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.

Blasting Gelatine, Gelatine Dynamite, Gelignite, &c.—­Fifty grains (= 3.29 grms.) of blasting gelatine are intimately mixed with 100 grains (= 6.5 grms.) of French chalk.  This is done by carefully working the two materials together with a wooden pestle in a wooden mortar.  The mixture is then gradually introduced into the test tube, with the aid of gentle tapping upon the table between the introduction of successive portions of the mixture into the tube, so that when the tube contains all the mixture it shall be filled to the extent of 1-3/4 inch of its height.  The test paper is then inserted as above described for nitro-glycerine.  The sample tested must stand a temperature of 160 deg.  F. for a period of ten minutes before producing a discoloration of the test paper corresponding in tint to the standard paper.

N.B.—­Non-gelatinised nitro-glycerine preparations, from which the nitro-glycerine cannot be expelled by water, are tested without any previous separation of the ingredients, the temperature being as above 160 deg.  F., and the time being seven minutes.

Gun-Cotton, Schultze Gunpowder, E.C.  Powder, &c.:  A. Compressed Gun-Cotton.—­Sufficient material to serve for two or more tests is removed from the centre of the cartridge by gentle scraping, and if necessary, further reduced by rubbing between the fingers.  The fine powder thus produced is spread out in a thin layer upon a paper tray 6 inches by 4-1/2 inches, which is then placed inside a water oven, kept as nearly as possible at 120 deg.  F. (49 deg.  C.).  The wire gauze shelves of the oven should be about 3 inches apart.  The sample is allowed to remain at rest for fifteen minutes in the oven, the door of which is left wide open.  After the lapse of fifteen minutes the tray is removed and exposed to the air of the room for two hours, the sample being at some point within that time rubbed upon the tray with the hand, in order to reduce it to a fine and uniform state of division.