Mr. W. Herapath's Experimeiits oti Oil cmd Coal Gas. 4:25 



crease the heated surface. The gas immediately after leavino- 

 the retort passed through a distilhng worm surrounded by ice*: 

 at the end of the worm an oil joint was placed, which enabled 

 us to collect the volatilized oil ; from hence it went straight to 

 the gasometer. 



Before stating any experiments on the hght afforded, we 

 would premise that we had ascertained, that Leslie's photome- 

 ter filled with the vapour of ether was not a more certain test 

 than judgement by the eye ; that two similar gasometers, each 

 capable of holding 1 ^ cubic foot, were used accurately graduated 

 to lOOths of a cubic foot. They were filled from their respec- 

 tive sources to one foot, and then turned off; so that the pres- 

 sure and every other circumstance were equal in each. In 

 Experiments 1, 3 and 5, the lights were adjusted so as to cast 

 an equal shadow at equal distances ; and the quantity of gas 

 consumed taken as dieir relative values. In Exps. 2 and 4, both 

 gases were allowed to burn to the best advantage, that is, as 

 high as possible so as not to smoke. The coal gas light was 

 brought near enough to cast an equal shadow, the squares of 

 the distances being taken as the intensity of light, which in- 

 tensity was multiplied inversely into the quantities consumed, 

 to give their relative values. In No. 5 the lights were com- 

 pared with an Argand lamp— hole T%ths, wick ^^i^ths of an inch 

 in diameter, and the gasometers and burners wei'e reversed ; 

 in No. 6 the gasometers only, the fine holes remaining with the 

 oil gas. The coal gas used was taken from the Company's 

 Main, all die gasometers of the Temple Backs station being 

 turned on. We were given to understand, that the cost price 

 of the coal delivered was 75. 9d. per ton by contract, and that 

 it produced from 5 to 7000 cubic feet per ton. 



Oil Gas, sp. gr. '876 — Coal Gas, sp. gr. '54:33. 



Vol. 61. No. 302. June 1.S23. 



3 II 



