of Oil Gas over Coal Gas. 2i3 



tr.re, " It may, I think, be stated with stifficiont accuracy for 

 practical purposes, that a gasometer containing 1000 cul)ic feet 

 of oil gas is adequate to furnish tlie same quantity of light as 

 one of 3000 of coal gas, provided due attention be paid to the 

 construction of the burners and to the distribution of the lights." 

 How the Professor could possibly ihink this, when even his own 

 calculations (erroneous as they may be readily proved) did not 

 bear him out by a deficiency of above 20 per cent., I know not. 

 The title of the paper from which this extract has been made, 

 is " On the Composition and Analvsis of the inflammable 

 gaseous Compounds resulting from the destructive Distillation of 

 Coal and Oil, with some Remarks on their relative heating and 

 illuminating Powers, by William Thomas Brande, Esq. Sec. R. S. 

 Professor of Chemistry R. I." published in the Philosophical 

 Transactions for 1820, Part 1., and in the Phil. Mag. for last 

 September. 



The chief object of this paper was to prove that no other 

 gaseous compound of carbon and hydrogen exists, but the one 

 usually called olefiant gas ; the second section institutes a com- 

 parison of the illuminating and heating powers of olefiant gas, oil 

 gas, and coal gas. How far he has succeeded in the undertaking, 

 may be partly ascertained by referring your readers to a review 

 of it by Professor Thomson in tiie 95th Number of the Annals of 

 Philosophy, and to the GSth Number of the Edinburgh Review. 

 A very short extract from each, will be suflicient to put us in pos- 

 session of the material errors from which Mr. Brande's ratios 

 against coal gas are deduced. Thomson observes, " His specific 

 gravities and atomic weights are without any exception inaccu- 

 rate; lam surprised at the low specific gravity of coal gas, which 

 he assigns, viz. 0*4430," which would serve most completely to 

 run down coal gas in all his after calculations. 



Dr. Henry found the specific gravity of coal gas of medium 

 quality to be -622, and of that produced from coal tar to be as 

 high as "780, The latter portions of coal gas, when made on 

 the old principles of long charges, of course are much lower, 

 sometimes as low as '390; but where three or four hours' charges 

 are ado))ted (as at Derby), or the tar converted into gas, which 

 for the last year I have found very practicable, and which will 

 soon be heard of on a very extended scale, the gas will be found 

 to be so far increased in illuminating power as generally to aver- 

 age from ".JoO to -GOO. 



From this it is evident that the coal gas will vary according to 

 a good or a i)ad method of manufacture, and all calculations of 

 comparison like Professor Brande's or Mr. Ricardo's, be thus in 

 a like ratio affected. The Edinburgh Review says, " We must 

 take leave to observe, that in some parts of his incjuiry, Mr. 



11 h 2 Bruude's 



