of Oil Gas over Coal Gas. 245 



the side of oil gas as the Professor makes it appear. He says, 

 " it appears (from his method of calculation) that to produce 

 the light of ten wax candles for one hour, there will be required 

 2600 cubical inches of olefiant gas. 

 4875 . . . . of oil gas, 



13120 .. .. of coal gas." 



As well might he have said, on the same princiole, that be- 

 cause it requires 800 cubic inches of oil gas to equal the light of 

 one candle, therefore it requires 8000 cubic inches to pioduce 

 the light of ten candles! Had he multiplied 1312 by 8, as he 

 did the oil gas by 6, or the olefiant by 4, the product !049(j 

 (= 6074 feet) would have been much nearer the truth. Their 

 ratios then would have been 



Olefiant gas .. .. 2600 ratio 1. 



Oil gas 4875 .. 1875. 



Coal gas 10496 .. 4-037. 



Numbers so little short of 1. 2. 4, that for practical purposes, 

 where good coal gas is to be obtained, we may rest assured that 

 two cubical feet of it, properly applied, will be found equal in 

 illuminating power to one of oil gas*. 



Before we quit this part of our subject, it may not be amiss 

 to hint at one other source of discrepancy too frequently over- 

 looked in the analysis of these gases, that of experimenting upmi 

 the gases immediately after their production, or after they have 

 been made some time and transmitted to a great distance, per- 

 haps miles (as was the coal gas in Mr. Brande's casef) through 

 a series of cold pipes, whereby the deposition of a highly vola- 

 tile oil takes place, which in the former case would have added 

 greatly to its illuminating power, to its specific gravity, and of 

 course to the quantity of oxygen it would consume. 



Having now reviewed with some minuteness, yet T trust with 

 candour, the theoretical basis of Mr. Ricardo's comparative state- 

 ment, " that 20 cubic feet of oil gas will give as much light as 

 70 of coal gas," I will endeavour to travel through the other 

 stages of his paper at a quickened pace. 



• After Mr. Lowe's paper was in the hands of the printer, I received a 

 letter from him oontainiiijr the following paragraph : 



" My chemical library having this day received the very valuahle acqui- 

 .sltion of Dr. Andrew Ure's Dictionary of Chemistry, I hope it is yet in the 

 Editor's power to add (as a note) the weight of testimony to my argument, 

 which tlie Doctor, under the article ' Oil Gas,' ali'ords nie; he says * 'i'A? 

 ail friui I have been accuxtomcil to make has onlif a double Ulaia'iiiMtiiig power 

 ciimpnred to tfuod coal i^as.' I should be sorry that Mr. liicardo or your 

 I '-adcrs should lack evidence like this. "• — Knrr. 



t The oil gas made use of in Mr. Brande's experiments WBS manufac- 

 tured in the Institution ; but the coal gas came from the Gas-work, l*eter- 

 slrcet, Wcbtminatcr. 



Theory 



