~Testing Dynamite, Blasting Gelatine, and Gelatine Dynamite.~--Nitro- glycerine preparations, from which the nitro-glycerine can be extracted in the manner described below, must satisfy the following test, otherwise they will not be considered as manufactured with "thoroughly purified nitro-glycerine," viz., fifteen minutes at 160 deg. F. (72 deg. C.). ~Apparatus required.~--A funnel 2 inches across (_d_), a cylindrical measure divided into grains (_e_), Fig. 47. ~Mode of Operation.~--About 300 (19.4 grms.) to 400 grains (26 grms.) of dynamite (_b_), finely divided, are placed in the funnel, which is loosely plugged by freshly ignited asbestos (_a_). The surface is smoothed by means of a flat-headed glass rod or stopper, and some clean washed and dried kieselguhr (_c_) is spread over it to the depth of about 1/8 inch. Water is then poured on from a wash bottle, and when the first portion has been soaked up more is added; this is repeated until sufficient nitro- glycerine has collected in the graduated measure (_e_). If any water should have passed through, it must be removed from the nitro-glycerine by filter paper, or the nitro-glycerine may be filtered. [Illustration: FIG. 47.--APPARATUS FOR SEPARATING THE NlTRO-GLYCERINE FROM DYNAMITE.] [Illustration: FIG. 48.--TEST TUBE ARRANGED FOR HEAT TEST.] ~Application of Test.~--The thermometer is fixed so as to be inserted through the lid of the water bath into the water, which is maintained at 160 deg. F. (72 deg. C.), to a depth of 2-3/4 inches. Fifty grains (= 3.29 grms.) of nitro-glycerine to be tested are weighed into the test tube, in such a way as not to soil the sides of the tube (use a pipette). A test paper is fixed on the hook of the glass rod, so that when inserted into the tube it will be in a vertical position. A sufficient amount of a mixture of half distilled water and half glycerine, to moisten the upper half of the paper, is now applied to the upper edge of the test paper by means of a glass rod or camel's hair pencil; the cork carrying the rod and paper is fixed into the test tube, and the position of the paper adjusted so that its lower edge is about half way down the tube; the latter is then inserted through one of the holes in the cover to such a depth that the lower margin of the moistened part of the paper is about 5/8 inch above the surface cover. The test is complete when the faint brown line, which after a time makes its appearance at the line of boundary between the dry and moist part of the paper, equals in tint the brown line of the standard tint paper.