294 



An Account of the Application of the Gas from Coal to economical 

 Purposes. By Mr. William Murdoch. Communicated by the Right 

 Hon. Sir Joseph Banks, Bart. K.B. P.R.S. Read February 25, 

 1808. [Phil. Trans. 1808,;?. 124.] 



An apparatus for the production of the gas from coal having been 

 prepared by Mr. Murdoch, for the very extensive cotton manufactory 

 of Messrs. Philips and Lee, at Manchester, which is now illuminated by 

 means of this alone upon a very large scale, this instance was selected 

 as the best for estimating the expense of employing the gas lights. 



The quantity of light there employed was ascertained by compa- 

 rison of the shadows to be equal to that of about 2500 mould candles 

 of six in the pound, each of which consumes about four tenths of an 

 ounce of tallow per hour. 



The coal is distilled in large iron retorts, and the gas conveyed by 

 pipes of iron to large reservoirs or gasometers, where it is washed 

 and purified before it is conveyed to the mill. The main pipes branch 

 off into a variety of ramifications (the aggregate length of which 

 amounts to several miles), the several branches diminishing in dia- 

 meter in proportion as the quantity of gas to be passed through 

 them becomes less. 



The burners where the gas is consumed communicate with the 

 main by short pipes, furnished each with a cock to regulate the ad- 

 mission of gas. These burners are of two kinds : one is on the 

 principle of the Argand lamp, and the other has a conical termination 

 with three holes, one at its point, and the other two placed laterally 

 about one thirtieth of an inch in diameter. The former, of which 

 there are 271, are each equal to four candles ; and the latter amount- 

 ing to 633, are each equal to 2^ candles ; so that the total amount 

 is, as above stated, about equal to 2500 candles. 



For the hourly supply of these burners, 1 250 cubic feet of gas are 

 necessary ; and since the lights are used for about two hours, the 

 daily consumption of gas is 2500 cubic feet. 



For the production of this quantity of gas, seven hundred weight 

 of cannel coal is employed, which, notwithstanding its high price, is 

 found to be the most economical, on account of the superior quality 

 and quantity of the gas it yields. The number of working days be- 

 ing 313, the annual consumption of cannel coal is 1JO tons, of which 

 the cost is 125/. But these 110 tons yield 70 tons of coke, the value 

 of which is 93/., leaving a difference of 32/., to which must be added 

 20/. for the value of 40 tons of good common coal employed for 

 heating the retorts. 



But by far the greatest part of the cost of employing this species 

 of light consists in interest of capital employed in furnishing the 

 apparatus, and in repairing the wear and tear, which are stated toge- 

 ther by Mr. Lee at about 550/. per annum, making a total annual 

 expenditure of 600/. instead of 2000/., which would be required to 

 produce an equal quantity of light from 2500 candles burning toge- 

 ther, at Is. per pound. 



