Faraday to William Varlo Hellyer   12 June 1834¹

R. Institution | June 12, 1834

My dear Sir,

I can only give general answers to your questions. I have no doubt that either asphaltene or wood and asphaltene could be used instead of coal but they would require alterations in the furnaces to consort with their mode of combustion and make the heat available and then the effect would probably come near coal. The relation of heating power obtained from coal and asphaltene must be obtained by experiment on a good large scale. The quantity of steam will be obtained at the same time. The stowage will depend upon the quantity of each fuel required to give an equal quantity of steam and will therefore be told by the same expts. I should expect that good coal would be the best, at least until repeated trial and improvement have given the most perfect mode of applying the combustion of asphaltene to the raising of steam.

I am Dear Sir | Most truly yours, | M. Faraday