1920.] 



Air Pollution by Coal Smoke. 



69 



AIR POLLUTION BY COAL SMOKE. 



Arthur G. Ruston, B.A., B.Sc. (Lond.), M.Sc. (Leeds), 



Lecturer in Farm Economics, Department of Agriculture, The University, 



Leeds. 



Among the many subjects that in recent years have engaged 

 the attention of those interested in the improvement of the 

 public health of our city communities, the question of atmos- 

 pheric pollution has obtained a place which is slowly gaining 

 in importance. The subject is commonly discussed, however , 

 as if the pollution were rigidly confined within the municipal 

 boundaries, and solely of importance in its bearing upon the 

 health of the ratepayer and the appearance and durability of 

 his property. In view, however, of the undoubted damage 

 done by smoke pollution to vegetation in general and to garden 

 crops in particular, the question has also a significance for the 

 agriculture of the neighbouring semi-urban districts. 



Comparison of Domestic and Boiler Soot. 



A good coal contains a large amount of carbonaceous matter., 

 leaves a small residue of ash on burning, and has a low 

 sulphur and arsenic content. When coal is burnt some of the 

 carbonaceous matter escapes into the air in the gaseous form 

 either as carbon monoxide or carbon dioxide ; some distils and 

 comes over as tar ; some goes up the chimney unconsumed 

 and is deposited as soot. When one considers the varying 

 conditions under which coal is burnt, it is obvious that the 

 character and composition of soot must vary considerably. 

 The higher temperature and stronger draught of a factory 

 furnace produce a soot which contains more ash and less tar 

 than is the case with the domestic grate. The soot also varies 

 in character with the distance at which it has been deposited 

 from the grate ; another factor which will influence the charac- 

 ter and composition of the soot will be the kind of coal used. 



The following analyses illustrate these facts very clearly : — 



Analyses of Soot from the University. 





Domestic Soot. 





Boiler Soot. 









Base. 



70 ft. up. 



Top no ft 





Per cent. 



Per cent. 



Per cent. 



Per cent. 



Carbon 



.. 40-50 



16-66 



21 80 



27-00 



Hydrogen 



•• 4'37 



o-86 



1-44 



i-68 



Nitrogen 



409 



o-oo 



1-18 



I -21 



Ash 



.. 1816 



75 -oi 



6604 



61 -8c 



Tar 



.. 25-91 



009 



o-8o 



1-66 



Sulphur 



299 



2-67 



2-58 



2-84 



Chlorine 



519 



o-ii 



1 -46 



1 -6o 



Arsenic 





0-078 





0-I2 



Acidity as H, S0 4 0-37 



i'33 



0-58 



0-56 



