90 Mr. F. A. Abel [April 28, 



consequent friction of their bare surfaces against each other ; the 

 results being, the ignition of the mixture of air and fine flour-dust by 

 which the millstones were surrounded, and the rapid communication 

 of flame thereby to the mixture of dust and air which filled the 

 conduits in communication with the exhaust box : this being the 

 common receptacle into which the mixture of dust and air is drawn, 

 by an exhaust fan, through the conduits communicating with the several 

 mills. From the exhaust box, where a portion of the suspended flour- 

 dust was deposited, the air, still laden with dust, passed, in the 

 Tradeston as in other flour mills, to another chamber, called the 

 stive room, where a further quantity of the flour dust would deposit. 

 A connected series of channels and larger enclosed spaces was there- 

 fore filled with a dust-laden atniosphere, through which flame was so 

 rapidly transmitted from the millstones where the first ignition 

 occurred as to produce violent explosive efi'ects, which succeeded 

 each other with very great rapidity in different parts of the building. 

 The production of the blaze at the millstones was observed to be 

 immediately succeeded by a crackling noise as the flame rajndly 

 spread through the conduits to the exhaust box upon an upper floor, 

 whence a loud report almost at once proceeded. 



Messrs. Eankin and Macadam's inquiries elicited the facts that 

 other flour-mill explosions had been attended by a similar succession 

 of effects to those above indicated, and that at the Tradeston Mills 

 themselves a less violent explosion, resulting in the bursting open of 

 an exhaust box, attended by injury to some workmen, and the blowing 

 out of windows and loosening of tiles, had taken place on a previous 

 occasion. In the later accident, the more violent explosion of the 

 exhaust box was followed by other distinct explosions in distant parts of 

 those extensive mills, to which fire was led by the dust-laden air existing 

 in the many channels of communication, and in which the cleansing and 

 sifting operations, all attended by the escape of dust, were carried on. 



Messrs. Eankin and Macadam ascertained that accidents of this 

 nature at flour mills were of frequent occurrence, especially since the 

 exhaust arrangements had been applied to the larger flour mills, and 

 in their report they point out that it seems scarcely possible to guard 

 against such accidents, though their frequency may be reduced by 

 adopting efficient precautions for avoiding the stoppage of the feed 

 to the millstones and the access of nails or other iron j^articles to 

 the stones; and by prohibiting the employment of naked lights in 

 the vicinity of the mills or dust passages. They also suggest that 

 measures should be taken to reduce, as far as possible, the violence of 

 explosions and the risk of injury to life and property, by constructing 

 all receptacles into which the dust-laden air is drawn or passed from 

 the mills, &c., as lightly as possible, so as to offer little resistance to 

 the sudden expansion due to the ignition of an inflammable mixture, 

 and by placing such receptacles as the exhaust box and stive room 

 outside the building. 



Since the publication of Messrs. Kankin and Macadam's valuable 



