310 



FLOUR-HILLS, EXPLOSION IK 



flour, and other processes. The dust is gathered, 

 and, in mixture with air, is collected in confined 

 spaces, mainly through the action of the exhaust. 

 "VVe have ascertained, by direct experiment, the in- 

 flammability and explosiveness of this mixture. We 

 have also calculated that, when the theoretical pro- 

 portions best suited to produce an explosion are ex- 

 actly realized, the pressure of the resulting gaseous 

 products, if confined in a limited space, suddenly be- 

 comes equal to about eight times that of the atmos- 

 pherebeing sufficient to produce effects of great 

 violence in the way of bursting exhaust-boxes, throw- 

 ing down partitions and walls and the like. It is 

 probable that, through deviations from the precise 

 theoretical conditions, the before-mentioned great 

 pressure is not actually attained, but still it is certain 

 that a very intense and destructive pressure must be 

 produced. 



As for the source of heat which inflames the ex- 

 plosive mixture of dust and air, that may be fur- 

 nished by the flame of a lamp incautiously brought 

 in contact with the dusty cloud, but more frequently 

 through the millstones striking fire when happening 

 to run empty. A pair of millstones, when the feed is 

 accidentally suspended, readily fire with each other, 

 for they are made of a flinty or other very hard sili- 

 ceous rock, and the sparks from them are capable of 

 inflaming any combustible substance. The occa- 

 sional suspension of the feed is an accident which 

 cannot be wholly prevented by any amount of cau- 

 tion. A still more dangerous kind of spark is 

 formed when a piece of metal, such as an iron nail, 

 gets between the millstones, for the sparks then 

 produced are globules of molten metal at a white 

 heat and in a state of combustion. We have ascer- 

 tained that the presence of a nail between the mill- 

 stones can set fire to the dusty atmosphere, even 

 when the feed is on. In fact, to guard against this 

 last danger, from the dropping of nails into the hop- 

 per, magnets have been placed in the feeding-spouts. 

 It is not to be expected, however, that the mere pla- 

 cing of magnets in the position indicated will wholly 

 prevent the passage of the nails, but will only reduce 

 the danger from this cause to a minimum. 



Having given these preliminary explanations as to 

 the nature of fire-explosions in general, and of those 

 in flour-mills in particular, we next proceed to state 

 the grounds of the conclusions at which we have 

 arrived respecting the fire-explosion at Tradeston 

 Mills, together with the special reasons which have 

 led us to form those conclusions. 



In arriving at the facts connected with this fire- 

 explosion, we have taken the evidence of all the sur- 

 vivors who were in the mill at the time. 



In bringing this evidence to bear upon the imme- 

 diate cause of the fire-explosion, we have personally 

 visited and inspected the working of other flour- 

 mills in Glasgow, Newcastle, Leith, and Kirkcaldy, 

 and have made particular inquiries at, and examined 

 eye-witnesses of other fire-explosions which have 

 occurred in, such mills. We have also read accounts 

 of similar fire-explosions which are recorded in 

 French and German publications. 



The evidence of Dickson Young, James Black- 

 wood, and of John Rooney, is of the greatest impor- 

 tance. Dickson Young was one of the men in charge 

 of the stones at the time of the explosion. He was 

 the first to observe that a pair of stones, which were 

 engaged in grinding sharps, were running empty 

 from a feed being off, and were striking each other. 

 He immediately called the attention of James Black- 

 wood, who had a partial superintendence of that part 

 of the mill, and they were both engaged in examining 

 the feed-spout when a "lowe" or blaze burst forth 

 from the centre part of the stones which scorched 

 the men Blackwood very severely, who was then 

 rendered, for a time, unconscious. Four other men 

 and a boy were on the same floor, but these were all 

 killed. No other survivor, therefore, saw, or could 

 have seen, what happened up to this point. No light 

 was brought near the stones, and the sparks which 



gave rise to the "lowe" or blaze must have origi- 

 nated in the stones rubbing against each other and 

 striking fire. The flame which issued forth from 

 the stones must have been caused by the inflaming 

 of the flour-dust and air, probably intensified at the 

 moment by the feed coming on. 



Immediately after observing the blaze and flame 

 from the pair of stones, Dickson Young distinctly 

 remembers hearing the crackling noise of an explo- 

 sion travelling along the roans or conduits which 

 convey the finer flour-dust to the exhaust-box, which 

 was situated in the next higher or fourth floor, and 

 this ended in a loud report from the direction of the 

 said exhaust-box. James Blackwood was uncon- 

 scious at this time, but John Eooney, who was on 

 the fourth floor, heard the crackling noise under his 

 feet, felt the floor shake, and thereafter heard the 

 explosion in the exhaust-box, which was at the far- 

 ther or west end of the flat he was on. We have as- 

 certained that a similar crackling noise, followed by 

 a report, has been observed in the cases of former 

 fire-explosion in other mills which we have investi- 

 gated. Indeed, the readiness with which flame can 

 be transmitted through an atmosphere of flour-dust 

 and air may be experimentally shown by showering 

 some of the fine dust through a sieve placed' a few 

 feet above a gas-jet or other flame. The combustion 

 of the dusty atmosphere takes place with explosive 

 rapidity, and, in some respects, resembles the flame 

 travelling along a train of gunpowder or flashing 

 through a mixture of coal-gas and air. 



The flour-dust mainly consists of starch and glu- 

 ten, accompanied by smaller proportions of gum. 

 sugar, and oil. All these substances are composed 

 in greater part of carbon, hydrogen, and oxygen, and, 

 when burned, they yield carbonic-acid and' carbonic- 

 oxide gases, and water-vapor. These gases neces- 

 sarily tend to occupy a greater space than the dust 

 and air which gave riee to them^ and this extra 

 space demanded by the products of the combustion 

 is much enlarged by the high temperature produced 

 during the burning, and which tends greatly to ex- 

 pand the volume or the gases. We have already 

 given an estimate of eight atmospheres as the in- 

 crease of pressure produced by the effort of the gases 

 to expand when they arc confined within a limited 

 space. 



The fire explosion which occurred in the exhaust- 

 box must have burst the sides of the box. Both 

 Dickson Young and John Kooney thought so at the 

 time, and we have ascertained that during a previous 

 explosion, which occurred in the same mill about six 

 years ago, the wooden planking of the sides of the 

 exhaust-box was dislodged, two men were scorched, 

 several windows were blown out, and some slates 

 were loosened from the roof of the building. How- 

 ever, we have determined by direct experiment that 

 flour-dust diffused through the air contained in a 

 box, and set fire to, explodes with violence, splits up 

 the wood, bursts the sides, and lifts up the box even 

 when laden with the heavy weights. Indeed, the 

 mixture of flour-dust and air is destructively explo- 

 sive, and there can be no doubt that the fire explo- 

 sion of the dusty atmosphere in the exhaust-box in 

 the Tradeston Mills, which was 18 feet long, 9 feet 

 high, and 7 feet wide, would shatter the sides and 

 force the accumulated fine dust lying on the shelves 

 and floor out of the box into the atmosphere of the 

 mill, at least on the fourth floor. 



It is also to be observed that all parts of the mill 

 were in communication by means of elevators, hatch- 

 ways, and other passages, through which dust and 

 flame would readily pass, and also that in other parts 

 of the mill various cleansing and sifting processes 

 went on, which produced large quantities of com- 

 bustible dust, which would be quickly diffused 

 through the air in the different floors by the shock 

 and blast of the first explosioia in the exhaust-box. 

 This diffusion of the flour-dust through the air 

 would necessarily lead to the partial obscuring of 

 the light, or to the apparent momentary darkness 



