310 RESPIRATION 



as well as, to a certain extent, on the luminosity of its flame when 

 no mantle is used, water gas is usually "carbureted" by the ad- 

 dition of cheap oil in a chamber where the oil is "cracked" by 

 means of heat. The product is known as carbureted water gas, 

 and is very largely used as a substitute for ordinary coal gas. It 

 has a luminous flame and more or less satisfactory calorific value, 

 but contains about 30 per cent of CO. 



It is evident that with gas containing 30 per cent of CO, poison- 

 ing will occur very readily with an escape of gas during the night 

 in a house. On inquiring into the deaths from gas poisoning in 

 American towns supplied with carbureted water gas, the com- 

 mittee referred to above found that about 100 to 200 times as 

 many deaths occurred from gas poisoning with a given distribu- 

 tion of gas as in English towns supplied with coal gas only. The 

 gas was also used very extensively for purposes of suicide, and 

 sometimes also as a means of murder. Apart from actual danger 

 from poisoning, there was also the constant anxiety as to danger 

 from gas poisoning. An American mother, for instance, told me 

 that she regularly got up every night to make sure that gas was 

 not escaping where her children were sleeping. The result of the 

 committee's inquiries was to show that if gas is to be used for 

 domestic purposes the percentage of CO in it should be reasonably 

 low ; and in consequence of this finding the use of undiluted car- 

 bureted water gas was discontinued in Great Britain, where, 

 indeed, it had only been introduced in one or two places, though 

 with unfortunate results which led to the inquiry. It should, how- 

 ever, be mentioned that with the general introduction of mantles 

 the danger of poisoning from accidental escapes from burners is 

 considerably diminished, as less gas escapes, and if there is a 

 pilot flame the risk is further greatly diminished. 



Gas poisoning in houses may not only occur from escapes 

 within the house, but also from escapes from street gas mains; 

 and many serious accidents from this cause have occurred, par- 

 ticularly with carbureted water gas. The danger is much increased 

 from the fact that in passing through earth the odoriferous con- 

 stituents (benzene, etc.) of the gas are apt to be more or less 

 absorbed, so that the gas entering the basements of houses is more 

 or less odorless. Probably, also, it may have lost a good deal of 

 its hydrogen by diffusion, and this will make it more poisonous. 

 A large number of persons in several houses and many different 

 rooms may be poisoned by one serious breakage of a main. 

 Pettenkofer recorded an interesting case where, in the times before 



