a comparatively recent develop- 

 ment of the petroleum industry, particularly in the 

 United States. The gas employed for this purpose is 

 that which so frequently accumulates in the top of 

 oil-well casings, or which, under pressure varying 

 from a few to several hundred pounds, is forced along 

 the flow lines leading from the casing head. Com- 

 posed of lower members of the paraffin series than 

 ordinary petrol obtained by refining crude oil, natural 

 gas gasoline is far more volatile and inflammable, and 

 therefore its use per se is normally inadmissible. 

 But mixed with some of the heavier fractions derived 

 from crude oil, it forms a fuel ranging from o-66o to 

 0-750 in gravity, in all respects suitable for internal 

 combustion engines of the automobile type. 



There are three recognised processes for extracting 

 oil from natural gas — the compression process, the 

 absorption process, and the combined compression 

 and absorption system. The compression process 

 consists in the liquefaction by pressure and refrigera- 

 tion of the heavier paraffins present in the gas, and 

 is usually employed where the initial density of the 

 gas exceeds o-8, i.e. where the gas is rich in the heavier 

 hydrocarbons. The plant employed entails a com- 

 pressor, condensing or cooling coils and collecting 

 tanks. The average yield of oil by this process is 

 2-5 gallons per m. cubic feet ; 73 per cent, of the out- 

 put of natural gas gasoline for 1920 in the United 

 States was produced by the compression process. 1 



The absorption process has the advantage that it is 

 applicable to " lean " gas, i.e. gas yielding anything 

 from o-i to 0-5 gallons per m. cubic feet, and by 

 this process much so-called dry gas has been utilised 

 which would otherwise have been wasted, being of too 

 low a grade to be treated profitably by the compression 

 process. The absorption system necessitates passing 



^ l " Natural Gas Gasoline in 1920," by E. G. Sievers. Min. Res. Unit. 

 States, 1920, Part II., pp. 289-300. (Unit. States Geol. Survey.) 



NO. 2771, VOL. I IO] 



the gas through an oil of higher gravity than ordinary 

 petrol, from which it is recoverable by fractional dis- 

 tillation. The combination process is a more recent 

 development, whereby the gas is compressed under 

 low pressure to a smaller volume, then absorbed by 

 seal oil and subsequently recovered by distillation. 

 This process has been employed recently by pipe-line 

 companies in the United States to recover gasoline 

 from low grade wet gas accumulated in gas distribut- 

 ing lines. The average yield of oil by the absorption 

 process is o-2 gallons per m. cubic feet. 



The principal States in America producing natural 

 gas gasoline are Oklahoma, West Virginia, California, 

 and Texas, besides eight other States giving a sub- 

 ordinate output. The bulk of the products is sent 

 to the northern States and California, where in the 

 latter case the oil is mixed with petrol obtained from 

 low grade crude oils. Much of the Canadian natural 

 gas gasoline is being blended with petrol obtained 

 from Mexican crude oil, and in this way, also, many 

 oil wells which would otherwise be derelict are, by 

 their yield of low grade wet gas, giving good results, 

 quite apart from the better known and more valuable 

 gas wells. 



Some idea of the remarkable growth of the industry 

 in America can be gauged from the fact that whereas 

 only 7J million gallons of gas gasoline were produced 

 in 1911, nearly 400 million gallons were produced in 

 1920. This constitutes more than 7 per cent, of the 

 total production of gasoline in the United States for 

 that year. 



Quite apart from any statistical evidence, it is 

 clear that this new industry now firmly established in 

 America will, by its steady progress, have a far- 

 reaching consequence on the available supplies of 

 fuel-oil for world consumption in the future. Many 

 fields which have hitherto been poor producers may 

 quite conceivably be rendered sound from a com- 

 mercial standpoint by the utilisation of the natural 

 gas now allowed to run to waste. In such countries 

 as Russia, Persia, Burma, Egypt, and Trinidad, the 

 processes are, by reason of the large quantities of 

 natural gas available, especially applicable, though 

 little, if anything, has so far been done in this direc- 

 tion. Wherever natural gas can be controlled at the 

 casing head, the possibility of its treatment for the 

 recovery of light oil should be taken into account. 

 In the fields cited above, especially in Trinidad, 

 the value of such recovery lies not so much in the 

 actual production of petrol, but in the enhanced 

 value attained by low grade crude oil fractions as a 

 result of careful mixing. 



