212 Mr, Ricardo on the Comparative Advantages [March^ 



rj^er night, and 56,000 of coal gas. To produce that quantity of 

 the former, eight or 10 retorts would be sufficient, each retort 

 six feet long, and six inches diameter. One of this dimension 

 would, if necessary, produce 3000 feet per day, but it is found 

 more advisable not to work them to their full extent, and always 

 to have some in reserve. One gasometer containing 12,000 cube 

 feet, or two of 6000 each, would be required. The oil cistern, 

 the condenser, and wash vessel, are so constructed as to occupy 

 but very little space, the condenser being over the cistern, and 

 the wash vessel under it, the gasometer occupying by far the 

 largest portion of room. From the repeated trials in various oil 

 gas establishments, it has been ascertained that 10 gallons of oil 

 produce 1000 cube feet of gas, and require one bushel of coals, 

 for decomposition : 2,000,000 feet of oil gas, therefore, would 

 require 20,000 gallons of oil, weighing between 78 and 7^> tons, 

 and 74 tons of coal ; so that about 153 tons of materials would 

 be annually wanted in this establishment, all of which would be 

 consumed, or converted into gas. 



In the coal gas works, 40 retorts at least would be required.* 

 Each retort is six feet long, and one foot in diameter, and would 

 be charged with two bushels of coals, which quantity would 

 require eight hours for decomposition. At the end of this time, 

 the coke would be removed, and fresh coals put in. The above- 

 mentioned quantity of coals would give out 660 cube feet of gas, 

 estimating 10,000 cube feet for every chaldron. The utmost 

 quantity of gas which one retort could produce would be 1680 

 •cube feet, working night and day without intermission : 34 is the 

 number actually necessary ; but in an establishment like this, 

 the wear and tear would always be requiring some to be 

 replaced, I have, therefore, taken the number at 40. The vessel 

 to receive the condensed tar, oil, and ammoniacal liquor, must 

 be of considerable size, as also those for burning the gas, and 

 for washing it. One gasometer of 40,000 cubic feet, or two of 

 20,000 each, would be scarcely sufficient. To produce 7,000,000 

 cube feet of coal gas would require 700 chaldron of coals, and 

 175 for carbonisation, weighing altogether 1,181 tons, besides 

 -50 tons of lime for purifying. 



In a coal gas establishment there will be a conveyance 

 required for 1230 tons of materials, the greater part of which are 

 returnable in bulky articles, such as coke, tar, ammoniacal 

 liquor, for each of which a market must be found, as the greater 

 part of our estimated profit is derivable from them ; and of the 

 two latter articles, the product is already so great as very far to 

 exceed any possible demand for them : so that a further convey- 

 ance is required for more than three-fourths of the above esti- 

 mated materials, and large premises and reservoirs to contain 

 them till disposed of. Added to these, there is produced a very 



" See Peckston on Gas Lights. 



