Emmensite has been subjected to experiment by the direction of the U.S. Secretary for War, and found satisfactory. A sample of Emmensite, in the form of a coarse powder, was first tried in a pistol, and proved superior in propelling power to ordinary gunpowder. When tested against explosive gelatine, it did very good work in shattering iron plates. It is claimed for this explosive that it enjoys the distinction of being the only high explosive which may be used both for firearms and blasting. This view is supported by the trials made by the American War Office authorities, and shows Emmensite to be a useful explosive both for blasting and as a smokeless powder. Its explosive power, as tested, is 283 tons per square inch, and its specific gravity is 1.8.
Abel proposed to use picric acid for filling shells. His Picric Powder consisted of 3 parts of saltpetre, and 2 of picrate of ammonia. Victorite consists of chlorate of potash, picric acid, and olive oil, and with occasionally some charcoal. It has the form of a coarse yellowish grey powder, and leaves an oily stain on paper, and it is very sensitive to friction and percussion. The composition is as follows:—KClO_{3} = 80 parts; picric acid, 110 parts; saltpetre, 10 parts; charcoal, 5 parts. It is not manufactured in England. Tschiner's Powder is very similar to Victorite in composition, but contains resin. A list of the chief picric powders will be found in the late Colonel J.P. Cundill, R.A.'s "Dictionary of Explosives."
CHAPTER VII.
ANALYSIS OF EXPLOSIVES.
Kieselguhr Dynamite—Gelatine Compounds—Tonite—Cordite—Vaseline—
Acetone—Scheme for Analysis of Explosives—Nitro-Cotton—Solubility Test—
Non-Nitrated Cotton—Alkalinity—Ash and Inorganic Matter—Determination
of Nitrogen—Lungé, Champion and Pellet's, Schultze-Tieman, and Kjeldahl's
Methods—Celluloid—Picric Acid and Picrates—Resinous and Tarry Matters—
Sulphuric Acid and Hydrochloric Acid and Oxalic Acid—Nitric Acid—
Inorganic Impurities—General Impurities and Adulterations—Potassium
Picrate, &c.—Picrates of the Alkaloids—Analysis of Glycerine—Residue—
Silver Test—Nitration—Total Acid Equivalent—Neutrality—Free Fatty
Acids—Combined Fatty Acids—Impurities—Oleic Acid—Sodium Chloride—
Determination of Glycerine—Waste Acids—Sodium Nitrate—Mercury
Fulminate—Cap Composition—Table for Correction of Volumes of Gases, for
Temperature and Pressure
~Kieselguhr Dynamite.~—The material generally consists of 75 per cent. of nitro-glycerine and 25 per cent. of the infusorial earth kieselguhr. The analysis is very simple, and may be conducted as follows:—Weigh out about 10 grms. of the substance, and place over calcium chloride in a desiccator for some six to eight days, and then re-weigh. The loss of weight gives the moisture. This will generally be very small, probably never more than 1 per cent., and usually less.
Mr James O. Handy, in order to save time, proposes to dry dynamite in the following manner. He places 1 grm. of the material in a porcelain crucible 1 inch in diameter. The crucible is then supported at the bottom of an extra wide-mouthed bottle of about 600 c.c. capacity. Air, which has been dried by bubbling through strong sulphuric acid, is now drawn over the surface of the sample for three hours by means of an ordinary aspirator. The air should pass approximately at the rate of 10 c.c. per second. The tube by which the dry air enters the bottle extends to within 1 inch of the crucible containing the dynamite. An empty safety bottle is connected with the inlet, and another with the outlet of the wide-mouthed bottle. The first guards against the mechanical carrying over by the air current of sulphuric acid from the acid bottle into the sample, whilst the second prevents spasmodic outbursts of water from the exhaust from reaching the sample. The method also gave satisfactory results with nitro-glycerine. The dry substance may now be wrapped in filter paper, the whole weighed, and the nitro-glycerine extracted in the Soxhlet apparatus with ether. The ether should be distilled over at least twenty-four times.
I have found, however, that much quicker, and quite as accurate, results may be obtained by leaving the dynamite in contact with ether in a small Erlenmeyer flask for twenty-four hours—leaving it overnight is better— and decanting, and again allowing the substance to remain in contact with a little fresh ether for an hour, and finally filtering through a weighed filter, drying at 100° C., and weighing. This gives the weight of the kieselguhr. The nitro-glycerine must be obtained by difference, as it is quite useless to evaporate down the ethereal solution to obtain it, as it is itself volatile to a very considerable extent at the temperature of evaporation of the ether, and the result, therefore, will always be much too low. The dry guhr can, of course, be examined, either qualitatively or quantitatively, for other mineral salts, such as carbonate of soda, &c. An actual analysis of dynamite No. 1 made by the author at Hayle gave— Moisture, 0.92 per cent.; kieselguhr, 26.15 per cent.; and nitro- glycerine, 72.93 per cent., the last being obtained by difference.
~Nitro-Glycerine.~—It is sometimes desired to test an explosive substance for nitro-glycerine. If an oily liquid is oozing from the substance, soak a drop of it in filter paper. If it is nitro-glycerine it will make a greasy spot. If the paper is now placed upon an iron anvil, and struck with an iron hammer, it will explode with a sharp report, if lighted it burns with a yellowish to greenish flame, emitting a crackling sound, and placed upon an iron plate and heated from beneath, it explodes sharply.
If a few drops of nitro-glycerine are placed in a test tube, and shaken up with methyl-alcohol (previously tested with distilled water, to see that it produces no turbidity), and filtered, on the addition of distilled water, the solution will become milky, and the nitro-glycerine will separate out, and finally collect at the bottom of the tube.