338 THE , ADDRESSES, LECTURES, ETC., OF 



Taking the coal used, 9,000,0.00 tons, at 12s., equal 5,400,000?., 

 it follows that the by-products alone exceed in value the coal used 

 by very nearly 3,000,000/. 



In using raw coal for heating purposes these valuable products 

 are not only absolutely lost to us, but in their stead we are 

 favoured with those semi-gaseous by-products in the atmosphere 

 too well known to the denizens of London and other large towns 

 as smoke. Professor Roberts has calculated that the soot in the. 

 pall hanging over London on a winter's day amounts to fifty tons, 

 and that the carbon present as hydro-carbons and in the half- 

 burnt form of carbonic oxide, a poisonous compound, resulting 

 from the imperfect combustion of coal, may be taken as at least 

 five times that amount. Mr. Aitken has shown, moreover, in an 

 interesting paper communicated to the Royal Society of Edinburgh, 

 last year, that the fine dust resulting from the imperfect com- 

 bustion of coal is mainly instrumental in the formation of fog ; 

 each particle of solid matter attracting to itself aqueous vapour ; 

 these globules of fog are rendered particularly tenacious and 

 disagreeable by the presence of tar vapour, another result of 

 imperfect combustion of raw fuel, which might be turned to much 

 better account at the dye-works. The hurtful influence of smoke 

 upon public health, the great personal discomfort to which it 

 gives rise, and the vast expense it indirectly causes through the 

 destruction of our monuments, pictures, furniture, and apparel, 

 are now being recognised, as is evinced by the success of recent 

 Smoke Abatement Exhibitions. The most effectual remedy would 

 result from a general recognition of the fact that wherever smoke 

 is produced, fuel is being consumed wastefully, and that all our 

 calorific effects, from the largest down to the domestic fire, can 

 be realised as completely and more economically, without allowing 

 any of the fuel employed to reach the atmosphere unburnt. This 

 most desirable result may be effected by the use of gas for all 

 heating purposes, with or without the addition of coke or 

 anthracite. 



The cheapest form of gas is that obtained through the entire 

 distillation of fuel in such gas-producers as are now largely used 

 in working the furnaces of glass, iron, and steel works ; but gas 

 of this description would not be available for the supply of towns 

 owing to its bulk, about two-thirds of its volume being nitrogen. 



