246 THE ADDRESSES, LECTURES, ETC., OF 



1'lbt of coal therefore produces 990,000 = 12g2 unitg of heat 



772 



instead of 10,500, or only one-eighth part of the utmost possible 

 effect. 



To melt steel in pots in the old-fashioned way still practised 

 largely at Sheffield, 2 tons of best Durham coke are consumed 

 per ton of cast steel produced. The latent and sensible heat 

 really absorbed within a pound of steel in the operation, does not 

 exceed 1,800 units, whereas 2| Ibs. of coke are capable of pro- 

 ducing 13,050 x 2'5 = 32,625 units, or 18 times the amount actually 

 utilized. 



In domestic applications the waste of fuel is also exceedingly 

 great, but it is not easy to give precise figures representing this loss, 

 owing to the manifold purposes to be accomplished, such as cook- 

 ing .and the heating and ventilating of apartments. If ventilation 

 might be neglected, close stoves such as are used in Russia would 

 unquestionably furnish the most economical mode of heating our 

 apartments ; but health and comfort are after all of equal 

 importance with economy, and these are best secured by means of 

 an open chimney. Not only does the open chimney give rise to 

 an active circulation of air through our rooms, which is a necessity 

 for our well-being, but heat is supplied to them by radiation from 

 incandescent material instead of by conduction from stove sur- 

 faces ; in the one case the walls and furniture of the room absorb 

 the luminous heat rays, and yield them back to the transparent 

 air, whilst, in the latter case, the air is the first recipient of the 

 stove heat, and the walls of the room remain comparatively cold 

 and damp, giving rise to an unpleasant musty atmosphere, and to 

 dry rot or other mouldy growth. The adversaries of the open 

 fire-place say that it gives warmth on only one side, but this one- 

 sided radiant heat produces upon the denizens of this somewhat 

 humid country, and indeed upon all unprejudiced people, a parti- 

 cularly agreeable sensation ; which is proof I think of its healthful 

 influence. The hot radiant fire imitates indeed the sun in its 

 effect on man and matter, and before discarding it on the score of 

 wastefulness and smokiness, we should try hard I think to cure it 

 of its admitted imperfections. 



If incandescent solid matter is the main source of radiant heat, 

 why, it may be asked do we not resort at once to coke for our 



