18 REPORT— 1882. 



Bdinburgh, last year, that the fine dust resulting from the imperfect 

 combustion of coal is mainly instrumental in the formation of fog ; each 

 particle of solid matter attracting to itself aqueous vapour ; these glo- 

 bules 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 wastefnlly, 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 distilla- 

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

 the furnaces of glass,i 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. The use of water-gas, resulting 

 from the decomposition of steam in passing through a hot chamber filled 

 with coke, has been suggested, but this gas also is objectionable, because 

 it contains, besides hydrogen, the poisonous and inodorous gas carbonic 

 oxide, the introduction of which into dwelling-houses could not be 

 effected without considerable danger. A more satisfactory mode of 

 supplying heating separately from illuminating gas would consist in 

 connecting the retort at different periods of the distillation with two 

 separate systems of mains for the delivery of the respective gases, as 

 has been proposed by me elsewhere. Experiments made some years ago 

 by Mr. ElLisen of the Paris gasworks have shown that the gases rich in 

 carbon, such as defiant and acetylene, are developed chiefly during an 

 interval of time beginning half an hour after the commencement and 

 terminating at half the whole period of distillation, whilst during the 

 remainder of the time marsh gas and hydrogen are chiefly developed, 

 which, while possessing little illuminating power, are most advantageous 

 for heating purposes. By resorting to improved means of heating the 

 retorts with gaseous fuel, such as have been in use at the Paris gasworks 

 for a considerable number of years, the length of time for effecting each 

 distillation may be shortened from six hours, the usual period in former 

 years, to four, or even three hours, as now practised at Glasgow and else- 

 where. By this means a given number of retorts can be made to produce, 

 in addition to the former quantity of illuminating gas of superior quality, a 

 similar quantity of heating gas, resulting in a diminished cost of production 



