Experiments on the Gas from Coal. 117 



high temperature here, and likewise the immense quantities of 

 animal and vegetable matter continually rendered putrid by it, 

 oflfensive exhalations continue to exist, that affect, particularly at 

 night, the sense of smelling in the strongest degree, and that oc- 

 casionally extend even to ships in the harbour after the land-breeze 

 has sprung up. 



[To be continued.] 



XXI. Expeiiments on the Gas from Coal, chiefly with a view 

 to its practical Application. By William Henry, M.D. 

 F.R.S. «^c.* 

 JL HE chemical properties and composition of the gas from coal 

 formed a principal object of two different series of experiments, 

 the results of which I laid before the public many years ago. 

 The firstof these communications, entitled " Experiments on the 

 Gases obtained by the destructive Distillation of Wood, Peat, 

 Pit-coal, Oil, Wax, &c. with a view to the Theory of their Com- 

 bustion, when employed as Sources of artificial Light," appeared 

 in Mr. Nicholson's Philosophical Journal for June 1S05 f ; and 

 the second memoir was published in the Transactions of the Royal 

 Society for 180S. 



By the first train of experiments, I endeavoured to derive, from 

 a careful analysis of the compound combustible gases, a measure 

 of their illuminating power, admitting of more exact appreciation 

 than the optical method of a comparison of shadows. The one, 

 which I was led to propose as the most accurate and which I 

 still think entitled to preference, was the determination of the 

 quantities of oxygen gas consumed, and of carbonic acid formed, 

 by the combustion of equal measures of the different inflammable 

 gases J that gas having the greatest illuminating power, which, 

 in a given volume, condenses the largest quantity of oxygen. 

 The average results of a great variety of experiments were com- 

 prised in the following table. 



Oxygen gas required 

 Kinds of gas. to saturate 100 Caibonic acid 



measures. produced. 



Pure hydrogen 50 



Gas from moist charcoal . . GO 35 



wood (oak) . . M 33 



dried peat , . (i<S 43 



canncl coal ..170 100 



lamp-oil .. .. 1!)0 124 



wax 220 137 



Olefiantgas 284 179 



• From tlie Memoirs of tlie Literary and I'liilosopiiical Society of Man- 

 chester, vol. iii. Second Series. f ^^*'o Series, vol. xi. page C5. 



H 3 In 



