UC-NRLF 15 7fl4 Cents, IATERIALS Tte PiianoiR8R8 and Theories of Exlosiosi > THK : , | -; - . ; ,' ; ..^a EditrSon, Revised aktt Knlarged NEW TOEK D, VAN NOSTRAND COMPANY ; MURRAY AND 27 WARREN STIU 1907 from the French of A. Mallet. Second edition, revised with results of American Practice, by Richard H. Buel, C.E. *No. 11. THEORY OF ARCHES. By Prof. W. Allan./ I No. 12. THEORY OF VOUSSOIR ARCHES. By Prof. Wm. Cain. Third edition, revised and enlarged. THE VAN NOSTRAND SCIENCE SERIES No. 13. GASES MET WITH IN COAL MINES. By J. J. Atkinson. Third edition, revised and enlarged, to which is added The Action of Coal Dusts by Edward H. Williams, Jr. No. 14. FRICTION OF AIR IN MINES. By J. J. Atkinson. Second American edition. No. 15. SKEW ARCHES. By Prof. E. W. Hyde, C.E. Illustrated. Second edition. No. 16. GRAPHIC METHOD FOR SOLVING Certain Questions in Arithmetic or Algebra. By Prof. G. L. Vose. Third edition. *No. 17. WATER AND WATER-SUPPLY. By Prof. W. H. Corfield, of the University College, London. Second American edition. No. 18. SEWERAGE AND SEWAGE PURHI- cation. By M. N. Baker, Associate Editor "Engineer- ing News." Fourth edition, revised and enlarged. No. 19. STRENGTH OF BEAMS UNDER Transverse Loads. By Prof. W. Allan, author of "Theory of Arches." Second edition, revised. No. 2O. BRIDGE AND TUNNEL CENTRES. By John B. McMaster, C.E. Second edition. No. 21. SAFETY VALVES. By Richard H. Buel, C.E. Third edition. No. 22. HIGH MASONRY DAMS. By E. Sher- man Gould, M. Am. Soc. C.E. Second edition. No. 23. THE FATIGUE OF METALS UNDER Repeated Strains. With various Tables of Results and Experiments. From the German of Prof. Ludwig Spangenburg, with a Preface by S. H. Shreve, A.M. No. 24. A PRACTICAL TREATISE ON THE Teeth of Wheels. By Prof. S. W. Robinson. Third edition, revised, with additions. No. 25. THEORY AND CALCULATION OF Cantilever Bridges. By R. M. Wilcox. No. 26. PRACTICAL TREATISE ON THE PROP- erties of Continuous Bridges. 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Revised by Prof. J. E. Denton, D. S. Jacobus, and A. Riesenberger. Sixth edition, revised. EXPLOSIVE MATERIALS The Phenomena and Theories of Explosion AND THE CLASSIFICATION, CONSTITUTION AND PREPARATION OF EXPLOSIVES BY COLONEL JOHN P. WISSEE COAST ARTILLERY CORPS Military Attache to the American Embassy in Berlin Second Edition, Revised and Enlarged NEW YORK D. VAN NOSTRAND COMPANY 23 MUBBAY AND 27 WABBEN SlBEETS 1907 Copyright 1898, 1907, BY D. VAN NOSTBAND COMPANY PREFACE. THE first edition of this number of Van Nostrand's Science Series having become exhausted, it became necessary, in order to keep the series complete, to issue a new edition. But in the fifteen years which have elapsed since the appearance of the first edition, many changes have taken place in the views regarding the phenomena of explosions, and many new explosives have attracted the world's at- tention, particularly the important class of smokeless powders. Therefore, since the theory advanced by Berthelot no longer accounts for all the known phe- nomena, it was deemed best by the pub- lishers to have the entire number re- written. The present volume is the result of this decision. The subject-matter is based on the original essay of Berthelot, and suck 360390 IV PREFACE. matter has been added, as it is believed, will render the little work more generally useful. We are indebted to Prof. J. P. Cooke of Harvard University for the first clear explanation of the action of explosive compounds, and for directing attention to the necessity for studying structural for- ulse in this connection. The few pages devoted to the subject of explosives in the~new work of Professor Tillman of the U. S. Military Academy, present the sub- ject in simple language, but in a most satisfactory way, especially as regards the distinctions between the classes of explo- sive compounds. But the greatest author- ity on explosives in this country is prob- ably Professor C. E. Munroe, formerly of the U. S. Naval Torpedo Station, now of Columbia University, Washington, D. C. Traces of his work are evident in all the later literature on the subject, and much of the interest in the field of explosives in this country was inspired by his labors. Lieutenant Walke, in charge of the De- partment of chemistry and explosives at PREFACE. V the U. S. Artillery School, has embodied the gist of Professor Munroe's lectures in the new edition of his work, which has, besides, excellent descriptions of the latest processes of manufacturing the principal explosives. The dictionary of Lieutenant- Colonel J. P. Cundill, R. A. (now in its second edition) is, of course, invaluable in the study of the latest forms of smokeless and other powders, and we were fortunate, too, in learning the views of Professor Mendeleef on explosives, through the Proceedings U. S. Naval Institute, Revise d' Artillerie and Arms and Explosives. The author, therefore, desires to express his obligations to the following works, besides the original volume (No. 70) of this series. The New Chemistry. Prof. J. P. Cooke, Jr. D. Appleton & Co. Descriptive General Chemistry. Prof. S. E. Tillman, U. S. Military Academy. Lectures on Chemistry and Explosives. Prof. Charles E. Munroe, Naval Torpedo Station. Lectures on Explosives. Lieut. W. Walke, U. S Artillery School. Wiley & Sons. VI PREFACE. Ordnance and Gunnery. Gapt. L. L. Bruff, U. S. Military Academy. Wiley & Sons. Dictionary of Explosives. Lieut. - Col. J. P. Cundill, R. A. London : Eyre & Spottiswoode. Militaer - Wochenblatt. Mittler u. Sohn, Berlin. Proceedings U". S. Naval Institute. Annapolis, Md. Revue d* Artillerie. Paris, France. Arms and Explosives. London, England. J. P. W. FORT MONROE, VA., March 8, 1898. EXPLOSIVE MATERIALS. An explosive, in the most general sense, is a substance capable of a sudden and considerable increase of volume. This increase of volume may be the re- sult of purely physical changes, or both physical and chemical changes. The expansion of gases by heat, the ex- plosive action of which is exemplified in the bursting of boilers ; the expansion of gases by diminution of pressure in the surrounding medium, illustrated in the cyclone, when the low barometer area passes over a closed house ; the bursting of iron shells by the freezing of water confined in them ; and many similar phe- nomena are examples of explosive effects purely physical in character. The explosion of an explosive mixture of gases is the simplest example of both chemical and physical action, the gases first combining chemically, then the heat produced by this chemical action expand- ing the resulting gas or gases physically. The explosion of gunpowder, guncotton or nitroglycerine involves, in addition, the physical change of state from solid or liquid to gas. Explosive materials or Explosives, in a restricted sense, are substances capable of a sudden and great increase of volume, due to a change of state from solid or liquid to gas, accompanied by chemical action resulting in the evolution of great heat, the latter aiding in increasing the original volume by expanding the gases produced. Explosive materials may be divided into three classes : I. Compounds. II. Mixtures, containing nitro-com- pounds or organic nitrates. III. Mixtures, containing no nitro-com- pounds nor organic nitrates. Chemical action takes place only at in- finitely short distances. Now, the chemi- cal molecules of substances are infinitely smaller than the smallest particles into which substances can be mechanically divided, and since, in the case of com- pounds, reaction takes place between the atoms of each molecule, we have the most favorable conditions (in this respect) pos- sible. In mechanical mixtures of any kind, however finely divided the ingredi- ents may be, their particles are still of ap- preciable size, and very large as compared with molecules. Now, in the case of explosives of the second class the reac- tions take place partly "between the atoms of the same molecules, and partly between the atoms of different molecules, in the former the reacting atoms being at infin- itely small distances apart, in the latter all except those at and near the surfaces of contact of the different particles being at considerable distances apart; hence/ the conditions are less favorable than in case of plain compounds. Finally, in the case of explosives of the third class, the essential reaction takes place entirely be- tween elements of different substances; hence, the conditions are the least favor- able. Explosives are also classified as liigli ex- plosives and low explosives, the former in- cluding those in which the chemical action is rapid and energetic, the latter those in which the action is relatively slow ; one producing a crushing or shattering effect, the other a propelling or pushing effect. Technically, the high explosives comprise the first two classes of explosive materials, the low explosives the third class, but the terms are merely relative, ordinarily, so that the chlorate group of the third class may be regarded as high when compared with the nitrate group, whereas some of the modern smokeless powders, since they are fit for use in cannon and small-arms, although containing high explosive in- gredients, are themselves low explosives. THE PHENOMENA OF EXPLOSION. The various explosives differ greatly in force of explosion, and even in the same explosive the force is modified by the physical condition of the explosive, the external conditions surrounding the ex- plosive, and the method of initial inflam- mation. In all cases where the chemical reac- tions are accurately known, the following data are required to define the action of the explosive : 1. The cliemical composition of the ex- plosive. 2. The chemical composition of the prod- ucts of explosion at every step (includ- ing dissociation). 3. The rapidity with which the action takes place, comprising both the rapidity of changes at the origin of the reactions and the rapidity of propagation of the reactions (including explosion by in- fluence). In all cases where the chemical reac- tions are not accurately known, the fol- lowing data are required to define the ac- tion of the explosive : 1. The quantity of heat given off during the reaction. 6 2. The volume of the gases formed (meas- ured under normal pressure). 3. The rapidity with which the reaction takes place, comprising both the rapid- ity of changes at the origin of the reactions, and the rapidity of propa- gation of the reactions (including ex- plosion by influence). CHEMICAL COMPOSITION OF EXPLOSIVES. The characteristic features common to all explosives are their instability and their capacity to form very rapidly a large volume of gaseous products. Their in- stability is due to the fact that the ele- ments present are not combined with one another according to their greatest affini- ties, a condition which leads to their easy and rapid decomposition with little loss of heat, while their capacity to form rapidly a a large volume of gaseous products de- pends on their rapid decomposition, on the fact that the elements tend to re-combine according to their greatest affinities, there- fore giving off great heat, and on the fact that the products are gaseous, and are expanded by the resultant heat. In the case of explosive gases, or mix- tures of gases, there is no change of state, but in all ordinary explosives there is a change of state from liquid or solid to gas, which* still further increases the effect. All ordinary explosives, except a few of the chlorate class of mixtures, contain ni- trogen, an element of very feeble affini- ties, and to it their instability is largely due, but is also increased by the fact that other elements present are not combined according to their greatest affinities. In the chlorates the weak element is the chlorine, not because it is generally a weak element for it is on the contrary usually a very strong element, but be- cause in these compounds it is united ac- cording to its weakest affinity, that is with oxygen. The foregoing considerations are suffi- cient to explain the explosion of the binary nitrogen compounds. But, all explosives, which have received 8 important practical application, have in addition to the element of instability, ni- trogen (or chlorine in the chlorates), the oxidizable elements carbon and hydrogen (or carbon alone) and oxygen. Explo- sion in such cases is really a form of com- bustion, the reaction being very energetic and rapidly propagated. In explosive compounds these elements are all present in the molecule, but combined in a manner not according to their greatest affinities, and in order to understand the action in their explosion it is necessary to study their structural formulae. Thus, the explosion of tetra - nitro - naphthalene may be represented by the following equation: C IO H 4 (N O 2 ) 4 = 2H 2 + 6CO + 4CN, but this reaction in itself does not explain the production of heat, because true simple decomposition (not complicated by further recomposition) always absorbs heat, and if the elements were combined, and their affinities satisfied in the original compound exactly as they are in the products then cold would be the result of tlie change and not heat. The structural formula, however, makes all this clear. 0=-N=0 0=N=O -< 0=N=O O=N=O The oxygen atoms are not united di- rectly to either hydrogen or carbon atoms 5 indeed, they are removed as far as possible from the hydrogen atoms (for which their affinity in this molecule is greatest), and are connected with the carbon atoms (their next greatest affinity) only through an atom of nitrogen (for which they have the least affinity). When explosion takes place the molecule is broken up, and 10 the oxygen atoms rush for the carbon and hydrogen atoms, their energy being made evident in the form of heat. In mixtures the oxidizable substance is usually one constituent and the necessary oxygen is usually contained in another con- stituent. The action in the case of mix- tures is" not only less energetic on account of the appreciable size of the minute par- ticles of the constituents (as compared with the molecules of compounds) and the consequent greater distance between reacting atoms, but is also slower because the molecules (or atoms in them) of the particles are removed from the surface of the particles in succession, the latter wearing away in successive layers as the the action continues. Hence, true mix- tures (those in which the principal reac- tion is between atoms of different mole- cules) are less energetic than true com- pounds, or than those mixtures containing nitrous or nitric derivatives, (in which the principal reaction is between atoms of the same molecule). The practically useful explosives are in 11 the liquid or solid state, and this for two- reasons, first, because they are easier to transport and handle, secondly, because the change of state to gas implies an increase in the increase of volume. In the case of true mixtures there is another advantage in the fact that a large quantity of oxygen,, available for the oxidation of the carbon or hydrogen, is concentrated in a very small volume (in the form of nitrates,, chlorates, etc.), resulting in greatly in- creased chemical activity when oxidation once begins, and a higher temperature is thus produced because the action takes place in a small space, and the heat evolved is better utilized in raising the temperature of the products; moreover, the oxygen atoms are probably separated from these compounds in the nascent state, that is, as separate atoms (O), with high combining power, and not as mole- cules (0=0), in which the affinity of the atoms is satisfied (in a low degree) by other atoms of the same kind, as it exists, in gaseous oxygen or atmospheric air. 12 THE ORIGIN OF THE REACTIONS. Every chemical compound is deter- mined by the kind, the number, and the arrangement of the atoms in its molecule. The molecules of all substances are in constant motion. Anything that increases the amplitude of the vibrations beyond a certain limit, breaks up the molecule. Thus, heat (a form of molecular motion) is one of the commonest agents used to decompose compounds; light (another form of molecular motion) decomposes compounds in photography and in vege- table life ; and finally, electricity (still another form of molecular motion) causes chemical decomposition in electrolysis. The origin of the chemical transforma- tion in explosion is always some force due to matter in motion, either the motion of the matter in mass, such as a shock, pres- sure or friction, or the motion of the molecules of bodies, such as heat, syn- chronous vibration (sound waves,) or vor- tex-ring motion. This motion, if motion in mass, is communicated to the molecules 13 of the explosive, is transformed into heat, and appears at the initial point as that effect of heat called temperature, every explosive having its particular temperature of explosion, which, however, varies with- in certain limits, depending on the rate at which the heat is communicated, substan- ces being able to exist at temperatures above their temperature of decomposition, but for a time which decreases as the tem- perature rises. If the motion be that of vibrations syn- chronous with those which would result from the explosion of the substance con- sidered, the latter being in a state of high chemical tension, it is communicated through space, without appreciable change of temperature at any particular point, to the molecules of the explosive, and either produces its explosion directly, or makes it more sensitive to the effect of shock, thus causing its explosion indirectly. If vortex motion is set up by explosion at one point, due to the fact that the sur- faces surrounding the explosion gases are more curved at some points than at 14 others, producing tlie greater strain at the points of greater curvature, then at short distances from the center of disturbance greater effects are produced in some direc- tions than in others, and these effects may again lead to explosion ; at considerable distances the effects tend to become uni- form in all directions. The last two actions explain sympa- thetic explosions, or explosions by influ- ence. The physical condition of an explosive has a great influence on the explosive re- action : thus, frozen nitro-glycerine can be fired only with great difficulty, and we$ guncotton requires a primer of dry gun- cotton. , THE RAPIDITY OF THE REACTIONS. The rapidity of the chemical reaction in explosion varies greatly in different ex- plosives, and even in the same explosive is much affected by various circumstances. The rapidity of the reaction increases with the temperature according to a very rapid law; it also increases with the pres- sure in the case of gaseous explosives; and finally, it depends upon the relative proportions of the components. The presence of an inert body since it absorbs heat and consequently lowers the temperature, without exerting any influ- ence to hasten the reaction, retards the actions. In this way the character of an explosive may be modified or entirely changed. When the speed of the reactions is not great, a portion of the heat is dissipated, and the rise of temperature soon ceases. This limit is that at which the loss of heat by radiation, conduction, etc. is equal to the gain due to the internal reactions. In this case the reaction takes place with a nearly constant rapidity, and does not be- come explosive, but produces what is called deflagration. Explosions resulting from simple spon- taneous decomposition are explained in the same way. A small mass of such a substance would merely decompose, but a large mass, since the heat produced inter- 16 nally might increase considerably while the loss of heat externally might not change materially, could have its temper- ature raised so as to produce explosion in- stead of simple decomposition. THE PROPAGATION OF THE REACTIONS. The explosive reactions in a homogene- ous gaseous mixture, surrounded by con- ditions of pressure and temperature iden- tical in all its parts, should, apparently de- velop instantaneously in all parts at once. But, as a matter of fact a certain amount of time is consumed in the process, and this time varies in different bodies. Now, in the ordinary case of explosives, the different parts of which are exposed to different conditions, such as those which arise from being ignited at one point or from a local shock, in order that the transformation may be propagated with explosive effect, it is necessary that the same physical conditions of tempera- ture, of pressure, etc. which prevail at the initial point, should successively be pro- 17 duced and propagated, molecule by mole- cule, through all portions of the mass. The rapidity of combustion of explo- sives depends to a great extent on the pressure of the air or the surrounding gases. Thus the velocity of the combus- tion of gunpowder in the open air is about 10 to 13 mm. a second, whereas in the bore of a gun it is about 230 mm. a sec- ond (Piobert).' The rapidity of progres- sive combustion of uncompressed guncot- ton is about eight times that of gunpowder (Piobert), therefore about 100 mm. a sec- ond, while that of compressed and deto- nated guncotton is about 5000 m. a second (Dr. Rudolf Blochman). In granulated mixtures, especially low explosives, the size of the grain has a great effect on the velocity with which the reactions are propagated. Finally, by varying the process used for originating the reactions any effect from quiet decomposition without flame to per- fect detonation may be produced, even in high explosives. 18 Generally, two kinds of explosion are distinguished : Explosions of the first order or detonation. Explosions of the second order, or ordinary explosion. All explosions are brought about by heat, synchronous vibrations or vortex motion. Heat may be applied directly as heat, or indirectly as a shock, which is converted into heat. The order of explo- sion if due to shock, depends on the in- tensity of the original shock, therefore, detonators consisting of small quantities of some violent explosive, are used to pro- duce explosions of the first order. In case of detonation by shock the pres- sures resulting from the shock are too rap- id to become uniformly dispersed through- out the entire mass, and the energy is transformed into heat in the first layers of the explosive ; these layers are deton- ated and the resulting gases produce a new shock on the next layer, raising its temperature and detonating it in the same way, and so on, the effect being thus prop- agated with great rapidity by the alternate 19 conversion of energy into heat and heat into energy. To produce detonation the initial velocity of decomposition must rise above a certain minimum value, and there is therefore a critical velocity of initial de- composition which determines the kind of reaction that ultimately takes place ; and there is a minimum temperature which some part of the explosive must reach in order to have detonation by heat or shock. In detonation by influence the explosive either takes up the vibrations of the deto- nator throughout its mass and thus deto- nates itself, or the vortex motion caused by differences in the surfaces surrounding the initial explosion, since its effects are greater in certain directions than in others, will detonate the explosive if it be in one of these paths of greater effect. Ordinary explosion results as follows: the portion of the substance first heated explodes, the gases by expansion are cooled, but still heat a small portion of the explosive to the temperature of explosion ; this then explodes, cooling again takes place, and so on. 20 The sensitiveness of an explosive is de- pendent on the individual structure of the explosive, on the conditions of heating, and on the method of propagation of the reactions j it is greatest for the same sub- stance at temperatures nearest to that at which the substance begins to decompose spontaneously; it depends, in different substances, on the cohesion of the sub- stance which governs the transformation of the shock into heat, on the temperature of decomposition, and on the quantity of heat set free by the decomposition. Thus, mercury fulminate detonates at a higher temperature than silver oxalate and at a lower one than nitrogen sulphide, yet it is much more sensitive to shock or friction than either of these substances. Celluloid, which does not detonate at or- dinary temperatures, acquires that prop- erty at a temperature approaching that at which it decomposes. The temperature of decomposition is lower for potassium chlorate than for the nitrate, and the former is the more sensitive. 21 THE PRODUCTS OF EXPLOSION. Equations representing explosions (lik$ all other chemical reactions) are not de- ductive, but are the result of observation and experiment. Nevertheless there are certain genera) principles which enable us to write out the equation that represents the principal reaction in the explosion, when we know the exact chemical composition of the components. In the explosion of compounds contain- ing carbon, hydrogen, oxygen and nitro- gen, we know that the hydrogen first takes all the oxygen it requires to oxidize to water vapor. If there be any excess of hydrogen it will combine with some of the carbon and form marsh gas ; if there be an excess of oxygen (above what is required by the hydrogen) it will combine with carbon and form carbon dioxide, if there be enough oxygen, or carbon mon- oxide, if there be no more oxygen than i& required to convert the carbon to this oxide, or both these oxides, if there be an 22 intermediate quantity o oxygen; if there l>e an excess of oxygen above that required by the hydrogen, but below that required to convert all the carbon into carbon mon- oxide, free carbon would be left, but this combines with nitrogen to form cyanogen, or with hydrogen to form marsh gas; if there be an excess of oxygen above that required to oxydise all the hydrogen to water vapor and all the carbon to carbon dioxide, it is given off in the free state; nitrogen is generally given off in the free state, but if there be an excess of carbon it may appear in part as cyanogen. Of course, some of the gaseous pro- ducts undergo dissociation at the tempera- tures produced by the explosions, but the fact that a material slowly decomposed at a given temperature is able to exist for a short time at much higher temperatures, prevents much dissociation from taking place. The abruptness of cooling imme- diately after explosion preserves these compounds from destruction, because it brings them to temperatures at which they are stable. 23 These principles are the basis of the preparation of certain of the explosive mixtures. Compounds which have a defi- ciency of oxygen are made more energetic in their explosive action by mixing them with some oxidizing agent; and com- pounds with an excess of oxygen can be advantageously mixed with those having a deficiency, or with some oxidizable sub- stance. The total quantity of heat given out in any chemical reaction is fixed, no matter what its rate, but the temperature to which the products are raised depends, among other things, on the specific heat of these products, hence, explosives whose products have a low specific heat have an advantage over those with a high one ; and since dissocation tends to lower the temperature, the more permanent the gases in the products the better. THE FORCE OF EXPLOSION. The force of explosion may be measured either by the pressure of the gases given off, or by the work done. The pressure of the gases depends upon their nature, their volume and their tem- perature. The work done depends upon the quan- tity of heat given off. The maximum work which an explosive is capable of doing, or its potential energy, is determined by multi- plying the number of units of heat given off by the mechanical equivalent of a unit of heat ; but it must be remembered that it is a limit which is never reached in practice, because there is always loss of Jieat as such, by conduction, radiation, etc., moreover, part of the work done is not useful work and is therefore lost. Pinally, much of the heat remains stored Tip in the gases that escape. To fully define the force of an explo- sion, however, after we consider both the pressures of the gases evolved and the i\rork which the heat given off is capable of doing, the following data are necessary ; 1. The chemical composition of the ex- plosive. 25 2. The chemical composition of the products of explosion at every step (including dissociation). 3. The quantity of heat given off dur- ing the reaction. 4. The volume of the gases formed (measured under normal pressure). 5. The rapidity with which the reac- tion takes place, comprising both the rapidity of the changes at the origin of the reactions, and the rapidity of propagation of the reactions (includ- ing explosion by influence). Of course, if the chemical reactions are positively known the third and fourth may be deduced from the first and second. The various kinds of explosives, based on the force of their explosion, are used for different purposes. Strong and very rapid explosives. Strong and very rapid explosives are used when it is desired to obtain principally breaking effects. In their case the elasticity of the mass acted upon has not time to come into play and the material is broken into small fragments. In their employment in 26 mining it is not necessary to tamp much because the pressure is communicated to the solid rock before the gases formed have time to drive away the compressed air. Fulminate of mercury and the stronger dynamites are the types of the strong and very rapid explosives. Strong and less rapid explosives. If the decomposition of strong and very rapid explosives be retarded a little, the poten- tial energy still remaining considerable, there will be a tendency to produce a tear- ing or shearing in the lines of least resist- ance, and when the tenacity is not great the result is dislocation without projection. These explosives are used in quarrying large blocks of rocks of great resistance. The weaker dynamites are the types of this class, but the stronger can also be used in case the block is outlined by a furrow with a central drill-hole, or by making the effect of successive small ex- plosions in the same chamber cumulative. Strong and slow explosives. Strong and slow explosives 'are used when it is de- 27 sired to break the material into as large pieces as possible, as in mining coal, or merely into a comparatively small number of pieces, as in the bursting of shell. The gradual increase of pressure is of advan- tage for some purposes, as in the displace- ment of earth. Ordinary gunpowder is the type of the strong and slow powders, but the modern mixtures containing high explosives are so varied in their qualities that all shades of effect can now be produced by them. The order of the explosives according to their respective strengths, or forces of explosion, varies considerably according to the instrument used in measuring them, or the method employed, so that any order must be regarded in a general sense, and not as in any way absolutely accurate. The following table condensed from a more complete one in Lieutenant Walke's Lectures on Explosives, gives the order of the principal explosives according- to the force of explosion, as determined by thp Quinan pressure-gauge : Explosive gelatine - 106.17 Helehoffite - - 106.17 Nitroglycerine - 100.00 Guncotton (U.S.N. Torpedo Station) 83.12 Dynamite, No. 1 - - 81.31 Emmensite - - 77.86 Tonite - - 68.24 Bellite - 65.70 Atlas Powder - - 64.43 Rackarock - - 61.71 Melinite - - 50.82 Mercury fulminate - - 49.91 Mortar Powder (Dupont) - 28.13 Professor Mendel6ef proposes, as the most reliable way of comparing the ballis- tic efficiencies of powders, the simple con- sideration of the volumes of evolved gases, without regard to conditions of tempera- ture. Thus, if the explosion of brown powder be represented by : 4 K NO, + C 6 H 4 + S = K, S0 4 (solid) + K, CO, (solid) + 4 CO + 2 H, + 2 N t . Mol. wt. = 4 x 101 + 80 + 32 = 516. Vols. of gases =4x2 + 2x2 X 2 = 16. We have, 516 : 16 :: 1000 : V 10CO = 31.0. That is, a thousand parts by weight of the explosive furnish 31 volumes of gas (meas- ured at a fixed temperature and pressure). For pyrocollodion, V 1000 = 81.5. Hence, the relative energies of brown powder and pyrocollodion for equal weights are as 81.5 : 31.0, which is very nearly what actual experiments show, viz.: 2.6:1. Admitting the effect of temperature, he holds that our methods of determining the temperatures developed by explosives are unreliable, and our assumptions in regard to the specific heats of gases at high tem- peratures may be wrong, hence, the vol- umes of gases are our only safe means of comparison. THE SPRENGEL CLASS OF EXPLOSIVES. The Sprengel safety mixtures are based on the principle of keeping separate, for safety in handling, transportation and stor- age, the essential constituents of an ex- plosive mixture (an oxidizable substance 30 and an oxidizing agent), and mixing them only when required for use. The separate constituents are, of course, not explosive, and can be manipulated with safety. The mixing of those which have received practical approval can also be effected with safety, but it is difficult to secure uniformity in the resulting ex- plosive without special mixing apparatus worked by skilled workmen. These explosives are all powerful, and most of them are very stable, requiring strong detonators to explode them per- fectly. They possess another advantage in that the power may be varied con- siderably by simply varying the propor- tions of the ingredients in mixing before use. The principal disadvantages are that they require workmen of more than ordin- ary intelligence, that in mine galleries and other confined localities it is inconvenient and dangerous to mix those containing essentially nitric acid or carbon bisulphide, and finally, that it is necessary to protect the copper capsule containing the detona- tor from the action of the nitric acid in 31 those which contain this acid as an essen- tial ingredient. The principle explosives of this class are: Rack-a-Rock, Hellhoffite, Oxonite, Panclastite, and Romite. SMOKELESS POWDERS. The principle involved in the preparation of smokeless powder is the production of an explosive which shall have in its products of explosion no gases readily condensible into liquids or solids, and at the same time give moderate pressures. The demand for the smokeless powders was created by the modern magazine small- arms and the rapid-fire and machine guns r because the accumulation of smoke with the old powders soon put a limit to the use of these powerful engines. But these new powders are rapidly finding application not only in military arms but also in sport- 62 ing rifles and elsewhere, and are fast Superseding the old ones. The only class of smokeless powders that has proven practically useful and re- liable is that derived from guncotton or its modifications (with or without nitro- glycerine). In stability and ballistic properties these powders are generally superior to the old powders. They are more difficult to ignite than black powder and require stronger caps j they are unaffected by water or air ; they are not sensitive to shock and leave no residue when burned j and they give high velocities with comparatively low pressures, and great uniformity of action. The force of these powders is explained by the fact that the potential energy is high, since the quantity of heat evolved is large, and that the total volume of gas given off is very great. The low pres- sures, on the other hand, are explained by the fact that the rapidity of reaction in these mixtures has been greatly decreased below that of the high explosives entering into their composition, by the admixed de- 33 torrents, and by the physical form given them in practice, so that the gases are given off comparatively slowly ; moreover, the gases can expand into the entire space behind the projectile, whereas in gunpow- der over halfilDLQ space is occupied at the moment of ^explosion by solid gunpowder, and less than half is therefore available for the gases to expand into ; while the high velocities given to the projectile, with such low pressures (which, as measured, are not the average pressures while the projectile is in the bore, but the maximum pressures reached) are explained by the fact that, although the initial pressure is less, the total force exerted on the pro- jectile while it is in the bore, due to the great volume of gas and the high poten- tial energy, is greater ; moreover, in these smokeless powders none of the force is wasted in throwing out the unconsumed powder, as it is in the case of black, or even brown, gunpowder. Finally, it is probable that dissociation (the effect of which is explained under Brown Powder) comes into play. The low pressures also 34 account for the fact that these powders, although they contain high explosive con- stituents, do not detonate. They are, in reality, strong and slow powders, but in a special sense : strong, as compared with gunpowder (not so strong as guncotton or dynamite), and slow, as compared with the high explo- sives (but more rapid in reality than gun- powder), with the effect of being less rapid even than gunpowder, on account of the entire space behind the projectile being available for the gases to expand into. In an exhaustive study of the general subject of smokeless powders, the Russian chemist, Professor Mendel6ef, arrived at the following conclusions in regard to the kind of substances that promise to be used in future in the manufacture of these powders. The conditions to be fulfilled by smoke- less powders are : 1. That they shall leave no solid resi- due after combustion, and that their gases exercise no injurious effect upon the metal of the gun. 2. That they undergo no change upon keeping for long periods of time, and con- tain no volatile ingredients. 3. That they may be readily prepared in quantities sufficiently abundant for practical needs. The first condition limits the substances suitable for conversion into powder, to compounds of hydrogen and nitrogen with oxygen and carbon. But in any powder the energy is derived from the conversion of the mass into gases, the transformation being accompanied by great heat. The greatest volume of gas (measured at a fixed temperature and pressure) would be obtainable from H in in the solid or liquid form (provided such a substance existed), for we should then have : H tn = wH,, orV l000 = 1000, but no such substance is known, or ex- pected. The binary compounds, while giving larger volumes of gas (V 1000 = 133.3, 93.0 T etc.,) than any others, do not fulfill the third condition, but even if they did, such 36 compounds do not decompose gradually enough to be used in guns. The neces- sary progressive combustion can take place only in explosives containing carbon and hydrogen, which are consumed by the oxygen that is held in close proximity to them, but which is not directly combined with them. ICOMPOUNDS. . Explosive compounds may be divided into five groups : 1. Nitrides. 2. Azo-Compounds. 3. Fulminates. 4. Nitro-Compounds. 5. Organic Nitrates. There are a few compounds not included in this classification, but they are of little importance practically, and add nothing to our understanding of the theory of ex- plosives. The explosive character of all these compounds is due to three great causes : first, they are comparatively unstable com- 3? pounds, all of them containing nitrogen, the most indifferent of all the elements so far as chemical affinity is concerned, and therefore their molecules are readily broken up; secondly, the atoms in the molecule are not combined according to their great- est affinities, hence, little heat is absorbed in decomposing the molecules, while great heat is given out in the re-combination of the atoms according to their higher affini- ties, and the resultant heat, which is the algebraic sum of the two, is therefore very great; and thirdly, the products are all gases at the temperature produced by the explosion, and most of them permanent gases. Hence, all the conditions for ex- plosive action are present and in a high degree, viz.: change of state from solid or liquid to gas, rapid chemical change, evolu- tion of great heat, and the production of a large volume of gas; in other words, a small volume of the explosive can suddenly pro- duce a very large volume of gas. I. NITRIDES. This group comprises the simplest of 38 the explosive compounds. Some may be regarded as formed theoretically from ammonia, N H 3 , by replacing all ( or part ) of the hydrogen by another (metallic) element, others from hydrazoic acid, H N 3 , by replacing the hydrogen by a metallic element, and are therefore all nitrides (or hydro-nitrides): CZgN(orN t HCZ 8 ). S N. H N 3 . Br 3 N. A?.N. (NH 4 )N t . I 8 N. C/ 6 N t . A#N 8 . F 3 N. H<7 6 N,. Nitrogen Chloride. Nitrogen chloride, or Chloramide, is formed by passing chlorine gas into a warm solution of sal-ammoniac. It is a heavy oily liquid. When heated to 93 C. it explodes violently, and its ex- plosion is also caused by contact of substances which have an affinity for chlorine, such as phosphorus, arsenic, oils, turpentine and alkalies. Its exact chemical symbol has not been determined, but it is usually regarded as N C 3. Its structural formula will there- fore be C I N C I and its explosion may Gl be represented by the equation 2NC/3 = N, + 3C7,,or f Gl - Cl Cl N CZ = N = N + ICl Gl I ' (Cl Gl Gl V,. 00 = 37.56; the evolution of heat in this case is ex- plained by the fact that the heat required to decompose the explosive molecule (which involves only the overcoming the affinity of nitrogen for chlorine, as seen in the structural formula), is very small, while that evolved in the union of the nitrogen atoms to form the nitrogen molecule, and of the chlorine atoms to form the chlorine molecule, is very great, the resultant effect being the evolution of a large quantity of heat. Nitrogen Iodide. Nitrogen iodide, or iodoamide, N I 8 , may be made by gently triturating in a porcelain mortar finely divided iodine with a large excess of 4:0 concentrated amonia water at C. It is a brownish-black powder, which may be exploded when dry by the touch of a feather, and under water by friction. Nitrogen Bromide. Nitrogen bromide, or Bromamide, may be formed by decom- posing nitrogen chloride with an aqueous solution of potassium bromide. It is a dense, blackish-red, volatile oil, which may be exploded violently by contact with phosphorus or arsenic, which have a great affinity for bromine. Nitrogen Fluoride. Nitrogen floride, or Fluoramide, may be formed by passing an electric current through a concentrated solution of ammonium fluoride. It is an oily liquid, which may be exploded by contact with glass, silica, or organic matter (due to the affinity of fluorine for silicon or hydrogen). Nitrogen Sulphide. Nitrogen sulphide, or Sulphur nitride, N S, may be prepared by passing dry ammonia gas through a solu- tion of sulphur dichloride in ten or twelve times its volume of carbon bisulphide, filtering off the yellow liquid, allowing it to 41 crystallize by spontaneous evaporation, and dissolving out the admixed sulphur by car- bon bisulphide. It is a golden yellow, crystaline solid, which can be exploded by percussion. Silver Amine. Silver amine, or Silver nitride, Ag 3 N, may be prepared by acting on silver oxide with ammonia. It is a black powder, which is exploded by the slightest shock. Copper Amine. Copper amine, C u 9 N $f is formed by passing dry ammonia gas over finely powdered cupric oxide heated to 250 C. It is a dark green powder, ex- ploding at 310 C. Mercury Amine. Mercury amine, Hg 9 N s , may be prepared by passing dry am- monia gas over dry mercuric oxide, and then heating the resulting mass cautiously at a temperature not exceeding 150 C. It explodes by heat or percussion. Nitrohydric Acid. Nitrohydric acid, or hydrazoic acid, N 3 H, is very explosive it- self and forms highly explosive salts. It furnishes a remarkably great volume of gas: 2 N s H = H 2 + 3 N t , so that V 1000 = 93.0. Ammonium Hydrazoate. Ammonium hy- drazoate, N 8 (NH 4 ), is the ammonium salt of hydrazoic acid, and is also explosive-: N 8 (NH 4 ) = 2H, + 2N a , giving V 1000 = 133.3. Silver Hydraeoate. Silver Hydrazoate, N^ I N N 8 A#, or Ag N / , is the silver salt, and has been proposed as a substitute for mercury fulminate. None of these compounds have as yet received any important practical applica- tion, although silver amine is supposed to have been the initial detonating agent in the bomb that killed the Czar, and nitrogen sulphide could be used as a substitute for mercury fulminate; but they are interest- ing in connection with the theory of ex- plosives. 2. Azo-COMPOUNDS. The azo-compounds are derived theoret- cally from the benzene series by substitu- 43 tion of 2 atoms of nitrogen for two atoms. of hydrogen. Practically, they are pre- pared by the action of reducing agents on. the nitro-derivatives of the benzene series, or by the oxidation of aniline (prepared from nitro-benzene). Thus^azo-benzene, C 12 H 10 N a , is formed by the action of sodium-amalgam on nitro- benzene. Its structural formula is : 'H c C H H (J ^C BE I II I ,C H H-C ^,C_H P. Griess, the great German investiga- tor of the azo-compounds, isolated a num- ber of explosive salts of this class, most of which are crystalline. They are interest- ing in the theoretical study of explosive compounds, and may find some practical application in the fniuee.-(Berichte Deutsche Chem. GeseU.} The more important are : Paraditriazobenzene, Metaditriazobenzoic acid, C 7 H 5 (N 8 ) a 2 . Metamidotriazobenzoic acid, C 6 H g? COOH, NH,,N,NC.H,, (NHJ, Meta-amidodiazobenzoUmide, a yellow oil, C 6 H 6 N 4 ,or C 6 .N ' X Para-amidodiazobenzoic acid, C 7 H 5 N 8 O a . Triazo-A zobenzene, \N 3. FULMINATES. The fulminates are intermediate in com- position between the binary nitrogen com- pounds and the nitrous derivatives of the benzene group. They contain some oxygen, but only enough to convert the carbon into carbon monoxide. They are generally re- garded as salts of fulmmic acid, C 2 N 2 O 2 H 2 . Their explosive action is explained by the fact that in the molecule the atoms of the elements are united in a manner which is not according to their highest affinities^ and in the resultant gases they are so united. The structural formula is probably this: N = C O M' N = C O M' in which part of the affinity of carbon i& satisfied by that of other carbon, and an- other part by that of nitrogen, only one- fourth of its maximum affinity being satis- fied by oxygen, whereas in the result, M', C, N, 8 = M', + 2 C O + N 8> 46 one-half the maximum affinity of carbon is satisfied by oxygen. Mercury Fulminate. Mercury fulminate, Jig C 2 N t O 2 , is manufactured by dissolving in a carboy one part of mercury in one part of nitric acid (sp. gr. 1.4.), the liquid, containing nitrous acid and solution of mercuric nitrate being then poured into another carboy containing ten parts of alcohol (sp. gr. 0.83.), connected through a series of Wolff's bottles placed in a trough of water, with a condensing tower. The condensed vapors are used again in- stead of pure alcohol. The fulminate is washed and dried till it contains about fifteen per cent, of moist- ure, and is then stored under water, OP packed in papier mache boxes containing about 8 grammes each. It is a white or grayish crystalline sub- stance, which explodes violently when struck, or when heated to 195 C. Its principal practical application is in the manufacture of cap composition and detonators. Silver Fulminate. Silver Fulminate, Ag % 47 C, N, O,, may be made by a process similar to that for making the mercury salt. It explodes much more violently than the latter, and when dry the slightest touch will set it off. It is used in minute quanti- ties in detonating toys. The other fulminates have received no practical application, although they are all explosive. The following are known to chemistry : Gold Fulminate. Platinum Fulminate. Zinc Fulminate. Copper Fulminate. Silver-Ammonium Fulminate. Silver-Potassium Fulminate. 4. NlTRO-COMPOUNDS. The most important of the explosive compounds are formed by the action of nitric acid on organic substances containing carbon and hydrogen, or carbon, hydrogen and oxygen, and belong to the fourth and fifth groups. 48 The nitro-compounds or nitro-substitu- tion compounds, may be represented by the general symbol R N0 2 , in which R is an organic radical; and they are derived from hydrocarbon compounds, or compounds of carbon, hydrogen and oxygen, by the substitution of the acid radical, N O g , for the hydrogen of the or- ganic compound, the N O 2 replacing, not the hydrogen of hydroxyl as required in forming oxysalts, but the hydrogen con- nected directly to carbon atoms, that could in a similar way be replaced by chlorine, bromine, etc. Again, if we regard the result as produced by substitution in the acid symbol, then the organic radical re- places, not the hydrogen of the acid, as in true oxysalts, but the hydroxyl. Conse- quently, these compounds are not salts, but true substitution products. They are generally more stable com- pounds and less energetic in their action than the organic nitrates, facts which may .be explained by the position of the nitryl 49 molecule, N O s , determining as it does the heat of formation (which is a measure of the stability) and the distance the atoms have to travel in recombining in explosion (a measure of the intensity of action in ex- plosion). One of the greatest affinities ni- trogen shows is for carbon, as exemplified in cyanogen, and in the molecules of the compounds included in this group (since the nitryl molecule is united directly to a carbon atom) this strongest affinity is par- tially satisfied, a fact which assists in ac- counting for the comparitive stability of these substances. A. Derivatives of the Benzene (or Aromatic) Series. The compounds in this section are formed by the action of nitric acid on the benzene series of hydrocarbons (or on derivatives of that series), resulting in the replace- ment of one or more hydrogen atoms by molecules of the radical nitryl, N O 2 . The benzene series comprises the hy- drocarbons of the general symbol C n H 2n _ 8 in which n is at least 6. The lowest mem- 50 ber of the series is C 6 H e , from which the others are derived by replacing the hydro- gen atoms by C H 2 . The structural formula for benzine is: H- and if one of the hydrogen atoms be replaced by C H 8 we have toluene, C 7 H 8 ; but when more than one atom of hydro- gen is replaced, the product, although its chemical symbol remains the same, differs according to the position of the hydrogen atoms replaced, two adjacent ones forming the ortho compounds, two alternate ones the meta compounds, and two opposite ones the para compounds ; such compounds, having the same chemical formula but different structural formulas are called isomeric 51 compounds. The position of the atom or atoms replaced affects the stability of the compound produced, the symmetrical be- ing the more stable. This principle ap- plies in a number of organic compounds. This section of explosive compounds may be divided into two sub-sections : Derivates of Benzene. Derivates of Toluene. d. Derivatives of Benzene. The members of this sub-section are : The Nitrobenzenes. The Picrates. The Nitrobenzenes. The nitrobenzenes are obtained by the nitration of benzene, C 6 H 8 . Three de- grees of nitration have thus far been ef- fected, resulting in the replacement of one, two or three atoms of hydrogen by a corresponding number of nitryl molecules. Mono-nitrobenzene. Mono-nitrobenzene, C 6 H 5 , N O 2 , is prepared by gradually add- ing 1 part of pure benzene to a mixture of 1.2 parts nitric acid (sp. gr. 1.4) and 1.8 parts sulphuric acid (sp. gr. 1.84), cooling by means of a current of water 5 the acids are then removed by means of a siphon, and the product is washed. The reaction is thus represented : C 6 H. + H N 3 = C, H 6 (NO,) + H 2 O, and the structural formula of the com- pound is : H C C H H_C C_H ^^ i Mono-nitrobenzene is a colorless or red- dish-orange oily liquid, capable of dissolv- ing nitrocellulose in the cold. If thrown upon an iron plate at a red heat it deto- nates, but under ordinary circumstances it is not an explosive. The formula shows that there is not 53 enough oxygen present in tlia molecule to oxidize even the hydrogen, and there is a large excess of carbon, hence there can- not be explosion. On the red hot iron plate, on the contrary, this excess of carbon is taken up, forming iron carbide on the surface and liberating gases : 2 C 6 H 5 (N O 2 ) + 44 F e = 11 Fe 4 C + 4 H 2 O + N 2 + C H 2 . It is used as an ingredient of explosive mixtures, however, either as an essential constituent or as a deterrent, to retard or prevent explosion. Di-nitrobenzene. Di-nitrobenzene, C 6 H 4 (N O a ) 2 , is prepared by mixing 0.8 parts nitric acid (sp. pr. 1.5) and 1.2 parts sul- phuric acid (sp. gr. 1.845), and while the mixture is still hot adding 1 part mono- nitrobenzene. The result is generally a mixture of the three isomeric compounds, ortho-, meta-, and para-di-nitrobenzene. It is a hard, crystalline yellow solid, not in itself explosive, but forming strong explosive mixtures with substances rich in oxygen and giving it up readily. 54 Tri-nitrobenzene. Tri-nitrobenzene, C 6 H 3 (N O 2 ) 8 , may be prepared by treating meta-di-nitrobenzene with a mixture of concentrated nitric and Nordhause,n sul- phuric acids. It has been proposed as a substitute for picric acid in explosive mixtures. The Picrates. The picrates are obtained by the nitration of carbolic acid, or phenol, C 6 H 6 O, which is a derivative of benzene (one of the hydrogen atoms in the latter being replaced by hydroxyl). The structural formula of carbolic acid is: H O I II I H C C H 55 and that of the picrates : H (or M) O I O 0=N c C N=aO H C C H O= N =O The nitryl ( N 2 ) molecules are attached directly to the carbon atoms, as in the other true nitro-compounds. Picric Acid. Picric acid, or tri-nitro- phenol, C 6 H 3 (N O 2 ) 3 O , is manufactured by melting carbolic acid, mixing with strong nitric acid, diluting with water, and cooling; the picric acid crystallizes out and is purified. The reactions are somewhat complicated, but the nitric acid has its usual action ia such cases, viz. : the substitution of 3 molecules of N O 3 for 3 atoms of hydrogen : 56 H.O. It is a yellow crystilline solid, and in the dry state may be detonated by means of a fulminate detonator, or by detonating a small quantity of picric acid near it, while the wet picric acid may be detonated by a primer of the dry acid; moreover, a thin layer of it may be exploded by percussion^ the energy required diminishing as the temperature of the explosive is raised. Its explosion may be thus represented: 4 C 6 H 3 ( N 2 ) 8 O = 6 H 2 O + 22 C O + The supply of oxygen is sufficient only for the partial oxidation of the carbon, hence the use of this substance in explosive mixtures with oxidizing agents. The explosion is explained by the pre- sence of nitrogen, rendering the compound unstable, the fact that the elements are combined in the molecule not according to their greatest affinities, whereas in the products they are so combined, resulting in the production of great heat, and finally the change of state from solid to gas. 57 Potassium Picrate. Potassium picrate^ C e H 2 K ( N 2 ) 3 0, is made "by mixing warm potassium carbonate with a boiling solution of picric acid in water. It is a yellow, crystalline solid, which explodes by percussion or heat. It is used in explosive mixtures with oxidizing agents. Ammonium Picrate. Ammonium picrate r C 6 H 2 N H 4 (N 2 ) 3 O, is made by saturat- ing warm picric acid with concentrated ammonia water, or by treating picric acid with ammonium carbonate. It is an orange^ or citron-yellow, crystalline solid, which explodes when heated to 310 C, but is- almost insensitive to blows or friction. It is used in explosive mixtures with oxidizing agents. b. Derivatives of Toluene. Toluene, C 7 H 8 , is the second member of the benzene series, and furnishes a series of nitro-compounds similar to those ob- tained from benzene. Mono-nitrotoluene. Mono-nitr otoluene, G 6 H 4 (N O 8 ) C H 8 , is formed when toluene 05 is acted upon by a mixture of nitric and sulphuric acids, the ortho-nitrotoluene be- ing commonly present when the mixture is heated for some time. Di-nitrotolmne. Di-nitrotoluene, C^ H 3 (N O 2 ) 2 C H 3 , is prepared by treating tolu- ene with a mixture of the strongest nitric and sulphuric acids. It is a colorless, crystalline solid, not itself explosive, but used in explosive mixtures. Tri-nitrotoluene. tf-Tri-nitrotoluene, C 6 H 2 (N O 2 ) s C H 3 , (1:2:4: 6), is one of the products of the continued boiling of tolu- ene in a mixture of nitric and sulphuric acids. Tri-nitrocresol. Cresol, C 7 H 8 O, is de- rived theoretically from toluene, by replac- ing one of the hydrogen atoms in the mole- cule by hydroxyl, just as carbolic acid is de- rived from benzene. Tri-nitrocresol, or Cresilite, C 7 H 5 (N 2 ) 3 O, is prepared by treating cresol with strong nitric acid. It is a yellow crystalline solid, not ex- plosive itself, but used in explosive mix- tures. Ecrasite. Ecrasite, C 7 H 4 N H 4 (N O 2 ) $ 53 0, is made by neutralizing a boiling-hot saturated solution of tri-nitrocresol by means of ammonium hydrate. It is a greasy yellow solid, unaffected by moisture, heat, cold or concussion, which explodes violently under the action of a fulminate detonator. It is used in Austria for charg- ing shells,, has been much experimented with, and has attracted considerable atten- tion quite recently. The shells charged with this explosive are designed more par- ticularly for the attack of fortifications. B, Derivatives of the Naphthalene Series. The naphthaline series comprises hydro- carbons of the general symbol C n H 2n _ 12 in which n is at least 10. Derivatives of Naphthalene. Naphthalene, C 10 H 8 , is the lowest mem- ber of the naphthalene series, and fur- nishes a series of nitro-compounds similar to those obtained from benzene and tolu- ene. Its structural formula is : 60 t r ' i i Four degrees of nitration have been ob- tained. Mono-nitronaphihalene. Mono-nitronaph- thalene, C 10 H 7 (N O 2 ), may be prepared by introducing finely pulverized naphtha- lene into a mixture of four parts nitric acid (sp. gr. 1.4) and five parts sulphuric acid (sp. gr. 1.84), keeping the tempera- ture above 160 F. It is a yellow crystalline solid, which de- composes when heated above 300 C. It is not explosive, as may be inferred from the small proportion of oxygen in the com- pound, but is used in explosive mixtures. Di-nitronaphthalene. Di-n itronaphtha- lene, C 10 H 6 (NO 2 ) 2 , may by made by treat* 61 ing naphthalene at 70 C., with a mixture of one part concentrated nitric acid and two parts sulphuric acid. It is a yellow, crystalline solid, which deflagrates if heated suddenly. Tri-nitro-naphtlialene. Tri-nitro-naphtha- lene, C 10 H 5 (N O a ) 3 , is made by boiling di- nitro-naphthalene with fuming nitric acid- It is a yellow crystalline solid, which explodes when heated. Tetra-nitro- naphthalene. Tetra-nitro- naphthalene, C, H 4 (NO 2 ) 4? is made by boiling di-nitro-naphthalene with fuming nitric acid and continuing the action be- yond that required to form the tri-com- pound. It is a yellow crystalline solid, which explodes when heated. All the nitro-naphthalenes are used in explosive mixtures. 5. ORGANIC NITRATES. The organic nitrates may be represented by the general symbol R-0-N0 , 62 in which R is an organic radical, and they are derived from H O N O a ( nitric acid) by the substitution of a basic organic radical (C 3 H 5 , etc.) for the hydrogen of the acid, or by the substitution of the acid radical, N O 8 , for the hydrogen of the hy- droxyl of the organic compound, according to the two general methods in which all oxysalts may be conceived to be formed. These compounds, being true nitrates, are distinguished from the nitro-substitu- tion compounds by the fact that the N O 2 group in each is united to the carbon atom of the organic radical not directly, but through an atom of oxygen. They may be divided into two sections : Derivatives of the Benzene Series. Derivatives of the Alcohol Series. A. Derivatives of the Benzene Series, There is but one important compound in this section of explosives. Di-azobenzene Nitrate. Di-azobenzene nitrate, C 6 H 5 N 2 N O 3 , is prepared by pas- sing nitrous acid vapor into a flask con- 63 taining aniline nitrate moistened with a small quantity of water, -and cooled with ice 5 the resulting liquid is filtered, alcohol and ether are added, and the diazobenzene nitrate separates as a crystelline mass : 2H 2 0. Its structural formula is: O=N=O H ^C H i i H 0] = 16 H 2 + 48 C +12 N 9 . V =77 * i nnn * I W 1000 Its present composition is not known. It is a yellow crystalline solid, and when used in shells about two-thirds of the space is first filled with cresilite, the re- maining third being then packed with melinite. Lyddite. Lyddite, the great English explosive, is probably similar to the origi- nal melinite. It is used in shells, aud is considered a safe and reliable explosive. A powder fuse will not detonate it, but many metallic oxides and nitrates, when brought in contact with it at a high tem- perature will, and the fuse in the English service probably utilizes this principle. 115 11. GUNCOTTON AND NITROTOLUENE MIXTURES. Containing no other organic nitrate or nitro- compound. The principle of these mixtures is that the nitrotoluene acts as a deterrent, and also so modifies the physical state of the guncotton as to enable us to regulate and control its rate of explosion. Plastomenite. The only nitrotoluene mixture of any importance is the new smokeless* powder, called Toluol Powder, or Plastomenite. It has been greatly improved in the past two years, and as manufactured at the Guttler Factory in Reichenstein, Germany, contains, according to the analysis of Doc- tor Gottig, Professor at the Eoyal Artillery and Engineer School : Nitrated -Toluene, ^-trinitrotoluene (1 : 2 : 4 : 6), C 6 H, (N O t ) f C H 3 , and ortho- nitrotoluene, C 6 H* (N 2 ) C H 8 22.06 Nitrocellulose (partly soluble, 12.33 % nitrogen), C,,H M (N0 3 ) 9 4 , - 67.48 Barium nitrate, ... 9.76 116 Moisture, - - 0.90 The reaction for its explosion at high pressure is, according to Professor Gott'g, as follows : C H 3 + 4 B a (N 3 ) 3 = 4 B a C O 3 + 67 H 2 O + 73 C O 3 + 101 C + 52 N t + 15 CH 4 + 9C + 5H 1 . As regards residue and freedom from smoke the new powder meets all require- ments 5 the weight and volume of the charge required is still an objection, but this is more than counterbalanced by the advantageous properties of the explosive, namely, its strength, stability at high tem- peratures, and resistance to the action of atmospheric moisture, safety in prepara- tion and handling, and easy inflammability in the gun. 12. GUNCOTTON AND NITROGLYCERINE MIXTURES. The guncotton and nitroglycerine mix- tures are among the most important and energetic of the explosives. 117 The principles involved in their manu- facture are: 1. Guncotton has a deficiency of oxy- gen and nitroglycerine a slight excess, so that a proper mixture would appear to be advantageous. 2. Guncotton is solid and porous, and nitroglycerine is liquid, so that a solid mass results from their mixture, which is more convenient to handle than the liquid nitro- glycerine. 3. The addition of camphor, resin, and similar substances causes a change in the cohesion of the mass, increasing its solidity and elasticity, so that a much larger mass takes up the initial shock in explosion, hence there is less danger of a local sudden rise of temperature (which is essential for detonation), and the explosive is therefore less sensitive. 4. Certain substances (low explosive mixtures, etc.,) moderate the force of ex- plosion of these high explosives, and their admixture, consequently, enables us to make explosives of various grades from the same ingredients. 118 Explosive Gelatine. Explosive Gelatine, or Blasting Gelatine, is composed of nitro- cotton (with not over 11 per cent, of nitro- gen), carefully dried, mixed with nitro- glycerine, also carefully dried, the amount of nitrocotton varying from 4 to 8 per cent. ; after kneading, the mixture is made into cartridges by a special machine, which forces it out- in the form of a long cylinder, the latter being then cut into proper lengths, and each cartridge wrapped with paraffined paper or parchment paper. It is a yellow, translucent, elastic solid, practically unaffected by water, which when not confined burns but does not ex- plode, but when confined explodes at about 204 C. It is less liable to freeze than dy- namite, but when frozen is more sensitive. Military Gelatine. Military Gelatine is an explosive gelatine with a small per centage of camphor added. There are several varities : Austrian. Italian. Nitroglycerine, - CO 92 Soluble guncotton, - - 10 8 Camphor (added), 4$ 5$ 119 The reactions for explosion (assuming the tetraiiitrate) are : C 12 H 14 4 (N0 3 ) 4 (HO), + 18C 3 H 5 (N O 3 ) s = 53 H 8 O + 61 C O a + 5 C O + 29 N f , and O i> H^Q ft (N.O.)i(HO) l + 22C 3 H 5 (N 3 ) s = 63 H t O + 75 C O, + 3 C O + 35 N 2 . Evidently, the oxidation in the second case is a little more complete than in the first. Military gelatine resembles explosive gelatine in appearance and properties, but is much less sensitive. Cordite. Cordite, the British smokeless powder, is composed of 58 parts nitrogly- cerine, 37 parts guncotton and 5 parts vaseline. The nitroglycerine is poured over the guncotton, and the two are mixed by hand; the resulting mass, which looks like moist sugar, is placed in the kneading machines with the proper amount of acetone and incorporated; the vaseline is added and the incorporation continued; the cordite is first pressed, and is then squeezed through 120 dies, and issued in the form of cords of various sizes, which are cut into proper lengths. It is a horny substance, which cannot be heated for any length of time above 100 F. The vaseline acts merely to re- strain the violence of the explosion, and serves to produce a little smoke, which acts as a lubricant in the bore of the gun. The cords burn progressively from sur- face to center, so that the rate of combus- tion can be regulated by the size of the cord. Explosion reaction: 4C 12 H U 4 (N0 8 ) 6 + 14C 3 H 5 (N0 3 ) 3 = 63 H 2 O + 61 C O 2 + 29 C O + 33 N 2 . W.-A. Powder. W.-A. Powder is one of the smokeless powders, and is made by the American Smokeless Powder Company ; it Artillerie, . . . .VI INDEX. 13 Page. Rifleite, . . . . .111 Roburite, . . . .94 Romite, ..... 31 Saccharose, . . . . .73 Safety Powder, . . 89, 97, 101, 104, 138 " Cologne-Rottweiler. . 138 Schultze Powder, . . - .40 Securite, ..... 92 Sensitiveness of an Explosive, . . 20 Sevran Livry Explosive, . . .108 Silver Amine, .... 41 Silver-ammonium Fulminate, . . 47 Silver Fulminate, . . . .46 Silver Hydrazoate, . . . .42 Silver Nitride, .... 41 Silver-potassium Fulminate, . . 47 Smokeless Powder, . . . .31 11 Ballistite . . 120 " Cordite . . .119 " Filite . . .120 " Indurite. . . 112 " Leonard. . . 122 " Maxim-Schiipphaus 107, 121 " Peyton . . .122 " Plastomenite . .115 " PoudreB . . 107 " PoudreB N . . 110 " PyrocoUodion . . 29, 76 1 Eifleite . . .111 44 Schultze 40 14: INDEX. Page. Smokeless Powder, Swiss Normal . . 107 Troisdorf . . 109 IT. S. Naval . . 109 " W.-A. . . . 120 " Wetteren . . 122 Soluble Nitrocotton, . . . .75 Spontaneous Decomposition Causing Explosion, 15 Sprengel Class of Explosives, . 29 " " Rack-a-Rock 28, 31, 92 Hellhoffite 28, 31, 93 " " Oxonite . 31, 94 " " Panclastite 31, 124 " " Komite . . 31 Starch, ..... 72 Stonite, . . . .105 Strength of Explosives, . . ^ .28 Sulphur Nitride, . . . .41 Swiss Normal Powder, . . . 107 Synchronous Vibrations in Explosion by In- fluence, . . . .13 Tetranitronaphthalene, . . .61 Tillman, S. E., Professor . . . . IV Toluene, . . . . .57 Toluene, Derivatives of . .57 Toluol Powder, . . . .115 Tonite, .... 28, 108 Triatomic Alcohols, Derivatives of . . 65 Triazo-Azobenzene, . . . .44 Trinitrobenzene, . . . .54 Trinitrocresol, . , . .58 \ INDEX. 1 5 Page. Trinitronaphthalene, . .61 Trinitrotoluene, . . . .58 Troisdorf Powder, . . . .109 U. S. Naval Friction Fuse Composition, . 142 * * Smokeless Powder, . . 109 VieUe's Powder, . . . .107 Vigorite, . . . . .104 Volney Powders, . . . .96 Vortex Motion in Explosion by Influence, . 13 Vulcan Powder, .... 103 Walke, lieut. W. . . . . IV, V W.-A. Powder, . . . .120 Westphalite, . . . . .138 Wetterdynamite, . 101 Wetteren Powder, . . . .122 White Powder, .... 142 Xyloidine, . . . . , 74 THE VAN NOSTRAND SCIENCE SERIES No. 47. LINKAGES: THE DIFFERENT FORMS and Uses of Articulated Links. By J. D. C. De Roos. No. 48. THEORY OF SOLID AND BRACED Elastic Arches. By William Cain, C.E. Second edi- tion, revised and enlarged. No. 49. MOTION OF A SOLID IN A FLUID. By Thomas Craig, Ph.D. No. 50. DWELLING-HOUSES; THEIR SANI- tary Conduction and Arrangements. By Prof. W. H. Corfield. No. 51. THE TELESCOPE: OPTICAL PRINCI- ples Involved in the Construction of Refracting and Reflecting Telescopes, with a new chapter on the Evolution of the Modern Telescope, and a Bibliography to date. 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