The quantity of gas to be supplied each night, was, as in the preceding process, fifty thousand cubic feet.
The number of retorts required to produce that quantity, was forty-two, and to make them last twelve months instead of six months, as in the preceding process, it was necessary to work them at a temperature, at which a chaldron of coal produces from seven thousand, to eight thousand cubic feet of gas.
The result of this operation was as follows:
| Cost of forty-two retorts, with brick-work foundation, cast-iron coke hearth, perpendicular dip pipe,connected with the hydraulic main, at £. 23 each | £. 966 | 0 | 0 | |||
| Eight workmen, four by day and four by night, at £ 1. 6s. each the week | £. 540 | 16 | 0 | |||
| 2555 chaldron of Coal, requisite for producing the gas, at£. 2 8s. the chaldron | £. 6123 | 0 | 0 | |||
| Wear and tear of grate bars, fire shovels, tongs and rackers | 42 | 0 | 0 | |||
| 638 chaldron of Coal for fuel, at £ 2. 1s. the chaldron | 1307 | 18 | 0 | |||
| £. 8979 | 14 | 0 | ||||
| Deduct the market price of 2555 chaldron of coke, produced by the process, at £ 1. 3s. thechaldron. | £. 2938 | 5 | 0 | |||
| 6383⁄4 chaldron of small coke, or breeze, at 10s. the chaldron | 319 | 7 | 6 | |||
| £. 3257 | 12 | 6 | ||||
| There remains for the annual expence of maintaining the apparatus | £. 5722 | 1 | 6 | |||
| Subtract the annual expence of Process I. | 4816 | 0 | 9 | |||
| The balance in favour of Process I. is | £. 906 | 0 | 9 | |||
Process A.
In the following additional processes, the retorts when begun to be worked, were also new, and were left in a fit working state. The quantity of gas required to be produced daily, was 102,000 cubic feet.[26]
[26] These Experiments were made at the Westminster Gas Works, under the superintendance of Mr. Clegg, to whom I am indebted for this communication.
The retorts were worked at a temperature at which they produced 10,000 cubic feet of gas from the chaldron, (27 Cwt.) of Newcastle coal.
| To sixty-eight retorts, twice replaced, at £ 15. each | £. 2040 | 0 | 0 | |||
| Deterioration of grate bars, fire shovels, tongs, and rackers | 91 | 16 | 0 | |||
| 3723 chaldron of coal for obtaining the gas, at £ 2. 8s. the chaldron | 8935 | 4 | 0 | |||
| 930 chaldron, 27 bushels of Coal, for fuel, at £ 2. 1s. the chaldron | 1908 | 0 | 9 | |||
| 14 Men at £ 1. 6s. each, the week,being 7 for the day, and 7 for the night | 946 | 8 | 0 | |||
| £. 13,921 | 8 | 9 | ||||
| Deduct the market price of 3723 chaldron of saleable coke, at £ 1. 3s. the chaldron | £. 4281 | 9 | 0 | |||
| 9303⁄4 chaldron of small coke, or breeze, at 10s. the chaldron | 465 | 7 | 6 | |||
| £. 4746 | 16 | 6 | ||||
| Cost of obtaining, 37,230,000 cubic feet of gas | £. 9174 | 12 | 3 | |||