296 THE WORLDS LUMBER ROOM. 



one unites with the oxygen of the other to form water, and 

 the chlorine is set free. Being wanted, however, in the form 

 of a solid, not a gas, it is sent into lime, with which it forms 

 the well-known bleaching powder, chloride of lime, also 

 much used as a disinfectant, which is worth ij a ton. 



Two hundred thousand tons of common salt are annually 

 consumed in Great Britain for the preparation of nearly the 

 same weight of soda-ash, of which the value is about 

 ^2,000,000 ; and more than 1,000 tons of impure hydro- 

 chloric acid are produced every week in South Lancashire 

 alone during the process, all of which was, until of late 

 years, not merely wasted but allowed to be positively 

 destructive. The sulphur used in the process is still a waste 

 product, and from its bad smell is a great nuisance ; but no 

 doubt in time some use will be found for this also. 



Another waste product which at present is allowed to 

 be a general nuisance is the unconsumed carbon, which 

 escapes from our chimneys in the shape of finely-divided 

 soot, or smoke. The weight of soot in the air on a winter 

 day in London is estimated by Dr. Siemens at fifty tons, 

 while of poisonous carbonic oxide there are five times as 

 much, and the two together " destroy public monuments, 

 waste life, sight, and cheerfulness," and deprive us of 

 so much warmth. Mills, furnaces, factories, bakehouses, &c., 

 are now obliged to consume their own smoke, and all that is 

 needed in private houses is some means of subjecting the 

 smoke to heat sufficient to consume it before allowing it to 

 enter the chimney. 



It is said that smoke is a great disinfecting agent in 

 populous towns, and as such it may be considered useful ; 



