Application of the Gas from Coal. 131 
be obtained, compared with that of equal quantities of light 
yielded by oils and tallow. 
My apparatus consisted of an iron retort, with tinned copper 
and iron tubes through which the gas was conducted to a 
considerable distance ; and there, as well as at intermediate 
points, was burned through apertures of varied forms and di- 
mensions. The experiments were made upon coal of different 
qualities, which I procured from distant parts of the kingdom, 
for the purpose of ascertaining which would give the most 
economical results. The gas was also washed with water, and 
other means were employed to purify it. 
In the year 1798, I removed from Cornwall to Messrs. 
Boulton, Watt, and Co’s, works for the manufactory of 
steam engines at the Soho Foundry, and there I constructed 
an apparatus upon a larger scale, which during many succes- 
sive nights was applied to the lighting of their principal build- 
ing, and various new methods were practised, of washing and 
purifying the gas. 
These experiments were continued with some interruptions, 
until the peace of 1802, when a public display of this light 
was made by me in the illumination of Mr. Boulton’s manu- 
factory at Soho, upon that occasion. 
Since that period, I have, under the sanction of Messrs. 
Boulton, Watt, and Co. extended the apparatus at Soho 
Foundry, so as to give light to all the principal shops, where 
it is in regular use, to the exclusion of other artificial light ; 
but I have preferred giving the results from Messrs. Philips' 
and Lee’s apparatus, both on account of its greater extent, 
and the greater uniformity of the lights, which rendered the 
comparison with candles less difficult. 
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