Explosive and test numbers, charge 100 grammes with 1 lb. of clay stemming, average length of flame and average duration of flame, for comparison with photographs produced by 40% dynamite under like conditions.
Powder and test numbers, weight of charge, and compression produced in blocks.
15.—Calories Developed.
Number of large calories developed per kilogramme of explosive, for comparison with 1,000 grammes of 40% dynamite, which develop, on an average, 1,229 large calories.
Blasting Powder Separator.
The grains of black blasting powder are graded by a separator, similar to those used in powder mills, but of reduced size. It consists of an inclined wooden box, with slots on the sides to carry a series of screens, and a vertical conduit at the end for carrying off the grains as they are screened into separate small bins (Fig. 1, [Plate X]). At the upper end of the screens is a small 12 by 16-in. hopper, with a sliding brass apron to regulate the feed. The screens are shaken laterally by an eccentric rod operated by hand. The top of the hopper is about 6½ ft. above the floor. The box is 6 ft. 10 in. long, from tip to tip, and inclines at an angle of 9 degrees.
Fig. 1.—Separator for Grading Black Powder.