. Annual report of the Board of Regents of the Smithsonian Institution . FiG. 1.—Smokeless Flake Powder Seen Under theMicroscope in Ordinary Light. ., -^ -:^:»:- ?.^?y V^^^^ Fig. 2.—Smokeless Flake Powder Seen Under theMicroscope in Polarized Light. PROGRESS IN EXPLOSIVES GUTTMANN. 287 powder gun; the latter are made for modern weapons. The usual bulk powders are composed of soluble nitrocotton mixed withpotassium or barium nitrate, and generally worked up in an in-corporating mill or drum. The mixture is then either sprinkled withwater in a rotating drum, so as to form grains, or extended on

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. Annual report of the Board of Regents of the Smithsonian Institution . FiG. 1.—Smokeless Flake Powder Seen Under theMicroscope in Ordinary Light. ., -^ -:^:»:- ?.^?y V^^^^ Fig. 2.—Smokeless Flake Powder Seen Under theMicroscope in Polarized Light. PROGRESS IN EXPLOSIVES GUTTMANN. 287 powder gun; the latter are made for modern weapons. The usual bulk powders are composed of soluble nitrocotton mixed withpotassium or barium nitrate, and generally worked up in an in-corporating mill or drum. The mixture is then either sprinkled withwater in a rotating drum, so as to form grains, or extended on ashaking table making short and rapid oscillations. Alternatively itmay be put into an hydraulic press and then broken into grains, thesolvent being in every case sprinkled over when the grains are alreadyformed. The condensed powders are usually made by rolling the paste into very thin sheets ( millimeter and less), which are then cutinto small flakes to obtain the requisite rapidity of combustion. Suchpowders are dried fairly quickly, and they may someti

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Keywords: ., bookauthorsmithsonianinstitutio, bookcentury1800, bookdecade1840