348 



SCIENCE. 



[N. S. Vol. IX No. 219. 



tents of an ordinary sack, when mixed with 

 4,000 cabic feet of air, will degenerate force 

 enough to throw 2,500 tons mass to a height 

 of 100 feet. If we now consider the many 

 tons of flour there must have been in a mill 

 such as the Washburn ' A,' where as much 

 as 1,000 pounds of dust per day was col- 

 lected from a single pipe, we can readily 

 comprehend how such great destruction 

 could be wrought. 



It is to be regretted that the experts who 

 duly considered all the circumstances con- 

 cluded that, while, by suitable precautions, 

 the frequency of these flour-mill explosions 

 may be diminished and the extent of the 

 damage inflicted may be very much re- 

 stricted, the nature of the operations is 

 such that these explosions cannot be alto- 

 gether prevented. 



Since mixtures of wheat-dust with air 

 Lave proved to be so explosive, we should 

 naturally expect that analogous solids would 

 form similar explosive mixtures with air, 

 and, as a fact, we have recorded explosions 

 of oatmeal in the Oliver mill in Chicago, of 

 starch in a New York candj' factory, * of 

 rice in rice mills, of malt dust in breweries, 

 of spice dust in spice mills, together with 

 numerous instances of sawdust explosions, 

 the more prominent being those which oc- 

 curred in the Pullman car shops and at 

 Geldowsky's furniture factory in Cam- 

 bridge, Mass., still we should scarcely look 

 for an explosion from such a cause in a soap 

 factory. Yet a violent explosion occurred 

 in 1890, in a Providence soap-works, in 

 which the finely powdered saponaceous 

 substance known by the trade name of 

 ' Soapine ' was being prepared, and the Cor- 

 oner held in his finding that the explosion 

 through which such injury was inflicted 

 was caused by the ignition of soapine dust. 

 Experiments made in this connection 

 showed that this substance will explode 



* L. W. Peck, Explosions from Combustible Dusts, 

 Pop. Sci. Month., 14, 159-166 ; 1878. 



under certain conditions with more violence 

 than flour and apparently with the produc- 

 tion of more heat. 



The most unusual case of dust explosions, 

 however, with which we have met was that 

 of finely powdered metallic zinc which oc- 

 curred at the Bethlehem Zinc Works in 

 1854. At that time Col. Wetherill devised 

 a plan for utilizing the ' blue powder ' which 

 is the finely divided metallic zinc that is 

 deposited in the prolongation of the conden- 

 ser by swedging the powder into blocks and 

 piling these blocks one above another in a 

 furnace where they were melted down and 

 run into spelter. The workmen in charge 

 sought to facilitate the process by feeding 

 the uncompressed powder directly into the 

 furnace, but on trying to do so an explosion 

 followed the loading of the first shovelful, 

 and with such violence that the workman 

 was blown from the top of the furnace and 

 the blade of the shovel was driven into the 

 roof of the building. 



In pharmacy and the arts substances 

 have been made either knowingly or acci- 

 dentally from mixtures of combustible sub- 

 stances and supporters of combustion which 

 have given rise to accidents, such as those 

 from the parlor match and the chlorate 

 troches,* or from sodium peroxide and so- 

 dium bisulphite mixtures, as in the White- 

 cross Street explosion, j and the latter class 

 of mixtures are to be particularly dreaded 

 as the chemical action and subsequent ex- 

 plosion may be incited not only by contact 

 with fire, but also by contact with water. 

 Cavazzi J points out that mixtures of sodium 

 nitrate and hypophosphite detonate on heat- 

 ing, while Violette§ proposed to use a mix- 

 ture of sodium nitrate and acetate as a sub- 

 stitute for gunpowder, and these are but a 

 few among the many explosive mixtures 

 which may be compounded. 



* U. S. Nav. Inst. 11, 774 ,' 1885. 



t J. Soo. Chem. Ind. 13, 19S-300 ; 1894. 



JGaz. Chim. Ital., 1886. 



'i Berthelot sur la force de la poudre (3) 2, 315. 



