FLOUR-MILLS, EXPLOSION" IN. 



311 



which was observed "by some of the survivors be- 

 tween the first and second explosions. 



The diffusion of the combustible dust throughout 

 the atmosphere of the mill would be immediately 

 followed by the inflaming and explosion of the 

 whole, leading to the falling of the gable-walls, and 

 the breaking up and firing of the wooden flooring. 

 Several of the survivors speak distinctly of the 

 period of darkness being succeeded by a period of 

 light, when they saw their way of escape from the 

 burning ruins by descending over the debris of the 

 gable-walls. The fact of these walls being blown 

 out, and the upper parts of the building being al- 

 lowed to fall through loss of support, was proved 

 by the position of various objects among the ruins ; 

 while, in one case, at least, the difficulty of escaping 

 from the fire arose from the manner in which the 

 men were confined by the fallen beams. 



The testimony of the survivors bears out the sud- 

 denness of the firing of all parts of the mill. Those 

 who were escaping from the mill in a conscious state 

 felt themselves surrounded by the flames. Those 

 who were in the second and fifth floor gangways 

 were singed and scorched by the flames rushing out 

 by the doorways, while, at the same moment, a blast 

 of flame and air swept out from the first floor across 

 a narrow court, and burst in the windows of the 

 offices. As soon as the proprietor, manager, and 

 foreman, who were in the office at the time, heard 

 the main explosion, they ran into Commerce Street, 

 and by that time the gable-walls were down, and 

 fire was raging throughout the disjointed timber. 

 On returning to the office, and opening an iron trap 

 communicating with the sunk flat, the foreman ob- 

 served that the fire was raging below. 



The sudden and practically simultaneous firing of 

 the whole building is only explainable on the ground 

 of the first explosion in the exhaust-box leading di- 

 rectly or indirectly to the production of a dusty at- 

 mosphere in all the floors, which was immediately 

 thereafter fired with explosive rapidity. For it 

 should be observed that trie smutting process, which 

 produces a large quantity of very explosive dust, 

 was carried on in the two lower floors of the build- 

 ing. 



The firing of the stores or granaries by the flame 

 passing along the gangways, and by burning ma- 

 terial dropping through the attic-windows or sky- 

 lights, is proved by the evidence of the manager and 

 foreman, as also of William Watt, who went up to 

 the granary-floors after the miH was on fire, and saw 

 that the iron doors of communicotion with the mill 

 were closed, and who observed the progress of the 

 fire in the manner stated. 



A sample of the flour, taken by us from tke ruins 

 clearly proved, on chemical analysis, that no sub- 

 stance, either of an explosive or non-explosive na- 

 ture, was used in the grinding or treatment of the 

 grain or flour ; and, even after the demolition of the 

 walls, we found the boilers uninjured. Wo were in- 

 formed that the safety-valve was open at the com- 

 mencement of the conflagration, and the boilers thus 

 saved from bursting by Mr. Oexle, acting under the 

 orders of Mr. Thomas Muir. 



All our observations, inquiries, and experiments, 

 therefore, lead us to consider that the cause of the 

 fire explosion in the Tradeston Flour-Mills was a 

 temporary and accidental stoppage of the feed in a 

 pair of stones grinding sharps, which led (1) to the 

 stones striking fire ; () the inflaming of the dusty 

 atmosphere in the exhaust-roans, or conduits, and 

 exhaust-box ; and thereafter (3) of the fire-explosion 

 of the dusty atmosphere throughout the mill gener- 

 ally. These events would necessarily succeed each 

 other with the greatest rapidity, which accounts for 

 the fact that, while some of the survivors distinctly 

 speak of hearing two explosions, others only recol- 

 lect one report. 



The severity of the fire-explosion in the Tradeston 

 Mill, as compared with other explosions of a like na- 

 ture, is undoubtedly due to the accidental circum- 



stance of all parts in the train of combustion being 

 at the instant charged with readily-inflammable 

 mixtures. 



In conclusion, we proceed to state what precau- 

 tions we think it desirable to adopt in order to pre- 

 vent the fatal and destructive consequences of such 

 accidents in the future. It is manifest that the great 

 danger in the operations carried on in a flour-mill 

 does not lie in the grinding process proper, but in 

 the plan pursued in the storing up of the finest and 

 most impalpable of the flour-dust. So long as the 

 grinding operations are carried on in the simple 

 manner pursued in small mills, where the stones are 

 merely covered in with wooden boarding, and there 

 is no exhaust, if the feed goes off and the stones 

 strike fire, or a nail or other foreign substance gets 

 between the stones, and luminous sparks are given 

 off, there can only be a limited amount of flour-dust 

 to inflame, and the combustion and explosion must 

 be at a minimum, be confined to a small space, and 

 ba not capable of exerting disastrous effects. The 

 fire explosion will be localized in the pair of stones 

 where it originates, or at most not extend beyond 

 the meal-spout attached thereto. 



But it is otherwise where the exhaust is employed, 

 and all the fine dust is drawn up by a fan into an 

 exhaust-box either with or without a supplemental 

 stive-room where the powder accumulates, and 

 where a flame, sucked up from the stones, must in- 

 evitably lead to an explosion of a more or less seri- 

 ous nature. The danger necessarily increases when 

 ten, twenty, or thirty pair of stones are connected 

 with the same exhaust-box and stive-room, and the 

 maximum danger is arrived at when the exhaust- 

 box, with its supplemental stive-room, is placed 

 within the mill, and ^ren occupies part of one of the 

 floors. A similar remark applies to the methods 

 employed in cleansing the wheat. 



In fact, all these proceses of cleansing the grain 

 and separating and sifting the flour, which the great 

 improvements in milling have introduced of late 

 years, for the ostensible and laudable purpose of 

 raising the quality of the flour, have more or less 

 tended to bring about a condition of matters which 

 renders the majority, at least, of the larger flour- 

 mills liable to accidental fire-explosions of a more or 

 less disastrous nature. 



We have, therefore, to recommend for future guid- 

 ance and safety, that all receptacles in flour-mills, in 

 which a dusty atmosphere collects, should be placed 

 outside the mill in buildings so constructed as to be 

 readily blown to pieces, in order that any explosion 

 which may take place in them may easily find vent, 

 and not be forced to travel back into the mill. 

 Among such receptacles, we include exhaust-boxes, 

 stive-rooms, smut-rooms, and exhaust-fans. If this 

 arrangement be carried out, any flame which may 

 originate in the stones, and even travel along the 

 exhaust roans or conduits, will be sucked out of the 

 mill by the exhaust-fan into the exhaust-box, and, 

 should the conditions of a fire-explosion be at the 

 time in the said box, the force will spend itself in 

 blowing off the roof, or bursting the sides of the ex- 

 haust-box, and probably also of the connecting-room 

 called the stive-room. It will be necessary to ar- 

 range that the roan or conduit leading from the mill 

 to the fans outside be of small size, so that the in- 

 flamed gas may only find vent to a very limited ex- 

 tent into the mill itself, and probably this may be 

 altogether hindered by the construction of a swing 

 door placed in the exhaust-roan before the fan. The 

 construction of the exhaust-roans or conduits of 

 metal would also diminish the probability of the fire 

 spreading through such, by conducting away the 

 heat, and thus reducing the temperature of the flame. 

 The latter arrangement may be objected to, how- 

 ever, on the ground of its leading to the condensa- 

 tion of moisture, and the formation of paste with 

 the flour-dust. 



There should be no other direct communication 

 between the mill and the exhaust-box and stive- 



