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diate development of a proportionally increased amount of 
heat. I mention these facts to prove that the practical 
application of gas as a heating power is not ideal, but 
absolutely in operation. Nor, I believe, is Mr. Appold's a 
solitary instance. 
One more suggestion, and I will bring this somewhat 
too lengthy paper to its termination. In the manufacture 
of iron and other metallurgical and manufacturing opera- 
tions, the elimination of very large quantities of combustible 
gases is common. The emission of olefiant gas, carburetted 
hydrogen, and other hydro-carbons, is daily attested by the 
immense volume of flames which illuminate the country near 
large iron manufactories. These gases might by various 
expedients be collected and applied to heating and illumi- 
nating the various buildings connected with the works. In 
an admirable report published by Chevalier Bunsen and 
Dr. Lyon Playfair, on the gases existing in iron furnaces, 
it is clearly -demonstrated that one of the largest resources 
of the country is wasted by the neglect of these important 
considerations. I do not hesitate to say, that the expendi- 
ture of fuel to produce steam power for the blast and other 
mechanical operations, might be wholly economised by the 
application of such combustible gases in lieu of it. 
In all manufacturing processes we are too apt to attend 
solely to the production of one commercial article, and to 
neglect others which necessarily arise during its formation. 
But in these days, when a vast struggle for superiority in 
commerce and in agriculture, in manufacture and in science, 
is shaking all European nations to their foundations, the 
importance of any, even the smallest, bye-product, cannot be 
overrated; and it should be the object of the manufacturer 
to discover the whole of the compounds eliminated, and 
by applying each to its respective purpose, equalise the 
expense of the generation of all. I might enlarge on the 
