Bulletin 59 T P DEPARTMENT OF THE INTERIOR BUREAU OF MINES JOSEPH A. HOLMES, DIRECTOR INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS IC-NRLF CLARENCE HALL AND SPENCER P. HOWELL WASHINGTON GOVERNMENT PRINTING OFFICE 1913 Bulletin 59 DEPARTMENT OF THE INTERIOR BUREAU OF MINES JOSEPH A. HOLMES, DIRECTOR INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS BY CLARENCE HALL AND SPENCER P. HOWELL WASHINGTON GOVERNMENT PRINTING OFFICE 1913 First edition. June, 1913. \ \ CONTENTS. Page. Introduction 5 Preliminary considerations 7 Theory of detonation 9 Detonation of high explosives 10 Electric detonators tested 11 Explosives used in the tests 12 Tests previously used to determine strength of detonators and electric detonators . 14 Tests for determining directly the strength of P. T. S. S. electric detonators. . . 18 Character of electric detonators tested 18 Squirted lead block tests 20 Cast lead block tests 21 Tests by explosion of detonating fuse (Cordeau detonant) by influence 22 Tests by depression of lead plates 24 The nail test 25 Tests for determining indirectly the strength of P. T. S. S. electric detonators. . 27 Rate-of-detonation tests 27 Tests with an explosive of class 1, subclass a 27 Tests with an explosive of class 1, subclass b 29 Tests with a 20 per cent " straight" nitroglycerin dynamite 31 Tests with a 40 per cent strength ammonia dynamite containing nitro- substitution compounds 32 Tests with a 40 per cent strength ammonia dynamite 33 Tests with a 35 per cent strength gelatin dynamite 2 years old 33 Tests with a 40 per cent strength gelatin dynamite, frozen 35 Tests with a 35 per cent strength gelatin dynamite 3 years old 35 Small lead block tests 36 Tests with a 20 per cent "straight" nitroglycerin dynamite with 6 per cent of added water 36 Tests with a 20 per cent "straight" nitroglycerin dynamite, frozen and containing less than 6 per cent of added water '. 37 Tests with a 20 per cent "straight" nitroglycerin dynamite, frozen and containing 6 per cent of added water 37 Tests with a 40 per cent strength ammonia dynamite with 6 per cent of added water 38 Tests with a 40 per cent strength gelatin dynamite, frozen 39 Explosion-by-influence tests 40 Tests with an explosive of class 1, subclass a 41 Tests with an explosive of class 4 41 Tests with a 40 per cent strength ammonia dynamite containing nitrosubstitution compounds 43 Tests with a 35 per cent strength gelatin dynamite 2 years old 43 Percentages of detonations in indirect tests of P. T. S. S. electric detonators . 44 Comparative explosive efficiency 44 Comparative explosive efficiency of P. T. S. S. electric detonators 46 Tests of four No. 6 electric detonators of different makes 46 Physical examination 47 Weight and composition of charges 47 Results of calorimeter tests 49 Squirted lead block tests 49 Cast lead block tests 50 Tests with lead plates 50 Detonators on end 50 Detonators on side '- 51 M185882 4 CONTENTS. Tests of four No. 6 electric detonators of different makes Continued. Nail tests Rate-of-detonation tests Tests with an explosive of class 1, subclass a Tests with an explosive of class 1, subclass b Tests with a 20 per cent "straight" nitroglycerin dynamite Tests with a 40 per cent strength ammonia dynamite containing nitro- substitution compounds Tests with a 35 per cent strength gelatin dynamite 2 years old Tests with a 40 per cent strength gelatin dynamite, frozen Tests with a 35 per cent strength gelatin dynamite 3 years old Small lead block tests Tests with a 20 per cent "straight'* nitroglycerin dynamite Tests with a 40 per cent strength ammonia dynamite Tests with a 40 per cent strength gelatin dynamite, frozen 57 Explosion-by-influence tests 58 Tests with an explosive of class 1, subclass a. .' 58 Tests with an explosive of class 4 58 Tests with a 40 per cent strength ammonia dynamite containing nitrosubstitution compounds 59 Tests with a 35 per cent strength gelatin dynamite 2 years old 60 Trauzl lead block tests 61 Percentages of detonations in indirect tests of four kinds of No. 6 electric detonators Comparative explosive efficiency Comparative explosive efficiency of four kinds of No. 6 electric detonators. . Relative strength of detonators and electric detonators Tests with a trinitrotoluene detonating fuse Tests with detonators distributed in charge Use of two kinds of explosives in the same drill hole Publications on mine accidents and tests of explosives ILLUSTRATIONS. PLATE I. Results of cast lead block tests of P. T. S. S. electric detonators . . . II. Scoring of lead plates by P. T. S. S. electric detonators Nos. 3, 4, 5, 6, 7, and 8 laid on end III. Scoring of lead blocks by P. T. S. S. electric detonators Nos. 3,4,5, 6, 7, and 8 laid on side IV. A, Results of nail tests of P. T. S. S. electric detonators Nos. 3,4,5, 6, 7, and 8; B, Results of nail tests of No. 6 electric detonators V. A, Results of small lead block tests of P. T. S. S. electric detonators Nos. 3, 4, 5, 6, 7, and 8; B, Results of small lead block tests of No. 6 electric detonators; C, Scoring of lead plates by four No. 6 electric detonators laid on side VI. Results of cast lead block tests of four No. 6 electric detonators VII . Scoring of lead plates by four No. 6 electric detonators placed on end . FIGURE 1. Cross-sectional view of six P. T. S. S. electric, detonators 2. Nail in position for test of electric detonator 3. Comparative explosive efficiency of six grades of P. T. S. S. electric detonators as determined by indirect tests 46 A. Cross-sectional view of four No. 6 electric detonators of different makes 47 5. Comparative explosive efficiency of four kinds of No. 6 electric detonators as established by indirect tests 64 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. By CLARENCE HALL and SPENCER P. Ho WELL. INTRODUCTION. Among the more important factors involved in the use of high explosives in blasting operations is the means employed to bring about the detonation of the charge. When flame is applied to high explo- sives many of them may burn if not confined; but all of them when burning under certain conditions of confinement may detonate. Detonation may also be effected by mechanical means, such as fric- tional impact caused by a blow or by rubbing between surfaces. By this means, however, the full effect of the explosive charge may not be developed,, so that a partial detonation, often accompanied by the burning of the explosive, results. When nitroglycerin was first used it was fired by the application of flame, but considerable difficulty was experienced in exploding it with certainty and in ob tabling uniform results. In 1864 Alfred Noble, a Swedish engineer, discovered that nitroglycerin could be surely and completely detonated by exploding in contact with it a small quantity of an initiatory explosive. Mercury fulminate was the substance then found capable of producing the best results There are many other fulminates and other substances that will produce complete detonation of commercial " high " explosives, but detonators or electric detonators containing mercury fulminate as the characteristic ingre- dient are still almost exclusively used in this country. The term " detonator" is used in the publications of the Bureau of Mines to designate what the miner calls a "blasting cap' 7 a copper capsule containing a small quantity of some detonating compound that is ignited by a fuse. The term " electric detonator" is applied to a blasting cap that is similar except for being ignited by means of a small wire which is heated to incandescence or fused by the passage of an electric current. One of the conditions prescribed by the Bureau of Mines for a per- missible explosive a is that it shall be fired by a detonator, or prefer- ably an electric detonator, having a charge equivalent to that of the standard detonator used at the Pittsburgh testing station. A further a Permissible explosives have a short, quick flame and are intended especially for use in coal mines containing inflammable gases or dusts. (See Miners' Circular 6, Bureau of Mines.) 5 6 *' : INV^&T3X\ilbNS OF DETONATORS AND ELECTRIC DETONATORS. :tK$b ^this charge shall consist by weight of 90 parts of mercury fulminate and 10 parts of potassium chlorate (or their equiv- alents). At the request of a manufacturer of permissible explosives, an inves- tigation was undertaken by the bureau to determine the relative strength of detonators and electric detonators having different com- positions. The tests of electric detonators herein reported were conducted by H. F. Braddock, junior chemist; J. W. Koster, J. E. Tiffany, junior mining engineers; and A. S. Crossfield, junior explo- sives chemist, at the Pittsburgh testing station of the bureau. Similar tests of detonators were not conducted because it was believed that the results would not show sufficient variation to warrant such tests. It is hoped that the conclusions drawn from the tests made will be of service to those using explosives by enabling them to select the grade of detonator or electric detonator that will insure the most effective results. The conclusions are given in this bulletin, which is published by the Bureau of Mines as one of a series of publications dealing with the testing of explosives and the precautions that should be taken to increase safety and efficiency in the use of explosives in mining operations. The results of the experiments described in this bulletin show that the average percentage of failures of explosives to detonate was in- creased more than 20 per cent when the lower grades of electric detonators were used instead of No. 6 electric detonators, and was increased more than 50 per cent when these lower grades were used instead of No. 8 electric detonators. It is noteworthy, however, that when sensitive explosives, such as 40 per cent strength ammonia dynamite (p. 33), were tested under conditions ideal for detonation, the same energy was developed irrespective of the electric detonator used. When tests were made with a less sensitive explosive, such as a 40 per cent strength ammonia dynamite containing nitrosubstitution compounds (p. 32), the energy developed increased with the grade of the electric detonator used. For example, the average efficiency of four different explosives was increased 10.4 per cent when a No. 6 electric detonator was used instead of a No. 4 electric detonator, and 14.9 per cent when a No. 8 electric detonator was used (see tabulation on p. 45). The results of the tests emphasize the importance of using explosives in a fresh condition, but as fresh explosives can not always be had in mining work, strong detonators should be used in order to offset any deterioration of explosives from age. The results obtained substantiate the following conclusions: (1) That for any particular manufacturer's detonators or electric deto- nators the explosive efficiency increases with their grade, and (2) that the four No. 6 electric detonators, of different makes, tested have practically the same explosive efficiency as, and each is considered equivalent to, the Pittsburgh testing station standard No. 6 electric PELIMINARY CONSIDERATIONS. 7 detonator for use with permissible explosives in coal mines when the No. 6 grade is prescribed. PRELIMINARY CONSIDERATIONS. Methods for determining the strength of detonators or electric deto- nators by mechanical effects may be classed as either direct or indi- rect. The direct method comprises those tests in which the mechan- ical effect of the detonators or electric detonators is determined. The indirect method comprises those tests in which the mechanical effect of the explosives with which the detonators or electric detonators are used is determined. The direct method offers the advantage of sim- plicity, and usually of cheapness, but may lead to grave inaccuracies unless checked by mechanical effects indirectly determined. The discussion under the heading, " Tests Previously Used to Determine the Strength of Detonators" illustrates this. The indirect method of determining the mechanical effects of ex- plosives, or the energy developed by them, approximates practical conditions and offers an accurate means for determining the relative efficiency of detonators and electric detonators in bringing about complete detonation of commercial u high" explosives. As all direct methods of testing detonators are therefore dependent on the indirect method for verification, the first experiments under- taken were to determine the relative strength of electric detonators indirectly by comparing the energy developed by different commercial explosives when fired with different grades of electric detonators. Afterwards tests were made by determining the relative strength of electric detonators by direct means, and a test was devised that, although not entirely satisfactory, gave results that approximated more closely those established by the indirect tests. Detonating explosives develop their energy in the most efficient way when fired with detonators or electric detonators that completely detonate or explode them. Obviously, if the detonation be incom- plete, a part of the potential energy of the explosive will not be released, and the loss of energy will be proportional to the percentage of the charge that did not detonate. In blasting operations an incom- plete detonation is not only a menace to safety, by reason of the pos- sible explosion of the unexploded part of the charge and of the harm- ful gaseous products resulting from the blast, but in many cases it acts like an underloaded shot and performs little, if any, useful work. If an explosive is in a fresh condition and is sensitive to detonation and no obstacles are present to hinder its detonation, then any deto- nator effective enough to cause its complete detonation will develop its full energy. In practice, however, conditions ideal for detonation rarely and perhaps never exist, because the commercial explosives are somewhat insensitive to detonation or because they may have deteriorated by 8 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. aging before use. Furthermore, crimped paper ends of the cartridges, loose material in the drill hole, air spaces between the cartridges, or cartridges of too small diameter may hinder detonation. An explosive is said to age when any physical or chemical change during storage affects its sensitiveness, its uniformity, or its stability. Such changes are usually caused by the temperature and the humidity of the air or by sunlight, and even gravity may have an important effect. If the explosive is placed in the sunlight, it may become unstable. If a cartridge of dynamite is subjected to a temperature above 90 F., gravity may cause the segregation of nitroglycerin in the lower end or side of the cartridge. If nitroglycerin explosives are subjected to temperatures alternately above and below 52 F., the nitroglycerin tends to segregate in the cartridge. These conditions affect the uniformity of the explosives. If explosives, especially those containing ammonium nitrate or other hygroscopic salts, are subjected to a moist atmosphere they tend to absorb moisture. If the temperature is less than 52 F., nitroglycerin explosives other than low-freezing ones may freeze, and low-freezing explosives will freeze at a temperature less than 35 F. Recently, there have been placed on the market nitroglycerin explosives, styled nonfreezing explosives, that are declared by the manufacturers to remain unfrozen when the temperature falls as low as F. Both moisture and freezing affect the sensitiveness of explosives. The results of preliminary tests indicated that it would be impos- sible to discriminate between commercial electric detonators by deter- mining the energy developed by explosives used with them unless the explosives were insensitive to detonation or tested under conditions which would simulate their use under actual mining conditions; con- sequently the authors, in testing electric detonators indirectly, used explosives in an insensitive condition. This was done by using those that were naturally insensitive, such as an explosive of class 1, sub- class b; by using explosives in cartridges having small diameters, such as the 20 per cent " straight" nitroglycerin dynamite in cartridges of J-inch diameter; in an aged condition, such as the 35 per cent strength gelatin dynamite two years old ; in a frozen condition, such as 40 per cent strength gelatin dynamite ; and, in the case of ammonia dynamite, by the addition of water. The apparatus used in the experimental study were the Mettegang recorder, small lead blocks, and Trauzl lead blocks. The results of the tests differentiated the electric detonators in two ways. In the first place the electric detonator either did or did not cause the deto- nation of the explosives. In tabulating such results the number of detonations is expressed as the percentage of the number of trials. Only the tests of those explosives were considered in which at least one failure to detonate occurred and in which detonation occurred in a For an explanation of classification see p. 12. THEORY OF DETONATION. 9 at least one trial. In the second place, those trials in which detona- tion occurred were used as a basis of comparing the relative explosive efficiency of the electric detonators. The results of only those tests in which each of the electric detonators of the series caused detonation were recorded. The results are expressed in percentages of explosive efficiency as compared with the Pittsburgh testing station standard No. 6 electric detonator. This electric detonator offered the advan- tage of being included in both groups tested the Pittsburgh testing station standard and the four No. 6 electric detonators. THEORY OF DETONATION. A short discussion of the theory of detonation as presented by Berthelot a is necessary in order that a better interpretation of the experiments herein reported can be made. The theory is called the u explosive-wave " theory, and it has been generally accepted because all detonation phenomena can be best explained by it. In order to analyze the propagation of an explosive wave, the wave is considered as a recurring cycle of released and transformed energy with four phases, as follows: Mechanical to calorific, calorific to chemical (the phase in which the potential energy of the explosive material is released), chemical to calorific, and calorific to mechanical. This cycle can best be readily understood by indicating how the explo- sive wave is propagated through a cylindrical file of a homogeneous explosive without the loss of enough energy to interrupt propagation. 1 . Transformation of mechanical energy to calorific energy. When an explosive detonates a part of the mechanical energy of a layer of the explosive is converted instantly into heat energy in the adjacent layer by reason of the impact of molecules. The efficiency of this conversion is low certainly less than 50 per cent as the movement of the molecules is radial and they are only partly confined by the layer of explosive in the file. The mechanical energy that is not converted into heat energy exerts pressure on the confining medium and thus becomes the vehicle through which work is accomplished. There is good reason for believing that the thickness of the layer of explosive that enters into the first phase of the cycle varies with the physical properties of the explosive material, principally with its elasticity and partly with the velocity of the molecules that are in molecular vibration. The less elastic the explosive material and the greater the velocity of the molecules the thinner the layer, and hence the more times the cycle will recur in a unit length of the explosive material. 2. Transformation of calorific energy to chemical energy. Some of the calorific energy of the layer is used to overcome the chemical stability of the explosive material, which may vary widely, and thus release the potential energy of the layer; the rest of the calorific a Berthelot, M., Explosives and their power, 1892, pp. 88-113. 10 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. energy is used to accelerate and reinforce the chemical action. The layer of explosive by this time is developing a tremendous Mnetic energy as expressed in phase 3. 3. Transformation of chemical energy to calorific energy. All com- mercial explosives develop heat on detonation. This phase is different from the others because each of those represents some kind of kinetic energy derived entirely from the preceding phase, and consequently no one of them can have more kinetic energy than the preceding phase is capable of transferring. The conversion in this phase is complete because all the potential energy released becomes kinetic energy, which is largely calorific energy. 4. Transformation of calorific energy to mechanical energy. A simple statement of this phase is that the larger volume of gases then formed from the layer of explosives is in an extremely active state of molecular vibration and that these molecules are then manifesting their energy as mechanical energy. The efficiency of conversion of calorific energy to mechanical energy is high because the conversion is very rapid and radiation and conduction losses are correspondingly small. DETONATION OF HIGH EXPLOSIVES. All methods used to initiate the explosive wave, or to detonate high explosives, involve the application of heat. If heat be applied directly by means of a flame such as is produced by a fuse, squib, or electric igniter, or by a spark or an incandescent solid, and the explosive be of the first order, or directly explosive, such as mercury fulminate or iodide of nitrogen, then detonation is sure and effective. If, however, the explosive be of the second order, or indirectly explo- sive, such as dynamite, permissible explosives, trinitrotoluene, or guncotton, then detonation, especially complete detonation, does not usually occur; hence the direct application of heat is not a sure and effective means of producing detonation. If heat, such as is produced by the physical resistance of the explo- sive to a blow or impact, be applied indirectly to high explosives, then any sufficient blow or impact will cause detonation; that is, it will initiate the four-phase energy cycle, or explosive wave. Because the impact produced by detonators is extremely quick, and their mercury-fulminate composition has a high density and releases considerable kinetic energy, the force of the impact is in- stantly converted into heat which is applied to a thin layer of the explosive material, thereby overcoming the chemical stability of that layer and initiating the explosive wave. Experience and investigation has proved this means of producing the detonation of explosives, those not too insensitive, to be both sure and effective ; hence one is not surprised to learn that detonators are universally used. As the mercury-fulminate composition of detonators is an explo- sive of the first order it may be detonated by fire, and hence fuse may ELECTRIC DETONATORS TESTED. 11 be used in connection with them. Fuse is made of a uniform out- side diameter and detonators are made of a uniform inside diameter such that the fuse fits snugly into them. In using fuse, it is cut square across and inserted into the detonator until it gently touches the fulminate mixture and then the detonator is crimped on the fuse. Similarly a detonator may be fired by means of a small platinum wire embedded into the priming composition and brought to incan- descence or fused by the passage of an electric current. (See figs. 1 and 4.) The priming composition may be simply an easily inflamed material such as loose guncotton, a match composition, an explosive of the first order such as mercury fulminate, or a mercury-fulminate composition. The priming composition is placed in the detonator directly above and in contact with the main charge. The platinum bridge is attached at each end to an insulated wire; the two wires, called the legs, pass through the plug and the filling, and are con- nected by leading wires to the source of the electric current. When a detonator is fitted with means of firing by an electric current it is called an electric detonator. Electric detonators are particularly adapted to shot firing in fiery mines, or to the simultaneous firing of several charges. They are also adapted to any purpose for which detonators may be used, and as their use offers a greater assurance of safety they are growing in favor. ELECTRIC DETONATORS TESTED. The electric detonators tested were designated as the Pittsburgh testing station standard No. 3, No. 4, No. 5, No. 6, No. 7, and No. 8, the Western Coast No. 6, the special No. 6, and the foreign No. 6. For brevity the expression Pittsburgh testing station standard is abbreviated in this paper to P. T. S. S. The P. T. S. S. No. 3 electric detonators were made at the testing station from No. 3 detonators. A cross-sectional view of one of these electric detonators is shown in figure 1. The priming charge consisted of 0.02 gram of dry, loose guncotton directly above and in contact with the compressed charge. The sulphur plug, the insulated- wire legs, and the platinum bridge were so placed that the bridge was embedded in the loose guncotton. Then the molten sulphur was poured over the plug until the cap was filled. As detonators in this country are made of a uniform inside diam- eter of 0.220 inch and electric detonators of a uniform inside diameter of 0.260 inch, the P. T. S. S. No. 3 electric detonators are smaller in diameter than all the others except the special No. 6 electric detonators which were also assembled at the Pittsburgh testing station. It was impossible to procure No. 3 electric detonators in the open market, as their manufacture has recently been discontinued. The priming charge used in the No. 3, the No. 5, and the No. 7 electric detonators consisted of loose guncotton; that in the No. 4, 12 INVESTIGATIONS OF DETONATOES AND ELECTRIC DETONATORS. the No. 6, and the No. 8 electric detonators was commercially pure mercury fulminate. The Western Coast No. 6 and the foreign No. 6 electric detonators were used as received. The special No. 6 electric detonator was made at the testing station in the same manner as the P. T. S. S. No. 3. The primer of the western coast No. 6 was loose guncotton; that of the foreign No. 6 was a mixture of picric acid and chlorate of potash. The foreign No. 6 was so called because the detonator was imported, but the priming charge, sulphur plug, and wires were assembled by a manufacturer in this country. These electric detonators are representative of all the electric detonators commercially used in the United States. The P. T. S. S. No. 4, No. 5, No. 6, No. 7, and No. 8 were used as received from the manufacturers. Because of the seemingly erratic results of tests with the P. T. S. S. No. 5 electric detonators, attention is called to the fact that they were from 3 to 3J years old when used, and that although the sulphur plug protected the fulminating com- position somewhat, they were not in first-class condition. EXPLOSIVES USED IN THE TESTS. The explosives used in the tests are enumerated below; they in- cluded certain permissible explosives and different grades of commer- cial dynamites. Explosives designated as permissible by the bureau are grouped in four classes. Class 1, ammonium-nitrate explosives, includes all explosives in which the characterisitc material is ammo- nium nitrate. The class is divided into two subclasses: Subclass a, including every ammonium-nitrate explosive that contains a sensi- tizer that is itself an explosive, and subclass 6, including every ammonium-nitrate explosive that contains a sensitizer that is not in itself an explosive. Class 2, hydrated explosives, includes all explo- sives in which salts containing water of crystallization are the char- acteristic materials. Class 3, organic-nitrate explosives, includes all explosives in which the characteristic material is an organic nitrate other than nitroglycerin. Class 4, nitroglycerin explosives, includes all explosives in which the characteristic material is nitroglycerin. The permissible explosives used in the tests were as follows: Sam- ple 1, sample 2, and sample 3 of an explosive of class 1, subclass a; sample 1 and sample 2 of an explosive of class 1, subclass 6; and an explosive of class 4. The commercial grades of dynamites used were a 20 per cent "straight" nitroglycerin dynamite; a 40 per cent strength ammonia dynamite (containing nitrosubstitution compounds); a 40 per cent strength ammonia dynamite; a 35 per cent strength gelatin dynamite (2 years old); a 35 per cent strength gelatin dynamite (3 years old); and a 40 per cent strength gelatin dynamite. a See Miners' Circular 6, Bureau of Mines, 1912, p. 16, EXPLOSIVES USED IN TESTS. 13 The results of physical examination of the above-mentioned explosives were as follows: Results of physical examination of explosives used in tests. Class and grade of explosives. 1 Diameter of car- tridge. i & a 5* M g jA 3f Cartridges re- dipped. O 1 8 1 * if Color. Consistence. Class 1, subclass a (sam- ple 1). Class 1 subclass a (sam- In. li li In. 8 g Gms. 160 174 No.. Yes 1.01 1.09 Corn do Granular and fibrous; fine; soft; dry; slightly cohesive. Do. pie 2). Class 1, subclass a (sam- ple 3). Class 1 , subclass 6 (sam- ple 1). Class 1, subclass 6 (sam- ple 2). Class 4 li H U ij 8 8 8 g 227 277 278 166 Yes. Yes. Yes. No .93 .88 .88 1.00 Mauve Corn do do Powdered; very fine; soft; dry; not cohesive. Powdered; very fine; very dry; very soft; not cohesive. Do. Granular and fibrous; soft; fine; 20 per cent "straight" i g 103 No i is do drv; slightly cohesive. Do, nitroglycerin dyna- mite. 40 per cent strength am- monia dynamite (con- taining nitrosubstitu- tion compounds). H 71 g 226 241 Yes. Yes 1.34 1 43 do Drab Fibrous; very fine; dry; soft; slightly cohesive. Granular; fine; dry; soft; slightly monia dynamite. 35 per cent strength gel- atin dynamite (2 years old). If 13 7i 71 265 339 No.. No 1.63 1 66 Corn ... do. . cohesive. Gelatinous; fine; wet; soft; mod- erately cohesive. Do. atin dynamite (3 years old). 40 per cent strength gel- atin dynamite. U 7J 295 No.. 1.60 Drab Do. Certain of the different explosives used in the tests were analyzed, with results as follows: Results of analyses of certain explosives used in tests. Kind qf explosives. L e3 A AS an ^ fe Q jd^^' ' Q.ti SoTS S || a r 1 Constituent. a i* || i- G^K | || |-of gt2 ! I- C? 8 o.j2 fi w gi g 8* ^ .s jtgj sjfj ft s a oj r 8 fla s 5 08 ^5 %*** Moisture . . 1 20 1 93 0.88 1.89 5.86 1.47 Nitroglycerin 19.54 16.28 21.60 29.03 28.10 30.70 Nitrololuene... 4.97 Nitrocellulose .88 1.17 .88 Sodium nitrate c62 09 47.14 46.04 48.62 52.20 54.27 Ammonium nitrate 18 78 18.86 Wood pulp 15.22 5.45 5.55 8.58 Wood pulp and crude fiber 2.84 2.15 Calcium carbonate 1 95 1.44 1.13 Zinc oxide .62 .88 1.07 1.02 Sulphur. . . 2 84 4.85 4.83 4.58 3.08 Starch 3 79 11.47 Vaseline .81 Paraffin 1.24 Rosin .23 Total . 100.00 100.00 100.00 100.00 100.00 100.00 Analyst, W. C. Cope. & Analyst, A. L. Hyde, c Contains 1.04 per cent sodium chloride. 14 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. TESTS PREVIOUSLY USED TO DETERMINE STRENGTH OF DETONATORS AND ELECTRIC DETONATORS. Six principal tests have been used previously to determine the strength of detonators or electric detonators. They are as follows: 1. Weight of charge. Ever since it was observed that certain ex- plosives would not always detonate with a certain weight of charge of mercury fulminate or mercury-fulminate composition and that these same explosives would always detonate if the weight of charge hi the detonator was increased, it has been customary to vary the charge in the detonators and to consider the weight of the charge to be an indication of the strength of the detonator. There are several grades of detonators, and they are designated by the charge of ful- minate composition contained in them. Bigg-Wither a arranged the following table, which was published in 1900: Weight of charge in different grades of detonators. Charge per detonator. Grams. Grains. 1 0.30 4.6 2 .40 6.2 3 .54 8.3 4 .65 10.0 5 .80 12.3 6 1.00 15.4 6* 1.25 19.2 7 1.50 23.1 8 2.00 30.9 It is to be noted that in 1900 there was no great variation in the composition of detonators. There is no indication that the rela- tion between the effectiveness of the detonator and the weight of the charge was other than directly as the first-power function. 2. Deformation or penetration of lead or iron plates. b Guttman* states: "One of the oldest and most frequently used tests for meas- uring the power of caps (used only with ordnance) consisted of ex- ploding them on a lead or iron plate resting on a hollow iron ring and estimating their strength from the deformation or the penetration of the block. For larger detonators of between one-half gram and 1 gram charge as used for borehole shots, the plate would have to be of greater thickness." 3. Radial lines on lead plates. Bigg- Wither, hi the article men- tioned above, describes in considerable detail tests made with differ- ent detonators. He used lead plates 3 mm. thick for detonators Nos. 1 to 3 and lead plates 5 mm. thick for detonators Nos. 4 to 8. o Bigg-Wither, H., Notes on detonators: Trans. Inst. Min. Eng., vol. 21, 1900, p. 442. & Munroe, C. E., Lecture on chemistry and explosives, 1888, pp. 22-23. c Guttman, Oscar, Manufacture of explosives, vol. 2, 1895, p. 369. TESTS PREVIOUSLY USED. 15 The lead plates were supported on the edges, and the detonators were placed vertically on the centers of the plates. He further states that after the tests the plates may be taken as direct pictorial records of the efficiency of the detonators but that they do not record the report of the explosion, the recording of which is essential; that the detonating effect is not shown so much by the punctures as by the fine radiating marks upon the surface of the plates; that the fine markings show that the force of the explosion smashes the copper tubing to powder, some of which often adheres to the sides of the plates, and that when there are fine radiating lines around the cen- ter there are heavier markings outside. The difference in effect is probably due to the upper part of the fulminate not being com- pletely detonated. The results of tests show that detonators may absorb moisture when stored and emphasize the importance of using a detonator of higher power than would be otherwise actually requisite. It appears, then, that this test is one that might readily be used to distinguish between good and poor or defective detonators regardless of the charge that they contain, and for this purpose the test appears to have considerable merit. However, as an indication of the rela- tive effectiveness of detonators of different grades, that is, contain- ing different weights of charge, it appears to have little value. 4. Photographs of fashes from electric detonators. De Grave a con- ceived the idea that the flash or flame of a detonator might vary with the grade of the detonator, and such was the result of tests made by him. He also showed that there was little, if any, difference whether the electric detonator was of high or low tension. The following table gives the results for low- tension detonators: Results of photographs of flashes of low-tension detonators. Grade No. Dimension of flash. Inches. 3 1.0 by 0.22 6 1.6 by .22 7 7 1.76 by .22 1.76 by .22 8 2.0 by .22 8 2.0 by .22 This test was rather unique, but from the results of tests reported it is evident that this test offers no advantage over that of the simple determination of the weight of charge contained within the detonator. 5. Ability of detonator to explode similar detonators. This test is fully stated in a circular dated September 10, 1903, issued by the chief inspector of explosives (Great Britain) to the manufacturers a Photographs of flashes of electric detonators: Trans. Inst. Min. Eng., vol. 15, 1897, p. 203. 78875 Bull. 5913 2 16 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. and importers of detonators. The detonator is there defined as "A capsule or case of such strength and construction and contain- ing one or the other of the following explosives of the fulminate class in such quantities that the explosion of one capsule or case will communicate the explosion to other capsules or cases: (1) Fulminate of mercury, (2) fulminate of mercury and chlorate of potash, (3) other compositions." It is obvious from the definition that with this test no discrimina- tion between the detonators of different grades is possible. 6. Effect on lead Hock when detonator is fired in bore hole. At the Massachusetts Institute of Technology in 1888-89, tests were con- ducted by Robert C. Williams and J. B. Seager and reported by Frederick W. Clark. 6 Tests were made of 20 explosives, triple and quintuple detona- tors (caps) being used. In order that some of the effect of the detona- tor itself might be eliminated its effect was determined in the follow- ing way: The lead block used was a frustum of a cone 5J inches high, 5 inches in diameter at the bottom, and 5 inches in diameter at the top. The axial bore was also a frustum of a cone three-fourths of an inch in diameter at the top, five-eighths of an inch in diameter at the bottom, and 2 inches deep. In casting the blocks the lead was poured when "just barely melted"; the finished block weighed about 45 pounds. The detonator was placed in the bore hole, tamped with dry quartz sand, and fired by means of fuse. As the detonators were slightly less than one-fourth of an inch in diameter the distance between the caps and the walls of the bore hole averaged three-sixteenths of an inch. A tabulation of the results of the tests follows: Results of firing detonators in bore holes of lead blocks. Grade of detonator (cap). Capacity of bore hole. Difference. Average. Before firing detonator. After firing detonator. "Eagle" Do.. Do triples C.c. 14.3 14.3 14.3 14.3 14.3 C.c. 17.0 16.3 16.6 17.2 17.5 C.c. 2.7 2.0 2.3 2.9 3.2 C.c. 2.3 } 3.! "Eagle" Do. quintuple 6 At that time the commercial grade name of the Pittsburgh testing station No. 3 detonator. 6 At that time the commercial grade name of the Pittsburgh testing station No. 5 detonator. It is evident that the method of conducting these tests was such that only a part of the energy of the detonator was represented by the expansion of the bore hole because much of the energy was o Practical Coal Mining, vol. 2, 1903, p. 237. ft Some tests of the relative strength of nitroglycerin and other explosives: Trans. Am. Inst. Min. Eng., VOl. 18, 1890, p. 515. TESTS PREVIOUSLY USED. 17 used to disintegrate and pulverize the sand. This was proven by tests made at the Pittsburgh testing station with electric detonators containing similar charges. A No. 3 electric detonator when fired in a cast-lead block with a bore hole of such size that the detonator would fit snugly within it produced an expansion of 5.8 c. c. A similar test with a No. 5 electric detonator gave an expansion of 9.2 c. c. In the tests at the Massachusetts Institute of Technology, two deto- nators fired simultaneously within the bore hole produced consid- erably more than twice the expansion produced by one detonator, probably because the distance between the charge and the sides of the bore hole was less and, accordingly, the charging density was increased. The following tabulated results show this: Results of firing simultaneously two detonators in bore hole of lead block. Grade of detonator (cap). Capacity of bore hole- Difference. Average. Before firing detonator. After firing detonator. "Eagle" triple C.c. 14.3 14.3 14.3 C.c. 21.9 20.4 20.0 C.c. 7.6 6,1 9.7 C.c. } 6.8 9.7 Do "Eagle" quintuple Further lead-block tests were made with 13 sensitive explosives, both triple and quintuple detonators (caps) being used. The charge consisted of 6 grams of explosive, loaded and fired as previously described. The conclusion drawn was that explosives when fired with a quintuple detonator produce 9.7 per cent greater expansion than that produced with a triple detonator. It is evident that in arriving at this conclusion the author did not take into consideration the fact that the quintuple detonator had a charge of 0.80 gram of fulminating composition, that the triple detonator had only a 0.54-gram charge, and that therefore the weight of the total charge, including the quintuple detonator, was increased 4.0 per cent over the weight of the total charge when triple detonators were used. Furthermore, the 4.0 per cent increase in weight represented principally mercury fulminate, a powerful, quick-acting explosive which, under the conditions of the tests, would exert its full effect in enlarging the bore hole. From the data presented, the results can not be properly interpreted as indi- cating that, with small charges (in this case 6 grams) of an explo- sive detonating directly under the influence of a detonator, an increase of the force of the explosive was obtained with a detonator of the higher grade. 18 INVESTIGATIONS OF DETONATOKS AND ELECTRIC DETONATORS. The results of tests made at the Pittsburgh testing station with sensitive explosives do not substantiate the conclusions drawn. In order to differentiate between grades of electric detonators, it was necessary to use large quantities of insensitive explosives under conditions simulating those of actual blasting operations. TESTS FOR DETERMINING DIRECTLY THE STRENGTH OF P. T. S. S. ELECTRIC DETONATORS. CHARACTER OF ELECTRIC DETONATORS TESTED. Tests for determining directly the strength of electric detonators were made with six grades of P. T. S. S. electric detonators (fig. 1). No. 3 No. 4 .1 .2 .3 .4 .5 No. 5 No. 6 SCALE IN INCHES. 1 No. 7 No. 8 LEGEND |||;|||Asphaltic composition. fegrglSl Loose gun cotton. E&Pfol Loose mercury fulminate. JHHI Compressed mercury fulminate composition. FIGURE 1. Cross-sectional view of six P. T. S. S. electric detonators. A physical examination of each showed the results tabulated below. Each measurement represents an average of the measurements of five electric detonators of a given grade. DIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 19 Results of physical examination of P. T. S. S. electric detonators. Grade of electric detona- tor. Length of shell. Outside diameter f shell. Inside diameter of shell. Thickness of shell. Length of com- pressed charge. Length of priming charge. Length of sulphur plug. Length of asphaltic composi- tion, i f any. Length of sulphur filling. No. 3... No. 4 No.5 No. 6... Inches. 1.00 1.25 1.55 1.55 1.75 2.00 Inches. 0.234 .274 .274 .274 .274 .274 Inches. 220 260 260 260 260 260 Inches. 0.007 .007 .007 .007 .007 .007 Inches. 0.28 .16 .28 .28 .62 .75 Inches. 0.37 .24 .37 .27 .38 .20 Inches. 0.25 .31 .28 .25 .25 .31 Inches. Inches. 0.10 .16 .62 .25 .50 .24 0.38 .50 No. 7 No. 8 .50 Details of the wiring of the electric detonators tested are given below : Details of the wiring of six grades of P. T. S. S. electric detonators. Distance Distance wires from Grade of electric detonator. projected below end of insulation sulphur plug. to end of wires. Inches. Inches. No 3 0.16 16 No. 4 . .12 .88 No.5 16 16 No. 6... .12 .94 No. 7 .19 16 No. 8 .12 .75 The outside diameter and the thickness of the shells were deter- mined with micrometers. The inside diameter of the shells was computed from the figures so determined. For grades Nos. 3, 5, and 7 the priming charge was guncotton. No. 3 electric detonators could not be procured from the manufacturers, so the priming charge, sulphur plug, and sulphur filling were placed in a No. 3 detonator at the Pittsburgh testing station; all other electric detonators were purchased from manufacturers. The weights and the results of chemical analyses of the charges of the six grades of electric detonators were as follows : Weigttts and results of chemical analyses of charges of P. T. S. S. electric detonators. Grade of electric detonator. Weight of com- pressed charge. Weight of priming charge. Weight of total charge. Percentage in compressed charge of Percentage in priming charge of Percentage in total charge of Mer- cury fulmi- nate. Chlo- rate of potash. Gun- cotton. Mer- cury fulmi- nate. Mer- cury fulmi- nate. Chlo- rate of potash. Gun- cotton. No. 3 a Grams. 0.4920 .3255 .6990 .6485 1.4854 1.5110 Grams. 0.0200 .3230 .0240 .3510 .0247 .3000 Grams. 0.5120 .6485 .7230 .9995 1.5101 1.8110 Per ct. 87.94 88.51 89.13 88.82 88.93 89.77 Perct. 12.06 11.49 10.87 11.18 11.07 10.23 Perct. 100.00 "166.66" Perct. Perct. 84.50 94.24 86.17 92.75 87.47 91.47 Perct. 11.59 5.76 10.51 7.25 10.89 8.53 Perct. 3.91 "3 ."32 No. 4 100.00 No.5&... No.66 No. 7c.... 100.00 100.00 1.64 No.Sd 100.00 a Analyst, A. L. Hyde. b Analyst, W. C. Cope. c Analyst, C. A. Taylor. d Analyst, J. H. Hunter. '. 20 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. The results of calorimeter tests are tabulated below: Results of calorimeter tests of six grades of P. T. S. S. electric detonators. Heat evolved per electric detonator on Grade of electric detonators. Number of electric detonators used in each test. Number of tests averaged. Heat evolved per electric detonator. Total charge per electric detonator. the basis of a charge of 77.7 per cent mer- cury fulminate and 22.3 per cent chlorate of potash (exact combust ion), a Large calories. Grams. Large calories. No. 3 30 1 0.35 0. 5120 0.36 No. 4 25 2 .48 .6485 .46 No. 5 20 2 .49 .7230 .51 No. 6 15 2 .62 .9995 .71 No 7 10 2 1.01 1.5101 1.07 No. 8 10 2 1.14 1.8110 1.28 a Berthelot, M., Explosives and their power, 1892, p. 470. The tests were made with the explosives calorimeter a of the Pittsburgh testing station and the rise in temperature of the water surrounding the bomb was about 0.140 C., an increase too small to insure the most accurate results. Nevertheless, the results are valuable as showing the potential energy of the electric detonators and that the potential energy is approximately a direct function of the total charge. The last column is added to show how close the heat evolved per electric detonator was to that which was to be expected had the mercury-fulminate composition been of mercury fulminate and chlorate of potash in the proportions necessary for exact combustion. SQUIRTED LEAD BLOCK TESTS. Tests of the six grades of electric detonators were made with squirted-lead blocks. The blocks were squirted 2 inches in diameter and were cut 3 inches long. The axial bore hole was drilled a depth equal to the length of the electric detonator to be tested and a diameter such that the electric detonator would fit snugly into it. The volume of the bore hole was measured with water before and after firing the shot. The tendency of the squirted blocks, because of their small diameter (2 inches), to bulge around the sides makes a comparison between the low-grade and the high-grade electric detonator more difficult and makes impossible a comparison of the increase in volume with the weight of total charge. Nevertheless, the volume increases with the weight of total charge as is to be expected. a Hall, Clarence, Snelling, W. O., and Howell, S. P., Investigations of explosives used in coal mines; with a chapter on the natural gas used at Pittsburgh, by G. A. Burrell, and an introduction by C. E. Munroe: Bull. 15, Bureau of Mines, 1912, p. 109. DIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 21 The results of the tests are tabulated below: Results of tests P. T. S. S. electric detonators with squirted-lead blocks. Volume of bore hole Increase of Grade of electric detonator. Test No. Before firing detonator. After firing detonator. after firing electric detonator. increase of volume. total charge. No. 3 AA47 C.c. 0.9 C.c. 7.5 C.c. 6.6 C.c. \ R A Qrams. No. 4 AA48 AA45 .9 1.35 7.2 11.0 6.3 9.6 1 b.4 I OK No. 5 AA46 AA20 1.35 1.8 10.8 13.3 9.4 11.5 ) .6485 No 6 AA27 AA10 1.7 1.7 12.6 20.0 11.1 18.3 .7230 No 7 > AA11 AA18 1.7 2.1 19.8 38.5 18.1 36.4 j- 18.2 I OC T .9995 No. 8 AA19 a AA16 1.9 2.1 38.9 49.7 37.0 47.6 > 36. 7 \ A-7 R 1.5101 <*AA17 2.15 49.6 47.45 } 47.5 1.8110 o Bottom blown out of block; it was fastened in with paraffin before volume of bore hole was measured. CAST LEAD BLOCK TESTS. Tests of the six grades of P. T. S. S. electric detonators were made also with cast-lead blocks. The blocks were cast as solid cylinders 100 mm. in diameter and 100 mm. high. The axial bore hole of each was drilled a depth equal to the length of the electric detonator to be tested, and of a diameter such that the electric detonator would fit snugly into it. The volume of the bore hole was measured with water before and after the shot. When more than two trials were made with any given electric detonator, the two trials that were within 5 per cent variation were selected for averaging. A comparison of the average increase of volume (y) with increase of the weight of total charge (x) shows that the relation y=15.5 (a; = 0.12) is closely maintained. Plate I shows the comparative effects of the different electric detonators on the cast-lead blocks. The details of the cast lead block tests are tabulated below : Results of tests with cast-lead blocks of P. T. S. S. electric detonators. Volume of bore hole- Increase of volume as Grade of electric detonator. Test No. Increase of volume. Average increase of volume. Weight of total charge. compared with total charge, by formula Before fir- ing electric After fir- ing electric detonator. detonator. y=15.5 C.c. C.c. C.c. C.c. Grams. No.3 / AA49 \ AA50 0.9 .9 6.6 6.8 5.7 5.9 j 5.8 0.5120 6.1 No.4 / AA51 \ AA52 .35 .35 9.3 9.1 7.95 7.75 1 " .6485 8.2 No.5 ( AA3 \ AA39 .7 .7 11.1 10.7 9.4 9.0 9.2 .7230 9.3 No 6 J AA30 \ AA55 .7 .6 16.0 15.2 14.3 13.6 14.0 .9995 13.6 No 7 / AA37 \ AA44 .9 .9 23.0 22.8 21.1 20.9 } 21.0 1.5101 21.5 No 8 J AA42 \ AA43 2.1 2.1 28.6 28.0 26.5 25.9 \ 26.2 1.8110 26.2 22 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. TESTS BY EXPLOSION OF DETONATING FUSE (CORDEAU DETO- NANT)a BY INFLUENCE. The usual method of firing detonating fuse (cordeau detonant) is to place a detonator on the end of the fuse. Some detonators will explode detonating fuse when not in direct contact with it. Hence, in the expectation that the strength of an electric detonator might be determined by varying the distance between the electric detonator and the detonating fuse, trials with a few electric detonators were made in such a way as to fix for each grade a limiting distance at which no explosion would occur, explosion occurring if the distance were lessened 1 mm. The detonating fuse was arranged in the four different ways indi- cated in the following tables: Results of explosion-by -influence tests in which detonating fuse was placed parallel with electric detonator. Grade of electric detonator. Test No. Trial. Separating distance. Result. No 6 M243 a Mm. 20 No explosion No. 8 M245 b c d e f I a 10 5 Do. Do. Do. Do. Do. Do. Do. Do. b c Do. Do. Results of explosion-by -influence tests in which side of detonating fuse touched the end of the electric detonator and was at right angles to it. Grade of electric detonator. Test No. Trial. Result. No. 6.... M244 a No explosion No 8 M246 b c d e a Do. Do. Do. Do. Do b Do. Results of explosion-by -influence tests in which detonating fuse and electric detonator were placed in the same axial line. Grade of electric detonator. Test No. Trial. distance. Result. No. 4 M253 a Mm. 5 Explosion 6 d e f I i i 8 6 6 6 7 7 8 8 8 8 No explosion. Do. Do. Explosion. No explosion. Explosion. No explosion. Do. Do. Do. o See p. 66. DIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 23 Results of explosion-by-influence tests in which detonating fuse and electric detonator were placed in the same axial line Continued. Grade of electric detonator. Test No. Trial. Separating distance. Result. No. 6 M251 a Mm. 3 Explosion. b 4 Do. c 5 Do. d 6 Do. 7 No explosion. i 7 Do. g 7 Do. \ 7 Explosion. j 8 Do. j 9 Do. k 10 No explosion. I 10 Do. m 10 Do. n 10 Do. 10 Do. No 8 M247 a o Explosion. b Do. c 10 No explosion. d 5 Do. e 1 Explosion. f 3 Do. I i 4 4 5 No explosion. Explosion. No explosion. j 5 Do. i 5 Do. I 5 Do. Results of explosion-by-influence tests in which detonating fuses were placed at right angles to electric detonators but at different distances from them in such a way that axial line of detonating fuse intersected side of electric detonator. Grade of electric detonator. Test No. Trial. Distance from cen- ter line of detonating fuse to end of deto- nator. Separat- ing dis- tance. Result. No. 4 M254 a Mm. 5 Mm. 2 No explosion b 1 Explosion c 2 No explosion d 2 Do. e / 2 2 Do. Do. No. 6 . M252 a 7 5 Do. b 4 Do c 3 Do. d 2 Do. e f ; 1 o Do. Do. , I 2 Explosion. No explosion i 2 3 Explosion. No explosion. { I 3 3 Do. Do. m 3 Do. No.8 M250 a 10 Explosion. b 4 Do. c d 5 5 No explosion. Do. e f a 5 6 6 Explosion. No explosion. Do. 1 i 6 6 Do. Do j 6 Do. 24 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. The above results are so much at variance with the established ex- plosive efficiency of detonators (see pp. 45 and 46) that this method of determining the strength of detonators is considered of little value. The tests made with the No. 4 and the No. 6 electric detonators placed in the same axial line as that of the detonating fuse would indicate that in actual blasting there may be some advantage gained from inserting the electric detonator in the top of the primer or cartridge. Although it has been impossible to show by tests any loss in energy resulting from the detonation of an explosive when the electric detonator is placed in the side of a primer that is, having the end of the electric detonator intersect the axial line of the primer, it is believed that the former method of insertion is preferable. When the top of the primer is opened and an electric detonator is pushed into it and the paper ends of the cartridge are gathered together and bound with twine, the electric detonator is held firmly hi place. When this method is used there is less danger of the wires becoming short- circuited, and it is impossible for the end of the detonator to project through the side of the cartridge, a position that would not only tend to reduce its effectiveness, but would also be a source of danger in loading and tamping the drill hole. TESTS BY DEPRESSION OF LEAD PLATES. The strength of the electric detonators was also determined directly by tests involving the depression of lead plates. The details of the tests are indicated in the tabulations following: Results of depression tests of electric detonators placed on end on %-inch lead plates. Grade of electric detonator. Test No. Volume of water held in depression.?* Diameter of crater. Depth of crater. Height of cone on bottom. No.3... M-264 C.c. 0.35 Mm. 11 Mm. 7 Mm. 2 No. 4 M262 .50 13 7 4 No. 5 M157 .40 13 6 4 No. 6 M149 .40 13 7 3 No. 7 M151 .40 13 6 2 No. 8. M147 .35 13 7 2 a See PI. II. b The measurement of volume, which was determined with water, was unsatisfactory because of the action of surface tension, and the results are accurate only within 50 per cent. No result obtained agrees even approximately with the established results of the explosive efficiency of electric detonators (see p. 45). Results of depression tests of electric detonators placed on side on %-inch lead plates. a MEASURED WITH WATER. Grade of electric detonator. Test No. Volume.^ Length of crater. Width of crater. Depth of crater. No.3 M265 C.c. 0.30 Mm. 10 Mm. 10 Mm. 4 No 4 > M263 .25 15 10 4 No. 5. M158 .40 15 11 4 No. 6 cMloO .50 21 13 5 No. 7... cM152 .60 20 14 5 No. 8. M148 .90 31 14 6 a See PL III. 6 See footnote of preceding table. c Bottom of plate slightly raised; not raised in other tests. !# m DIRECT TESTS OP P. T. S. S. ELECTRIC DETONATORS. 25 Results of depression tests of electric detonators placed on side on \-inch lead plates Con. MEASURED WITH SAND. a Grade of electric Plate Weight of sand containe No. d in dep ression Aver- age of five Grand Vol- detonator. No. 1 2 3 4 5 meas- ure- ments. age. ume.b No. 3 No. 4 No. 5 M302 M303 M304 1 2 3 1 2 3 1 Grams. 0.129 .191 .226 .379 .327 .415 .361 Grams. 0.122 .191 .209 .405 .325 .393 .359 Grams. 0.121 .194 .235 .376 .333 .397 .340 Grams. 0.142 .172 .221 .405 .302 .404 .355 Grams. 0.146 .197 .229 .365 .312 .386 .381 Grams. 0.132 .189 .224 .386 .320 .399 .359 Grams. 0.182 .368 C.c. 0.128 .259 No. 6 M301 2 3 1 .382 .361 .574 .380 .365 .565 .393 .377 .620 .379 .355 .620 .390 .366 .590 .385 .365 .594 .370 .261 No. 7 M305 2 3 1 .580 .622 .891 .586 .600 .867 .607 .615 .890 .569 .601 .880 .596 .598 .892 .588 .607 .884 .596 .420 No 8 M306 2 3 1.002 1.114 1.183 .994 1.076 1.173 1.034 1.081 1.230 .994 1.108 1.150 1.002 1.144 1.244 1.005 1.105 1.196 .998 .'703 2 3 1.245 1.269 1.237 1.252 1.252 1.257 1.272 1.260 1.216 1.320 1.244 1.272 1.237 .871 a The sand was fine and dry. b The volume was computed from the grand average weight by dividing it by the specific gravity of the sand, which was 1.42. This test was acceptable because the volume of the depression varied approximately as the explosive efficiency of the electric detonator. THE NAIL TEST. It was evident that the methods previously used for the direct determination of the relative strength of detonators were not satis- factory or accurate. During the latter part of the investigation an endeavor was made to devise a test that would give results approxi- mating those obtained by the indirect tests. In the tests made with the four No. 6 detonators having different compositions, described later, each electric detonator caused the same amount of energy to be developed from both sensitive and insensitive explosives. However, by the direct methods of testing detonators, one of the No. 6 detonators showed a much higher calorific value than any of the others, and one developed a much greater enlarge- ment of the lead block. Nevertheless it was concluded that al- though the temperature developed and the volume of gases pro- duced are functions of the efficiency of detonators, the rate of detona- tion or the rapidity with which the gases are developed is the prime factor and any tests that emphasized this factor should be given con- sideration. The test finally decided upon is known as the nail test. This test depends on the angle formed by a nail when a detonator or electric detonator is fired in close proximity to it. For simplicity and cheapness the nail test commends itself. Four-inch wire finishing nails (20-d.) are used in the test. For the tests herein reported the nails were selected so that they were approx- 26 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. imately of the same length, the same gage, and the same weight. The bottom of the electric detonator was placed If inches from the face of the head of the nail and was laid parallel to the nail and separated from it by two 22-gage (0.025-inch) copper wires that were wrapped around the electric detonator. The electric detonator was fastened in posi- tion by one strand of a similar copper wire, which was wrapped around it and the nail midway between the ends of the electric detonator. The whole was suspended horizontally in the air in such a manner that the nail was directly above the electric detona- tor, which was then fired. (Fig. 2.) The impact of the exploding electric deto- nator bent the nail and projected it upward. Care was taken that the nail was not hurled against any solid surface and further distorted. Five trials were made with each grade of electric detonator. The angle through which the nail was FIGURE 2. Nail in position for test of electric detonator. bent rrom its normal posi- tion was measured. The angle (average of five trials) was taken as a measure of the strength of the electric detonator. The results were as follows: Results of nail tests a of six grades of P. T. S. S. electric detonators. Grade of electric detonator. Test No. Angle of bending resulting from trial No. Average. 1 2 3 4 5 No.3... M279 M280 M281 M288 M283 M284 12 12 11 23 60 68 10 11 13 24 50 78 8 14 14 25 53 76 9 11 13 24 54 86 7 16 8 26 59 98 9.2 12.8 11.8 24.4 55.2 81.2 No. 4 No. 5... No. 6 No. 7... No. 8 a See PI. IV, A. The variation in the results of individual trials was largely due to variation in the individual electric detonators. An attempt was made to get more uniform results with annealed nails, but with these there was practically the same variation in results. In such tests, as well as in all physical tests of explosives, discrepancies result- ing from unavoidable sources of error can not be eliminated, and, accordingly, only averages should be considered in comparing the practical value of the electric detonators. BUREAU OF MINES BULLETIN 59 PLATE IV A. RESULTS OF NAIL TESTS OF P. T. S. S. ELECTRIC DETONATORS NOS. 3, 4, 5, 6, 7, AND E. RESULTS OF NAIL TESTS OF NO. 6 ELECTRIC DETONATORS, a, WESTERN COAST; b, SPECIAL; c, P. T. S S.; d, FOREIGN. INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 27 TESTS FOR DETERMINING INDIRECTLY THE STRENGTH OF P. T. S. S. ELECTRIC DETONATORS. Details of different forms of tests made to determine indirectly the strength of P. T. S. S. electric detonators are given below. RATE-OF-DETONATION TESTS.** The rate of detonation of the explosive was determined by placing the cartridges end to end in a 28-gage (B. & S.) galvanized-iron tube 42 inches long, which was of slightly larger diameter than the cartridges. The paper ends of each cartridge were cut off squarely in order that the explosive material of the cartridges would be continuous through- out the file, which was a little more than 1 meter long. Four copper wires were inserted through perforations in the tube and the cartridge file so that the distance between adjacent wires made it possible to determine the rate of detonation through the first quarter meter, the second quarter meter, the last half meter, and the entire meter, and the data were so recorded. Each wire carried an electric current and was attached to a Mette- gang recorder in such a way that at the instant the wire was broken a spark was recorded on a rapidly moving soot-covered drum. From the sparks thus recorded and the speed of the drum, the time interval between the breaking of the wires in the meter file was computed and was expressed as rate of detonation in meters per second. The rate-of-detonation tests were carried on with different explo- sives as described below. TESTS WITH AN EXPLOSIVE OF CLASS 1, SUBCLASS a. In one series of tests sample 1 of an explosive of class 1, subclass a an ammonium-nitrate explosive containing a sensitizer that is itself an explosive was used. The cartridges were seven-eighths of an inch in diameter. The results were as follows : Results of rate-of-detonation tests with sample 1 of an explosive of class 1, subclass a. Grade of electric detonator. Test No. Rate of detonation in tube. First quarter. I Second quarter. Second half. Full length. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. No.3 No. 4 No. 5 No. 6 No. 7 No. 8 Gran ( M242 \ M242 I M248 / M248 \ M248 ( D963 \ D9bO { D966 \ D967 f D964 \ D965 / D968 \ D969 d average. Meters per second. Detonati< 3 inches t Detonati< Detonatic Detonatk 2,921 2 inches t 2.445 2,472 2,777 2,922 2,184 2,250 Meters per second. )n complel down off; )n complel m complel m complet Meters per second. e; 16inch< 16 inches o e; 16incht e; 16 inche e; 16 inche 1,956 f 2,678 \ 2,586 I 2,586 \ 2,556 f 2,250 \ 2,320 Meters per second. js of explos [ explosive ,s of explos s of explos s of explos 20 inches j- 2,632 } 2,571 } 2,285 Meters per second. ive used, used, ive used. ive used, ive used. detonated f 2,205 \ 2,205 / 2,381 \ 2,368 / 2,472 \ 2,380 Meters per second. \ 2,205 } 2,374 } 2,426 Meters per second. I 2,368 \ 2,356 / 2,521 \ 2,535 / 2,337 \ 2,331 Meters per second. } 2,362 } 2,528 } 2,334 lown off. } 2,458 } 2,850 } 2,217 2,508 2,496 2,335 2,408 a For more detailed description of this test, see Bull. 15, Bureau of Mines: Investigations of explosives used in coal mines; with a chapter on the natural gas used at Pittsburgh, by G. A. Burrell,and an intro- duction by C. E. Munroe, by Clarence Hall, W. O. Snelling, and S. P. Howell, 1912, pp. 92-95. 28 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. No detonation occurred in those tests in which 2 or 3 inches of the cartridge was blown off. In those tests in which 16 inches of the explosive was used no attempt was made to determine the rate of detonation. The grand average indicates that the rate fell off in the last half meter. Individual tests with a given detonator showed remarkable uniformity for each electric detonator of Nos. 6, 7, and 8, and with No. 6 the maximum rate was obtained in the second quarter, with No. 7 in the first quarter, and with No. 8 in the second half. The average rates for the full length of the tube did not vary greatly. The percentage of complete detonations with each detonator was as follows: Percentage of complete detonations in rate-of -detonation tests with sample 1 of an explosive of class 1, subclr^ ?. Grade of electric detonator. Number of tests. Number of tests in which incomplete detonation occurred. Complete detona- tions. No 3 3 1 Per cent. 67 No 4 . 2 100 No 5 2 1 50 No 6 2 100 No 7 2 o 100 No 8 . 2 100 These tests show that an explosive of class 1, subclass a, that is insensitive, tends more readily to become completely detonated with the higher grades of electric detonators, but that if the explosive detonates at all its rate is independent of the grade of electric detonator used. The results of tests with sample 2 of an explosive of class 1 , subclass a, follow. The cartridges used were 1J inches in diameter. Results of rate-of -detonation tests with sample 2 of an explosive of class 1, subclass a. Grade of electric detonator. Test No. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. No.3 No.7 D1154 D1155 D1156 D1157 D1158 D1149 D1150 D1151 D1152 Meters per second. 3,090 2,973 Meters per second. o2,977 3,324 Meters per second. 3,423 5,946 5,705 7,257 5,488 4,198 6,286 5, 174 3,134 Meters per second. 5,529 4,698 Meters per second. 4,734 2,973 3,708 3,435 3,516 3,069 2,933 3,739 3,618 Meters per second. 3,664 3,340 Meters per second. 3,854 3,398 Meters per second. o3,668 i 3,506 2.884 2,960 3,836 2,973 2,649 3,836 3,750 3,673 3,477 3,398 3,618 3,532 o Test No. D1156 not included in average. INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 29 The averages for each detonator show a positive acceleration in the second quarter meter and a negative acceleration in the second half meter. The rates for the meter length is within the experimental error, and they were, therefore, practically uniform. The results of tests with sample 3 of an explosive of class 1 , sub- class a, follow. The cartridges used were 1J inches in diameter. Results of rate-of -detonation tests with sample 3 of an explosive of class 7, subclass a. Grade of electric detonator. Test No. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. No.3 No. 7 {D1161 D1162 D1163 {D1127 D1128 D1129 D1130 Meters per second. a3,143 4,167 4,450 3,477 3,007 3,090 4,231 Meters per second. Meters per second. Meters per second. Meters per second. Meters per second. Meters per second. Meters per second. } 4,308 3,451 ( 3,571 \ 3, 134 4,045 4,363 4,541 3,729 \ 3,352 1 4, 170 / 2,980 \ 3,397 f 3,450 3,202 3,296 3,359 } 3,188 1 3,327 f 3,488 \ 3,532 3,589 3,371 3,477 3,636 } 3,510 3,518 a Detonation incomplete; test not averaged. The average rate for the meter length was practically uniform. The percentage of complete detonations for each electric detona- tor was as follows: Percentage of complete detonations in rate-of-detonation tests with sample 3 of an explosive of class 1, subclass a. Number of Grade of electric detonator. Number of tests. tests in which complete detonation Complete detona- tions. occurred. Per cent. No.3... 3 2 67 No 7 4 4 100 TESTS WITH AN EXPLOSIVE OF CLASS 1, SUBCLASS 6 The results of tests with sample 1 of an explosive of class 1 , subclass b an ammonium-nitrate explosive containing a sensitizer that is not in itself an explosive follow. The diameter of the cartridges used was If inches. Results of rate-of-detonation tests with sample 1 of an explosive of class 1, subclass b. Grade of electric detonator. Test No. Remarks. No. 3 M237 No detonation No. 4... M237 Do. No. 5.. D870 Do No 6 {D871 D869 Do. Do No 7 D871 f D869 Do. Do. No 8 \ D871 / D869 Do. Do. \ D871 Do. 30 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. These tests failed to make a discrimination between the different grades of electric detonators, and hence for the purposes of this investigation were useless. The results of tests with sample 2 of an explosive of class 1, sub- class &, follow. The cartridges used were If inches in diameter. Results of rate-of-detonation tests vrith sample 2 of an explosive of class 1, subclass b. Grade of electric detona- tor. Test No. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. Individ- Average ual rate. rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. No 3 M232 M241 M241 M240 M240 M231 M241 M241 M240 M240 M240 M241 M241 D923 D926 M249 D930 D931 D932 D1110 M241 M241 D928 D929 D956 M241 D925 D927 D954 D955 average. Meters per Meters per Meters per second. second. second. 6 inches o f cartridge blown off. 4inchesofcartridge blown off. 4 inches of cartridge blown off. 3 inches of cartridge blown off. 3 inches of cartridge blown off. 6 inches of cartridge blown off. 4 inches of cartridge blown off. 4 inches of cartridge blown off. 4 inches of cartridge blown off. 4 inches of cartridge blown off. 4 inches of cartridge blown off. 4 inches of cartridge blown off. 4 inches of cartridge blown off. 4 inches of cartridge blown off. 4 inches of cartridge blown off. Detonation complete; 16 inche 8 inches of cartridge blown off. 3,000) 3,000 3,750 8 inches of cartridge blown off. 5 inches of cartridge blown off. Detonation complete; 16 niche Detonation complete; 16 inch( 3,358(1 II 3,462 3,462 I 3,384 \\ 3,814 3,333 j I 3,491 Detonation complete; 16 inche 2,647 |f f 3,214 3,169 1 o n79 1 3,750 3 235 I 3 ' 072 I 3 055 3,235 ( I 3,142 Meters per second. s of explos 3,750 s of explos ss of explos 1 3,589 IB of explos 13,290 Meters per second. ive used. 3,333 ive used, ive used. f 3, 743 \ 3,082 I 3,464 ive used. f 4,286 3,147 3,358 3 384 Meters per second. 3,333 3,430 3,544 Meters per second. 3,333 ( 3,475 \ 3,333 I 3,437 3,462 3,285 3,247 3,283 Meters per second. 3,333 t 3,415 1 3,319 No. 4 No. 5. ... No. 6 No.7 No. 8 Grand 3, 180 3,460 3,475 3,357 It is probable that no detonation occurred in those tests in which 3 to 8 inches of the cartridge was blown off. In the trial listed under test M 241 only 16 inches of explosive was used and no attempt was made to determine the rate of detonation. The grand average shows the tendency of the rate of detonation to increase beyond the first quarter. It is interesting to observe that the rate of detonation for that 10 centimeters of a 1 J-inch cartridge just beyond the electric detonator, as determined with the cordeau detonant, was as follows: For a No. 7 electric detonator, 3,387 meters per second; for a No. 8 electric detonator, 3,387 meters per second. INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 31 The percentage of complete detonations for each detonator was as follows: Percentage of complete detonations in rate-of-detonation tests with sample 2 of an explosive of class 1, subclass b. Number of Grade of electric detonator. Number of tests. tests in which in- complete detonation Complete detona- tions. occurred. Per cent. No 3 5 No 4 5 5 No. 5 5 5 No 6 5 3 40 No. 7. . 5 100 No. 8 100 These tests show that an explosive of class 1, subclass 6, that is insensitive, tends more readily to become completely detonated with the higher grades of electric detonators, but that if the explosive detonates at all its rate is independent of the grade of electric deto- nator used. TESTS WITH A 20 PER CENT " STRAIGHT " NITROGLYCERIN DYNAMITE. The results of tests with a 20 per cent "straight" nitrogtycerin dynamite follow. The cartridges were seven-eighths of an inch in diameter. Results of rate-of-detonation tests with a 20 per cent "straight" nitroglycerin dynamite. Rate of detonation in tube. Grade of electric Test No. First quarter. Second quarter. Second half. Full length. detona- tor. Individ- Average Individ- Average Individ- Average Individ- Average ual rate. rate. ual rate. rate. ual rate. rate. ual rate. rate. Meters per second. Meters per second. Meters per second. Meters per second. Meters per second. Meters per second. Meters per second. Meters per second. No.3 f D1096 \ D1097 2,528 2,781 2, 654 I 3,648 \ 2, 967 } 3,308 ( 2, 853 \ 3, 156 } 3,004 J 2,918 \ 3,007 } 2,962 No. 4 / D1098 \ D1099 2,418 2,781 2,600 1 3,423 t 2, 967 } 3, 195 / 2,834 I 2,871 | 2, 852 / 2, 834 \ 2,871 j- 2, 852 No.o I D992 1 D993 3,225 2,747 1 2, 986 / 2, 781 i 2,928 } 2,854 I 2,908 \ 2,987 } 2,948 / 2, 947 \ 2,908 } 2,928 {D1000 3,729 1 {2,683 1 {2,767 } {2,933 ) No.6 D1001 o3,034 \ 3,838 3,034 } 2,563 3,121 ^ 3,038 3,077 \ 3,046 D1002 3,947 [ 2,443 j 3,309 I 3,158 1 No.7 J D1003 \ D1004 3,836 3,125 } 3, 480 ( 2,500 \ 2, 586 j- 2, 543 / 2, 947 \ 3, 192 j- 3, 070 / 2, 986 \ 3,000 I 2,993 No.8 I D1005 \ D1006 3,358 3,261 j 3,310 / 2,679 \ 2, 778 } 2,728 / 2,980 \ 3,041 | 3,010 I 2,980 \ 3,020 | 3,000 Grand average. 3,145 2 865 2,987 2,964 a Average rate for the first half meter; rate not included in average. 7S875 Bull. 5913 3 32 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. In the tests where electric detonators Nos. 3, 4, and 5 were used a considerably lower rate of detonation occurred in the first quarter than in the tests where electric detonators Nos. 6, 7, and 8 were used. Detonation was complete with every grade of electric detonator. The figures in the grand average indicate that the rate was influ- enced by a negative acceleration in the second quarter meter, followed by a positive acceleration in the second half meter, though the con- trary was true for electric detonators of grades Nos. 3 and 4. All tests except test D993 conformed to this. The uniformity of the rates for the last half meter and for the meter for every grade are noteworthy; this uniformity held for indi- vidual tests as well as for averages. TESTS WITH A 40 PER CENT STRENGTH AMMONIA DYNAMITE CONTAINING NITROSUBSTITUTION COMPOUNDS. The results of tests with a 40 per cent strength ammonia dynamite containing nitrosubstitution compounds follow. The cartridges used were seven-eighths of an inch in diameter and had been repacked. Results of rate-of-detonation tests with a 40 per cent strength ammonia dynamite contain- ing nitrosubstitution compounds. Grade of electric detonator. Test No. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. Individ- ual rate Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. No. 5 No. 6 No. 7 No.8 aD878 D882 D903 D921 oD875 D904 aD905 D919 D920 oD873 D906 D907 D918 D959 / D872 D881 D910 D911 oD915 D916 I D917 Meters per second. Meters per second. 2,498 2,363 2,543 2,310 Meters per second. *"*3," 929" 2,586 2,528 Meters per second. 3,014 2,594 2,709 3, 146 Meters per second. Meters per second. | 2,286 I 2,593 2,619 2,755 Meters per second. 2,811 2,350 2,446 2,439 2,659 2,446 2,521 2,695 2,439 2,658 2,557 2,641 2,647 2,619 2,514 2,597 2,561 2,557 2,195 2,795 2,752 Meters per second. 2,412 2,527 2,608 2,652 2.136 2,679 2,679 o AAA O, ODD 2.368 c2,285 2,472 2,250 2,631 2,394 c2,367 2,616 2,619 2,716 2,558 1^542 2,123 2,045 2,284 . 2,528 62,435 2,572 2,813 2,663 . 2,543 '62,668 2,830 2,987 2,528 2,500 ( 62,453 2,280 3,345 2,711 2,296 3,041 2,446 2,273 2,961 2,894 3,667 3,209 2,815 2,679 2,647 3,041 3,000 2,744 I 2,695 o Rate of detonation not averaged. & Rate for last three-fourths of a meter. c Rate for first one-half of a meter. INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 33 No tests were made with electric detonators Nos. 3 and 4. The average rate for the meter length increased slightly with the grade of electric detonator used. The fastest rate is recorded for the second quarter meter. The figures for the average rates and for most of the individual tests indicate that the rate increased up to a maxi- mum, and then decreased. With some electric detonators the maxi- mum was reached in the first quarter meter, as in test D903; with others in the second quarter meter, as in test D919; and with others in the second half meter, as in test D910. If it be assumed that the recorded rate was slightly erratic, but had a general tendency to increase to a maximum, and then to decrease toward an asymptotic normal rate, then the results of all the tests conformed to this assumption. TESTS WITH A 40 PER CENT STRENGTH AMMONIA DYNAMITE. The results of tests with a 40 per cent strength ammonia dynamite follow. The cartridges used were 1J inches in diameter. Results of rate-of -detonation tests with a 40 per cent strength ammonia dynamite. Grade of electric detonator. Test No. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. Individ- ual rate. Average rate. No. 3 f D1139 \ D1140 I D1141 Meters per second. 4,018 4,327 3,516 Meters per second. 3,954 Meters per second. f 4,412 \ 4,592 I 4,592 Meters per second. 4,532 Meters per second. f ,545 \ ,054 I ,128 \fetcrsper second. 4,242 Meters per second. f 4,369 \ 4,245 I 4,054 Meters per second. 4,223 No. 8 1D1136 D1137 D1138 3,437 3,250 3,750 3,479 {4,314 5,291 5,000 4,868 f ,889 I ,417 | 3,982 4,429 f 4,293 \ 4,213 I 4,128 4,211 Only the No. 3 and the No. 8 electric detonators were used. The average rate for the meter length is practically the same for the two detonators. The rate increased to a maximum in the second half meter and then decreased as shown by averages; the results of individual tests confirm this conclusion. The rate in the last half meter corresponded closely with the average rate for the meter length. TESTS WITH A 35 PER CENT STRENGTH GELATIN DYNAMITE 2 YEARS OLD. The results of tests with a 35 per cent strength gelatin dynamite (2 years old) follow. The cartridges used were 1J inches in diameter. 34 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. Results of rate-of -detonation tests with a 35 per cent strength gelatin dynamite (2 years old). Grade of electric detonator. Test No. Length of files blown off or deto- nated. Percentage inches that detonated. Average percent- age that deto- nated. Remarks. No 3 M231 Inches. 6.5 Per cent. 15 Per cent. 15.0 Partial detonation. No. 4.. No 5 M234 D887 7.5 7.0 18 18.5 Do. No detonation. D888 7 Do. No.6 D942 D943 D889 13.0 13.0 7.0 31 31 ""is. 5 Partial detonation. Do. No detonation. D896 18.0 43 Partial detonation. No 7 D958 D890 17.0 12.0 40 29 28.0 Do. Do. D895 12 29 Do. No 8 D957 D891 12.0 18.0 29 43 29.0 Do. Do. D892 12.0 29 Do. D940 15 36 Do. D941 14.0 33 35 Do. a Full length of file, 42 inches. The evidence of no detonation in tests D887, D888, and D889 was that nothmg but the noise of the detonator was audible when the trials were made. In tests M231 and M234 an 8-inch cartridge was used. In no trial was more than 18 inches of the 42 inches detonated. The part that detonated, in general, varied directly with the grade of the detonator. The number of partial detonations with each detonator was as follows: Number of partial detonations in rate-of-detonation tests with a 35 per cent strength gelatin dynamite (2 years old). Grade of electric detonator. Number of tests. Number of tests in which partial detonation occurred. Percentage of partial detona- tions. No 3 1 Per cent. 100 No 4 2 2 100 No 5 4 2 50 No 6 3 2 67 No 7 3 3 100 No 8 4 4 100 Except with the No. 3 and the No. 4 electric detonators, the number of tests with which was small, the percentage of partial detonations increased with the grade of the electric detonator. INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 35 TESTS WITH A 40 PER CENT STRENGTH GELATIN DYNAMITE, FROZEN. The results of tests with a 40 per cent strength gelatin dynamite (frozen) follow. The diameter of the cartridges used was If inches. Results of rate-of-detonation tests with a 40 per cent strength gelatin dynamite (frozen). Grade of electric detonator. Test No. Rate of detonation. First quarter. Second quarter. Second half. Total. No 3o D1087 D1088 D1089 D1093 D1094 D1095 Meters per second. 3 inches bio 4,018 6,250 4,167 4,687 4,018 Meters per second. wnoff. 6,429 7,258 7,759 6,429 7,500 Meters per second. 5,890 5,769 6,522 5,769 6,522 Meters per second. 5,376 6,207 5,921 5,591 5,806 No. 4 No 5 No. 6 No. 7 No. 8 Grand average 4,628 7,075 6,094 5,780 a No detonation occurred with the No. 3 electric detonator. The grand averages show that the maximum rate occurred in the second quarter, with a subsequent falling off in the rate; moreover, each individual test showed similar results, irrespective of the grade of the electric detonator used. The variation of 14.4 per cent in the average rate is rather high, and is seemingly due to the fact that results with frozen explosives are always erratic. Complete detonation occurred in each test with each of the six electric detonators except the No. 3, which failed to detonate. TESTS WITH A 35 PER CENT STRENGTH GELATIN DYNAMITE 3 YEARS OLD. The results of tests with a 35 per cent strength gelatin dynamite (three years old) follow. The cartridges used were 1J inches in diameter. Results of rate-of-detonation tests with 35 per cent strength gelatin dynamite (3 years old). Grade of electric detonator. Test No. Remarks. No. 3 M238 No. 4... M238 Do No. 5 D868 Do No. 7... D866 Do No. 8 D865 Do The explosive was so old and insensitive to detonation that for the purpose of discriminating between grades of electric detonators it was useless, because in no test did detonation occur. No tests were made with the No. 6 electric detonator. INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. SMALL LEAD BLOCK TESTS. The lead blocks used in the small lead block tests were squirted with a diameter of 1J inches and were cut to a length of 2 inches. An annealed steel disk 1 1 inches in diameter and one-quarter inch high was placed above each block and above this was placed the 100-gram charge of the explosive, held in position by a paper sleeve wrapped around the block and the disk and extending above them. The electric detonator used was centrally placed in the top of the charge. When the explosion was fired, the block rested on a firm horizontal steel base. The compression of the block was determined by measur- ing the difference in the height of the block before and after firing. TESTS WITH A 20 PER CENT " STRAIGHT" NITROGLYCERIN DYNAMITE WITH 6 PER CENT OF ADDED WATER. The results of tests of a 20 per cent " straight" nitroglycerin dyna- mite follow. The explosive contained 6 per cent of added water: Results of small lead block tests with a 20 per cent "straight" nitroglycerin dynamite con- taining 6 per cent of added water. Grade of electric detonator. Test No. Com- pression. ! Aver age com- pression. No. 3 .- B755 Mm. 14.00 Mm. ' No 4 B764 B773 B756 14.25 14.00 15 00 14.08 No. 5 B765 B774 B757 14.50 14.50 14.25 14.67 No. 6 B766 B775 B761 14.00 14.00 15.00 14.08 No 7 B770 B779 B762 15.00 15.00 15 25 .. iis.oo . No. 8 B771 B780 B763 14.75 15.75 15 50 15.25 B772 B781 15.75 15.25 15.50 The No. 8 electric detonator produced a compression 9.6 per cent greater than that of the No. 3 electric detonator; in general with the explosive tested, the compression increased with the grade of the detonator. The No. 4 electric detonator, however, developed more energy than did the No. 5. o For a more extended description of the small lead block test, see Bull. 15, Bureau of Mines: Investi- gations of explosives used in coal mines; with a chapter on the natural gas used at Pittsburgh, by G. A. Burrell, and an introduction by C. E. Monroe, by Clarence Hall, W. O. Snelliug, and S. P. Howell, 1912, pp. 113-114. INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 37 TESTS WITH A 20 PER CENT , FROZEN AND CONTAINING LESS THAN 6 PER CENT OF ADDED WATER. The results of tests with a 20 per cent "straight" nitroglycerin dynamite (frozen and containing no added water or 2.5 or 4 per cent of added water) are tabulated below: Results of small lead block tests of a 20 per cent "straight" nitroglycerin dynamite (frozen and containing less than 6 per cent of added water). Grade of electric detonator. Test No. Temper- ature of frozen explosive. Percent- age of added water. Com- pression. Average com- pression. No 3 . .. B616 c. +2.0 Mm. 14.25 Mm. No 4 B622 B647 B617 -1.0 -9.0 +2.0 2.5 4.0 13.25 12.50 14.50 13.33 No 5 B623 B648 B618 -1.0 -9.0 +2.0 2.5 4.0 13.25 12.50 13.50 13.42 No 6 B624 B649 B619 -1.0 -9.0 +2.0 2.5 4.0 13.00 12.50 13.50 13.00 No 7 B625 B653 B620 -1.0 -9.0 +2.0 2.5 4.0 13.25 13.00 15.00 13.25 No 8 B625 B654 B621 -1.0 -9.0 +2.0 2.5 4.0 13.50 13.00 15.25 13.83 B627 B655 -1.0 -9.0 2.5 4.0 13.25 13.25 13.92 The tests showed the tendency of the electric detonators to increase slightly in explosive efficiency with the grade, but again the No. 3 and the No. 4 electric detonators showed an increase over the No. 5 and even over the No. 6. TESTS WITH A 20 PER CENT " STRAIGHT" NITROGLYCERIN DYNAMITE, FROZEN AND CONTAINING 6 PER CENT OF ADDED WATER. As no failures had occurred with any of the electric detonators, when tested with the 20 per cent " straight" nitroglycerin dynamite, a sample of that explosive with 6 per cent of added water was frozen (temperature 9 C.) and was tested, with results as follows: Results of small lead block tests with a 20 per cent "straight" nitroglycerin dynamite (frozen and containing 6 per cent of added water). Grade of electric detonator. Test No. Compres- sion. Average compres- sion. No 3 B728 Mm. oO.OO Mm. No 4 B737 B746 B729 .00 .00 .00 0.00 B738 B747 .00 .00 .00 a Incomplete deto nation. 38 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. Results of small lead block tests with a 20 percent "straight" nitroglycerin dynamite (frozen and containing 6 per cent of added water) Continued. Grade of electric detonator. Test No. Compres- sion. Average compres- sion. No. 5 B730 Mm. aQ 00 Mm. ) No. 6 B739 B748 B734 a. 00 a. 00 a 00 0.00 1 No. 7.. B743 B752 B735 .oo a. 00 12 75 1 1 No. 8 B744 B753 B736 13.75 a. 50 12.75 9.00 I B745 B754 13.75 a 1.00 9.17 a Incomplete detonation. The number of complete detonations with each detonator was as follows : Number of complete detonations with a 20 per cent "straight" nitroglycerin dynamite (frozen and containing 6 per cent of added water). Number of tests in Percentage Grade of electric detonator. Number of tests. which complete of complete detona- detonation tions. occurred. No. 3. 3 No 4 3 c No. 5 3 No. 6 3 o No. 7 3 2 07 No. 8 3 2 07 The explosive was very insensitive and complete detonation occured only with the No. 7 and No. 8 electric detonators and with them in only two out of three trials with each. TESTS WITH A 40 PEE CENT STRENGTH AMMONIA DYNAMITE WITH 6 PER CENT OF ADDED WATER. The results of tests with a 40 per cent strength ammonia dynamite with 6 per cent of added water are tabulated below: Results of small lead block tests with a 40 per cent strength ammonia dynamite containing 6 per cent of added water. Grade of electric detonator. Test No. Compres- sion. Average compres- sion. No. 3 B656 Mm. 7 25 Mm. 1' B665 B674 BG83 B692 8.50 9.50 8.25 7.75 8.25 INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 39 Results of small lead block tests with a 40 per cent strength ammonia dynamite containing 6 per cent of added water Continued. Grade of electric detonator. Tost No. Compres- sion. Average compres- sion. No. 4 B657 Mm. 7.25 Mm. No 5 B666 B675 BC84 B693 B658 8.75 8.50 8.00 8.50 6.00 8.20 V No 6 B667 B676 B685 B694 B662 7.25 8.75 8.00 8.50 9 75 7.70 No. 7 B671 B680 B689 B698 B663 8.75 9.25 7.75 9.25 8.00 8.95 No. 8 B672 B681 , B690 B699 B664 8.75 10.00 10.25 8.75 8.75 9.15 B673 B682 B691 B700 9.50 10.75 9.75 9.75 9.70 This explosive showed a marked tendency to be erratic both with the higher and with the lower grades of electric detonators. The explosive efficiency of the electric detonators increased with the grade of the electric detonator, except that the efficiency of the No. 5 electric detonator was considerably low and that of the No. 3 a trifle high. TESTS WITH A 40 PER CENT STRENGTH GELATIN DYNAMITE, FROZEN. Following are the results (PL V, A) of tests with a 40 per cent strength gelatin dynamite that was in a frozen condition: Results of small lead block tests with a 40 per cent strength gelatin dynamite (frozen). Grade of electric detonator. Test No. Tempera- ture of frozen explosive. Compres- sion. Average compres- sion. No.3 B633 C. 2.5 Mm. 03.00 Mm. No. 4 B638 B701 B710 B719 B629 -5.0 +0.5 +2.5 +2.5 4.5 16.75 13.00 13. 50 13.75 a 1.50 1 14.25 No. 5 B639 B702 B711 B720 B630 -5.0 +0.5 +2.5 +2.5 4.5 15.50 10.75 11.00 13.25 a 1.00 12.62 BC40 B703 B712 B721 -5.0 +0.5 +2.5 +2.5 17.25 13.75 10.75 10.75 13.12 a Incomplete detonation. 40 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS, Results of small lead block tests with a 40 per cent strength gelatin dynamite (frozen] Con. Grade of electric detonator. Test No. Tempera- ture of frozen explosive. Compres- sion. Average compres- sion. No. 6 B631 a 4 5 Mm. 12 50 Mm. No. 7 B644 B707 B716 B725 B632 -5.0 +0.5 +2.5 +2.5 4 5 19.25 14.25 14.25 14.50 14 50 14.95 No. 8 ... . . B645 B708 B717 B726 B637 -5.0 +0.5 +2.5 +2.5 2 5 20.25 18.00 16.25 16.00 15 75 17.00 B646 B709 B718 B727 -5.0 +0.5 +2.5 +2.5 18.00 19.75 17.25 18.25 17.80 The results were yery erratic. The strength of the detonators increased with the grade of the electric detonator used, as shown by the average compression, except that the compression with the No. 3 electric detonator was comparatively high. The number of complete detonations with each detonator was as follows : Number of complete detonations in small lead block tests with a 40 per cent strength gelatin dynamite (frozen). Grade of electric detonator. Number of tests. Number of tests in which complete detonation occurred. Percentage of complete detona- tions. No. 3... 5 4 Per cent. 80 No. 4 5 4 80 No. 5... 5 4 80 No. 6 5 5 100 No. 7... 5 5 100 No. 8 5 5 100 The results tabulated above indicate that the tendency to complete detonation increases with the grade of the electric detonator used. EXPLOSION-BY-INFLTJENCE TESTS/* Explosion-by-influence tests were conducted by placing two car- tridges of an explosive at a definite distance apart; each cartridge was in a vertical position, one being directly above the other. The electric detonator was placed in the lower end of the lower cartridge, so that the lower cartridge on detonation either did or did not cause For a more extended description of the test, see Bull. 15, Bureau of Mines: Investigations of explo- sives used in coal mines; with a chapter on the natural gas used at Pittsburgh, by G. A. Burrell, and an introduction by C. E. Munroe, by Clarence Hall, W. O. Snelling, and S. P. Howell, 1912, p. 100. BUREAU OF MINES BULLETIN 59 PLATE V A. RESULTS OF SMALL LEAD BLOCK TESTS OF P. T. S. S. ELECTRIC DETONATORS NOS. 3, 4, 5, 6, 7, AND 8. a, BLOCK BEFORE TEST. B. RESULTS OF SMALL LEAD BLOCK TESTS OF NO. 6 ELECTRIC DETONATORS, a, BLOCK BEFORE TEST; 6, WESTERN COAST; c, SPECIAL; d, P. T. S. S.; e, FOREIGN. WESTERN COAST. SPECIAL. P. T. S. S. FOREIGN. C. SCORING OF LEAD PLATES BY FOUR NO. 6 ELECTRIC DETONATORS LAID ON SIDE. INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS, 41 detonation of the upper cartridge. The separating distance, estab- lished by successive trials, was but 1 inch greater than that at which the upper cartridge would detonate. With one explosive, however, certain trials were run with the cartridges separated by a given distance, and the number of times that the upper cartridge did or did not detonate was recorded. TESTS WITH AN EXPLOSIVE OF CLASS 1, SUBCLASS a. The results of tests with an explosive of class 1, subclass a (an ammonium-nitrate explosive containing a sensitizer that is itself an explosive), are tabulated below. The average weight of the car- tridges was 166 grams and they measured 1J by 8 inches. Results of explosion-by -influence tests with an explosive of class 1, subclass a. Grade of electric detonator. Test No. Distance separating cartridges. Result on upper cartridge. Distance established at No. 3 J874 Inches. 3 Did not explode. . . Inches. ); J875 J876 2 3 Exploded do , J877 J878 4 4 Did not explode... do No. 4 . J870 2 Exploded . No. 5 J871 J872 J873 J764 3 4 4 2 do Did not explode... do do .. J765 1 Exploded 2 No. 6 1766 J741 2 4 Did not explode... .. do... J742 J743 3 2 do do J744 1 Exploded 3 J745 2 do No. 7 J746 J747 3 3 Did not explode... do 1 No. 8 J748 J749 J750 2 3 3 Exploded Did not explode... do I 3 )" J751 J752 2 3 Exploded Did not explode... 3 These tests did not discriminate as to the relative efficiency of the different grades of electric detonators; the efficiency of the low-grade electric detonators was at least as great as that of the high-grade electric detonators. TESTS WITH AN EXPLOSIVE OF CLASS 4. Following are the results of tests with an explosive of class 4 (an explosive in which the characteristic material is nitroglycerin). Except for the trials under test J896, the average weight of each cartridge was 161 grams and the size of each was l by 8 inches. In the trials under test J896 the lower cartridge weighed 161 grams and the upper one weighed 110 grams, being only 5 inches long. In all 42 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. of the tests in which the distance separating cartridges was 5 inches, the bottoms of the cartridges (as packed) faced each other, whereas in all of the tests in which the separating distance was 4 inches, the tops of the cartridges faced each other. Results of explosion-by-influence tests with an explosive of class 4. Grade of electric detonator. Test No. Distance separating cartridges. Result upper cartridge. No. 3 No. 4. J895 J895 J895 J895 J896 J896 J896 J895 Inches. 5 5 5 5 4 4 4 5 Did not explode. Do. Exploded. Did not explode. Do. Do. Do. Do. No 5 J895 J895 J895 J896 J896 J896 J895 5 5 5 4 4 4 5 Do. Do. Exploded. Do. Do. Did not explode. Do No. 6. . . J895 J895 J895 J896 J896 J896 J895 5 5 5 4 4 4 5 Do. Do. Exploded. Did not explode. Do. Do. Do. No. 7. J895 J895 J895 J896 J896 J896 J895 5 5 5 4 4 4 Do. Do. Exploded. Do. Do. Did not explode. Do No.8 J895 J895 J895 J896 J896 J896 J895 5 5 5 4 4 4 5 Do. Do. Exploded. Do. Do. Did not explode. Do J895 J895 J895 J896 J896 J896 5 5 8 4 4 4 Do. Do. Do. Do. Exploded. Do. The following tabulation shows the number of explosions of the upper cartridge: Percentage of explosions of the upper cartridge in explosion-by-influence tests with an explosive of class 4- Grade of electric detonator. Number of tesls. Number of explosions of the second cartridge. Percentage of explo- sions. No. 3... 7 1 14 No. 4 7 3 43 No. 5... 7 1 14 No. 6. 7 3 43 No 7 7 3 43 No.8 .. . 7 2 29 INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 43 TESTS WITH A 40 PER CENT STRENGTH AMMONIA DYNAMITE CONTAINING NITROSUBSTITUTION COMPOUNDS. Following are tabulated the results of tests with a 40 per cent strength ammonia dynamite containing nitrosubstitution com- pounds. The cartridges used were 1J by 8 inches, their average weight being 226 grams. Results of explosion-by -influence tests with a 40 per cent strength ammonia dynamite con- taining nitrosubstitution compounds. Grade of electric detonator. Test No. Distance separating cartridges. Result on upper cartridge. Distance established at No 5 J708 Inches. 8 Exploded Inches. No 6 J709 J710 J689 9 9 14 Did not explode. . . do . ( ...do... 9 J690 12 do. J691 9 do J692 J693 J694 7 6 4 do do Exploded g J695 J696 J697 5 6 7 do do ...do J698 J699 8 8 Did not explode. . . .;. .do... No. 7 J720 9 do ) No 8 J721 J722 J704 8 9 8 Exploded Did not explode... Exploded 1 ' J705 J706 J707 9 10 10 do Did not explode... do 10 No tests made with detonators Nos. 3 and 4. TESTS WITH A 35 PER CENT STRENGTH GELATIN DYNAMITE 2 YEARS OLD. Following are the results of tests with a 35 per cent strength gelatin dynamite (two years old). The average weight of each cartridge was 265 grams and the size of each 1 i by 8 inches. Results of explosion-by -influence tests with a 35 per cent strength gelatin dynamite (2 years old). Grade of electric detonator. Test No. Distance separating cartridges. Result on upper cartridge. No. 6. J724 Inches. 6 No. 7 J725 J726 J727 J728 J729 J730 5 4 2 o Do. Do. Do. Do. Do. Do No. 8. . J731 J732 o Do. Do J733 Do. 44 INVESTIGATIONS OF DETONATOKS AND ELECTRIC DETONATORS. No tests were made with the No. 3, the No. 4, or the No. 5 electric detonators. The tests failed to discriminate between the different grades of electric detonators, except to the limited extent that in two trials the lower cartridge failed to detonate completely once with the No. 6. In no trial did the detonation of the lower cartridge cause the detonation of the upper cartridge. PERCENTAGES OF DETONATIONS IN INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. The percentages of detonations in the indirect tests of the P. T. S. S. electric detonators are given below. The percentages of detonations in the tests of each electric detonator are also averaged, each average percentage having a value proportional to the number of tests from which computed; that is, each percentage is multiplied by the num- ber of tests it represents, and the sum of the products is divided by the total number of tests of the electric detonator considered. Percentages of detonations in indirect tests of P. T. S. S. electric detonators. Class of explosive. Kind of test. Grade of electric detonator. No. 3. No. 4. No. 5. No. 6. No. 7. No. 8. Percentage of deto- nations. Number of tests. nrcentage f deto- tations. Number of tests. Percentage of deto- nations. Number of tests. Percentage of deto- nations. "o 3* g 3"^ fc Percentage of deto- nations. "o Is ! fc Percentage of deto- nations. Number of tests. Class 1, subclass b .... Rate of deto- nation. ...do... Per cent. G7 100 80 5 3 1 1 3 5 Per cent. 100 100 100 80 5 2 1 2 3 5 Per cent. 50 100 50 80 5 2 1 4 3 5 Per cent. 40 100 100 67 100 5 2 1 3 3 5 Per cent. 100 100 100 100 67 100 5 2 1 3 3 5 Per cent. 100 100 100 100 67 100 5 2 1 4 3 5 Class 1 , subclass a, 40 per cent strength gela- tin dynamite (frozen). 35 per cent strength gela- tin dynamite (two years old). 20 per cent "straight" mtroglycerin d y n a - mite (containing '6 per cent of added water and frozen). 40 per cent strength gela- tin dynamite (frozen). Total number of tests Average percentage of detonations. .. do . do Small lead block. do ~38.9 18 50." 6 18 40.6 20 63.2 19 94.7 19 95." 6" 20 COMPARATIVE EXPLOSIVE EFFICIENCY. The percentages of explosive efficiency of the different types of P. T. S. S. electric detonators were obtained by averaging all tests in which the rate of detonation or compression was determined for all the electric detonators. The percentages of the individual electric detonators were also averaged, each average percentage having a value proportional to the number of tests from which computed; that is, each percentage is multiplied by the number of tests it represents, and the sum of the products is divided by the total number of tests of the electric detonator considered. In each case the percentage of explosive efficiency of the No. 6 electric detonator is assigned a value of 100 and is used as the unit of comparison. INDIRECT TESTS OF P. T. S. S. ELECTRIC DETONATORS. 45 s^sa; jo jaquinN CN -f co co u> tn a Xouaiouja aAisoidxa jo aSt^uaojaj S uotssajdraoo ' ' *5 S3 S 2 eg iO os OO l- (puo -oas jad sja^ra) a^H Q 00 sjsaj jo jaquinN c* co co co o o (N ^ouaiouja aAisoidxa jo aa^uaojaj & * I t 31 O 8 6 uotssajdraoQ g : i 8. . s . " (puo -oas aad sja^ara) ajtJH ^ a ; ; ; i sjsa^ jo jaqrnnN CO W CO CO O "5 :?J Xouaiouja aAisojdxa jo aSB^uaojad .000 o o o ^11 8 2 03 uoissajduioo ^ : : 8 S S | i i 3 S3 3 - (puo -oas jad sjaiani) BJBH MM M 1 s;sa} jo jaqrantf (M c. O u fit? ^ Vestern Coast Special P.T.S.S Foreign In. 1.55 1.75 1.55 1.55 In. 0.274 .234 .274 .274 In. 0.260 .220 .260 .260 In. 0.007 .007 .007 .007 In. 0.62 .56 .28 .44 In. 0.23 .39 .27 .21 In. 0.25 .25 .25 .25 In. o.'so 0.45 .30 .25 .65 In. 0.16 .16 .12 .16 In. 0.19 .16 .94 .19 WEIGHT AND COMPOSITION OF CHARGES. Following is a tabulation presenting the weight of the charges and their chemical composition as determined by analysis: 78875 Bull. 5913 4 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. ' Si III! i 35 la fsj 33 til ' ai *** ^(N i-i oo eo Western SpeciaU P. T. S. Foreign TESTS OF FOUE NO. 6 ELECTRIC DETONATORS. RESULTS OF CALORIMETER TESTS. 49 The results of calorimeter tests of the four kinds of No. 6 electric detonator are tabulated below. Results of calorimeter tests of four No. 6 electric detonators. Average heat evolved per elec- tric detonator had each con- Kind of electric detonator. Number of electric de- tonators used in each test. Number of tests aver- aged. Average heat evolved per electric detonator. Total charge per electric de- tonator. tained the same weightofacharge consisting of 77, 7 per cent of mer- cury fulminate and 22.3 per cent of chlorate of pot- ash (exact com- bustion).* Large calones. Grams. Large calories. Western Coast 15 2 60.95 0.8682 0.61 Special 15 2 .75 .9283 .66 P.T.S.S 15 2 .62 .9995 .71 Foreign 15 3 cl.12 1.1748 .83 c Berthelot, M.. Explosives and their power, 1892, p. 470. & This unusually high value is partly due to the high heat of total combustion of nitrocellulose (about three times that of mercury fulminate). c This unusually high value is partly due to the high heat of total combustion of picric acid (about four times that of mercury fulminate). SQUIRTED LEAD BLOCK TESTS. The results of the squirted lead block tests are given herewith. Results of squirted lead block tests a of four No. 6 electric detonators. Kind of electric detonator. Test No. Volume of bore hole. Increase of volume. Average increase of volume. Weight of total charge. Before test. After test. Western Coast / AA14 \ AA15 / AA 9 \ AA41 f AA10 \ A All f AA12 \ AA26 C.c. 1.7 1.7 1.4 1.5 1.7 1.7 1.7 1.7 C.c. 27.7 28.7 20.6 19.3 20.0 19.8 28.9 28.6 C.c. 26.0 27.0 19.2 18.8 18.3 18.1 27.2 26.9 C.c. } 26.5 } 19.0 } 18.2 } 27.0 Grams. 0.8682 .9283 .9996 1.1748 Special P.T.S.S Foreign ... . For a description of the procedure in these tests, see p. 20. 50 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. CAST LEAD BLOCK TESTS. Following are tabulated the results (PI. VI) of cast lead block tests of the four kinds of No. 6 electric detonators : Results of cast lead block tests of four No. 6 electric detonators. Kind of electric detonator. Test No. Volume of bore hole. Increase of volume. Average increase of volume. Weight of total charge. Before test. After test. Western Coast / AA 6 \ AA31 / AA33 \ AA58 / AA30 \ AA55 / AA 5 \ AA54 C. c. 1.8 1.7 1.4 1.4 1.7 1.6 1.7 1.7 C.c. 22.7 23.2 16.1 15.2 16.0 15.2 19.7 20.0 C.c. 20.9 21.5 14.7 13.8 14.3 13.6 18.0 18.3 C.c. \ 21.2 J 14.2 14.0 18.2 Grams. 0.8682 .9283 .9995 1.1748 Special P. T. S. S Foreign TESTS WITH LEAD PLATES. Two series of tests of the four No. 6 electric detonators were made by the use of ^-inch lead plates. In one series the electric detonators were placed on end on the plates and were detonated, the resultant depression of the plates being recorded. In the other series each electric detonator was placed on its side on the lead plate before deto- nation. DETONATORS ON END. The results of the lead-plate tests in which the detonators were placed on end (PL VII) are tabulated below: Results of lead-plate tests of four No. 6 electric detonators, detonators being placed on end. Kind of electric detonator. Test No. Volume of water con- tained in depression. Diameter of crater. Depth of crater. Height of cone on bottom. Western Coast Ml 55 C.c. 15 Mm. 11 Mm. 5 Mm. Slight Special Ml 59 .25 11 6 2 P T S.S. Ml 49 40 13 7 3 Foreign M153 .45 13 7 3 Results of lead-plate tests of four grades of electric detonators, detonators being placed on side. Kind of electric detonator. Test No. Volume of water con- tained in depression. Diameter of crater. Depth of crater. Height of cone on bottom. Western Coast M156 45 26 12 4 Special M160 .50 19 11 4 P. T. S. S a M150 50 21 13 5 Foreign M154 50 22 13 5 a Bottom of plate slightly raised; not raised in other tests. BUREAU OF MINES BULLETIN 59 PLATE VII WESTERN COAST. SPECIAL. i * * * ' P. T. S. S. FOREIGN SCORING OF LEAD PLATES BY FOUR NO. 6 ELECTRIC DETONATORS PLACED ON END. TESTS OF FOUR NO. 6 ELECTRIC DETONATORS. 51 DETONATORS ON SIDE. Following are tabulated the results when the detonators were placed on their side (PL V, (7) on the lead plates before detonation: A second series of tests with the J-inch lead plates, the electric detonators being fired on their side, was made, and the resultant de- pressions of the plates were measured with sand. The results are tabulated below: Depression of^-inch lead plates when electric detonators were fired on their side, depression measured with sand. Kind of electric detonator. Test No. Plate No. Weight of sand contained in depression, measurement No. Avr Grand aS aver ' age - age. Vol- ume.a 1 2 3 4 5 Western Coast Special . . . M307 M307 M301 M307 1 2 3 1 2 3 1 2 3 1 2 3 Grams. 0.535 .591 .476 .507 .551 .540 .574 .580 .622 .635 .602 .580 Grams. 0.565 .601 .470 .557 .563 .536 .565 .586 .600 .668 .584 .560 Grams. 0.544 .602 .489 .562 .566 .568 .620 .607 .615 .678 .594 .540 Grams. 0.551 .560 .472 .540 .573 .542 .620 .569 .601 .684 .587 .511 Grams. 0.553 .602 .485 .587 .590 .551 .590 .596 .598 .573 .610 .520 Grams. Grams. 0.550 \) .591 \\ 0.540 .478 J .551 1 .569 } .556 .547 f .594 \] .588 V .596 .607 1 . 648 1 .595 \\ .595 .542 j C. c. 0.380 .392 .420 .419 P.T. S. S Foreign a The volume was computed from the grand average by dividing this by the specific gravity of the sand- in this case 1.42. The results of the tests are fairly satisfactory, as they practically agree with the explosive efficiency established for electric detonators by the indirect methods. NAIL TESTS. The nail tests previously described were also used in connection with the investigation of the four grades of No. 6 electric detonators. The results (PL IV, B) are tabulated below: Results of nail tests of four No. 6 electric detonators. Kind of electric detonator. Test No. Angle of bending resulting from trial No. Average. Minimum. 1 2 3 4 5 Western Coast... M286 M287 M288 M300 24.2 21.4 24.4 20.6 20 16 23 17 22 16 23 17 24 35 24 31 20 17 25 18 28 16 24 19 27 23 26 18 Special P. T. S. S Foreign 52 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. . RATE-OF-DETONATION TESTS. Rate-of-detonation tests similar to those with, the different grades of P. T. S. S. electric detonators were conducted with the four No. 6 electric detonators. The results, according to the explosive used, are presented below. TESTS WITH AN EXPLOSIVE OF CLASS 1, SUBCLASS . Following are the results of tests with an explosive of class 1, sub- class a (an ammonium-nitrate explosive containing a sensitizer that is itself a sensitizer) . The diameter of the cartridges used was seven- eighths of an inch. Results of rate-of -detonation tests with an explosive of class 1, subclass a. Kind of electric detonator. Test No. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. Indi- Aver- vidual age rate. rate. Indi- vidual rate. Aver- age rate. Indi- vidual rate. Aver- age rate. Indi- vidual rate. Aver- age rate. Western Coast f D970 \ D971 {D976 D978 D979 j D966 \ D967 / D974 i D973 Meters Meters per per second, second. 2,343 1 2 o, n 2,295 / 2 ' 319 1,891 1 2,419 \\ 2,234 2,393 J 2,445 \ o 4,3 2,472 / Z' 45 * 2,778 X o 4^ 2,143 || 2>46C Meters per second. f 2,295 \ 2,250 (2,296 2,393 2,206 f 2,678 \ 2,586 / 1,814 \ 2,393 Meters per second. J 2,272 I 2,298 | 2,632 } 2,104 Meters per second. I 2,585 \ 2,556 {2,761 2,459 2,419 ( 2,205 \ 2,205 / 2,795 \ 2,866 Meters per second. } 2,570 I 2,546 } 2,205 } 2,830 Meters per second. 1 2,445 1 2,406 ( 2,368 \ 2,432 ( 2,356 f 2,368 \ 2,356 / 2,459 \ 2,528 Meters per second. j- 2,426 1 2,385 ) 2,362 } 2,494 Special . P.T.S. S Foreign Grand average 2,393 2,326 2,538 2,417 The average rate for the meter length was practically uniform, but such difference as was shown indicated that the ascending order of explosive efficiency of the detonators is as follows: P. T. S. S., spe- cial, Western Coast, foreign. The percentage of complete detonations with each detonator was as follows: Percentage of complete detonations with an explosive of class 1, subclass a. Number of Kind of electric detonator. Number of tests. tests in which in- complete detonation Percentage of com- plete de- tonations. occurred. Per cent. Western Coast 2 100 Special 5 100 P. T. S.S 2 o 100 Foreign 3 1 67 TESTS OF FOUR NO. 6 ELECTRIC DETONATORS. TESTS WITH AN EXPLOSIVE OF CLASS 1, SUBCLASS &. Two rate-of-detonation tests were made of each of the four kinds of No. 6 electric detonators on an explosive of class 1, subclass 6 (an ammonium-nitrate explosive containing a sensitizer that is not itself an explosive) being used. The cartridges used were If inches in diameter. In no test did detonation occur, so that the tests failed to discriminate between the different kinds of electric detonators. TESTS WITH A 20 PER CENT " STRAIGHT" NITROGLYCERIN DYNAMITE. The results of tests with a 20 per cent " straight" nitroglycerin dynamite are presented below. The diameter of the cartridges was seven-eighths of an inch. Results of rate-of-detonation tests with a 20 per cent "straight" nitroglycerin dynamite. Kind of electric detonator. Test No. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. Indi- vidual rate. Aver- age rate. Indi- vidual rate. Aver- age rate. Indi- vidual rate. Aver- age rate. Indi- vidual rate. Aver- age rate. Western Coast / D996 \ D997 t D998 \ D999 (D1000 \D1002 / D994 \ D995 Meters per second. 2,778 3,462 3,048 3,299 3,729 3,947 2,922 3,000 Meters per second. } 3,120 } 3,174 } 3,838 } 2,961 Meters per second. I 2,960 I 2,679 / 2,928 \ 2,587 ( 2,683 \ 2,443 / 3,125 \ 2,557 Meters per second. j-2,820 } 2,758 } 2,563 }2,841 Meters per second. I 3,147 \ 3,285 / 3,069 \ 3,027 / 2,767 \ 3,309 / 2,866 \ 3,061 Meters per second. } 3,216 | 3,048 } 3,038 } 2,964 Meters per second. / 3,000 I 3,147 / 3,027 \ 2,967 f 2,933 \3,158 / 2,941 \ 2,903 Meters per second. } 3,074 } 2,997 } 3,046 [ 2,922 Special P. T. S S Foreign Grand average 3,273 2,746 3,066 3,010 The figures representing the grand averages indicate that the rate was influenced by a negative acceleration in the second quarter meter followed by a positive acceleration in the second half meter. This acceleration occurred in all tests except D996 and D994. The uniformity of the rates for the last half meter and the meter is noteworthy. With a 20 per cent "straight " nitroglycerin dynamite such difference as was shown in the tests indicated that the ascending order of ex- plosive efficiency is: Foreign, special, P. T. S. S., Western Coast. TESTS WITH A 40 PER CENT STRENGTH AMMONIA DYNAMITE CON- TAINING NITROSUBSTITUTION COMPOUNDS. Following are tabulated the results of tests with a 40 per cent ammonia dynamite containing nitrosubstitution compounds. The explosive was repacked in cartridges seven-eighths of an inch in diameter. 54 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. Results of rate-of-detonation tests with a 40 per cent strength ammonia dynamite contain- ing nitrosubstitution compounds. Kind of electric detonator. Test Xo. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. Indi- vidual rate. Aver- age rate. Indi- vidual rate. Aver- age rate. Indi- vidual rate. Aver- age rate. Indi- vidual rate. Aver- age rate. Western coast Special... /D913 \D923 f D879 \D914 [D904 \ D919 ID920 /D912 \D922 Meters per second. 2,557 3,082 2,820 2,587 2,368 2,472 2,250 2,250 2,616 Meters per second. \ 2,820 } 2,704 t 2,363 | 2, 433 Meters per second. / 2,394 \ 2,500 / 2,588 \ 2,781 (2,296 3,041 2,446 / 3,129 \ 3,125 Meters per second. } 2,447 j- 2,684 I 2,594 } 3, 127 Meters per second, i 2,812 \ 2, 616 J 2,900 \ 3,048 f 2,572 \ 2,663 I 2,543 / 2,446 \ 2,557 Meters per second. } 2,714 \ 2,974 I 2,593 j- 2,502 Meters per second. ( 2,632 \2,687 / 2,794 \ 2,853 | 2,446 \ 2,695 I 2,439 / 2,528 \ 2, 542 Meters per second. | 2,660 \ 2,824 1 2,527 j 2,535 P. T. S. S Foreign The rate for the second quarter meter was the highest for the P. T. S. S. and the foreign electric detonators. With a '40 per cent strength ammonia dynamite containing nitro- substitution compounds the tests indicated that the ascending order of explosive efficiency is: P. T. S. S., foreign, Western Coast, special. TESTS WITH A 35 PEE CENT STRENGTH GELATIN DYNAMITE 2 YEARS OLD. The results of tests with a 35 per cent strength gelatin dynamite (two years old) are tabulated below. The diameter of the cartridges used was 1J inches. Results of rate-of-detonation tests with a 35 per cent strength gelatin dynamite two years old. Kind of electric detonator. Test No. Length a of part of file blown off or de- tonated. Percent- age of file that de- tonated. Average. Remarks. Western Coast ( D897 Inches. 7.0 Per cent. 17 Per cent. \ 18.0 /Partial detonation. Special \ D898 / D901 8.0 10.0 19 24 J \ 22.5 \ Do. f Do. P T S S \ D902 ( D889 I D896 9.0 7.0 18.0 21 43 / J27.5 \ Do. [No detonation. < Partial detonation Foreign I D958 / D899 17.0 6.0 40 14 . > 15.5 1 Do. / Do- \ D900 7.0 17 / \ Do. o Full length of file, 42 inches. The evidence of no detonation in test D889 was that nothing but the noise of the electric detonator was audible when the trial was made. TESTS OF FOUR NO. 6 ELECTRIC DETONATORS. 55 With the two-year-old sample of 35 per cent strength gelatin dynamite used the tests indicated that the ascending order of ex- plosive efficiency is: Foreign, Western Coast, special, P. T. S. S. The percentage of partial detonations with each electric detonator was as follows: Percentage of partial detonations with a 85 per cent strength gelatin dynamite two years old. Kind of electric detonator. Number of tests. Number of tests in which partial detonation occurred. Percentage of complete detona- tions. Western Coast 2 2 Per cent. 100 Special 2 2 100 P. T. S. S 3 2 67 Foreign 2 2 100 TESTS WITH A 40 PER CENT STRENGTH GELATIN DYNAMITE, FROZEN. Following are the results of tests with a 40 per cent strength gelatin dynamite (frozen). The diameter of the cartridges used was 1J inches. Results of rate-of-detonation tests with a 40 per cent strength gelatin dynamite, frozen. Kind of electric detonator. Test No. Rate of detonation in tube. First quarter. Second quarter. Second half. Full length. "Western Coast D1091 D1092 D1093 D1090 Meters per second. 3,273 4,167 4.167 3,090 Meters per second. 7,177 6,357 7,759 14,833 Meters per second. 5,705 6,013 6,522 5,361 Meters per second. 5,028 5,460 5,921 5,235 Special P. T. S. S Foreign Grand average 3,674 9,032 5,900 5,411 The figures included in the " grand average " show that the maxi- mum, rate occurred in the second quarter, with a subsequent falling off in the rate; moreover, the rate varied similarly in each individual test. With the explosive used in the tests the results indicate that the ascending order of explosive efficiency is: Western Coast, foreign, special, P. T, S. S. TESTS WITH A 35 PER CENT STRENGTH GELATIN DYNAMITE 3 YEARS OLD. One test each of the Western Coast, the special, and the foreign No. 6 electric detonators was made with a 35 per cent strength gela- tine dynamite 3 years old. The diameter of the cartridges used was 1J inches. No detonation took place in any of the tests, as the explosive was so old and insensitive to detonation that for the pur- pose of discriminating between detonators it was useless. 56 INVESTIGATIONS OF DETONATOES AND ELECTRIC DETONATORS. SMALL LEAD BLOCK TESTS. Small lead block tests were made with the four No. 6 electric detonators. The results, according to the explosive tested, are given below. TESTS WITH A 20 PER CENT " STRAIGHT" NITROGLYCERIN DYNAMITE. Three series of tests were conducted with a 20 per cent " straight" nitroglycerin dynamite in different conditions as indicated below. Results of small lead block tests with a 20 per cent "straight" nitroglycerin dynamite with 6 per cent of added water. Kind of electric detonator. Test No. Compres- sion. Average compres- sion. Western Coast ( B759 \ B768 Mm. 15.00 14.75 Mm. 115.00 Special I B777 | B760 1 B769 15.25 14.00 15 25 I 14 83 P. T. S. S I B778 | B761 ! B770 15.25 15.00 15.00 I 115 00 Foreign I B779 | B758 \ B767 15.00 14.25 14.75 (14.67 I B776 15.00 In the tests the explosive produced nearly uniform individual com- pressions and little difference in the average compressions, but such difference as was shown indicated that the ascending order of explosive efficiency is: Foreign, special, Western Coast, P. T. S. S. The results of tests with the same explosive, but containing 4 per cent of added water and frozen, were as follows : Results of small lead-block tests with a 20 per cent "straight" nitroglycerin dynamite con- taining 4 per cent of added water and frozen. Kind of electric detonator. Test No. Tempera- ture of frozen explosive. Percentage of water added. Compres- sion. Average compres- sion. Western Coast... B651 <7. -9.0 4.0 Mm. 12.75 Mm. 12.75 Special B652 9.0 4.0 12.50 12.50 P T S S B653 9.0 4.0 13 00 13.00 Foreign B650 9.0 4.0 12.75 12. 75 With the explosive in the condition mentioned, the results of the tests indicate that the ascending order of explosive efficiency is: Special, Western Coast, foreign, and P. T. S. S. Further tests were conducted with 6 per cent of water added to the explosive and the explosive frozen (temperature 9 C.)- Three tests were made with each of the four grades of electric detonators, but the explosive was too insensitive to detonation to be discrimi- native, as no compression of any of the blocks was produced. TESTS OF FOUR NO. 6 ELECTRIC DETONATORS. 57 TESTS WITH A 40 PER CENT STRENGTH AMMONIA DYNAMITE. Following are the results of tests with a 40 per cent ammonia dynamite, to which had been added 6 per cent of water: Results of small lead block tests with a 40 per cent strength ammonia dynamite containing 6 per cent of added water. Kind of electric detonator. Test No. "H-IF Western Coast B660 Mm. Mm. 8.25 I Special - B669 B678 B687 B696 B661 9.00 9.00 I 8.75 8.00 9.50 J 8.00 1 p T S S , B670 B679 B688 B697 B662 8.25 8.50 1} 8.40 7.75 9.25 J 9.75 B671 B680 B689 B698 B659 8.75 9.25 8.95 7.75 9.25 8.00 | B668 B677 B686 B695 10.00 9.25 ^ 9.20 9.50 9.25 J The results were obviously erratic. However, the tests indicated that the ascending order of explosive efficiency is: Special, Western Coast, P. T. S. S., foreign. TESTS WITH A 40 PER CENT STRENGTH GELATIN DYNAMITE, FROZEN. The results of tests with a 40 per cent strength gelatin dynamite (frozen) were as follows (PL V, B) : Results of small lead block tests with a 40 per cent strength gelatin dynamite, frozen. Kind of electric detonator. Test No. Tempera- ture of frozen explosive. Compres- sion. Average compres- sion. Western Coast B635 C. -2.5 Mm. 14.75 Mm. Special B642 B705 B714 B723 B636 -5.0 + .5 +2.5 +2.5 -2.5 17.75 12.50 12.50 12.00 12.75 13.90 P T S S B643 B706 B715 B724 B631 -5.0 + .5 +2.5 +2.5 -4.5 18.00 15.00 14.75 13.75 12.50 14.85 B644 B707 B716 B725 B634 -5.0 + -5 +2.5 +2.5 -2.5 19.25 14.25 14.25 14.50 11.00 14.95 B641 B704 B713 B722 -5.0 + .5 +2.5 +2.5 18.00 15.00 16.25 15.50 I 15. 15 58 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. As indicated by the table, the results of the tests were very erratic with this frozen gelatin dynamite. The insensitiveness of this explo- sive has been mentioned in a foregoing section regarding the incom- pleteness of detonation in tests with the Nos. 3, 4, and 5 electric deto- nators. With the No. 6 electric detonators, however, detonation was complete in every trial. EXPLOSION-BY-INFLUENCE TESTS. Tests involving explosion by influence as outlined in a foregoing section relative to tests of different grades of P. T. S. S. electric deto- nators were made of the four kinds of No. 6 electric detonators, as described below: TESTS WITH AN EXPLOSIVE OF CLASS 1, SUBCLASS a. Following are the results of tests with an explosive of class 1, sub- class a (an ammonium-nitrate explosive containing a sensitizer that is itself an explosive). The size of the cartridges used was 1J by 8 inches and the average weight was 166 grams. Results of explosion-by-inftuence tests with an explosive of class 1, subclass a (sample 1). Kind of electric detonator. Test No. Distance separating cartridges. Result on upper cartridge. Established distance at which deto- nation did not occur. Western Coast J758 Inches. 2 Did not explode. . . Inches. } J759 J760 1 2 Exploded Did not explode \ Special J761 1 Exploded P T S S J762 J763 J741 2 2 4 Did not explode do do 2 J742 3 ...do... J743 2 do J744 1 Exploded 3 J745 2 do ... J746 3 Did not explode Foreign J753 3 ...do... J754 2 do J755 J756 J757 1 1 do Exploded Did not explode 1 With the ammonium-nitrate explosive used, the results of the tests indicated that the ascending order of explosive efficiency is : Foreign, Western Coast and special, P. T. S. S. TESTS WITH AN EXPLOSIVE OF CLASS 4, The results of tests with an explosive of class 4 (an explosive in which the characteristic material is nitroglycerin) are tabulated below. The size of the cartridges used was 1J by 8 inches, their average weight being 161 grams, except that in the trials under test J896 the upper cartridge weighed 110 grams and was 5 inches long. TESTS OF FOUR NO. 6 ELECTRIC DETONATORS. 59 Results of explosion-by-inftuence tests with an explosive of class 4- Kind of electric detonator. Test No. Distance separat- ing car- tridges. Result on upper cartridge. Western Coast . J895 Inches. 5 Exploded. Special J895 J895 J895 J896 J896 J896 J895 5 5 5 4 4 4 5 Did not explode. Do. Do. Exploded. Do. Did not explode. Exploded. p. T. S. S J895 J895 J895 J896 J896 J896 J895 5 5 5 4 4 4 5 Did not explode. Do. Do. Exploded. Do. Did not explode. Do. Foreign J895 J895 J895 J896 J896 J896 J895 5 5 5 4 4 4 5 Do. Do. Exploded. Do. Do. Did not explode. Do. J895 J895 J895 J896 J896 J896 5 5 5 4 4 4 Do. Do. Do. Do. Do. Do. Percentage of explosions of the upper cartridge in explosion-by-inftuence tests with an explosive of class 4. Kind of electric detonator. Number of tests. Number of explosions of cartridge. Percentage of explo- sions of upper cartridge. Western Coast . . 7 3 Per cent. 43 Special 7 3 43 p. T. S. S 7 3 43 Foreign 7 In all tests in which the distance separating cartridges was 5 inches the bottoms of the cartridges (as packed) faced each other; in all tests in which the distance was 4 inches the tops of the cartridges faced each other. The tests indicated that the foreign electric detonator was not as effective under the conditions of the tests as were the other three. TESTS WITH A 40 PER CENT STRENGTH AMMONIA DYNAMITE CONTAIN- ING NITROSUBSTITUTION COMPOUNDS. Following are the results of tests with a 40 per cent strength ammonia dynamite containing nitrosubstitution compounds. The cartridges used measured 1J by 8 inches and their average weight was 226 grams. 60 INVESTIGATIONS OF DETONATORS AND ELECTRIC DETONATORS. Results of explosion-by-influence tests with a 40 per cent strength ammonia dynamite con- taining nitrosubstitution compounds. Kind of electric detonator. Test No. Distance separating cartridges. Result on upper cartridge. Distance at which detonation did not occur. Western Coast J714 Inches. g Exploded Inches. J715 9 Did not explode 9 J716 9 do [ Special J717 g do J718 7 Exploded g J719 g Did not explode. . . P. T. S. S . ... J689 14 . do... J690 12 do J691 g do . J692 7 do J693 g do J694 4 Exploded 8 J695 5 do . J696 6 ..do J697 7 do J698 g Did not explode J699 g do Foreign J711 g .. do I J712 7 Exploded I g J713 g Did not explode... J The tests show practically the same result regardless of the electric detonator used. TESTS WITH A 35 PER CENT STRENGTH GELATIN DYNAMITE 2 YEARS OLD. The results of tests with a 35 per cent strength gelatin dynamite (two years old) are tabulated below. The cartridges used were 1 J by 8 inches, their average weight being 265 grams. Results of explosion-by -influence tests with a 35 per cent strength gelatin dynamite (two years old). Kind of electric detonator. Test No. Distance separating cartridges. Result on upper cartridge. Western Coast J734 Inches. Did not explode. Special J735 J737 o Do. Do. P. T. S. S... J738 J724 6 Do. Do. Foreign J725 J726 J727 J728 J729 J736 5 4 2 o Do. Do. Do. Do. Do. Do. J739 Do. TESTS OF FOUR NO. 6 ELECTRIC DETONATORS. 61 These tests failed to discriminate between the different detonators, as in no trial did the explosion of the lower cartridge cause the detona- tion of the upper cartridge. TBAUZL LEAD BLOCK TESTS/* In testing the four kinds of No. 6 electric detonators the Trauzl lead block tests were used in addition to the tests previously described. The Trauzl lead blocks are cylindrical in shape, measuring 200 mm. in diameter and 200 mm. in height. They have an axial bore hole 25 mm, in diameter and 125 mm. in depth. The charge of 20 grams of the explosive in which the electric detonator was embedded was placed in the bottom of the bore hole and no stemming was used. The increase in the volume of water that the bore hole would contain after an explosion was the result recorded. Following is a tabulation of results of Trauzl lead block tests in which a 20 per cent "straight" nitroglycerin dynamite was used. The charge of explosive in each test was 20 grams, to which was added 6 per cent of water. Results of Trauzl lead block tests with a 20 per cent "straight" nitroglycerin dynamite. Kind of electric detonator. Test No. Expansion. Average expansion. Western Coast i A817 C.c. 175 C.c. Special \ A818 / A819 173 177 174 p. T. S. S \ A821 f A822 176 178 I7B Foreign ... V A824 / A815 175 178 171 \ A816 179 178 As indicated by the table, the average expansion of the blocks in each test was nearly the same. PERCENTAGES OF DETONATIONS IN INDIRECT TESTS OF FOUR KINDS OF NO. 6 ELECTRIC DETONATORS. The percentages of detonations in the indirect tests of the four kinds of No. 6 electric detonators are given below. The percentages of detonations in the tests of each electric detonator are also aver- aged, each average percentage having a value proportional to the number of tests from which it is computed; that is, each percentage is multiplied by the number of tests it represents and the sum of the products is divided by the total number of tests of the electric deto- nator considered. a For a more extended description of this test see Bull. 15, Bureau of Mines: Investigations of explosives used in coal mines; with a chapter on the natural gas used at Pittsburgh, by G. A. Burrell, and an intro- duction by C. E. Munroe, by Clarence Hall, W. O. Snelling, and S. P. Howell, 1912, pp. 114-110, 62 INVESTIGATIONS OF DETONATOKS AND ELECTRIC DETONATORS. Percentages of detonations in indirect tests of four kinds of No. 6 electric detonators. Western Coast. Special. P.T.S.S. Foreign. Class and grade of explosive. Character of test. Per- centage of deto- nations. Num- ber of tests. Per- centage of deto- nations. Num- ber of tests. Per- centage of deto- nations. Num- ber of tests. Per- centage of deto- nations. Num- ber of tests. Per ct. Per ct. Per ct. Per ct. Class 1, subclass a Rate of det- 100 2 100 5 100 2 67 3 (sample 1). onation. 40 per cent strength do 100 1 100 1 100 1 100 1 gelatin dynamite 35 per cent strength gelatin dynamite (2 years old). do 100 2 100 2 67 3 100 2 20 per cent "straight " nitroglycerin dyna- mite (frozen and con- Small lead block. 3 3 3 3 taining 6 per cent of added water). 40 per cent strength gelatin dynamite do .. 100 5 100 5 100 5 100 5 (frozen). 55 5 71.4 63 2 61 1 Total number of tests 18 21 19 18 COMPARATIVE EXPLOSIVE EFFICIENCY. The percentage of explosive efficiency of the four kinds of No. 6 electric detonators was obtained by averaging all tests in which the rate of detonation, compression, or expansion was determined for all detonators. Each percentage was given a value proportional to the number of tests from which the percentage was computed. In each case the percentage of explosive efficiency of the P. T. S. S. No. 6 electric detonator is given a value of 100 and is taken as the unit of comparison. TESTS OF FOUR NO. 6 ELECTRIC DETONATORS. 63 Kind of electric detonator. i I s?sa^ jo jaqmn^ $$ -O|dx9 jo gSB^uaojaj . ^ CT> CO 5 *< J-l 00 T-I CO 00 r-H IN uojsiredxa g ; : * : : '. ?S S : : : : : uoTssojdraoQ | : : 5 j? J2g : !^ -^ I A"OU8TOnj9 9 ATS -Ojdxa JO aitelUaOja^ Tt< oo o oa coo> o* coos o M) uoisuBdxg; ,$g : : : : : : : : : 8 g: : :: :: : ::"' uotssajduioo ^ ' -^ (N V OO e,,H g 8 5 ffi S "^ : : : |fc*" " SJ * ; | ; j i Western Coast. S1S8UO J9qmn N CM CS