522 



NATURE 



[December 22, 1921 



30 in. barometric pressure. As the carbonis- 

 ing temperature increased, however, the residual 

 coke became gradually harder, and therefore less 

 suitable for domestic consumption, especially in 

 an open fire-place with low draught. Indeed the 

 gas undertakings soon found themselves in the 

 position of producing a coke which was neither 

 a good domestic fuel nor yet a high-class, hard 

 metallurgical coke, with the result that its profit- 

 able disposal was often a matter of difficulty. 



An obvious way out was to convert part 

 of the coke into "water-gas," by one or 

 other of the processes which had been deve- 

 loped since the first Lowe plant had been installed 

 in Great Britain at the Leeds Forge in the year 

 1888. And by mixing some water-gas with the 

 coal-gas, a larger proportion of the potential heat- 

 units in the coal taken into the gas-works could be 

 sent out in the form of gas. Moreover, water- 

 gas is cheaper to produce, and has an even higher 

 calorific intensity (flame temperature), although 

 the thermal efficiency of its production is some- 

 what lower, than that of coal-gas. Another im- 

 portant advantage about water-gas is that the 

 plant for producing it occupies a much smaller 

 area than a coal-carbonising plant for equal 

 gas-therm yields; and, moreover, its operation is 

 so comparatively easy and labour-saving that, to 

 the harassed gas engineer, it is "a very present 

 help in time of trouble," e.g. when coal supplies 

 are unduly short or the demands of labour ex- 

 cessive. Up to the outbreak of the war, how- 

 ever, British gas undertakings had been com- 

 mendably chary in using water-gas ; indeed, it is 

 probable that in the. year 1913 the proportion of 

 water-gas sent out did not, on the average, exceed 

 (if it was as much as) 15 per cent, of the whole 

 gas output of the works. The public would, in 

 that year, be supplied with a gas of an average 

 gross calorific value of about 575 B.Th.U. per 

 cb.ft. at 60° F. and 30 in. pressure, of which the 

 content of carbon monoxide did not exceed 15 per 

 cent, at the most, and more probably in the 

 majority of cases would not be greater than 10 per 

 cent. 



It may here be mentioned that in the United 

 States, where the manufacture of water-gas 

 originated in 1885, the policy of converting the 

 coke into water-gas and of carburetting the latter 

 with oil-gas had, long before the war, been pushed 

 almost to its extreme limits. Thus New York 

 had long been supplied with a mixture of about 

 one part of " coal-gas " with as much as six or 

 seven parts of " carburetted water-gas"; 

 NO. 2721, VOL. 108] 



Chicago with a mixture of one to five parts ; 

 Boston with a mixture of equal volumes, and so' 

 on. In 191 7, the New York gas contained, on an 

 average, about 30 per cent, of COg, 270 of CO, 

 12-5 of heavy hydrocarbons, 200 of methane, 

 300 of hydrogen, and 7--^ of nitrogen ; and its 

 average calorific value would probably be about ^ 

 675 B.Th.U. per cb.ft. at 60° F. and 30 in. baro- 

 metric pressure. * 



During the war circumstances arose which 

 fully justified, as a temporary measure, the relaxa- 

 tion of some of the conditions formerly imposed 

 upon British gas undertakings, which were per- 

 mitted to supply gas of much lower calorific value 

 and higher water-gas content than in pre-war 

 days. In the circumstances this could not well 

 be helped, and it was endured by consumers with- 

 out complaint as a war necessity. Unfortunately, 

 however, the gas industry, having thus beer 

 liberated temporarily from former controls anc 

 restrictions, yearned for a more permanent" 

 emancipation therefrom ; and so what may be 

 termed a strong " life and liberty " movement set 

 in, more particularly in the direction of supplying 

 gas of lower calorific value, on the plea of benefit- 

 ing the consumer by giving him cheaper gas- 

 therms than otherwise he could obtain. 



At this point the Fuel Research Board stepped 

 in, at the request of the Board of Trade, with the 

 object of advising "what is the most suitable 

 composition and quality of gas and the minimum 

 pressure at which it should be generally supplied, 

 having regard to the desirability of economy in 

 the use of coal, the adequate recovery of by- 

 products, and the purposes for which gas is no\\ 

 used." The answer of the Fuel Research 

 Board to the prevailing view in the gat 

 industry "that the elasticity in manufacture 

 can best be secured by the fixing of a 

 sufficiently low calorific standard " was some- 

 what vague and hesitating; but the Board rightly j 

 based its recommendations upon the principle tha| 

 "the interests of the consumers can best be coi 

 served if their contract with the gas undertakin| 

 is based on the sale and purchase of heat energ^ 

 measured in fixed units which can be scientificall 

 determined by simple means." And it was there 

 fore proposed that "the consumer should b^ 

 charged for the thermal units which he actually 

 receives in the same way as the consumer of elec-' 

 tricity is charged for the Board of Trade units 

 which pass through his meter." This important 

 conclusion was, however, accompanied by a pro- 

 nouncement that "the natural diluent for coal- 



