ON FURNACES. 381 



I propose that Mr. Hackney should deliver his discourse on furnaces, 

 as far as he can before we adjourn, and that we should after the 

 adjournment view those models which there is not time at present to 

 display. 



ON FURNACES. 



Mr. HACKNEY : Furnaces, as used in the arts, may be defined as 

 the arrangements under which fuel is burned to produce heat, for the 

 purpose either of inducing permanent changes in the substances 

 heated, or of preparing them, by softening or fusion, for subsequent 

 treatment. 



This excludes two of the applications of fuel which together take up 

 the larger proportion of that consumed. The domestic use namely, 

 for cooking, and for warming, lighting, and ventilating inhabited 

 places ; and that for the generation of motive power. 



Even thus limited, the amount of fuel burned in furnaces is very 

 great, and the possibility of effecting further economies in its use 

 is a problem of vast importance. The quantity of coal burned, in this 

 kingdom alone, for smelting ores and for refining and manufacturing 

 metals, was, according to the statistics published by the Mining 

 Record Office, 35,802,000 tons in 1873, an d 34,400,000 tons in 1874. 

 Of these amounts the manufacture and working of iron, in its different 

 forms, took nearly the whole : 35,039,000 tons in 1873, and 33,562,000 

 tons in 1874 ; or more than 100,000 tons on every working day.* 



The subject of the construction and mode of working of the several 

 forms of furnaces in use is one of great extent, and can only be dealt 

 with briefly in such a paper as the present. They may be divided into 

 those in which solid fuel is intermixed with or directly surrounds the 

 matters to be heated, and those in which the heating is done, in one 

 way or another, by flame, without direct contact between the solid fuel 

 and the work. 



The characters of the fuel best fitted for these two kinds of furnace 

 are essentially different. Where the matters to be acted on, or the 

 vessels that contain them, are in direct contact with the fuel, as in a 



* Mineral Statistics, 1874, p. xiv. 



