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Carbon Monoxide in Public Gas Supplies 



MORE than ordinary interest is attached to 

 the Report before us.i inasmuch as it 

 deals with issues of considerable importance from 

 the points of view both of national economy and 

 of public health. To understand the question 

 involves not only some knowledge of the historj' 

 and conditions of public o^as supplies during the 

 past century, but also a right perspective in our 

 views as to the most economical solution of the 

 domestic smoke problem. 



For nearly eighty years after the establishment 

 of the first public gas-works in London in the 

 year 1813, the gas undertakings in Great Britain 

 i supplied their customers with what has been 

 called a " straight coal-gas," or, in other words, 

 with a gas obtained by the carbonisation of a 

 bituminous coal (sometimes mixed with a small 

 proportion of " cannel-coal ") in retorts.' In the 

 early days of the industry, cast-iron retorts were 

 employed, necessitating the use of comparatively 

 low temperatures (650-750° C.) and the pro- 

 duction of a rich lighting gas and a " soft " coke, 

 which latter could be utilised effectively in domes- 

 tic fire-places. It is significant that the name of 

 the first London gas undertaking was the Gas 

 Light and Coke Company, and that Frederick 

 Accum, who in 1819 wrote the first descriptive 

 treatise on the manufacture of coal-gas, was able 

 to say that *' the demand for coke in the capital, 

 since the establishment of the gas-light works, 



■D^^VL ^f8^'!^"°" .Act, 1920. Report to the Board of Trade of the 



NO. 2721, VOL. 108] 



has prodigiously increased. Numerous taverns, 

 offices, and public establishments which heretofore 

 burnt coal, now use coke to the total exclusion of 

 coal ; and in every manufactory which requires 

 extensive lighting' or heating, gas and coke are 

 now the means jointly employed." It would thus 

 appear that, a century ago, the London gas under- 

 takings, by their enforced practice of carbonising 

 coal at moderately low temperatures, supplied the 

 public with two " smokeless " coal products, 

 namely, gas for lighting and a soft coke for heat- 

 ing purposes, the combined use of which made 

 possible the abandonment of the burning of raw 

 coal in houses, offices, and public establishments. 

 As time went on, however, cast-iron retorts were 

 replaced by those of fireclay in the gas-works, with 

 the natural result that higher carbonising tem- 

 peratures were employed. But even fifty years 

 ago, when this change had become universal, the 

 chief object of the gas undertakings still 

 remained the production of a coal-gas of high 

 self-illuminating power together with a coke of 

 such " medium " porosity and texture that it 

 would answer most domestic fuel requirements. 

 The coal-gas of fifty years ago would probably 

 contain (about) 025 per cent, of COj, 60 of CO, 

 50 of "heavy hydrocarbons," 400 of methane, 

 450 of hydrogen, and 375 of nitrogen, and its 

 gross calorific value would be (about) 700 

 B.Th.L^. per cb.ft., measured dry, at 60° F. and 

 30 in. barometric pressure. 



With the rapid development, from 1890 

 onwards, of incandescent mantle gas lighting, 

 which followed close upon A. von Welsbach's 

 inventions in Germany (1885-95), and the con- 

 current increasing use of gas for cooking and 

 domestic heating purposes, which were the out- 

 come of Thomas Fletcher's pioneering efforts in 

 this country, the need of a rich gas of high self- 

 illuminating power diminished, and eventually 

 almost disappeared. The demand arose for a 

 cheaper gas of medium illuminating (say of 15-17 

 candle-power) but good heating power (say of 

 about 600 B.Th.U. gross per cb.ft. at 60° F. 

 and 30 in. barometric pressure). This led to 

 raising the carbonising temperature in the retorts 

 up to 1000° C. or more, and using " re- 

 generative " methods of firing the retort 

 settings, whereby some 12,000 cb.ft. of gas 

 per ton of coal were produced, containing about 

 2-5 per cent, of CO,, 60 of CO, 35 of heavy 

 hydrocarbons, 33-0 of CH^, 50 of H.2, and 50 

 of No, and having a gross calorific value up to 

 about 600 B.Th.U. per cb.ft. at 60° F. and 



