Nitro-Explosives: A Practical Treatise
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The Lead Oxide Method.—Two grms. of sample are mixed with about 40 grms. of pure litharge, and heated in an air bath to 130 deg. C. until the weight becomes constant, care being taken that the litharge is free from such lead compounds and other substances as might injuriously affect the results, and that the heating of the mixture takes place in an air bath free from carbonic acid. The increase in weight in the litharge, minus the weight of substance not volatilisable from 2 grms. of glycerine at 160 deg. C., multiplied by the factor 1.243, is taken as the weight of glycerine in the 2 grms. of sample. The glycerine must be fairly pure, and free from resinous substances and SO_{3}, to give good results by this process.

Analysis of the "Waste Acids" from the Manufacture of Nitro-Glycerine or Gun-Cotton. Determine the specific gravity by the specific gravity bottle or hydrometer, and the oxides of nitrogen by the permanganate method described under nitro-glycerine. Now determine the total acidity of the mixture by means of a tenth normal solution of sodium hydrate, and calculate it as nitric acid (HNO_{3}), then determine the nitric acid by means of Lunge nitrometer, and subtract percentage found from total acidity, and calculate the difference into sulphuric acid, thus:—

Total acidity equals 97.46 per cent.—11.07 per cent. HNO_{3} = 86.39 per cent., then (86.39 x 49)/63 = 67.20 per cent. H_{2}SO_{4}.

Then analysis of sample will be:—

Sulphuric acid = 67.20 per cent. Nitric acid = 11.07 " - Specific gravity = 1.7075. Water = 12.73 "

This method is accurate enough for general use in the nitric acid factory. The acid mixture may be taken by volume for determining nitric oxide in nitrometer. Two c.c. is a convenient quantity in the above case, then 2 x 1.7075 (specific gravity) = 3.414 grms. taken, gave 145 c.c. NO (barometer = 748 mm, and temperature = 15 deg.C.) equals 134.9 c.c. (corr.) and as 1 c.c. NO = .0282 grm. HNO_{3} 135 x .0282 = .378 grm. = 11.07 per cent. nitric acid.

Sodium Nitrate. Determine moisture and chlorine by the usual methods, and the total, NaNO{3}, by means of nitrometer—0.45 grm. is a very convenient quantity to work on (gives about 123 c.c. gas); grind very fine, and dissolve in a very little hot water in the cup of the nitrometer; use about 15 c.c. concentrated H{2}SO{4}. One cubic cent. of NO equals .003805 grm. of NaNO{3}. The insoluble matter, both organic and inorganic, should also be determined, also sulphate of soda and lime tested for.

Analysis of Mercury Fulminate (Divers and Kawakita's Method).—A weighed quantity of mercury fulminate is added to excess, but measured quantity of fuming hydrochloric acid contained in a retort connected with a receiver holding water. After heating for some time, the contents of the retort and receiver are mixed and diluted, and the mercury is precipitated by hydrogen sulphide. By warming and exposure to the air in open vessels the hydrogen sulphide is for the most part dissipated. The solution is then titrated with potassium hydroxide (KOH), as well as another quantity of hydrochloric acid, equal to that used with the fulminate. As the mercury chloride is reconverted into hydrochloric acid by the hydrogen sulphide, and as the hydroxylamine does not neutralise to litmus the hydrochloric acid combined with it, there is an equal amount of hydrochloric acid free or available in the two solutions. Any excess of acid in the one which has received the fulminate will therefore be due to the formic acid generated from the fulminate. Dr. Divers and M. Kawakita, working by this method, have obtained 31.31 per cent. formic acid, instead of 32.40 required by theory. (Jour. Chem. Soc., p. 17, 1884.)

Divers and Kawakita proceed thus: 2.351 grms. dissolved, as already described, in HCl, and afterwards diluted, gave mercury sulphide equal to 70.40 per cent. mercury. The same solution, after removal of mercury, titrated by iodine for hydroxylamine, gave nitrogen equal to 9.85 per cent., and when evaporated with hydroxyl ammonium chloride equal to 9.55 per cent. A solution of 2.6665 grms. fulminate in HCl of known amount, after removal of mercury by hydrogen sulphide, gave by titration with potassium hydrate, formic acid equal to 8.17 per cent. of carbon. Collecting and comparing with calculation from formula we get—

Calc. I. II. III.

Mercury 70.42 70.40 ... ... Nitrogen 9.86 9.85 9.55 ... Carbon 8.45 ... ... 8.17 Oxygen 11.27 ... ... ...

100.00

The Analysis of Cap Composition.—Messrs F.W. Jones and F.A. Willcox (Chem. News, Dec. 11, 1896) have proposed the following process for the analysis of this substance:—Cap composition usually consists of the ingredients—potassium chlorate, antimony sulphide, and mercury fulminate, and to estimate these substances in the presence of each other by ordinary analytical methods is a difficult process. Since the separation of antimony sulphide and mercury fulminate in the presence of potassium chlorate necessitates the treatment of the mixture with hydrochloric acid, and this produces an evolution of hydrogen sulphide from the sulphide, and a consequent precipitation of sulphur; and potassium chlorate cannot be separated from the other ingredients by treatment with water, owing to the appreciable solubility of mercury fulminate in cold water.

In the course of some experiments on the solubility of mercury fulminate Messrs Jones and Willcox observed that this body was readily soluble in acetone and other ethereal solvents when they were saturated with ammonia gas, and that chlorate of potash and sulphide of antimony were insoluble in pure acetone saturated with ammonia; these observations at once afforded a simple method of separating the three ingredients of cap composition. By employing this solution of acetone and ammonia an analysis can be made in a comparatively short time, and yields results of sufficient accuracy for all technical purposes. The following are the details of the process:—

A tared filter paper is placed in a funnel to the neck of which has been fitted a piece of rubber tubing provided with a clip. The paper is moistened with a solution of acetone and ammonia, the cap composition is weighed off directly on to the filter paper and is then covered with the solution of acetone and ammonia and allowed to stand thirty-four hours. It is then washed repeatedly with the same solution until the washings give no coloration with ammonium sulphide, and afterwards washed with acetone until washings give no residue on evaporation dried and weighed. The paper is again put in the funnel and washed with water until free from potassium chlorate, dried and weighed.

If _c_ = weight of composition taken, _d_ = " " filter paper, _a_ = " after first extraction, _b_ = " " second extraction, then _c+d-a_ = weight of fulminate, _c+d-a-b_ = " " KClO_{3}, _b-d_ = " " sulphide of antimony.

The composition should be finely ground in an agate mortar.

The results of the analysis by this method of two mixtures of known composition are given below—

A B Percentage Percentage Percentage Percentage Taken. Found. Taken. Found. Antimony Sulphide 36.47 36.25 37.34 37.22 Potassium Chlorate 33.25 33.71 46.03 46.43 Mercury Fulminate 30.27 30.02 16.61 16.34

The tendency of this method is to give slightly low figures for the fulminate, but since these are uniform within a negligible error, it does not affect the value of the results as a criterion of uniformity. The following test results were obtained by Dr Brownsdon:—

Fulminate Taken. Fulminate Found. Error. Grm. Grm. Grm. 0.0086 0.0083 -0.0003 0.0082 0.0081 -0.0001 0.0074 0.0071 -0.0003 0.0068 0.0066 -0.0002 Stibnite Taken. Sb{2}S{3}, Found. Error. Grm. Grm. Grm. 0.0085 0.0084 -0.0001 0.0098 0.0099 +0.0001 0.0160 0.0157 -0.0003 0.0099 0.0100 +0.0001

TABLE FOR CORRECTION OF VOLUMES OF GASES FOR TEMPERATURE, GIVING THE DIVISOR FOR THE FORMULA.

V_{1} = V x B/(760 x (1 + dt)) (d = 0.003665) 1 + dt from 0 deg. to 30 deg. C.

___________ t. 760x(1+dt). t. 760x(1+dt). t. 760x(1+dt). __ ___ __ ___ __ ___ deg.C. deg.C. deg.C. 0.0 750.000 1.7 764.7352 3.4 769.4704 .1 760.2785 .8 765.0137 .5 769.7489 .2 760.5571 .9 765.2923 .6 770.0274 .3 760.8356 2.0 765.5708 .7 770.3060 .4 761.1142 .1 765.8493 .8 770.5845 .5 761.3927 .2 766.1279 .9 770.8631 .6 761.6712 .3 766.4064 4.0 771.1416 .7 761.9498 .4 766.6850 .1 771.4201 .8 762.2283 .5 766.9635 .2 771.6987 .9 762.5069 .6 767.2420 .3 771.9772 1.0 762.7854 .7 767.5206 .4 772.2558 .1 763.0639 .8 767.7991 .5 772.5343 .2 763.3425 .9 768.0777 .6 772.8128 .3 763.6210 3.0 768.3562 .7 773.0914 .4 763.8996 .1 768.6347 .8 773.3699 .5 764.1781 .2 768.9133 .9 773.6485 .6 764.4566 .3 769.1918 5.0 773.9270 __ ___ __ ___ __ ___ ___________ t. 760x(1+dt). t. 760x(1+dt). t. 760x(1+dt). __ ___ __ ___ __ ___ deg.C. deg.C. deg.C. 5.1 774.2055 .9 787.5755 .7 800.9454 .2 774.4841 10.0 787.8540 .8 801.2239 .3 774.7626 .1 788.1325 .9 801.5025 .4 775.0412 .2 788.4111 15.0 801.7810 .5 775.3197 .3 788.6896 .1 802.0595 .6 775.5982 .4 788.9682 .2 802.3381 .7 775.8768 .5 789.2467 .3 802.6166 .8 776.1553 .6 789.5252 .4 802.8952 .9 776.4339 .7 789.8038 .5 803.1737 6.0 776.7124 .8 790.0823 .6 803.4522 .1 776.9909 .9 790.3609 .7 803.7308 .2 777.2695 11.0 790.6394 .8 804.0093 .3 777.5480 .1 790.9179 .9 804.2879 .4 777.8266 .2 791.1965 16.0 804.5664 .5 778.1051 .3 791.4750 .1 804.8449 .6 778.3836 .4 791.7536 .2 805.1235 .7 778.6622 .5 792.0321 .3 805.4020 .8 778.9407 .6 792.3106 .4 805.6806 .9 779.2193 .7 792.5892 .5 805.9591 7.0 779.4978 .8 792.8677 .6 806.2376 .1 779.7763 .9 793.1463 .7 806.5162 .2 780.0549 12.0 793.4248 .8 806.7947 .3 780.3334 .1 793.7033 .9 807.0733 .4 780.6120 .2 793.9819 17.0 807.3518 .5 780.8905 .3 794.2604 .1 807.6303 .6 781.1690 .4 794.5390 .2 807.9089 .7 781.4476 .5 794.8175 .3 808.1874 .8 781.7261 .6 795.0960 .4 808.4660 .9 782.0047 .7 795.3746 .5 808.7445 8.0 782.2832 .8 795.6531 .6 809.0230 .1 782.5617 .9 795.9317 .7 809.3016 .2 782.8403 13.0 796.2102 .8 809.5801 .3 783.1188 .1 796.4887 .9 809.8587 .4 783.3974 .2 796.7673 18.0 810.1372 .5 783.6959 .3 797.0458 .1 810.4175 .6 783.9544 .4 797.3244 .2 810.6943 .7 784.2330 .5 797.6029 .3 810.9728 .8 784.5115 .6 797.8814 .4 811.2514 .9 784.7901 .7 798.1600 .5 811.5299 9.0 785.0686 .8 798.4385 .6 811.8084 .1 785.3471 .9 798.7171 .7 812.0870 .2 785.6257 14.0 798.9956 .8 812.3655 .3 785.9042 .1 799.2741 .9 812.6441 .4 786.1828 .2 799.5527 19.0 812.9226 .5 786.4613 .3 799.8312 .1 813.2011 .6 786.7398 .4 800.1098 .2 813.4797 .7 787.0184 .5 800.3883 .3 813.7582 .8 787.2969 .6 800.6668 .4 814.0368 __ ___ __ ___ __ ___ ___________ t. 760x(1+dt). t. 760x(1+dt). t. 760x(1+dt). __ ___ __ ___ __ ___ deg.C. deg.C. deg.C. 19.5 814.3153 23.0 824.0642 .5 833.8131 .6 814.5938 .1 824.3427 .6 834.0916 .7 814.8724 .2 824.6213 .7 834.3702 .8 815.1500 .3 824.8998 .8 834.6487 .9 815.4925 .4 825.1784 .9 834.9273 20.0 815.7080 .5 825.4569 27.0 835.2058 .1 815.9865 .6 825.7354 .1 835.4843 .2 816.2651 .7 826.0140 .2 835.7629 .3 816.5436 .8 826.2925 .3 836.0414 .4 816.8222 .9 826.5711 .4 836.3200 .5 817.1007 24.0 826.8496 .5 836.5985 .6 817.3792 .1 827.1281 .6 836.8770 .7 817.6578 .2 827.4067 .7 837.1556 .8 817.9363 .3 827.6852 .8 837.4341 .9 818.2149 .4 827.9638 .9 837.7127 21.0 818.4934 .5 828.2423 28.0 837.9912 .1 818.7719 .6 828.5208 .1 838.2697 .2 819.0505 .7 828.7994 .2 838.5483 .3 819.3290 .8 829.0779 .3 838.8268 .4 819.6076 .9 829.3565 .4 839.1054 .5 819.8861 25.0 829.6350 .5 839.3839 .6 820.1646 .1 829.9135 .6 839.6624 .7 820.4432 .2 830.1921 .7 839.9410 .8 820.7217 .3 830.4706 .8 840.2195 .9 821.0003 .4 830.7492 .9 840.4981 22.0 821.2788 .5 831.0277 29.0 840.7766 .1 821.5573 .6 831.3062 .1 841.0551 .2 821.8859 .7 831.5848 .2 841.3337 .3 822.1144 .8 831.8633 .3 841.6122 .4 822.3930 .9 832.1419 .4 841.8908 .5 822.6715 26.0 832.4204 .5 842.1693 .6 822.9500 .1 832.6989 .6 842.4478 .7 823.2286 .2 832.9775 .7 842.7264 .8 823.5071 .3 833.2560 .8 843.0049 .9 823.7857 .4 833.5346 .9 843.2835 30.0 843.5620 __ ___ __ ___ __ ___

CHAPTER VIII.

FIRING POINT OF EXPLOSIVES, HEAT TESTS, &c.

Horsley's Apparatus—Table of Firing points—The Government Heat-Test Apparatus for Dynamites—Nitro-Glycerine, Nitro-Cotton, and Smokeless Powders—Liquefaction and Exudation Tests—Page's Regulator for Heat-Test Apparatus—Specific Gravities of Explosives—Table of Temperature of Detonation, Sensitiveness, &c.

The Firing Point of Explosives.—The firing point of an explosive may be determined as follows:—A copper dish, about 3 inches deep, and 6 or more wide, and fitted with a lid, also of copper, is required. The lid contains several small holes, into each of which is soldered a thick copper tube about 5 mm. in diameter, and 3 inches long, with a rather larger one in the centre in which to place a thermometer. The dish is filled with Rose's metal, or paraffin, according to the probable temperature required. The firing point is then taken thus:—After putting a little piece of asbestos felt at the bottom of the centre tube, the thermometer is inserted, and a small quantity of the explosive to be tested is placed in the other holes; the lid is then placed on the dish containing the melted paraffin or metal, in such a way that the copper tubes dip below the surface of the liquid; the temperature of the bath is now raised until the explosive fires, and the temperature noted. The initial temperature should also be noted.

THE FIRING POINT OF VARIOUS EXPLOSIVES (by C. E. Munroe). (Horsley's Apparatus used.)

deg.C. Nitro-glycerine, 5 years old (a single drop taken) 203-205 Gun-cotton (compressed military cotton, sp. gr. 1.5) 192-201 Air-dried gun-cotton, stored for 4 years 179-187 Ditto, stored for 1 year 187-189 Air-dried collodion-cotton, long staple "Red Island cotton," 3 years old 186-191 Air-dried collodion, 3 years old, stored wet 197-199 Hydro-nitro-cellulose 201-213 Kieselguhr dynamite, No. 1 197-200 Explosive gelatine 203-209 Mercury fulminate 175-181 Gunpowder (shell) 278-287 Hill's picric powder (shells) Been in store 10 years. 273-283 Ditto (musket) Composed of 282-290 Ammonium picrate 42.18 % Potassium picrate 53.79 " Charcoal (alder) 3.85 " 99.82 Forcite, No. 1 187-200 Atlas powder (75% NG) 175-185 Emmensite, No. 1 Sample had been stored in 167-184 magazine for some months in a wooden box. " No. 2 Stored in tin case. 165-177 " No. 5 " " 205-217 deg.C. Powder used in Chassepot rifle 191 By Leygue & Champion. French gunpowder 295 " " Rifle powder (picrate) 358 " " Cannon 380 " "

Horsley's apparatus consists of an iron stand with a ring support, holding a hemispherical iron vessel or bath in which solid paraffin is put. Above this is another movable support, from which a thermometer is suspended, and so adjusted that its bulb is immersed in the material contained in the iron vessel. A thin copper cartridge-case, 5/8 inch in diameter and 1-15/16 inch long, is suspended over the bath by means of a triangle, so that the end of the case is just 1 inch below the surface of the molten material. On beginning the experiment of determining the firing point of any explosive, the material in the bath is heated to just above the melting point; the thermometer is inserted in it, and a minute quantity of the explosive is placed in the bottom of the cartridge-case. The initial temperature is noted, and then the cartridge-case containing the explosive is inserted in the bath. The temperature is quickly raised until the contents of the cartridge-case flash off or explode, when the temperature is noted as the firing point.

Professor C.E. Munroe, of the U.S. Torpedo Station, has determined the firing point of several explosives by means of this apparatus.

The Government Heat Test (Explosives Act, 1875): Apparatus required.—A water bath, consisting of a spherical copper vessel (a), Fig. 46, of about 8 inches diameter, and with an aperture of about 5 inches; the bath is filled with water to within a quarter of an inch of the edge. It has a loose cover of sheet copper about 6 inches in diameter (b) and rests on a tripod stand about 14 inches high (c), which is covered with coarse wire gauze (e), and is surrounded with a screen of thin sheet copper (d). Within the latter is placed an argand burner (f) with glass chimney. The cover (b) has four holes arranged, as seen in Fig. II., No. 4 to contain a Page's[A] or Scheibler's regulator, No. 3 the thermometer, Nos. 1 and 2 the test tubes containing the explosive to be tested. Around the holes 1 and 2 on the under side of the cover are soldered three pieces of brass wire with points slightly converging (Fig. III.); these act as springs, and allow the test tubes to be easily placed in position and removed.

[Footnote A: See Chem. Soc. Jour., 1876, i. 24. F.J.M. Page.]

Test Tubes, from 5-1/4 to 5-1/2 inches long, and of such a diameter that they will hold from 20 to 22 cubic centimetres of water when filled to a height of 5 inches; rather thick glass is preferable. Indiarubber stoppers, fitting the test tubes, and carrying an arrangement for holding the test papers, viz., a narrow glass tube passing through the centre of the stopper, and terminating in a platinum wire hook. A glass rod drawn out and the end turned up to form a hook is better.

The Thermometer should have a range from 30 deg. to 212 deg. F., or from 1 deg. to 100 deg. C. A minute clock is useful.

Test Paper.—The test paper is prepared as follows:—45 grains (2.9 grms.) of white maize starch (corn flour), previously washed with cold water, are added to 8-1/2 oz. of water. The mixture is stirred, heated to boiling, and kept gently boiling for ten minutes; 15 grains (1 grm.) of pure potassium iodide (previously recrystallised from alcohol, absolutely necessary) are dissolved in 8-1/2 oz. of distilled water. The two solutions are thoroughly mixed and allowed to get cold. Strips or sheets of white English filter paper, previously washed with water and re-dried, are dipped into the solution thus prepared, and allowed to remain in it for not less than ten seconds; they are then allowed to drain and dry in a place free from laboratory fumes and dust. The upper and lower margins of the strips or sheets are cut off, and the paper is preserved in well- stoppered or corked bottles, and in the dark. The dimensions of the pieces of test paper used are about 4/10 inch by 8/10 inch (10 mm. by 20 mm.).[A]

[Footnote A: When the paper is freshly prepared, and as long as it remains in good condition, a drop of diluted acetic acid put on the paper with a glass rod produces no coloration. In process of time it will become brownish, when treated with the acid, especially if it has been exposed to sunlight. It is then not fit for use.]

In Germany zinc-iodide starch paper is used, which is considered to be more sensitive than potassium iodide.

Standard Tint Paper.—A solution of caramel in water is made of such concentration that when diluted one hundred times (10 c.c. made up to 1 litre) the tint of this diluted solution equals the tint produced by the Nessler test in 100 c.c. water containing .000075 grm. of ammonia, or .00023505 grm. AmCl. With this caramel solution lines are drawn on strips of white filter paper (previously well washed with distilled water, to remove traces of bleaching matter, and dried) by means of a quill pen. When the marks thus produced are dry, the paper is cut into pieces of the same size as the test paper previously described, in such a way that each piece has a brown line across it near the middle of its length, and only such strips are preserved in which the brown line has a breadth varying from 12 mm. to 1 mm. (1/50 of an inch to 1/25 of an inch).

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.

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.

The heat test is performed as before, except that the temperature of the bath is kept at 170 deg. F. (66 deg. C.), and regulator set to maintain that temperature. Twenty grains (1.296 grm.) are used, placed in the test tube, gently pressed down until it occupies a space of as nearly as possible 1-5/10 inch in the test tube of dimensions previously specified. The fine cotton adhering to the sides of the tube can be removed by a clean cloth or silk handkerchief. The paper is moistened by touching the upper edge with a drop of the 50 per cent. glycerine solution, the tube inserted in the bath to a depth of 2-1/2 inches, measured from the cover, the regulator and thermometer being inserted to the same depth. The test paper is to be kept near the top of the test tube, but clear of the cork, until the tube has been immersed for about five minutes. A ring of moisture will about this time be deposited upon the sides of the test tube, a little above the cover of the bath. The glass rod must then be lowered until the lower margin of the moistened part of the paper is on a level with the bottom of the ring of moisture in the tube. The paper is now closely watched, The test is complete when a very faint brown coloration makes its appearance at the line of boundary between the dry and moist parts of the paper. It must stand the test for not less than ten minutes at 170 deg. F. (The time is reckoned from the first insertion of the tube in the bath until the appearance of a discoloration of the test paper.)

B. Schultze Powder, E.C. Powder, Collodion-Cotton, &c.—The sample is dried in the oven as above for fifteen minutes, and exposed for two hours to the air. The test as above for compressed gun-cotton is then applied.

C. Cordite must stand a temperature of 180 deg. F. for fifteen minutes. The sample is prepared as follows:—Pieces half an inch long are cut from one end of every stick selected for the test: in the case of the thicker cordites, each piece so cut is further subdivided into about four portions. These cut pieces are then passed once through the mill, the first portion of material which passes through being rejected on account of the possible presence of foreign matter from the mill. The ground material is put on the top sieve of the nest of sieves, and sifted. That portion which has passed through the top sieve and been stopped by the second is taken for the test. If the mill is properly set, the greater portion of the ground material will be of the proper size. If the volatile matter in the explosive exceeds 0.5 per cent., the sifted material should be dried at a temperature not exceeding 140 deg. F, until the proportion does not exceed 0.5 per cent. After each sample has been ground, the mill must be taken to pieces and carefully cleaned. The sieves used consist of a nest of two sieves with holes drilled in sheet copper. The holes in the top sieve have a diameter = 14 B.W.G., those in the second = 21 B.W.G.

If too hard for the mill, the cordite may be softened by exposure to the vapour of acetone,[A] or reduced, to the necessary degree of subdivision by means of a sharp moderately-coarse rasp. Should it have become too soft in the acetone vapour for the mill, it should be cut up into small pieces, which may be brought to any desired degree of hardness by simple exposure to air. Explosives which consist partly of gelatinised collodion-cotton, and partly of ungelatinised gun-cotton, are best reduced to powder by a rasp, or softened by exposure to mixed ether and alcohol vapour at a temperature of 40 deg. F. to 100 deg. F.

[Footnote A: Mr W. Cullen (Jour. Soc. Chem. Ind., Jan. 31, 1901) says:— "Undoubtedly the advent of the horny smokeless powders of modern times has made it a little difficult to give the test the same scope as it had when first introduced." As a rule a simple explanation can be found for every apparently abnormal result, and in the accidental retention of a portion of the solvent used in the manufacture, will frequently be found an explanation of the trouble experienced.]

Ballistite.—In the case of ballistite the treatment is the same, except that when it is in a very finely granulated condition it need not be cut up.

Guttmann's Heat Test.—This test was proposed by Mr Oscar Guttmann in a paper read before the Society of Chemical Industry (vol. xvi., 1897), in the place of the potassium iodide starch paper used in the Abel test. The filter paper used is wetted with a solution of diphenylamine[A] in sulphuric acid. The solution is prepared as follows:—Take 0.100 grm. of diphenylamine crystals, put them in a wide-necked flask with a ground stopper, add 50 c.c. of dilute sulphuric acid (10 c.c. of concentrated sulphuric acid to 40 c.c. of water), and put the flask in a water bath at between 50 deg. and 55 deg. C. At this temperature the diphenylamine will melt, and at once dissolve in the sulphuric acid, when the flask should be taken out, well shaken, and allowed to cool. After cooling, add 50 c.c. of Price's double distilled glycerine, shake well, and keep the solution in a dark place. The test has to be applied in the following way:—The explosives that have to be tested are finely subdivided, gun-cotton, nitro-glycerine, dynamite, blasting gelatine, &c., in the same way as at present directed by the Home Office regulations. Smokeless powders are all to be ground in a bell-shaped coffee mill as finely as possible, and sifted as hitherto. 1.5 grm. of the explosive (from the second sieve in the case of smokeless powder) is to be weighed off and put into a test tube as hitherto used. Strips of well-washed filter paper, 25 mm. wide, are to be hung on a hooked glass rod as usual. A drop of the diphenylamine solution is taken up by means of a clean glass rod, and the upper corners of the filter paper are touched with it, so that when the two drops run together about a quarter of the filter paper is moist. This is then put into the test tube, and this again into the water bath, which has been heated to 70 deg. C. The heat test reaction should not show in a shorter time than fifteen minutes. It will begin by the moist part of the paper acquiring a greenish yellow colour, and from this moment the paper should be carefully watched. After one or two minutes a dark blue mark will suddenly appear on the dividing line between the wet and dry part of the filter paper, and this is the point that should be taken.

[Footnote A: Dr G. Spica (Rivista, Aug. 1897) proposes to use hydrochloride of meta-phenylenediamine.]

Exudation and Liquefaction Test for Blasting Gelatine, Gelatine Dynamite, &c.—A cylinder of blasting gelatine, &c., is to be cut from the cartridge to be tested, the length of the cylinder to be equal to its diameter, and the ends being cut flat. The cylinder is to be placed on end on a flat surface without any wrapper, and secured by a pin passing vertically through its centre. In this condition the cylinder is to be exposed for 144 consecutive hours (six days and nights) to a temperature ranging from 85 deg. to 90 deg. F. (inclusive), and during such exposure the cylinder shall not diminish in height by more than one-fourth of its original height, and the upper cut surface shall retain its flatness and the sharpness of its edge.

Exudation Test.—There shall be no separation from the general mass of the blasting gelatine or gelatine dynamite of a substance of less consistency than the bulk of the remaining portion of the material under any conditions of storage, transport, or use, or when the material is subjected three times in succession to alternate freezing and thawing, or when subjected to the liquefaction test before described.

Picric Acid.—The material shall contain not more than 0.3 part of mineral or non-combustible matter in 100 parts by weight of the material dried at 160 deg. F. It should not contain more than a minute trace of lead. One hundred parts of the dry material shall not contain more than 0.3 part of total (free and combined) sulphuric acid, of which not more than 0.1 part shall be free sulphuric acid. Its melting point should be between 248 deg. and 253 deg. F.

Ammonite, Bellite, Roburite, and Explosives of similar Composition.— These are required to stand the same heat test as compressed nitro-cellulose, gun-cotton, &c.

Chlorate Mixtures.—The material must not be too sensitive, and must show no tendency to increase in sensitiveness in keeping. It must contain nothing liable to reduce the chlorate. Chlorides calculated as potassium chloride must not exceed 0.25 per cent. The material must contain no free acid, or substance liable to produce free acid. Explosives of this class containing nitro-compounds will be subject to the heat test.

Page's Regulator.—The most convenient gas regulator to use in connection with the heat-test apparatus is the one invented by Prof. F.J.M. Page, B.Sc.[A] (Fig. 49). It is not affected by variations of the barometric pressure, and is simple and easy to fit up. It consists of a thermometer with an elongated glass bulb 5/8 inch diameter and 3 inches long. The stem of the thermometer is 5 inches long and 1/8 inch to 3/16 inch internal diameter. One and a half inch from the top of the stem is fused in at right angles a piece of glass tube, 1 inch long, of the same diameter as the stem, so as to form a T. A piece of glass tube (A), about 7/16 inch external diameter and 1-1/2 inch long, is fitted at one end with a short, sound cork (C, Fig. 50). Through the centre of this cork a hole is bored, so that the stem of the thermometer just fits into it. The other end of this glass tube is closed by a tightly fitting cork, preferably of indiarubber (I), which is pierced by a fine bradawl through the centre. Into the hole thus made is forced a piece of fine glass tube (B) 3 inches long, and small enough to fit loosely inside the stem of the thermometer.

[Footnote A: Chemical Soc. Jour., 1876, i. 24.]

The thermometer is filled by pouring in mercury through a small funnel until the level of the mercury (when the thermometer is at the desired temperature) is about 1-1/2 inch below the T. The piece of glass tube A, closed at its upper extremity by the cork I, through which the fine glass tube B passes into the stem of the thermometer, is now filled by means of the perforated cork at its lower extremity on the stem of the thermometer. The gas supply tube is attached to the top of the tube A, the burner to the T, so that the gas passes in at the top, down the fine tube B, rises in the space between B and the inside wall of the stem of the thermometer, and escapes by the T. The regulator is set for any given temperature by pushing the cork C, and consequently the tubes A and B, which are firmly attached to it, up or down the stem of the thermometer, until the regulator just cuts off the gas at the desired temperature.

As soon as the temperature falls, the mercury contracts, and thus opens the end of the tube B. The gas is thus turned on, and the temperature rises until the regulator again cuts off the gas. In order to prevent the possible extinction of the flame by the regulator, the brass tube which carries the gas to the regulator is connected with the tube which brings the gas from the regulator to the burner by a small brass tap (Fig. 2). This tap forms an adjustable bye-pass, and thus a small flame can be kept burning, even though the regulator be completely shut off. It is obvious that the quantity of gas supplied through the bye-pass must always be less than that required to maintain the desired temperature. This regulator, placed in a beaker of water on a tripod, will maintain the temperature of the water during four or five hours within 0.2 deg. C., and an air bath during six weeks within 0.5 deg. C.

To sum up briefly the method of using the regulator:—Being filled with mercury to about 12 inch below the T, attach the gas supply as in diagram (Fig. 2), the brass tap being open, and the tube B unclosed by the mercury. Allow the gas to completely expel the air in the apparatus. Push down the tube A so that the end of B is well under the surface of the mercury. Turn off the tap of the bye-pass until the smallest bead of flame is visible. Raise A and B, and allow the temperature to rise until the desired point is attained. Then push the tubes A and B slowly down until the flame is just shut off. The regulator will then keep the temperature at that point.

Will's Test for Nitro-Cellulose.—The principle of Dr W. Will's test[A] may be briefly described as follows:—The regularity with which nitro- cellulose decomposes under conditions admitting of the removal of the products of decomposition immediately following their formation is a measure of its stability. As decomposing agent a sufficiently high temperature (135 deg. C.) is employed, the explosive being kept in a constantly changing atmosphere of carbon dioxide, heated to the same temperature: the oxides of nitrogen which result are swept over red-hot copper, and are then reduced to nitrogen, and finally, the rates of evolution of nitrogen are measured and compared. Dr Will considers that the best definition and test of a stable nitro-cellulose is that it should give off at a high temperature equal quantities of nitrogen in equal times. For the purposes of manufacture, it is specially important that the material should be purified to its limit, i.e., the point at which further washing produces no further change in its speed of decomposition measured in the manner described.

[Footnote A: W. Will, Mitt. a. d. Centrallstelle f. Wissench. Techn. Untersuchungen Nuo-Babelsberg Berlin, 1902 [2], 5-24.]

The sample of gun-cotton (2.5 grms.) is packed into the decomposition tube 15 mm. wide and 10 cm. high, and heated by an oil bath to a constant temperature, the oxides so produced are forced over ignited copper, where they are reduced, and the nitrogen retained in the measuring tubes. Care must be taken that the acid decomposition products do not condense in any portion of the apparatus. The air in the whole apparatus is first displaced by a stream of carbon dioxide issuing from a carbon dioxide generator, or gas-holder, and passing through scrubbers, and this stream of gas is maintained throughout the whole of the experiment, the gas being absorbed at the end of the system by strong solution of caustic potash. To guard against the danger of explosions, which occasionally occur, the decomposition tube and oil bath are surrounded by a large casing with walls composed of iron plate and strong glass.

Dr Will's apparatus has been modified by Dr Robertson,[A] of the Royal Gunpowder Factory, Waltham Abbey. The form of the apparatus used by him is shown in Fig. 51.

CO_{2} Holders.—Although objection has been taken to the use of compressed CO_{2} in steel cylinders on account of the alleged large and variable amount of air present, it has, nevertheless, been found possible to obtain this gas with as little as 0.02 per cent. of air. Frequent estimations of the air present in the CO_{2} of a cylinder show that even with the commercial article, after the bulk of the CO_{2} has been removed, the residual gas contains only a very small amount of air, which decreases in a gradual and perfectly regular manner. For example, one cylinder which gave 0.03 per cent. of air by volume, after three months' constant use gave 0.02 per cent. The advantage of using CO_{2} from this source is obvious when compared with the difficulty of evolving a stream of gas of constant composition from a Kipps or Finkener apparatus. A micrometer screw, in addition to the main valve of the CO_{2} cylinder, is useful for governing the rate of flow. A blank experiment should be made to ascertain the amount of air in the CO_{2} and the correction made in the readings afterwards.

[Footnote A: Jour. Soc. Chem. Ind., June 30, 1902, p. 819.]

Measurement of Pressure and Rate of Flow.—Great attention is paid to the measurement of the rate of flow of gas, which is arrived at by counting with a stop-watch the number of bubbles of gas per minute in a small sulphuric acid wash bottle. A mercury manometer is introduced here, and is useful for detecting a leak in the apparatus. The rate of flow that gives the most satisfactory results is 1,000 c.c. per hour. If too rapid it does not become sufficiently preheated in the glass spiral, and if too slow there is a more rapid decomposition of the nitro-cellulose by the oxides of nitrogen which are not removed.

Decomposition Tube.—This is of the form and dimensions given by Dr Will (15 mm. wide and 10 cm. high), the preheating worm being of the thinnest hydrometer stem tubing. The ground-in exit tube is kept in position by a small screw clamp with trunnion bearings.

Bath.—To permit of two experiments being carried on simultaneously, the bath is adapted for two decomposition tubes, and is on the principle of Lothar Meyer's air bath, that is, the bath proper filled with a high- flashing hydrocarbon oil, and fitted with a lid perforated with two circular holes for the spiral tubes, is surrounded by an asbestos-covered envelope, in the interior of which circulate the products of combustion of numerous small gas jets. The stirrer, agitated by a water motor, or, better still, a hot-air engine, has a series of helical blades curved to give a thorough mixing to the oil. Great uniformity and constancy of temperature are thus obtained. The bath is fitted also with a temperature regulator and thermometer.

Reduction Tube—This is of copper, and consists of two parts, the outer tube and an inner reaching to nearly the bottom of the former. Into the inner tube fits a spiral of reduced copper gauze, and into the annular space between the tubes is fitted a tightly packed reduced copper spiral. At the bottom the inlet tube dips into a layer of copper oxide asbestos, on the top of which is a layer of reduced copper asbestos. Through the indiarubber cork passes a glass tube, which leads the CO_{2} and nitrogen out of the reduction tube. As the portion of the tube containing the spirals is heated to redness, water jackets are provided on both inner and outer tubes to protect the indiarubber cork.

Nitrogen Measuring Apparatus.—The measuring tube with zigzag arrangement is used, having been found very economical in potash. It is most convenient to take readings by counterbalancing the column of potash solution and reading off the volume of gas at atmospheric pressure. For this purpose the tap immediately in front of the measuring tube is momentarily closed, this having been proved to be without ill effect on the progress of the test. In all experiments done by this test the air correction is subtracted from each reading, and the remainder brought to milligrams of nitrogen with the usual corrections. As objection has frequently been taken to the test on the ground of difficulty in interpreting the results obtained, Dr Robertson made a series of experiments for the purpose of standardising the test, and at the same time of arriving at the condition under which it could be applied in the most sensitive and efficient manner. A variety of nitro-celluloses having been tested, there were chosen as typical, of stable and unstable products, service gun-cotton on the one hand, and an experimental gun- cotton, Z, on the other. The first point brought out by these experiments was the striking uniformity of service gun-cotton, first in regard to the rectilinear nature of the curve of evolution of nitrogen, and secondly in regard to the small range within which a large number of results is included, 15 samples lying between 6.6 and 8.7 mgms. of nitrogen evolved in four hours. In the case of service gun-cotton, little difference in the rate of evolution of nitrogen evolved is obtained on altering the rate of passage of CO_{2} gas through the wide range of 500 c.c. per hour to 2,500 c.c. per hour. With Z gun-cotton (see Fig. 52), however, the case is very different. Operating at a rate of 1,000 c.c. of CO_{2} per hour, a curve of nitrogen evolution is obtained, which is bent and forms a good representation of the inherent instability of the material as proved to exist from other considerations. Operating at the rate of 1,500 c.c. per hour, as recommended by Dr Will, the evolution of nitrogen is represented by a straight line, steeper, however, than that of service gun-cotton. The rate of passage of CO_{2} was therefore chosen at 1,000 c.c. per hour, or two-thirds of the rate of Dr Will, and this rate, besides possessing the advantage claimed of rendering diagnostic the manner of nitrogen evolution in Z gun-cotton, has in other cases been useful in bringing out relationships, which the higher rate would have entirely masked.

Readings are taken thirty minutes from the time the nitro-cellulose is heated, and are taken at intervals of fifteen minutes for about four hours; fresh caustic potash is added every thirty minutes or so. It is convenient to plot the results in curves. The curves given in Fig. 53 are from gun-cotton manufacturers in England at a private factory. The rate of evolution of nitrogen is as follows:—

In 1 hour. In 2 hours. In 3 hours. In 4 hours. N. N. N. N. in milligrammes. 1.25 2.55 4.5 5.75 1.5 3.25 5.25 6.75 These results are very satisfactory, the gun-cotton was of a very good quality. Several hours are necessary to remove all the air from the apparatus. Dr Will stated fifteen minutes in his original paper, but this has not been found sufficient. It has not been satisfactorily proved that Will's test can be applied to gelatinised nitro-cellulose powders. It is convenient to plot the results in curves; the nitrogen is generally given in cubic centimetres or in milligrammes, and readings taken every fifteen minutes. The steepness of the curve is a measure of the stability of the nitro-cellulose which is being examined. The steeper the curve the more nitrogen is evolved per unit of time, and the less stable the nitro- cellulose. In the case of unstable nitro-celluloses heated under the conditions described, the separation of nitrogen is much greater at first than at a later period. If the nitro-cellulose be very unstable, explosions are produced. If the separation of nitrogen is uniform during the prolonged heating, then the nitro-cellulose may be regarded as "normal." If it be desired to determine the absolute amount of nitrogen separated from a nitro-cellulose, the following conditions must be observed:—(1.) Accurate weighing of the nitro-cellulose; (2.) Determination of the amount of air in the CO_{2}, and deduction of this from the volume of gas obtained; (3.) Reduction of the volume of the gas to the volume at 0 deg. C. and 760 mm. pressure.[A]

[Footnote A: See also Jour. Soc. Chem. Ind., Dec. 1902, pages 1545-1555, on the "Stability of Nitro-cellulose" and "Examination of Nitro- cellulose," Dr Will.]

Bergrnann and Junk[A] describe a test for nitro-cellulose that has been in use in the Prussian testing station for some years. The apparatus consists of a closed copper bath provided with a condenser and 10 countersunk tubes of 20 cm. length. By boiling amyl-alcohol in the bath, the tubes can be kept at a constant temperature of 132 deg. C. The explosive to be tested is placed in a glass tube 35 cm. long and 2 cm. wide, having a ground neck into which an absorption bulb is fitted. The whole apparatus is surrounded by a shield, in case of explosion. In carrying out the test, 2 grms. of the explosive are placed in the glass tube and well pressed down. The absorption bulb is half filled with water, and fitted into the ground neck of the glass tube, which is then placed in one of the tubes in the bath previously brought to the boiling point (132 deg. C.). The evolved oxides of nitrogen are absorbed in the water in the bulb, and at the end of two hours the tubes are removed from the bath, and on cooling, the water from the bulb flows back and wets the explosive. The contents of the tube are filtered and washed, the filtrate is oxidised with permanganate, and the nitrogen determined as nitric oxide by the Schultze-Tieman method. The authors conclude that a stable gun-cotton does not evolve more than 2.5 c.c. of nitric oxide per grm. on being heated to 132 deg. C. for two hours, and a stable collodion-cotton not more than 2 c.c. under the same conditions. The percentage of moisture in the sample to be tested should be kept as low as possible. A sample of nitro-cellulose containing 1.97% of moisture gave an evolution of 2.6 c.c. per grm., while the same sample with 3.4% moisture gave an evolution of over 50 c.c. per grm. Sodium carbonate added to an unstable nitro-cellulose diminishes the rate of decomposition, but if sodium carbonate be intimately mixed with a stable nitro-cellulose the rate of decomposition will be increased. Calcium carbonate and mercury chloride have no influence. If an unstable nitro- cellulose be extracted with alcohol a stable compound is produced. The percentage solubility of a nitro-cellulose in ether-alcohol rises on heating to 132 deg. C. A sample which before heating had a solubility of 4.7% had its solubility increased to 82.5% after six hours' heating.

[Footnote A: Jour. Soc. Chem. Ind., xxiii., Oct. 15, 1904, p. 953.]

Mr A.P. Sy (Jour. Amer. Chem. Soc., 1903) describes a new stability test for nitro-cellulose which he terms "The Elastic Limit of Powder Resistance to Heat." The test consists in heating the powder on a watch glass in an oven to a temperature of 115 deg. C., after eight hours the watch glass and powder are weighed and the process repeated daily for six days or less. He claims that the powder is tested in its natural state, all the products of decomposition are taken into account, whilst in the old tests only the acid products are shown, and in the Will test only nitrogen, that it affords an indication of the effect of small quantities of added substances or foreign matters on the stability and that it is simple, and not subject to the variations of the old tests.

Obermueller (Jour. Soc. Chem. Ind., April 15, 1905) considers Bergmann and Junk's test is too complicated and occupies too much time; he proposes to heat gun-cotton to 140 deg. C. in vacuo, and to measure continuously by means of a mercury manometer the pressure exerted by the evolved gases, the latter being maintained at constant volume; the rate at which the pressure increases is a measure of the rate of decomposition of the nitro- cellulose.

SPECIFIC GRAVITIES OF EXPLOSIVES, &C.

Nitro-glycerine 1.6 Gun-cotton (dry) 1.06 " (25 per cent. water) 1.32 Dynamite No. 1 1.62 Blasting gelatine 1.54 Gelatine dynamite 1.55 Ballistite 1.6 Forcite 1.51 Tonite 1.28 Roburite 1.40 Bellite 1.2-1.4 Carbo-dynamite 1.5 Turpin's cast picric acid 1.6 Nitro-mannite 1.6 Nitro-starch 1.5 Emmensite 1.8 Mono-nitro-benzene 1.2 Meta-di-nitro-benzene 1.575 at 18 deg. C. Ortho-di-nitro-benzene 1.590 " Para-di-nitro-benzene 1.625 " British gunpowder, E.X.E. 1.80 " " S.B.C. 1.85 Cannonite (powder) 1.60 Celluloid 1.35 Cellulose 1.45 Ammonium nitrate 1.707 Mercury fulminate 4.42

TABLE OF THE TEMPERATURE OF DETONATION.

Blasting gelatine 3220 deg. Nitro-glycerine 3170 deg. Dynamite 2940 deg. Gun-cotton 2650 deg. Tonite 2648 deg. Picric acid 2620 deg. Roburite 2100 deg. Ammonia nitrate 1130 deg.

RELATIVE SENSITIVENESS TO DETONATION (by Professor C.E. Munroe, U.S. Naval Torpedo Station).

_____________ Maximum Distance at which Detonation occurred. CM. Gun-cotton 10 Nitro-glycerine 86.5 nitro-cotton 9.5, camphor 4 per cent. Explosive gelatine 20 NH_{4}NO_{3} 5 parts, (camphorated) C_{6}H_{4}(N0_{3})_{2} 1 part. Judson powder, R.R.P. 25 Emmensite (No. 259) 30 Rack-a-rock 32 KClO_{3} 79 parts, C_{6}H_{5}(NO)_{2} 21 parts. Bellite 50 Forcite No. 1 61 Kieselguhr dynamite No. 1 64 75 per cent. nitro-gycerine. Atlas powder No. 1 74 _____ __ _____

CHAPTER IX.

DETERMINATION OF THE RELATIVE STRENGTH OF EXPLOSIVES.

Effectiveness of an Explosive—High and Low Explosives—Theoretical Efficiency—MM. Roux and Sarrau's Results—Abel and Noble's—Nobel's Ballistic Test—The Mortar, Pressure, or Crusher Gauge—Lead Cylinders— The Foot-Pounds Machine—Noble's Pressure Gauge—Lieutenant Walke's Results—Calculation of Pressure Developed by Dynamite and Gun-Cotton— Macnab's and Ristori's Results of Heat Developed by the Explosion of Various Explosives—Composition of some of the Explosives in Common Use for Blasting, &c.

The Determination of the Relative Strength of Explosives.—Explosives may be roughly divided into two divisions, viz., those which when exploded produce a shattering force, and those which produce a propulsive force. Explosives of the first class are generally known as the high explosives, and consist for the most part of nitro compounds, or mixtures of nitro compounds with other substances. Any explosive whose detonation is very rapid is a high explosive, but the term has chiefly been applied to the nitro-explosives.

The effectiveness of an explosive depends upon the volume and temperature of the gases formed, and upon the rapidity of the explosion. In the high explosives the chemical transformation is very rapid, hence they exert a crushing of shattering effect. Gunpowder, on the other hand, is a low explosive, and produces a propelling or heaving effect.

The maximum work that an explosive is capable of producing is proportionate to the amount of heat disengaged during its chemical transformation. This may be expressed in kilogrammetres by the formula 425Q, where Q is the number of units of heat evolved. The theoretical efficiency of an explosive cannot, however, be expected in practice for many reasons.

In the case of blasting rock, for instance:[A]—1. Incomplete combustion of the explosive. 2. Compression and chemical changes induced in the surrounding material operated on. 3. Energy expended in the cracking and heating of the material which is not displaced. 4. The escape of gas through the blast-hole, and the fissures caused by the explosion. The proportion of useful work has been estimated to be from 14 to 33 per cent. of the theoretical maximum potential.

[Footnote A: C.N. Hake, Government Inspector of Explosives, Victoria, Jour. Soc. Chem. Ind., 1889.]

For the purposes of comparison, manufacturers generally rely more upon the practical than the theoretical efficiency of an explosive. These, however, stand in the same relation to one another, as the following table of Messrs Roux and Sarrau will show:—

MECHANICAL EQUIVALENT OF EXPLOSIVES.

Theoretical Work Relative in Kilos. Value.

Blasting powder (62 per cent. KNO_{3}) 242,335 1.0 Dynamite (75 per cent. nitro-glycerine) 548,250 2.26 Blasting gelatine (92 per cent. nitro-glycerine) 766,813 3.16 Nitro-glycerine 794,563 3.28

Experiments made in lead cylinders give— Dynamite 1.0 Blasting gelatine 1.4 Nitro-glycerine 1.4

Sir Frederick Abel and Captain W.H. Noble, R.A., have shown that the maximum pressure exerted by gunpowder is equal to 486 foot-tons per lb. of powder, or that when 1 kilo, of the powder gases occupy the volume of 1 litre, the pressure is equal to 6,400 atmospheres; and Berthelot has calculated that every gramme of nitro-glycerine exploded gives 1,320 units of heat. MM. Roux and Sarrau, of the Depot Centrales des Poudres, Paris, by means of calorimetric determinations, have shown that the following units of heat are produced by the detonation of—

Nitro-glycerine 1,784 heat units. Gun-cotton 1,123 " Potassic picrate 840 "

which, multiplied by the mechanical equivalent per unit, gives—

Nitro-glycerine 778 metre tons per kilogramme. Gun-cotton 489 " " Picrate of potash 366 " "

Nobel's Ballistic Test.—Alfred Nobel was the first to make use of the mortar test to measure the (ballistic) power of explosives. The use of the mortar for measuring the relative power of explosives does not give very accurate results, but at the same time the information obtained is of considerable value from a practical point of view. The mortar consists of a solid cylinder of cast iron, one end of which has been bored to a depth of 9 inches, the diameter of the bore being 4 inches. At the bottom of the bore-hole is a steel disc 3 inches thick, in which another hole has been bored 3 inches by 2 inches. The mortar (Fig. 54) itself is fitted with trunnions, and firmly fixed in a very solid wooden carriage, which is securely bolted down to the ground. The shot used should weigh 28 lbs., and be turned accurately to fit the bore of the mortar. Down its centre is a hole through which the fuse is put.

The following is the method of making an experiment:—A piece of hard wood is turned in the lathe to exactly fit the hole in the steel disc at the bottom of the bore. This wooden cylinder itself contains a small cavity into which the explosive is put. Ten grms. is a very convenient quantity. Before placing in the mortar, a hole may be made in the explosive by means of a piece of glass rod of such a size that the detonator to be used will just fit into it. After placing the wooden cylinder containing the explosive in the cavity at the bottom of the bore, the shot, slightly oiled, is allowed to fall gently down on to it. A piece of fuse about a foot long, and fitted with a detonator, is now pushed through the hole in the centre of the shot until the detonator is embedded in the explosive. The fuse is now lighted, and the distance to which the shot is thrown is carefully measured. The range should be marked out with pegs into yards and fractions of yards, especially at the end opposite to the mortar. The mortar should be inclined at an angle of 45 deg.. In experimenting with this apparatus, the force and direction of the wind will be found to have considerable influence.

Mr T. Johnson made some ballistic tests. He used a steel mortar and a shot weighing 29 Ibs., and he adopted the plan of measuring the distance to which a given charge, 5 grms., would throw the shot. He obtained the following results:—

Range in Feet.

Blasting gelatine (90 per cent. nitro-glycerine and nitro-cellulose) 392 Ammonite (60 per cent. Am(NO_{3}) and 10 per cent. nitro-naphthalene) 310 Gelignite (60 per cent. nitro-gelatine and gun-cotton) 306 Roburite (AmNO_{3} and chloro-nitro-benzol) 294 No. 1 dynamite (75 per cent. nitro-gelatine) 264 Stonite (68 per cent. nitro-gelatine and 32 per cent. wood-meal) 253 Gun-cotton 234 Tonite (gun-cotton and nitrates) 223 Carbonite (25 per cent. nitro-gelatine, 40 per cent. wood-meal, and 30 per cent. nitrates) 198 Securite (KNO_{3} and nitro-benzol) 183 Gunpowder 143

Calculation of the Volume of Gas Evolved in an Explosive Reaction.—The volume of gas evolved in an explosive reaction may be calculated, but only when they are simple and stable products, such calculations being made at 0 deg. and 760 mm. Let it be required, for example, to determine the volume of gas evolved by 1 gram-molecule of nitro-glycerine. The explosive reaction of nitro-glycerine may be represented by the equation.

C_{3}H_{5}O_{3}(NO_{2})_{3} = 3CO_{2} + 2-1/2H_{2}O + 1-1/2N_{2} + 1/4O_{2} By weight 227 = 132 + 45 + 42 + 8 By volume 2 = 3 + 2-1/2 + 1-1/2 + 1/4

The weights of the several products of the above reactions are calculated by multiplying their specific gravities by the weight of 1 litre of hydrogen at 0 deg. C. and 760 mm. (0.0896 grm). Thus,

One litre of CO{2} = 22 x .0896 = 1.9712 grm. " H{2}O = 9 x " = 0.8064 " " N{2} = 14 x " = 1.2544 " " O{2} = 16 x " = 1.4336 "

The volume of permanent gases at 0 deg. and 760 mm. is constant, and assuming the gramme as the unit of mass, is found to be 22.32 litres. Thus:—

Volume of 44 of CO{2}, at 0 deg. and 760 mm. = 44/1.9712 = 22.32 litres. 18 " H{2}O " " = 18/0.8044 = 22.32 " 28 " N{2} " " = 28/1.2544 = 22.32 " 32 " O{2} " " = 32/1.4366 = 22.32 "

Therefore

132 grms. of CO{2} at 0 deg. C and 760 mm. = 22.32 x 3 = 66.96 litres. 45 " H{2}O " " = 22.32 x 2-1/2 = 55.80 " 42 " N{2} " " = 22.32 x 1-1/2 = 33.48 " 8 " O{2} " " = 22.32 x 1/4 = 5.58 "

161.82 " Therefore 1 gram-molecule or 227 grms. of nitro-glycerine when exploded, produces 161.82 litres of gas at 0 deg. C and 760 mm.

To determine the volume of gas at the temperature of explosion, we simply apply the law of Charles.[A] Thus—

V : V' :: T : T' or V' = VT'/T

in which V represents the original volume. V' " new volume. T " original temperature on the absolute scale. T' " new temperature of the same scale In the present case T' = 6001 deg..

Therefore substituting, we have

V' = 161.82x6001/273 = 3557 litres

or at the temperature of explosion 1 gram-molecule of nitro-glycerine produces 3,557 litres of permanent gas.

[Footnote A: According to the law of Charles, the volume of any gas varies directly as its temperature on the absolute scale, provided the pressure remains constant. Knowing the temperature on the centigrade scale, the corresponding temperature on the absolute scale is obtained by adding 273 to the degrees centigrade.]

Pressure or Crusher Gauge.—There are many forms of this instrument. As long ago as 1792 Count Rumford used a pressure gauge. The so-called crusher gauge was, however, first used by Captain Sir Andrew Noble in his researches on powder. Other forms are the Rodman[A] punch Uchatius Eprouvette, and the crusher gauge of the English Commission on Explosives. They are all based either upon the size of an indent made upon a copper disc by a steel punch fitted to a piston, acted upon by the gases of the explosive, or upon the crushing or flattening of copper or lead cylinders.

[Footnote A: Invented by General Rodman, United States Engineers.]

Berthelot uses a cylinder of copper, as also did the English Commission, but in the simpler form of apparatus mostly used by manufacturers lead cylinders are used. This form of apparatus (Fig. 55) consists of a base of iron to which four uprights a are fixed, set round the circumference of a 4-inch circle; the lead plug rests upon the steel base let into the solid iron block. A ring c holds the uprights d together at the top. The piston b, which rests upon the lead plug, is a cylinder of tempered steel 4 inches in diameter and 5 inches in length; it is turned away at the sides to lighten it as much as possible. It should move freely between the uprights d. In the top of this cylinder is a cavity to hold the charge of explosive. The weight of this piston is 12-1/4 lbs. The shot e is of tempered steel, and 4 inches in diameter and 10 inches in length, and weighs 34-1/2 lbs. It is bored through its axis to receive a capped fuse.

The instrument is used in the following manner:—A plug of lead 1 inch long and 1 inch in diameter, and of a cylindrical form, is placed upon the steel plate between the uprights a, the piston placed upon it, the carefully weighed explosive placed in the cavity, and the shot lowered gently upon the piston. A piece of fuse, with a detonator fixed at one end, is then pushed through the hole in the shot until it reaches the explosive contained in the cavity in the piston. The fuse is lighted. When the charge is exploded, the shot is thrown out, and the lead cylinder is more or less compressed. The lead plugs must be of a uniform density and homogeneous structure, and should be cut from lead rods that have been drawn, and not cast separately from small masses of metal.

The strength of the explosive is proportional to the work performed in reducing the height of the lead (or copper) plug, and to get an expression for the work done it is necessary to find the number of foot-pounds (or kilogrammetres) required to produce the different amounts of compression. This is done by submitting exactly similar cylinders of lead to a crushing under weights acting without initial velocity, and measuring the reduced heights of the cylinders; from these results a table is constructed establishing empirical relations between the reduced heights and the corresponding weights; the cylinders are measured both before and after insertion in the pressure gauge by means of an instrument known as the micrometer calipers (Fig. 57).[A]

[Footnote A: An instrument called a "Foot-pounds Machine" has been invented by Lieut. Quinan, U.S. Army. It consists of three boards, connected so as to form a slide 16 feet high, in which a weight (the shot of the pressure gauge) can fall freely. One of the boards is graduated into feet and half feet. The horizontal board at the bottom, upon which the others are nailed, rests upon a heavy post set deep in the ground, upon which is placed the piston of the gauge, which in this case serves as an anvil on which to place the lead cylinders. The shot is raised by means of a pulley, fixed at the top of the structure, to any desired height, and let go by releasing the clutch that holds it. The difference between the original length and the reduced length gives the compression caused by the blow of the shot in falling, and gives the value in foot-pounds required to produce the different amounts of compression. (Vide Jour. U.S. Naval Inst., 1892.)]

The Use of Lead Cylinders.—The method of using lead cylinders to test the strength of an explosive is a very simple affair, and is conducted as follows:—A solid cast lead cylinder, of any convenient size, is bored down the centre for some inches, generally until the bore-hole reaches to about the centre of the block. The volume of this hole is then accurately measured by pouring water into it from a graduated measure, and its capacity in cubic centimetres noted. The bore-hole is then emptied and dried, and a weighed quantity (say 10 grms.) of the explosive pressed well down to the bottom of the hole. A hole is then made in the explosive (if dynamite) with a piece of clean and rounded glass rod, large enough to take the detonator. A piece of fuse, fitted with a detonator, is then inserted into the explosive and lighted. After the explosion a large pear- shaped cavity will be found to have been formed, the volume of which is then measured in the same way as before.

The results thus obtained are only relative, but are of considerable value for comparing dynamites among themselves (or gun-cottons). Experiments in lead cylinders gave the relative values for nitro-glycerine 1.4, blasting gelatine 1.4, and dynamite 1.0. (Fig. 58 shows sections of lead cylinders before and after use.)

Standard regulations for the preparation of lead cylinders may be found in the Chem. Zeit., 1903, 27 [74], 898. They were drawn up by the Fifth International Congress of App. Chem., Berlin. The cylinder of lead should be 200 mm. in height and 200 mm. in diameter. In its axis is a bore-hole, 125 mm. deep and 25 mm. in diameter. The lead used must be pure and soft, and the cylinder used in a series of tests must be cast from the same melt. The temperature of the cylinders should be 15 deg. to 20 deg. throughout. Ten grms. of explosive should be used and wrapped in tin-foil. A detonator with a charge of 2 grms., to be fired electrically, is placed in the midst of the explosive. The cartridge is placed in the bore-hole, and gently pressed against the bottom, the firing wires being kept in central position. The bore-hole is then filled with dry quartz sand, which must pass through a sieve of 144 meshes to the sq. cm., the wires being .35 mm. diameter. The sand is filled in evenly, any excess being levelled off. The charge thus prepared is then fired electrically. The lead cylinder is then inverted, and any residues removed with a brush. The number of c.c. of water required to fill the cavity, in excess of the original volume of the bore-hole, is a measure of the strength of the explosive. The results are only comparable if made with the same class of explosive. A result is to be the mean of at least three experiments. The accuracy of the method depends on (a) the uniform temperature of the lead cylinder (15 deg. to 20 deg. C. 7); (b) on the uniformity of the quartz sand; (c) on the uniformity of the measurements.

Noble's Pressure Gauge.—The original explosive vessels used by Captain Sir A. Noble in his first experiments were practically exactly similar to those that he now employs, which consists of a steel barrel A (Fig. 59), open at both ends, which are closed by carefully fitted screw plugs, furnished with steel gas checks to prevent any escape past the screw. The action of the gas checks is exactly the same as the leathers used in hydraulic presses. The pressure of the gas acting on both sides of the annular space presses these sides firmly against the cylinder and against the plug, and so effectually prevents any escape. In the firing plug F is a conical hole closed by a cone fitting with great exactness, which, when the vessel is prepared for firing, is covered with fine tissue paper to act as an insulator. The two firing wires GG, one in the insulated cone, the other in the firing plug, are connected by a very fine platinum wire passing through a glass tube filled with meal powder. The wire becomes red-hot when connection is made with a Leclanche battery, and the charge which has previously been inserted into the vessel is fired. The crusher plug is fitted with a crusher gauge H for determining the pressure of the gases at the moment of explosion, and in addition there is frequently a second crusher gauge apparatus screwed into the cylinder. When it is desired to allow the gases to escape for examination, the screw J is slightly withdrawn. The gases then pass into the passage I, and can be led to suitable apparatus in which their volume can be measured, or in which they can be sealed for subsequent chemical analysis.

The greatest care must be exercised in carrying out experiments with this apparatus; it is particularly necessary to be sure that all the joints are perfectly tight before exploding the charge. Should this not be the case, the gases upon their generation will cut their way out, or completely blow out the part improperly secured, in either case destroying the apparatus. The effect produced upon the apparatus when the gas has escaped by cutting a passage for itself is very curious. The surface of the metal where the escape occurred presents the appearance of having been washed away in a state of fusion by the rush of the highly heated products.

The Pressure Gauge.—The pressure is found by the use of a little instrument known as the pressure gauge which consists of a small chamber formed of steel, inside of which is a copper cylinder, and the entrance being closed by a screw gland, in which a piston, having a definite sectional area, works. There is a gas check E (Fig. 60) placed in the gland, and over the piston, which prevents the admission of gas to the chamber. When it is desired to find the pressure in the chamber of a gun, one or more of these crushers are made up with or inserted at the extreme rear end of the cartridge, in order to avoid their being blown out of the gun when fired. This, however, often takes place, in which case the gauges are usually found a few yards in front of the muzzle. The copper cylinders which register the pressure are made 0.5 inch long from specially selected copper, the diameters being regulated to give a sectional area of either 1/12 or 1/24 square inch.

Hollow copper cylinders are manufactured with reduced sectional areas for measuring very small pressures. It has been found that these copper cylinders are compressed to definite lengths for certain pressures with remarkable uniformity. Thus a copper cylinder having a sectional area of 1/12 square inch, and originally 1/2 inch long, is crushed to a length of 0.42 inch by a pressure of 10 tons per square inch. By subsequently applying a pressure of 12 tons per square inch the cylinder is reduced to a length of 0.393 inch. Before using the cylinders, whether for experimenting with closed vessels or with guns, it is advisable to first crush them by a pressure a little under that expected in the experiment. Captain Sir A. Noble used in his experiments a modification of Rodman's gauge. (Ordnance Dept., U.S.A., 1861.)

By Calculation.—To calculate the pressure developed by the explosion of dynamite in a bore-hole 3 centimetres in diameter, charged with 1 kilogramme of 75 per cent. dynamite, Messrs Vieille and Sarrau employ the following formula:—

P = V_{o}(1 + Q/273._c_)/(V - _v_).

Where V_{o} = the volume (reduced to 0 deg. and 760 mm.) of the gases produced by a unit of weight of the explosive; Q the number of calories disengaged by a unit of weight of the explosive; _c_ equals the specific heat at constant volume of the gases; V the volume in cubic centimetres of a unit of weight of the explosive; _v_ the volume occupied by the inert materials of the explosive. The volume of gas produced by the explosion of 1 kilogramme of nitro-glycerine (at 0 deg. and 760 mm.) is 467 litres.

V_{o} will therefore equal 0.75 x 467 = 350.25.

The specific heat c is, according to Sarrau, .220 (c); and according to Bunsen, 1 kilogramme of dynamite No. 1 disengages 1,290 (Q) calories. The density of dynamite is equal to 1.5, therefore

V = 1/1.5 = .666.

If we take the volume of the kieselguhr as .1, we find from above formula that

P = 350(1 + 1290/(273 x .222))/(.600 - .1) = 13,900 atmospheres,

which is equal to 14,317 kilogrammes per square centimetre. The pressure developed by 1 kilogramme of pure nitro-glycerine equals 18,533 atmospheres, equals 19,151 kilogrammes. Applying this formula to gun- cotton, and taking after Berthelot, Q = 1075, and after Vieille and Sarrau, V_{o} = 671 litres, and _c_ as .2314, and the density of the nitro-cellulose as 1.5, we have (V = O)

P = 671(1 + 1075/(273 x .2314))/.666 = 18,135 atmospheres.

To convert this into pressure of kilogrammes per square centimetre, it is necessary to multiply it by the weight of a column of mercury 0.760 m. high, and 1 square centimetre in section, which is equal to increasing it by 1/30. It thus becomes

P^{k} = (1 + 1/30).

P^{k} = 18,135 x 1.033 = 18,733 kilogrammes.

The following tables, taken from Messrs William Macnab's and E. Ristori's paper (Proc. Roy. Soc., 56, 8-19), "Researches on Modern Explosives," are very interesting. They record the results of a large number of experiments made to determine the amount of heat evolved, and the quantity and composition of the gases produced when certain explosives and various smokeless powders were fired in a closed vessel from which the air had been previously exhausted. The explosions were carried out in a "calorimetric bomb" of Berthelot's pattern.[A]

[Footnote A: For description of "bomb," see "Explosives and their Power," Berthelot, trans. by Hake and Macnab, p. 150. (Murray.)]

Table Showing Quantity of Heat and Volume and Analysis of Gas Developed per Gramme with Different Sporting and Military Smokeless Powders Now In Use

Name of Explosive. Calories Permanent Aqueous Total Volume per grm. Gases. Vapour. of Gas at 0 deg. and 760 mm. cc/grm cc/grm cc/grm E.C. powder, English 800 420 154 574 S.S. powder 799 584 150 734 Troisdorf, German 943 700 195 895 Rifleite, English 864 766 159 925 B.N., French 833 738 168 906 Cordite, English 1253 647 235 882 Ballistite, German 1291 591 231 822 Ballistite, Italian 1317 58l 245 826 and Spanish

The figures in column headed "Co-efficient of Potential Energy" serve as a measure of comparison of the power of the explosives, and are the products of the number of calories by the volume of gas, the last three figures being suppressed in order to simplify the results.

The amounts of water found were calculated for comparison as volumes of H_{2}O gas at 0 deg. and 760 mm.

E.C. powder consists principally of nitro-cellulose mixed with barium nitrate and a small proportion of camphor.

S.S. of nitro-lignine mixed with barium nitrate and nitro-benzene.

Troisdorf powder is gelatinised nitro-cellulose; rifleite gelatinised nitro-cellulose and nitro-benzene.

Cordite contains 58 per cent. nitro-glycerine, 37 per cent. gun-cotton, and 5 per cent. vaseline.

Ballistite (Italian) consists of equal parts nitro-cellulose and nitro- glycerine, and 1/2 per cent. of aniline. The German contains a higher percentage of nitro-cellulose.

TABLE SHOWING THE HEAT DEVELOPED BY EXPLOSIVES CONTAINING NITRO-GLYCERINE AND NITRO-CELLULOSE IN DIFFERENT PROPORTIONS.

Composition of Explosives. Calories per cent. Nitro-cellulose (N = 13.3 per cent.). Nitro-glycerine. 100 per cent. dry pulp 0 1061 100 " gelatinised 0 922 90 " 10 per cent. 1044 80 " 20 " 1159 70 " 30 " 1267 60 " 40 " 1347 50 " 50 " 1410 40 " 60 " 1467 0 " 100 " 1652 Nitro-cellulose (N=12.24 per cent.) Nitro-glycerine. 80 per cent. 20 per cent. 1062 60 " 40 " 1288 50 " 50 " 1349 40 " 60 " 1405 Nitro-cellulose (N = 13.3 per cent.). Nitro-glycerine. Vaseline. 55 per cent. 40 per cent. 5 per cent. 1134 35 " 60 " 5 " 1280

TABLE OF RESULTS OBTAINED BY LIEUT. W. WALKE., OF THE ARTILLERY, U.S.A, WITH QUINAN'S PRESSURE GAUGE.

Nitro-glycerine being taken as 100. (From U.S. Naval Inst. Jour.)

Compression Order of Name of Explosive. of Lead Strength. Inch. Explosive gelatine 0.585 106.17 Hellhoffite 0.585 106.17 Nitro-glycerine 0.551 100.00 Standard, N.G. Nobel's smokeless powder 0.509 92.38 Nitro-glycerine 0.509 92.37 Gun-cotton 0.458 83.12 U.S. naval torpedo gun-cotton Gun-cotton 0.458 83.12 Stowmarket. Nitro-glycerine 0.451 81.85 Vouges, N.G. Gun-cotton 0.448 81.31 Dynamite No. 1 0.448 81.31 Dynamite de Traul 0.437 79.31 Emmensite 0.429 77.86 Amide powder 0.385 69.87 Oxonite 0.383 69.51 Tonite 0.376 68.24 G.C. 52.5%, and Ba(NO{3}){2}, 47.5% Bellite 0.362 65.70 Rack-a-rock 0.340 61.71 Atlas powder 0.333 60.43 Ammonia dynamite 0.332 60.25 Volney's powder No. 1 0.322 58.44 Nitrated naphthalene. " No. 2 0.294 53.18 " " Melinite 0.280 50.82 Picric acid 70%, and sol. nitro-cotton 30%. Silver fulminate 0.277 50.27 Mercury 0.275 49.91 Mortar powder 0.155 28.13

Composition of some of the Explosives in Common Use.

Ordinary Dynamite.

Nitro-Glycerine 75 per cent. Kieselguhr 25 "

Amvis.

Nitrate of Ammonia 90 per cent. Chloro-di-nitro Benzene 5 " Wood Pulp 5 "

Ammonia Nitrate Powder.

Nitrate of Ammonia 80 per cent. Chlorate of Potash 5 " Nitro-Glucose 10 " Coal Tar 5 "

Celtite.

Nitro-Glycerine 56-59 parts. Nitro-Cotton 2-3.5 " KNO_{3} 17-21 " Wood Meal 8-9 " Ammonium Oxalate 11-13 " Moisture 0.5-1.5 "

Atlas Powders.

Sodium Nitrate 2.0 per cent. Nitro-Glycerine 75.0 " Wood Pulp 21.0 " Magnesium Carbonate 2.0 "

Dauline.

Nitro-Glycerine 50 per cent. Sawdust 30 " Nitrate of Potash 20 "

Vulcan Powder.

Nitro-Glycerine 30 per cent. Nitrate of Soda 52.5 " Sulphur 7.0 " Charcoal 10.5 "

Vigorite.

Nitro-Glycerine 30 per cent. Nitrate of Soda 60 " Charcoal 5 " Sawdust 5 "

Rendrock.

Nitrate of Potash 40 per cent. Nitro-Glycerine 40 " Wood Pulp 13 " Paraffin or Pitch 7 "

Ammonia Nitrate Powder.

Ammonia Nitrate 80 per cent. Potassium Chlorate 5 " Nitro-Glucose 10 " Coal Tar 5 "

Hercules Powders.

Nitro-Glycerine 75 to 40 per cent. Sugar 1 " 15.66 " Chlorate of Potash 1.05 " 3.34 " Nitrate of Potash 2.10 " 31.00 " Carbonate of Magnesia 20.85 " 10.00 "

Carbo-Dynamite.

Nitro-Glycerine 90 per cent. Charcoal 10 "

Geloxite (Permitted List).

Nitro-Glycerine 64-54 parts. Nitro-Cotton 5-4 " Nitrate of Potash 22-13 " Ammonium Oxalate 15-12 " Red Ochre 1-0 " Wood Meal 7-4 "

The Wood Meal to contain not more than 15% and not less than 5% moisture.

Giant Powder.

Nitro-Glycerine 40 per cent. Sodium Nitrate 40 " Rosin 6 " Sulphur 6 " Guhr 8 "

Dynamite de Trauzel.

Nitro-Glycerine 75 parts. Gun-Cotton 25 " Charcoal 2 "

Rhenish Dynamite.

Solution of N.G. in Naphthalene 75 per cent. Chalk, or Barium Sulphate 2 " Kieselguhr 23 "

Ammonia Dynamite.

Ammonia Nitrate 75 parts. Paraffin 4 " Charcoal 3 " Nitro-Glycerine 18 "

Blasting Gelatine.

Nitro-Glycerine 93 per cent. Nitro-Cotton 3 to 7 "

Gelatine Dynamite.

Nitro-Glycerine 71 per cent. Nitro-Cotton 6 " Wood Pulp 5 " Potassium Nitrate 18 "

Gelignite.

Nitro-Glycerine 60 to 61 per cent. Nitro-Cotton 4 " 5 " Wood Pulp 9 " 7 " Potassium Nitrate 27 "

Forcite.

Nitro-Glycerine 49 per cent. Nitro-Cotton 1.0 " Sulphur 1.5 " Tar 10.0 " Sodium Nitrate 38.0 " Wood Pulp 5 " (The N.-G., &c., varies.)

Tonite No. 1.

Gun-Cotton 52-50 per cent. Barium Nitrate 47-40 "

Tonite No. 2.

Contains Charcoal also.

Tonite No. 3.

Gun-Cotton 18 to 20 per cent. Ba(NO3)2 70 " 67 " Di-nitro-Benzol 11 " 13 " Moisture 0.5 " 1 "

Carbonite.

Nitro-Glycerine 17.76 per cent. Nitro-Benzene 1.70 " Soda 0.42 " KNO_3 34.22 " Ba(NO_3)_2 9.71 " Cellulose 1.55 " Cane Sugar 34.27 " Moisture 0.36 " __

99.99

Roburite.

Ammonium Nitrate 86 per cent. Chloro-di-nitro-Benzol 14 "

Faversham Powder.

Ammonium Nitrate 85 per cent. Di-nitro-Benzol 10 " Trench's Flame-extinguishing Compound 5 "

Favierite No. 1.

Ammonium Nitrate 88 per cent. Di-nitro-Naphthalene 12 "

Favierite No. 2.

No. 1 Powder 90 per cent. Ammon. Chloride 10 "

Bellite.

Ammonium Nitrate 5 parts. Meta-di-nitro-Benzol 1 "

Petrofacteur.

Nitro-Benzene 10 per cent. Chlorate of Potash 67 " Nitrate of Potash 20 " Sulphide of Antimony 3 "

Securite.

Mixtures of Meta-di-nitro-Benzol 26 per cent. and Nitrate of Ammonia 74 "

Rack-a-Rock.

Potassium Chlorate 79 parts. Mono-nitro-Benzene 21 "

Oxonite.

Nitric Acid (sp. gr. 1.5) 54 parts. Picric Acid 46 "

Emmensite.

Emmens Acid 5 parts. Ammonium Nitrate 5 " Picric Acid 6 "

Brugere Powder.

Ammonium Picrate 54 per cent. Nitrate of Potash 46 "

Designolle's Torpedo Powders.

Potassium Picrate 55 to 50 per cent. Nitrate of Potash 45 " 50 "

Stowite.

Nitro-Glycerine 58 to 61 parts. Nitro-Cotton 4.5 " 5 " Potassium Nitrate 18 " 20 " Wood Meal 6 " 7 " Oxalate of Ammonia 11 " 15 "

The Wood Meal shall contain not more than 15% and not less than 5% by weight of moisture. The explosive shall be used only when contained in a non-water-proofed wrapper of parchment—No. 6 detonator.

Faversham Powder.

Nitrate of Ammonium 93 to 87 Tri-nitro-Toluol 11 " 9 Moisture 1 " —

Kynite.

Nitro-Glycerine 24-26 parts. Wood-Pulp 2.5-3.5 " Starch 32.5-3.5 " Barium Nitrate 31.5-34.5 " CaCO_{3} 0-0.5 " Moisture 3.0-6.0 "

Must be put up only in water-proof parchment paper, and No. 6 electric detonator used.

Rexite.

Nitro-Glycerine 6.5-8.5 parts. Ammonium Nitrate 64-68 " Sodium Nitrate 13-16 " Tri-nitro-Tolulene 6.5-8.5 " Wood Meal 3-5 " Moisture .5-1.4 "

Must be contained in water-proof case (stout paper), water-proofed with Resin and Cerasin—No. 6 detonator.

Withnell Powder.

Ammonium Nitrate 88-92 parts. Tri-nitro-Toluene 4-6 " Flour (dried at 100 deg. C.) 4-6 " Moisture 0-15 "

Only to be used when contained in a linen paper cartridge, water-proofed with Carnuba Wax, Parrafin—No. 7 detonator used.

Phenix Powder.

Nitro-Glycerine 28-31 parts. Nitro-Cotton 0-1 " Potassium Nitrate 30-34 " Wood Meal 33-37 " Moisture 2-6 "

SMOKELESS POWDERS.

Cordite.

Nitro-Glycerine 58 per cent. +or- .75 Nitro-Cotton 37 " +or- .65 Vaseline 5 " +or- .25

Cordite, M.D.

Nitro-Glycerine 30 per cent. +or- 1 Nitro-Cotton 65 " +or- 1 Vaseline 5 " +or- .25

Analysis of— By W. Mancab and A.E. Leighton.

E.C. Powder.

Nitro-Cotton 79.0 per cent. Potassium Nitrate 4.5 " Barium Nitrate 7.5 " Camphor 4.1 " Wood Meal 3.8 " Volatile Matter 1.1 "

Walarode Powder.

Nitro-Cotton 98.6 per cent. Volatile Matter 1.4 "

Kynoch's Smokeless.

Nitro-Cotton 52.1 per cent. Di-nitro-Toluene 19.5 " Potassium Nitrate 1.4 " Barium Nitrate 22.2 " Wood Meal 2.7 " Ash 0.9 " Volatile Matter 1.2 "

Schultze.

Nitro-Lingin 62.1 per cent. Potassium Nitrate 1.8 " Barium Nitrate 26.1 " Vaseline 4.9 " Starch 3.5 " Volatile Matter 1.0 "

Imperial Schultze.

Nitro-Lignin 80.1 per cent. Barium Nitrate 10.2 " Vaseline 7.9 " Volatile Matter 1.8 "

Cannonite.

Nitro-Cotton 86.4 per cent. Barium Nitrate 5.7 " Vaseline 2.9 " Lamp Black 1.3 " Potassium Ferro-cyanide 2.4 " Volatile Matter 1.3 "

Amberite.

Nitro-Cotton 71.0 per cent. Potassium Nitrate 1.3 " Barium Nitrate 18.6 " Wood Meal 1.4 " Vaseline 5.8 "

Sporting Ballistite.

Nitro-Glycerine 37.6 per cent Nitro-Cotton 62.3 " Volatile Matter 0.1 "

The following is a complete List of the Permitted Explosives as Defined in the Schedules to the Explosives in Coal Mines Orders of the 20th December 1902, of the 24th December 1903, of the 5th September 1903, and 10th December 1903:—

Albionite. Ammonal. Ammonite. Amvis. Aphosite. Arkite. Bellite No. 1. Bellite No. 2. Bobbinite. Britonite. Cambrite. Carbonite. Clydite. Coronite. Dahmenite A. Dragonite. Electronite. Faversham Powder. Fracturite. Geloxite. Haylite No. 1. Kynite. Negro Powder. Nobel's Ardeer Powder. Nobel Carbonite. Normanite. Pit-ite. Roburite No. 3. Saxonite. Stow-ite. Thunderite. Victorite. Virite. West Falite No. 1. West Falite No. 2.

INDEX.

Abel's, Sir Frederick, method of manufacturing gun-cotton, 57.

Abel's heat test, 249.

Acid mixture for nitrating nitro-glycerine, 23.

Air pressure in nitrator, 28.

Alkalinity in nitro-cellulose, 217.

Amberite, 189.

Ammonite, 149.

Analyses of collodion-cotton, 81. gelatine dynamites, 123.

Analysis of explosives, 197. acetone, 209. blasting gelatine, 199. cap composition, 241. cordite, 206. celluloid, 230. dynamite, 197. forcite, 202. fulminate, 240. glycerine, 233. gun-cotton, 212. nitric acid, 24. picric acid, 230. tonite, 205. waste acids, 239.

Armstrong on the constitution of the fulminates, 159.

Atlas powder, 119.

Auld on acetone, 211.

Axite, 176.

Ballistite, 179.

Beater or Hollander for pulping gun-cotton, 64.

Bedson, Prof., on roburite explosion gases, 140.

Bellite, 142.

Benzene, explosives derived from, 132.

Benzene, mono-nitro- and di-nitro-benzene, 134.

Bergmann and Junk on nitro-cellulose tests, 268.

Bernthsen summary of nitro-benzenes, 133.

Blasting gelatine, 119.

Blasting charge, preparation of, 166.

B.N. powder, 190.

Boiling-point of N.G., 19.

Boutnny's nitro-glycerine process, 15.

Brown on wet gun-cotton, 56.

Brugere's powder, 195.

Bucknill's resistance coil, 13.

Calculation of volume of gas evolved in an explosive reaction, 276.

Cannonite, 189.

Cellulose, 2, 47.

Celluloid manufacture, 91. analysis, 230. cartridges, 91. uses of, 90. Field's papers on, 93. fibre for, 94. nitration of fibre, &c., 95. formula of, 57.

Champion and Pellet's method of determining nitrogen, 223.

Chenel's modification of Kjeldahl's method, 227.

Collodion-cotton, 79.

Comparative tests of black and nitro-powders, 193.

Compressing gun-cotton, 77.

Composition of waste acids from nitro-glycerine, 43.

Composition of some common explosives, 290.

Conduits for nitro-glycerine, 7.

Cooppal powder, 5, 189.

Cordite manufacture, 169. analysis, 206.

Cresilite, 158.

Cross and Bevan on nitro-jute, 107.

Crusher gauge, 284.

Cundill, Colonel, classification of dynamites, 112.

Danger area, 5.

Dangers in the manufacture of gun-cotton, 85.

Decomposition of cellulose, 54.

Definition of explosives in Order of Council (Explosives Act), 1.

Determination of N{2}O{4} in nitric acid, 24.

Determination of strength of H{2}SO{4}, 25.

Determination of relative strength of explosives, 272.

Detonators, 163.

Di-nitro-toluene, 138.

Dipping cotton in manufacture of gun-cotton, 60.

Divers and Kawakita on the fulminates, 159.

Dixon, Prof. H.B., on roburite explosions, 139.

Drying house for gun-cotton, 122.

Dynamite, efficiency of, 118. frozen dynamite, 116. gelatine dynamite, 119. properties of kieselguhr dynamite, 116. Reid & Borland's carbo-dynamite, 119. Rhenish dynamite, 119. various kinds of, 119.

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