1 879*1 Explosions from Combustible Dust. 673 
high, while, as we shall see presently, less than an ounce of 
flour is being consumed. 
I have fastened over the top of the spout five thicknesses 
of newspaper : upon igniting a boxful of dust as before, the 
paper is thrown violently into the air, accompanied by a loud 
report as it bursts. 
For the last experiment I have a box of 4 cubic feet 
capacity (Fig. 4) ; five sides are ij- inches thick, the re- 
maining side J inch. Upon igniting the dust in this box, 
filled as in the other cases, the quarter-inch side bursts, and 
a stream of fire shoots out half-way across the stage. 
One lb. of carbon and 2§ lbs. of oxygen, when they com- 
bine to produce carbonic acid, will evolve heat enough, if it 
