Sir,

Enclosed are the result of a series of experiments made under my direction with a view of ascertaining the relative value of the different modes of working cast-iron cylindrical retorts, from which you will perceive that it is more economical to work eight hours charges, as the workmen call it, that is to say, to suffer the distillatory process to go on for eight hours, when nearly two bushels of coal are contained in each retort, than to discontinue the operation at the end of six hours.

I am with respect,
Sir, Yours, &c.
T. S. Peckston.

To Mr. F. Accum,
Compton Street, Soho.

Process A.

Number of
Days the
Retorts
were
worked.		Number
of
Retorts
in
action.		Quantity of Coal
decomposed for
obtaining Gas.		Quantity of Coal
used for Fuel.		Quantity
of Gas
produced.		Quantity
of Gas from
one Chaldron
of Coal.
Chaldron. Bushel.Chaldron. Bushel.Cubic
Feet.		Cubic
Feet.
Monday87 10-30 4-24 94,9878,768
Tuesday88 14-24 6- 8128,5978,784
Wednesday88 14-24 6- 8122,1888,331
Thursday94 15-24 6-26131,1768,373
Friday96 16- 0 6-32127,6967,981
Saturday96 16- 0 6-20127,5367,971
Sunday96 15-18 6- 4125,4878,092
103-1243-14857,6678,300[18]

[18] Average proportion of gas from a chaldron of coal.

Expenditure of Process A.

Coals, decomposed, 103 chaldron 12 bushel, at £ 2. 11s. 6d. the chaldron, (27 Cwt.)£ 26620
Small Coal, 43 chaldron, 14 bushels, used for fuel, at £ 2. 2s. the chaldron9124
Wages of two additional workmen (not required had the retorts been worked at eight hours charges,) at £ 1. 16s. each man, the week3120
Total expenditure,£. 360170

Products of Process A.