Democratic Sentinel, Volume 2, Number 27, Rensselaer, Jasper County, 16 August 1878 — The Explosiveness of Flour. [ARTICLE]

The Explosiveness of Flour.

Profs. Peck and Peckbam, of the Uni versity of Minnesota, have been making an extensive series of experiments to determine the cause of the recent flourmill explosion at Minneapolis. The substances tested were coarse and fine bran, material from stone grinding wheat; wheat dust from wheat-dust house; middlings, general mill dust, dust from middlings machines, dust from flour-dust house (from stones) and flour. When thrown in a body on a light, all these substances put the light out. Blown by a bellows into the air surrounding a gas flame the following results were obtained: Coarse bran would not bum. Fine bran and flour dust bum quickly, with considerable blaze. Middlings burn quicker, but with less flame. All other substances bum very quickly, very much like gunpowder. In all these cases there was a space around the flash where the dust was not thick enough to ignite from particle to particle; hence it remained in the air after the explosion. Flonr dust, flour middlings, etc., when mixed with air, thick enough to ignite from particle to particle, and separated so that each parole is surrounded by air, will unite with the oxygen in the air, producing a gas at high temperature, which require an additional space, hence the bursting. There is no gas which comes from flour or middlings that is an explosive; it is the direct combination with the air that produces gas, requiring additional space. Powerful electric sparks from the electric machine and from the Leyden jar were passed through the air filled with dust of different kinds, but without an explosion in any case. A platinum wire kept at white heat by a galvanic battery would not produce an explosion. The dust would collect upon it and char to black coals, but would not blaze or explode. A piece of glowing charcoal, kept hot by the bellows, would not produce an explosion when surrounded by dust, but when fanned into a blaze the explosion followed. A common kerosene lantern, when surrounded by dust of all degrees of density, would not produce an explosion, but when the dust was blown into the bottom, through the globe and out of the top, it would ignite. To explode quickly the dust must be dry. Evidently when an explosion has been started iu a volume of dusty air, loose flour may be blown into the air and made a source of danger.