AIE 37 



dents, practically have as long a life as those which work 

 on the surface.* It has been said that the relative 

 innocuity of coal-dust, as compared with the dust of 

 tin-mines, pottery manufacture, file-cutting, and knife- 

 grinding, is due to the shape of the particles, which in coal- 

 dust are free from sharp points and corners. It is also 

 considered by some that coal-dust is inimical to the develop- 

 ment of the bacillus of tuberculosis. 



Pit ponies in hot dusty coal-mines are liable to become 

 ' broken winded ' after a few years' service, and many suffer 

 from acute spasmodic asthma, which in time frequently 

 terminates in broken wind. There is no such thing as 

 ' miners' lung ' amongst them, though many never come 

 to the surface for years. 



Alkali and Acid Works. — Hydrochloric acid gas is evolved 

 from alkali works. Prior to legislation the effect of alkali 

 works on herbage in their vicinity was to shrivel up and 

 discolour the leaves and stems of trees and farm crops. Act 

 of Parliamentt now provides that 95 per cent, of the hydro- 

 chloric acid gases and vapours produced must be condensed. 

 Only one-fifth grain per cubic foot is permitted by law to 

 escape into the atmosphere. In the case of sulphuric acid 

 works four grains per cubic foot is allowed to escape into 

 the air. 



From copper-smelting works arsenic, sulphurous acid 

 and small quantities of copper are given off. Before legis- 

 lation these produced among horses and cattle the so-called 

 ' copper - smoke disease,' which showed itself by ossific 

 deposits on the knees and hocks and general emaciation. 



Offensive Trades.— Ihe impurities due to the decomposi- 

 tion of organic matters in certain offensive trades have been 

 classified by Dr. Ballard I as follows: (i.) The keeping of 

 animals; (ii.) the slaughtering of animals; (iii., iv. and v.) 



* I am greatly indebted to Mr. W. Woods, F.R.C.V.S., Wigan, for 

 much valuable information regarding pit ponies. 



t Alkali, etc., Works Regulation Act. 



+ ' Effluvium Nuisances ' : Sixth, Seventh, and Eighth Report, 

 Medical Officer Local Government Board. 



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