108 REPORTS ON THE STATE OF SCIENCE. — 1919. 



shall not, in ordinary circumstances, exceed. It is diffi- 

 cult to assign a limit applicable to all circumstances. In 

 some cases 12 per cent, of carbonic oxide in the gas 

 supplied might be jD-roper, in others 16, or perhaps 20. 

 . . . We are of opinion that with the present conditions 

 of gas supply 20 per cent, is the highest proportion of 

 carbonic oxide that should be allowed, and that this per- 

 centage should be used only under special circumstances. 

 . . . Our attention has been called by several witnesses 

 to the very imperfect and unsatisfactory gas-fittings often 

 used in the poorer class of houses in large towns, and the 

 constant leakages which exist without any attempt to 

 discover or rectify them. . .' 



Clearly then, the 1899 Committee, having in mind the nature of 

 carbonic oxide poisoning and the faulty character of gas pipes and 

 fittings in the poorer class of houses, considered that the carbonic 

 oxide content of a public gas supply should in no circumstances be 

 allowed to exceed 20 per cent., and only exceptionally 16 per cent. 

 This Committee considers that even to-day a maximum limit of 20 per 

 cent, of carbonic oxide ought not to be exceeded. It may be pointed out 

 tha.t the Fuel Eesearch Board's recommendations would allow of a 

 gas company distributing a 40 per cent, coal gas plus 60 per cent, 

 water gas mixture containing between 27.5 and 30.0 per cent, of 

 carbonic oxide. 



(9) The Committee is unable to agree with the Fuel Eesearch 

 Board's apparent endorsement of the proposition that the relative 

 values of different grades of gases are strictly proportional to their 

 calorific values. On the contrary, they are of the opinion that the 

 chemical composition of the gas is not a matter of indifference to the 

 consumer, and that the cumulative results of forty years of scientific 

 research on the subject prove that the fundamental properties of the 

 explosive mixtures formed by different combustible gases with air. 

 arising from their own peculiar chemical characters and modes of 

 combustion, do affect profoundly their uses for power and heating 

 purposes. 



(10) It appears to the Committee that, in pai'ticular, the Board's 

 Eeport does not recognise sufficiently the importance of methane as 

 a constituent of a public gas supply. Owing to the relatively narrow 

 range of explosibility of its mixtures with air, and the low speeds at 

 which flame is propagated through them, methane (in addition to the 

 advantages of its high concentration of potential heat units) as a consti- 

 tuent has an important ' steadying' influence upon coal gas, rendering 

 it eminently us'able for domestic purposes. Hitherto the public 

 has been accustomed to using a gas containing 30 per cent, or more 

 of methane, and it is important that such proportions shall not 

 be unduly diminished. Accordingly the Committee would urge the 

 adoption of 20 per cent, as a minimum methane content in a public 

 gas supply intended for domestic consumption. 



(11) If the Committee's proposals in the preceding paragraphs be 

 adopted as safe and reasonable in the interests of domestic consumers, 



