■March 10, 1899.] 



SCIENCE. 



357 



W. C. Holmes & Co.* give the allowed 

 leakage as five per cent, and the average 

 leakage as ten per cent., while H. Tobey, in 

 his paper on ' Elusive Leakages from Mains 

 and Services,'! which was warmly discussed 

 by the gas association before which it was 

 read, shows that the condition still exists, 

 and he gives illustrations showing the dan- 

 ger consequent on leaving abandoned sew- 

 ers in place. 



Owing to the fact that Bunsen, Angus- 

 Smith, Letheby and Dui-and-Claye found 

 large quantities of methane, hj'drogen sul- 

 phide, and sometimes carbon monoxide, in 

 the gases from stagnant sewage decompos- 

 ing under water, there has arisen a belief 

 that ' sewer gas' is explosive. Simple con- 

 sideration of the facts that such stagnation 

 cannot occur in a properly constructed 

 sewer, and that such a change does not take 

 place in flowing sewage, is sufiBcient to cast 

 doubt on the existence of such a gas. It 

 has been completely shown by Professor 

 Wm. Ripley Nichols, in his Chemical Ex- 

 amination of Sewer Air, J as the result of 

 his own extended observations, and from the 

 discussion of numerous data by other in- 

 vestigators, that sewer air differs from ordi- 

 nary air only in containing a larger percent- 

 age of carbon dioxide, and that ' sewer air 

 is neither inflammable nor explosive. ' The 

 air of vaults and cesspools is, of course, a 

 different thing, as the material in these may 

 become stagnant. 



It was as early as 1819 that an English 

 patent was granted to David Gordon and 

 Edward Heard for compressing gas in 

 strong copper or other vessels fitted with 

 ingenious reducing valves for regulating its 

 rate of emission ; 30 feet of gas being com- 

 pressed into a volume of one cubic foot, 

 and gas so compressed in cylinders of two 



* Instructions for the Management of Gas Works, 

 p. 41, London, 1874. 



t Am. Gas Light J. 64, 767; 1896. 



{Kept. Snpt. of Sewers, Boston, Mass., 1879. 



cubic feet capacity were conveyed to the 

 houses of consumers, with which to operate 

 an isolated plant. Sometimes the pressure 

 was sufficient to liquefy the gas, and it is 

 interesting to note that it was in the liquid 

 from one of these reservoirs that Faraday 

 discovered benzene. 



Naturally the tension of the gas itself 

 tends to rupture the receptacle, and many 

 accidents from explosions of this nature 

 have occurred owing to defects in the cyl- 

 inders, or to the exposure of the filled cyl- 

 inders to unduly high temperatures, or to 

 shocks ; a recent accident that could not 

 be explained in any other way occurred at 

 Albany, N. Y. on December 6, 1893.* 



With the increased demand for com- 

 pressed gases of various kinds under high 

 tensions, such as carbon dioxide, sulphur 

 dioxide, ammonia, chlorine, nitrogen mon- 

 oxide, acetylene, air and others which are 

 being used or introduced for commercial, 

 scientific or domestic purposes, there is be- 

 ing developed a continued improvement in 

 the strength and homogeneity of the cylin- 

 ders, so that the danger from this cause is 

 diminishing. 



Although Dr. Robert Hare had invented 

 his oxyhydrogen blowpipe in 1801,1 yet in 

 1834 Gordon and Deville were granted a 

 patent for their calcium or ' lime ' light. It 

 was expected by the projectors that this 

 form of light would replace gas, as burned 

 from ordinary burners, for lighting streets, 

 and it caused the holders of gas securities 

 much anxiety, but as we are now aware the 

 device came to be used for geodetic, scien- 

 tific and exhibition purposes only. 



Where the gases stored in vessels are of 

 an inflammable nature there is an additional 

 risk to that due to the tension of the gas, 

 since by admixture with air or oxygen an 

 explosion occurs on ignition. One source 

 of these accidents arises from the diffusion 



■•<-Proo. U. S. Nav. Inst. 22, 63S ; 1896. 

 t J. Am. Chem. Soo. 19, 719; 1897. 



