Mr. W. Herapath's Expennenli on Oil and Coal Gas. 427 



equal distances above those lights, was considered as a relative 

 measure of the heat; and in those instances where the li<rhts 

 were at different distances from the shadows, the sapie correc- 

 tion was applied as in the case of lioht. 



Feb. 28. 



i5 =.1 



Description 



of 



Burner. 



Oil Gas, sp. gr. -886— Coal Gas, sp. gr. -4675 

 Dura' 



Gas 

 consumed. 



IXo. 



4. 15 usual holes 1-000 cf.i 3f in. 

 4. 15 fine holes -515 I 3 



Height 



of 

 Flame. 



H 



same burners 

 as above 



1-000 

 •495 



3 in. 



tion of I 



Dist. 



Experi-I from 

 menl. |Sliado« 



Deg. of! L'aku- 

 Heat I lated 



acquir- ' relative 

 ed. I Heat. 



10 57 |64i in. 

 same 



11 58 54 in. 

 — 48 in. 



125° \ I -47 to 

 85° ; 1-00 



corrected 

 104° i 1-47 to 

 84° 1-00 



Compared with Argand lamp, hole j^^^^th, wick ^s^-th of inch. 



3. usual holes 

 I 3. ditto 

 Argand lamp 



17 32 



equal 



96 11.31 to 

 73 1-00 

 42 I -57 



These three experiments show that coal gas gave out a heat 

 equal to 3, and oil gas 2 ; while sperm oil from the last ex- 

 periment was a little more than 1. 



The oil gas used in this experiment had stood 48 hours 

 over water, having lost 3 jjer cent, in volume, and in density 

 nearly 2 per cetif. from -902 to -886 ; and from the coal gas 

 having a low specific gravity compared with the first, viz. as 

 •4675 to -5433, I presume the oil gas must have lost some of 

 its lighting power. But we wish it to be understood, that al- 

 though only 9 experiments are here detailed, we have made 

 nearly 30 on gases of different densities widi many sorts of 

 burners, and varying them in every possible wa}', and we never 

 found 1 cubic foot of oil gas more than equal to 2^ of coal. 

 Considering the gases to be of such a description as would be 

 met with in commerce, I have had specimens which have given 

 different results ; for instance, where in a small apparatus 50 

 cubic feet only were drawn from } cwt. of coal compared with 

 oil gas, sp. gr. '886, the results were only as 1 to H; and again, 

 I had a specimen of oil gas presented to juc in London, which 

 from a comparison with sperm oil would liave equalled 3y'^ 

 of the coal gas described in the first series of experiments: but 

 such ought not to be considered fair specimens, as they are 

 dillcrent from what would be sold to the public. 'I'hese re- 

 marks will ap|)ly to a set of experiments recently made by two 

 able chemists, the results of wliich were laid belbrc the Com- 

 3 H 2 jiiit((..« 



