1882.] on Some of the Dangerous Properties of Dusts. 93 



and it is stated upon good authority that only about 20 per cent, of 

 the explosions in flour mills which can be actually substantiated, are 

 made public, the miller being unwilling to direct increased attention 

 to the risks of his business, which, as it is, have given rise to the 

 establishment of high rates of insurance upon corn mills. If efficient 

 measures can be adoi)ted in mills for preventing the dispersion of 

 fine flour-dust by other than the comparatively imperfect contri- 

 vances for promoting its partial deposition (as in the exhaust box 

 and stive room), flour-mill explosions will certainly be reduced in 

 frequency and importance. The efficiency of at any rate one simple 

 device for arresting the dust, by a species of filtration of the air 

 which is removed. from the millstone chambers, seems to have been 

 already decisively demonstrated by practical results, and there appears 

 reason to hope that the millowner will ere long have no valid excuse 

 for permitting a continuance of conditions favourable to what have 

 appeared to be hidden risks of danger to his property and to the 

 lives of those whom he employs. 



There appears no doubt that some instances of explosion or of 

 very rapidly spreading fire in flour mills have been ascribable to 

 the employment — accidentally, or with the permission of those in 

 authority — of naked lights in the vicinity of particular parts of the 

 factory where dust may be thrown into the air in large quantities. An 

 explosion from this cause occurred at the mills of Messrs. Ellis and 

 Co., of Bradford. A spout from a sieve having become choked, a 

 man removed the lid ; a quantity of dust at once flew out, and the 

 mixture, meeting either a lamp in the man's hand or a naked gas 

 flame close by, exploded, rendering the man insensible ; the flame 

 passed along an enclosed belt to a box containing a fan which was 

 driving a blast of air into five purifying chambers ; these purifiers 

 were fired simultaneously, and the explosion then passed to the 

 adjacent exhaust purifiers and thence to the dust room, so that the 

 mill was fired throughout almost immediately. In another instance, 

 the floor of a meal chamber broke, letting through the flour, which, on 

 falling into the air, was ignited by a flame in the vicinity, and speedily 

 fired the mill. Judging from statements made at a recent meeting of 

 the National Association of British and Irish Millers, the opinion is 

 entertained by many millowners that the running of millstones 

 empty must not be credited with too great a share in the origination 

 of explosions or fires in mills ; but that many are caused by the 

 so-called accidental ignition (by naked flames) of dust-and-air 

 mixtures. If such be the case, grave responsibilities are incurred by 

 millowners and managers who permit the existence of lights other 

 than safety lamps in localities where there is any possibility of a 

 considerable quantity of dust becoming suspended in the air, or do 

 not establish and strictly enforce regulations prohibiting the carrying 

 of naked lights in or near any working part of the mill. 



The important part played by coal dust, which exists in greater or 

 less abundance in all coal-mine workings, in aggravating and extending 



