4 ■ ■» : 1 TP sio ^3^ /^1i 3081 CORNELL UNIVERSITY LIBRARY 3 1924 073 210 837 •JOl B(9\ Cornell University Library The original of tiiis bool< is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924073210837 ^yoi e(^[ THE MODERN HIGH EXPLOSIVES. NITRO-GLYCERINE AND DYNAMITE; THEIR MANUFACTURE, THEIR USE, AND THEIR APPLICATION TO MINING AND MILITARY ENGINEERING; PYROXYLINE, OR GUN-COTTON; THE FULMINATES, PICRATES, AND CHLORATES. ALSO. THE CHEMISTRY AND ANALYSIS OF THE ELEMENTARY BODIES WHICH ENTER INTO THE MANUFACTURE OF THE PRINCIPAL NITRO-COMPOUNDS. BY MANUEL EISSLER, MINING ENGINEER. THIRD EDITION. SECOND THOUSAND. NEW YORK: JOHN WILEY & SONS, 53 East Tenth Street. 1899. Dhn JID . v- COPYRIGHT, 1884, By MANUEL EISSLER. Q\WO^'^^~ /v^?' ^.It^,£r//j/f6;-^-/'- PREFACE. In presenting this work to the public, the author has endeavored to acquaint the engineer, the contractor, and the chemist with the composition of the substances they are now so largely using, with theii peculiar characteristics, and their adaptation for certain results ; or, in a word, to familiarize them with the " high explosives." He has been led to do this by the lack of authentic information! on the subject, and the great increase in the use of these explosives.. As they are dangerous in the hands of the ignorant or vicious, so ai proper and wide-spread knowledge of them will do much to forefend their abuse either from ignorance or design, while in the industrial arts they have a place second to no agent man has yet employed to subdue the hostile forces of nature : hence it is believed that a careful study of this work will lead to the most beneficial results. The author has drawn largely from various official reports, and has endeavored to obtain the latest and most reliable data. The articles on the manufacture of nitro-glycerine are especially intended for the chemist, and a careful study of them will undoubtedly prevent the occurrence of such lamentable accidents as the country has lately experienced. The author has touched but lightly on the employment of these explosives for military purposes, preferring to deal with them at , length, in their grander and more useful field ; to wit, that of reducing 1 to a minimum the opposing forces nature has placed in the various V highways of advancing civilization ; and in this, their proper field, he 1 hopes to have the sympathy of every pioneer of progress; and for this class, whether civil, military, or mining engineer, the volume is specially designed, and dedicated to them by THE AUTHOR. CONTENTS. mxt I. CHAPTER I. CHEMISTRY AND ANALYSIS OF VARIOUS BODIES WHICH ENTER INTO THE MANUFACTURE OF THE HIGH EXPLOSIVES. PAGB I. Sodium Nitrate 3 II. Potassic Nitrate and Nitric Acid 3 Chemistry and Analysis of .Nitric Acid 5 Examination as to the Purity of Nitric Acid .... 5 Quantitative Determination of Nitric Acid 5 III. Sulphur 7 IV. Sulphuric Acid 8 Examination as to the Purity of Sulphuric Acid .... 10 Determination 11 V. Glycerine 11 Its History 11 Its Properties 12 Test 13 Its Chemical Relations 14 Oleate of Lead . . ■ 15 The Production of Glycerine in the Stearine Factories . . 16 Saponification of Fats with Alkalies ...;... 16 Saponification of Fats with Acids i-/ Decomposition of Fats by Steam 20 The Composition of the Glycerine Waters '20' Production of Glycerine from the Lyes of Soap Manufacturers . 21 Production of Pure Glycerine .... . . 23 The Filtering of the Glycerine 24 Purification of Glycerine from its Lime 25, The Beaujard Process 26 Examination of Glycerine 29 VI. The Saccharine Group 31 VII. Cellulose 31 VIII. Dextrine -33 V VI CONTENTS. CHAPTER II. NITRO-GLYCERINE.— ITS MANUFACTURE, CHEMICAL AND PHYSI- CAL PROPERTIES. PAGE I. Explosives 3^ XI. Nitro-glycerine ........... 37 Historical Notes 38 The Chemistry of its Production 39 Mowbray's Process for its Manufacture 4° Mowbray on its Use in Tunnelling 44 Nobel's Process for its Production 45 Properties of Nitro-Glycerine .... ... 46 Incompatibles 48 ■Gases of Nitro-Glycerine 50 Various Notes S3 Introduction of Caps 54 CHAPTER III. the various high explosives prepared with nitro-glycer- ine, and their properties. Dynamite, or Giant-Powder ... . . -55 Composition and Properties of Nobel's Dynamite .... 55 Dynamite No. i 56 Dynamite with Chemically Inactive Absorbents .... 57 Its Manufacture 57 Its Properties . . ' 58 Temperature 6i Confinement and Compression 62 Metallic Cases 63 Thawing and Enclosing 64 Experimental Tests ........ 64 Actual Experience 65 Authority 66 Proper Regulations for their Transportation .... 66 Dynaviite No. .2 ............ 67 Discussion of its Properties 67 Forcite 85 The Method employed in Continental Dynamite Works for the Manu- facture of Nitro-Glycerine . . ^ . . . . '85 The Washing of Nitro-Glycerine 88 The System employed by the Forcite Company to manufacture Nitro- Glycerine 88 Apparatus for the Denitrification of Resting Acids .... go Cartridge Machines gi Qualities of Forcite , . 91 CONTENTS. VI 1 CHAPTER IV. OTHER VARIETIES OF HIGH EXPLOSIVES. Different Dynamites with chemically Active Absorbents I. Lithofracteur . . 1 1. Colonia Powder III. Brain's Blasting-Powder rv. Lignose V. Dualine VI. Explosive Gelatine Decomposition of Explosive Gelatine To test the Action of Water on Explosive Gelatine Storing Explosive Gelatine Details of Experiments made in France Trials as to the Transmission of the Sympathetic Explosion of Nitro- Gelatine PAGE 93 93 94 94 95 95 96 lOI lOl 102 103 105 CHAPTER V. PYROXYLINE, GUN-COTTON, NITRO-CELLULOSE. GUN-CoTTON 107 History of 107 Its Manufacture 109 Compressed Gun-cotton 113 Its Manufacture ... 113 Its Properties 115 Its Fumes 117 In Mining Operations 117 Nitro-Cellulose 120 Its Preparation 120 Collodium 122 Preparation, Properties, etc 122 Tonite 124 CHAPTER VI. fulminating compounds. Fulminates . . . 126 Fulminate . , 129 Preparation of Fulminate of Mercury 130 Properties of Fulminate of Mercury 131 Fulminates of Silver 132 Preparation, etc. . 132 Phosphides of Copper . . . . 1 34 Sulphides of Copper 134 VI U CONTENTS. PAGE Picrates , . . . . . . . . . . ■ • '35 Picrate of Potash, of Ammonia 136 Borlinetto's, DesignoUes' Powders 136 Brougere's Picrate Powder . 137 Chlorates 13S CHAPTER VII. ANALYSIS OF NITRO-GLYCERINE COMPOUNDS. Analysis .... 14' Siewert's Method .... 144 Lunge's Nitrometer .... .... 145 Walter Hempel's Nitrometer 147 Hampe's Method 149 Quantitative Analysis of Nitro-Glycerine Compounds . . . . 152 Determination of Gun-Cotton, Saltpetre, and Soda . , . .154 Determination of Cellulose and Ash 155 ^art M. CHAPTER I. DIRECTIONS FOR USING THE HIGH EXPLOSIVES. In what Condition to use the Nitro-Glycerine Compounds . . -159 Thawing-out Apparatus 160 Preparation of the Charge 160 Deportment under Water, and General Rules 164 CHAPTER II. ELECTRICITY AS APPLIED TO BLASTING OPERATIONS, Simultaneous Ignitions Advantages of Electric Firing . Material for Electric Blasting Different Systems of Electric Firing Frictional Apparatus Bornhardt 'j Frictional Machine Magneto-Electric Apparatus . G. Mowbray^ s Exploder Dynamo-Electric Apparatus . Wheatstone and Siemens^ Exploder Magneto Machine .... Platinum Fuses . The Wires Electric Conductibility of Different Metals Preparing the Blast .... Connecting the Shots ... 166 166 167 167 16S 1 68 173 174 174 '75 177 179 180 182 183 '85 CONTENTS. IX PAGE Electric Fuses i86 High and Low Tension i86 General Classification of Fuses 1S7 Conditions common to all Fuses 1S9 Theory of Ignition 190 Abel Magnet Fuse, Low Tension 191 Abel Submarine Fuse, Medium Tension 191 Ebner's Fulminating Compound, Medium Tension .... 192 The Dowse Fuse, Medium Tension 192 Abel on Electricity applied to Explosive Purposes .... 193 Part HE. CHAPTER I. , PRINCIPLES OF BLASTING. w Principles of Blasting 229 CHAPTER H. Force and Effect of Explosive Bodies 240 Determination of Weight of Powder-Charges to be used in blasting on Rocky Slopes 243 Chambering of Deep Holes 246 Application of Bore-holes in Rock 247 Recapitulation 248 Determination of Powder-Charges in Rock-blasting, and Tables. . 248 Rodman Crusher 252 CHAPTER in. / MINING AND ENGINEERING PROBLEMS. Mining Problems ; ■ 254 Determination of Powder-Charges for blasting in Tunnels . . 255 System of .blasting in St. Gothard Tunnel 261 Determination of Powder-Charges for blasting in Shafts . . . 262 Charging of a Bore-hole 263 Havelay Tunnel 263 Mole of the Central Pcuific Railroad at Oakland, Cal. 264 The Effect of Shots charged with Dynamite 268 CHAPTER IV. large mines. Big Blasts 271 Chambering with Hydrochloric Acid 273 Quarry of Ruisseau, Algeria 273 CONTENTS. PAC.R Morgeret Quarry 275 Method of Blasting, Lyttelton Harbor, New Zealand . . . -275 Blasting in Earth 277 Bank-blasting of the Hydraulic Mines 278 Bank-blasting 279 Report upon Blasting Operations at Lime Point ...... 282 The Suez Canal -293 The Panama Canal 295 The Corinth Canal 299 CHAPTER V. destruction of walls, obstructions to navigation, iron plates, and cannons. Demolishing Walls and Structures 307 Obstructions to Navigation ......... 3^7 Breaking up Sunken Vessels 309 Oil-well Torpedoes 311 Blasting of Iron Plates . . . . . . . . . . .311 Disruption of Cannon-barrels . . . , . . . . . 3^2 CHAPTER VI. THE APPLICATION OF HIGH EXPLOSIVES IN AGRICULTURE.— BLASTING OF TREES. — GRUBBING OF STUMPS. — BLASTING OF PILES. The Application in Agriculture 314 Blasting or felling of Trees 315 Grubbing or blasting of Stumps 316 Blasting of Piles and Beams ......... 321 Blasting of Piles under Water 323 Blasting of Piles below the River-Bottom 324 Submarine Wood-Blasting 324 Blasting of Ice ............ 326 CHAPTER Vn. SUBMARINE MINES. SuB-AQUEOus Blasting 327 Boring under Water . 327 Blasting Submarine Rocks .......... 329 Tower and Corwin Rocks, Boston Harbor, Mass 330 Recent Improvements in Submarine Drilling 338 Destruction of a Dam across the River Moselle .... 343 Removal of the Hell-Gate Rocks . 344 CONTENTS. XI CHAPTER VIII. THE APPLICATION OF THE HIGH EXPLOSIVES FOR MILITARY PURPOSES. PAGE Application for Military Purposes 358 Destruction o£ Palisades 358 Doors, Wooden Enclosures, Plastering 359 Trials on Walls 359 Destruction of Houses 364 Sppentiii. Questions relating to the Preservation of Nitro-Glycerine Compounds . . 367 Proofs of Stability 368 Dynamite with Nitrate of Ammonium Base 370 Nitro- Gelatine 37° Gun-Cotton 37' The Qualities of Explosive Bodies 372 Explosions by Influence 37 5 The Origin of the Nitrates 384 PART I, CHAPTER I. THE CHEMISTRY AND ANALYSIS OF VARIOUS BODIES WHICH ENTER INTO THE MANUFACTURE OF THE HIGH EXPLOSIVES. I. — SODIUM NITRATE (NaNOj). This salt, sometimes called cubic nitre, or Chili saltpetre, occurs in its native state, and in enormous quantities, at Tara- paca, in Southern Peru, where it forms regular beds of great extent, together with gypsum, common salt, and remains of recent shells. The pure salt commonly crystallizes in rhombo- hedrons, resembling those of calcareous spar. It is deliques- cent, and very soluble in water. Sodic nitrate is employed for making nitric acid, but cannot be used for gunpowder, as the mixture burns too slowly, and becomes damp in the air. It has been lately used with success in agriculture, as a superficial manure or top-dressing, and also for preparing potassic nitrate (KNO3). II. — POTASSIUM NITRATE (Saltpetre) AND NITRIC ACID (HNO3). In certain parts of India, and in other hot, dry climates where rain is rare, the surface of the soil is occasionally covered by a saline efflorescence, resembling that sometimes apparent on newly plastered walls : this substance collected, dissolved in hot water, and crystallized from the filtered solution, furnishes the highly important salt known in commerce as nitre, or salpetre, and consisting of potassic nitrate. To obtain nitric acid, equal weights of powdered nitre and strong sulphuric acid are introduced into a glass retort, and heat is applied by means of a gas-lamp or charcoal-furnace. 3 4 THE MODERN HIGH EXPLOSIVES. A flask, covered by a wet cloth, is adapted to the retort, to serve as a receiver. No tubing of any kind must be used. As the distillation advances, the red fumes which first arise disappear; but, towards the end of the process, they again become manifest. When this happens, and very little liquid passes over, and while the greater part of the saline matter of the retort is in a state of tranquil fusion, the operation may be stopped ; and when the retort is quite cold, water may be intro- duced to dissolve out the saline residue. The re-action consists in an interchange between the potassium of the nitre and half the hydrogen of the sulphuric acid (hydrogen sulphate), whereby there are formed hydrogen nitrate, which distils over; and hydrogen and potassium, which remain in the retort. KNO3 -f H,S04 = HNO3 + HKSO4. Potassium nitrate Hydrogen sulphate Hydrogen nitrate Potassic hydrogen (nitre) . (sulphuric acid) . (nitric acid). sulphate. In the manufacture of nitric acid on a large scale, the glass retort is replaced by a cast-iron cylinder, and the receiver by a series of earthen condensing-vessels connected by tubes. Sodium nitrate, found in a native state in Peru, is now gener- ally substituted for potassic nitrate. Nitric acid thus obtained has a specific gravity of from 1.5 to 1.52; it has a golden yellow color, due to nitrogen tri-oxide, or tetroxide, which is held in solution, and, when the acid is diluted with water, gives rise by its decomposition to a disengagement of nitrogen di-oxide. Nitric acid is exceedingly corrosive, stain- ing the skin deep yellow, and causing total disorganization. Poured upon red-hot powdered charcoal, it causes brilliant com- bustion, and, when added to warm oil of turpentine, acts upon that substance so energetically as to set it on fire. Although nitric acid in a more dilute form acts very violently upon many metals, and upon organic substances generally, this is not the case with the most concentrated acid : even at a boiling heat, it refuses to attack iron or tin ; and its mode of action on lignine, starch, and similar substances, is quite pecul- iar, and very much less energetic than that of an acid contain- ing more water. NITRIC ACID. 5 Chemistry and Analysis of Nitric Acid. — The re-actions for nitric acid and nitrates are as follows : — 1. Mix the solution with an equal or one-and-a-half volume of concentrated pure sulphuric acid, and let the mixture cool ; and along the sides of the test-tube let a few drops of concen- trated solution of ferrous sulphate flow, so that it will float on top. In the presence of nitric acid, on the point of contact, a violet color appears, turning violet-brown, and finally into brown. 2. Tinge the solution with indigo carmine solution : if after a few minutes decolorization sets in, or rather a change to yellow color, then free nitric acid is present. If this yellow coloring sets in only after addition of H^SO^, then we have a nitrate. If the indigo tincture contains sulphuric acid, this test will only be of value for nitrates. This re-action has value only in the absence of chloric, bromic, and iodic acids. 3. Put in the solution some quicksilver or copper filings ; add sulphuric acid. A disengagement of red, brown, and yellow vapors takes place, which, in contact with starch-paper moist- ened with potassium iodide, produces a violet, blue, or purple coloration. This re-action is delicate where the evolution of nitrous gases is hardly perceptible. 4. Put the test-liquor in a small cup, in contact with caustic potash (potassic hydrate) and some zinc-dust. Evolution of ammonia takes place, which is recognized if a glass rod, moist- ened with hydrogen chloride (hydrochloric acid), is brought in the vicinity. 5. If not too dilute, it will color linen yellow. 6. Nitrates thrown on live coals will deflagrate. Examination as to the Purity of Nitric Acid. — i. Ought not to show any color, even after mixing with twice its volume of water. 2. No re-action, occurs with baric nitrate. 3. No re-action occurs with argentic nitrate. 3. No re-action occurs with hydrogen sulphide (sulphuretted hydrogen) after addition of chloroform, and agitating. 5. Test with potassic permanganate for one or two minutes. If it does not stand this test, it can be liberated from the nitrous compounds by boiling. Quantitative Determination of Nitric Acid. — Free nitric 6 THE MODERN HIGH EXPLOSIVES. acid is neutralized in a liquid form by baric carbonate or calcic carbonate. When baric carbonate is used, the filtrate is mixed with sulphuric acid, and baric sulphate is precipitated ; and this is weighed. BaS04 X 0.463s = the nitric acid present. In the other case, the lime is precipitated as an oxalate, slightly heated, and the calcic carbonate weighed : then CaCOj X 1.08 = the nitric acid present. If the material examined contains a nitrate, it is mixed with a surplus of ammoniac sulphate ; the mixture is dampened, and dried in a water-bath, triturated and extracted with pure alco- hol, which dissolves the produced ammoniac nitrate. This solution ought to be mixed with a solution of potassic hydrate in alcohol, till a precipitate is produced ; which is washed in pure alcohol, dried, and weighed. KNO3 X 0.534654 = the nitric acid present. Nitric acid can be estimated when mixed with H^SO^, or HCl, by its conversion into ammonia. By placing zinc in a mixture of the two acids, there is no disengagement of gas ; whilst the nitric acid is converted into ammonia. Hydrogen, in its nascent state, combines with the oxygen of the nitrogen compound, produced by the nitric acid alone. Metallic zinc, with dilute nitric acid, gives nitrogen protoxide; and, by taking one equivalent of this gas and four equivalents of hydrogen, water and ammonia may be formed. N,0 + 8H = 2NH3 + H,0. The nitric acid, acting gradually and slowly on the zinc, is transformed into ammonia. When this re-action has ceased, then follows a disengagement of hydrogen gas from the zinc, which is permitted for a few seconds. It now remains to ascertain the percentage of ammonia. The ammonia may be SULPHUR. distilled off, and then absorbed by a normal or previously ascertained quantitative solution of oxalic acid, and afterwards ascertain the quantity of oxalic acid not taken up, deduct this from the original quantity contained in the absorbing solution, and the result gives the percentage of oxalic acid neutralized by the absorption of the ammonia ; from this the ammonia is calculated.' III. — SULPHUR (Atomic Weight 32, Symbol S). This is an elementary body of great interest and importance. It is often found in the free state, in connection with deposits of gypsum and rock-salt, and in the fissures of volcanic craters. Sicily furnishes a large proportion of the sulphur employed in Europe. On the Pacific coast, the deposits at Rabbit Hole in the State of Nevada are of importance, and furnish an ex- <;ellent article ; and very noteworthy are the interesting layers of this substance at the Sulphur-banks Mines in Lake County, California, where quicksilver ores are mixed with the matrix con- taining sulphur. A great deal of sulphur comes to us also from Japan, where it occurs in the volcanic regions of the seacoast. Sulphur also occurs abundantly in combination with iron and other metals, and as sulphuric acid, united to lime and magnesia. Pure sulphur is a pale-yellow, brittle solid. It melts when heated, and distils over unaltered if air be excluded. The crystals of sulphur exhibit two distinct and incompatible forms : namely, first, an octahedron with rhombic base, which is the figure of native sulphur, and that assumed when sulphur sepa- rates from solution at common temperatures, as when a solution of sulphur in carbon disulphide is exposed to slow evaporation in the air ; and, secondly, a lengthened prism having no rela- tion to the preceding; this happens when a mass of sulphur is melted, and, after partial cooling, the crust on the surface is broken, and the fluid portion poured out. The specific gravity of sulphur varies according to the form in which it is crystallized. The octahedral variety has the specific gravity 2.045 \ the prismatic variety, the specific grav- ity 1.982. Sulphur melts at iii" C. (232" F.) : at this temperi- ' The author, thinking the able treatise of M. Berthelot on formation of nitrates will be •of interest to chemists and others, has given an abstract of it on p. 384 of t'he appendix. 8 THE MODERN HIGH EXPLOSIVES. ture it is of the color of amber, thin and fluid as water ; when further heated, it begins to thicken, and to acquire a deeper color; and between 221° C. (430° F.) and 249° C. (480° F.) it is so tenacious that the vessel in which it is contained may be inverted for a moment without the loss of its contents. If in this state it be poured into water, it retains for many hours a remarkably soft and flexible condition, which may be looked upon as the amorphous state of sulphur. After a while it again becomes brittle and crystalline. From the temperature last mentioned to the boiling-point, — about 400° C. (702° F.), — sulphur again becomes thin and liquid. In the preparation of commercial flowers of sulphur, the vapor is conducted intO' a large cold chamber, where it condenses in minute crystals. Sulphur is insoluble in water and alcohol, but oil of turpentine and the fat oils dissolve it : the best substance for the pur- pose, however, is carbon bisulphide. In its chemical relations,, sulphur bears great resemblance to oxygen ; and to very many oxides there are corresponding sulphides, while the sulphides often unite among themselves, forming crystallizable com- pounds analogous to oxysalts. IV. — SULPHURIC ACID (H2SO4). The preparation of this important acid depends upon the fact that when sulphurous oxide, nitrogen tetroxide, and water are present together in certain proportions, the sulphurous oxide becomes oxidized at the expense of the nitrogen tetroxide, which, by the loss of one-half of its oxygen, is reduced to the condi- tion of nitrogen dioxide. The operation is thus conducted : A large and very long chamber is built of sheet-lead supported by timber framing ; on the outside and at one extremity, a small furnace or oven is constructed, having a wide tube leading into the chamber. In this, sulphur is kept burning, the flame of which heats a crucible containing a mixture of nitre and oil of vitriol (hydrogen sulphate). A stratum of sulphuric acid occu- pies the floor of the chamber, and a jet of steam is also intro- duced. Lastly, an exit is provided at the remote end of the chamber for the spent and useless gases. The effect of these SULPHURIC ACID. 9 arrangements is to cause a constant supply of sulphurous oxide, atmospheric air, nitric-acid vapor, and water in the state of steam, to be thrown into the chamber, there to mix and re-act upon each other. The nitric acid immediately gives up a part of its oxygen to the sulphurous oxide, and is itself reduced to nitrogen tetroxide, N^O^, or NO^ : it does not remain in this state, however, but suffers further de-oxidation until it becomes reduced to nitrogen dioxide, N^O^, or NO. That substance, in contact with free oxygen, absorbs a portion of the latter, and once more becomes tetroxide, which is again destined to undergo de-oxidation by a fresh quantity of sulphurous oxide. A very small portion of nitrogen tetroxide, mixed with atmos- pheric air and sulphurous oxide, may thus in time convert an indefinite amount of the latter into sulphuric acid by acting as a kind of carrier between the oxygen of the air and sulphurous oxide. The presence of water is essential to this re-action, which may be represented by the equation : — NO, -I- SO3 -h H3O = NO -h H,S04. The priming at the bottom of the chamber thus becomes loaded with sulphuric acid. When the acid at the bottom of the chamber has reached a certain height, the acid is drawn off, and concentrated by evaporation, first in leaden pans, and after- wards in stills of platinum, until it attains a density (when cold) of 1.84, or thereabouts: it is then transferred to carboys, or large glass bottles fitted in baskets, for sale. Sulphuric acid is now more frequently made by burning iron pyrites or poor copper ores, or zinc-blende, instead of Sicilian sulphur. As thus prepared, it very frequently contains arsenic ; from which it may be freed, however, by heating it with a small quantity of sodium chloride, or by passing through the heated acid a current of hydrochloric-acid gas, whereby the arsenic is volatilized as trichloride. The most concentrated sulphuric acid, or oil of vitriol as it is often called, is a definite combination of forty parts sulphuric oxide and nine parts of water, and is represented by the formula (S^'O"), (0"H')'., or H.SO^. It is a colorless, oily liquid, having a specific gravity of 1.841 (at 17.5° C), of intensely acid taste lO THE MODERN HIGH EXPLOSIVES. and re-action. Organic matter is rapidly charred and destroyed by it. At the temperature of —26° C. (—15° F.), it freezes ; at 327° C. (620° F.), it boils, and may be distilled without decomposition. Oil of vitriol has a strong affinity for water. It withdraws aqueous vapors from the air ; and, when it is diluted with water, great heat is evolved, so that the mixture always requires to be made with caution. Sulphuric acid acts readily on metallic oxides, converting them into sulphates. It also decomposes carbonates with the greatest ease, expelling carbon di-oxide with effervescence. With the aid of heat, it likewise decomposes all other salts containing acids more volatile than itself. The sulphates are a very important class of salts, many of them being extensively used in the arts. Most sulphates are soluble in water, but they are insoluble in alcohol. The baric, calcic, strontic, and plumbic salts are insoluble, or very slightly soluble, in water ; and are formed by precipitating a soluble salt of either of these metals with sulphuric acid or a soluble metallic sulphate. Baric sulphate is quite insoluble in water : conse- quently sulphuric acid, or its soluble salts, may be detected with the greatest ease by solution of baric nitrate or chloride ; a white precipitate is thereby formed, which does not dissolve in nitric or hydrochloric acid. Examination as to the Purity of Sulphuric Acid. — i. Evapo- ration on platinum foil. If there is a fixed residue, the same indicates the presence of potassic, sodic, plumbic, and calcic sulphate. 2. Diluted with water, with or without the addition of a few drops of concentrated hydrochloric acid, in case of a whitish cloudiness it indicates plumbic sulphate, which can be proved by introducing sulphuretted-hydrogen gas in the sulphuric acid which has been mixed with ammoniac carbonate. 3. With water and zinc, it must produce hydrogen free of arsenic. This is easily recognized by the following simple method : — One c.c. H.SO^ is diluted with 10 c.c. water, and 30 drops of a solution of cupric sulphate are added, which prevents, in case sulphurous acid is present, a disengagement of sulphuretted hydrogen. Put 4 to 5 c.c. of the mixture in a glass cylinder, GL YCERINE. 1 1 add a piece of pure zinc, close with a split cork in which there is inserted a piece of parchment paper impregnated with solu- tion of argentic nitrate. If the same is blackened, it indicates the presence of hydrogen arseinde (arsenide). 4. Solution of silver. If a white precipitate soluble in ammo- nium appears, it indicates hydrochloric acid. 5. Iron vitriol. If added in small pieces, red coloration on the point of contact indicates nitric or nitrous acids. Sulphuric acid is recognized through the insoluble precipitate this acid forms with baric chloride. Determination. — This acid is determined on adding solution of baric chloride to the hot solution, which may contain sul- phuric acid or a sulphate, and acidulating it beforehand with hydrochloric acid. In case the muriatic acid already produces a precipitate, then we choose nitric acid or baric nitrate as a precipitant. The precipitate is allowed to settle well, and is filtered, and well washed with hot water. The precipitate with the filter is dried in a platinum crucible over a light flame, then it is heated strongly, and after cooling weighed. The same con- tains 34.356^ sulphuric acid. v. — GLYCERINE (CjHsOj). Its History. — Glycerine was discovered by Scheele in the year 1779; but only in later years has it found practical uses in the industries, and its manufacture on a large scale been carried out. A close study of the pure glycerine has shown that this body contains properties which make it applicable in the preparation of cosmetic products, and also for many pharmaceutical articles. The properties which glycerine possesses after nitrating it are of the greatest importance, as this preparation furnishes the base of the most powerful blasting compounds known at the present time. It enters also largely into the manufacture of wine, beer, and fine liquors. The latest statistics in Europe furnish us the following data as to the present production of glycerine : — 12 THE MODERN HIGH EXPLOSIVES. • France 4,ooo tons. Germany and Austria 1, 5°° " Holland 900 " Russia 900 " Belgium 800 " Italy 400 " England 300 " Spain 200 " United States S°° " Total 9>Soo " By far the largest portion, of these ninety-five hundred tons enters into the manufacture of nitro-glycerine. Scheele already noticed some very peculiar properties of this body, especially its sweetish taste; and he called it "oil-sweet." The name "glycerine," from the Greek yXwKvs, was first em- ployed by Chevreul in the year 18 14; and he studied the chemical composition and decomposition products of this body. Although a great quantity of glycerine was left in the residues of the soap-manufacturer, it was not utilized on a large scale, as no method was then known for its economic extraction, and also there was no demand for it. It is now extracted by means of centrifugal machines. When, in the year 1821, the manufacture of stearine candles was commenced, there was seen a necessity of finding some use for the large quantities of glycerine left as a by-product ; but some time elapsed before it could be produced in a state of purity. The house which first brought pure glycerine into com merce is the firm of A. Sarg & Co., near Vienna, who, about 1850, produced the first clear glycerine. In England, it was Price's Candle Company, of London, who introduced their product into the market about the same 'time. Properties. — Glycerine is a neutral, clear, thick, viscous liquid, without color or smell, having sweetish taste, and very hygroscopic ; boils at 554° F. In an atmosphere charged with steam, at a temperature of 618° F., it distils over in an un- changed condition. At 212" it evaporates in very small parti- cles. In spite of these properties, it is considered a substance which does not desiccate. With water, alcohol, or ether, it gives clear mixtures, and is insoluble in chloroform and benzine. GLYCERINE. 13 Six parts of ether and alcohol in equal proportions dissolve one part glycerine. In contact with sulphuric acid it changes into sulpho-glyceric acid : with potassic hydrate it mixes with- out changing physically. Specific gravity of pure glycerine at 50° F. is 1.267. If glycerine contains water, its per cent content at 60° F. is as follows : — Specific Gravity. Percentage Glycerine. Specific Gravity. Percentage Glycerine. 1.267 1.251 I.2I2 I.218 100 95 90 85 1.203 I.188 1. 1 82 80 75 73 If strongly heated, glycerine evaporates, and its vapors are easily inflammable. If free of water, it crystallizes at 42° F. It is a great solvent, and dissolves alkaline earths, alkalies, oxides of metals, and many salts which are hard to dissolve otherwise. When poured into an ammoniacal solution of ar- gentic nitrate, and heated to boiling, metallic silver is precipi- tated in the shape of a mirror of silver. If diluted, the silver will precipitate as a -brown-gray precipitate. At ordinary tem- peratures there is no re-action. Test. — Heat one or two drops of glycerine in a test-tube, or with strong H3S04, or potassic sulphate, or other salts having afl&nity for water, and vapors of acrolein ' are evolved, recogniz- able by their powerfully irritating effect on the eyes and res- piratory passages. If the glycerine be in solution with water, it must be evaporated as much as possible before applying this test. Add a few drops of the fluid suspected to contain gly- cerine, to a little powdered borax ; stir well together ; dip the looped end of a platinum wire into the mixture, and expose to a Bunsen flame : a deep green color is produced, for the glycer- ine liberates boracic acid, and the latter colors the flame. Liquids containing much indefinite organic matter must some- times be evaporated to dryness, and the residue extracted by ' From acer (sharp) and oleum (oil). 14 THE MODERN HIGH EXPLOSIVES. alcohol ; then the latter may be tested for glycerine. To detect traces, the liquids must be concentrated. Glycerine in its Chemical Relations. — Glycerine does not appear in nature in its free state ; but it is found in many com- binations, and is produced by certain chemical re-actions. According to the researches which Chevreul has made in the first quarter of this century, all animal and vegetable fats are composed of combinations of glycerine with various acids ; and, as fatty matter is found largely propagated amongst plants and animals, we can consider glycerine as a substance very largely diffused in nature. According to its chemical constitution, glycerine is an alcohol in which three atoms of hydrogen can be replaced by three acid radicals ; and when this takes place, compounds are pro- duced which can be designated as compound ethers ; and those fats which contain glycerine are such compound ethers or glycerides. The composition of glycerine can be expressed by the formula CjHgOj ; but as, in the three hydroxyl radicals which are con- tained in glycerine, all the hydrogen can be replaced through acid radicals, the formula of glycerine is : — C3H3(OH)3, or (C3H5)" ^Q^^ ^^ C3H5 H H (C3-H/)"'(0"H')'3 H J O3, or CH,(OH) . CH(OH) . CH,(OH). If R designates an acid radical, the following combinations of glycerine are produced : — C3H31 C3H5I C3H5I H H O3, H R O3, R R R R R , o. These combinations can all be produced. The glycerine combinations which exist in nature are compounds, in which three atoms of hydrogen are replaced by monovalent acid GL YCERINE. 1 5 radicals. Stearic acid has tlie composition C.sHjeO^ or C.^Hjs COOH ; in fatty bodies it exists as a glyceride, known as tri- stearin, having the composition C3H5 (OC,8H350)3. Tripalmitin has the composition : C3H5(OC,sH3,0)3. Triolein " " : C3H5(O.C,8H330)3. If one of the above compositions, or a mixture of them, is treated with a caustic alkali, the glyceride is decomposed in such a manner that to the radical of the glycerine C3H5 three hydroxyl radicals 3 (OH) are taken up, and form glycerine. This process, which is carried out on a large scale, is the one which is known under the name of saponification. C3H5(OC,8H350)3 + 3KHO = C3H5(OH)3 + 3 K . OC.SH35O. Potassic hydrate. Glycerine. Potassic stearate. In the place of the potash, the oxide of a metal, like lime, lead, etc., can be used. The glycerine goes into solution in a pure state, and this was the method which was formerly em- ployed to produce glycerine. Other methods will be given farther on. Oleate of Lead. — Boil together in a small dish some very finely powdered plumbic oxide, with about twice its weight of olive-oil, and ten to twenty times as much water ; stirring the mixture thoroughly, and from time to time replacing the water that has evaporated. The product will be a white mass of plumbic oleate, — Pb (0181^3302)2, — and glycerine remaining in solution in the water. Larger quantities are prepared in the same manner. 2C3H5(C,8H3302)3 + 3PbO + 3 0H2=2C3H5(OH)3 + 3(C,8H3302)2Pb. Oleine, or glyceric oleate. Glycerine. Plumbic oleate. The action between the oxide of lead and olive-oil is slow, requiring several hours for its completion. The glycerine may be obtained by treating the aqueous product of the above re-action with sulphuretted hydrogen to remove a trace of lead ; then digesting with animal charcoal, filtering, and evaporating. I6 THE MODERN HIGH EXPLOSIVES. The Production of Glycerine in the Stearine Factories. — In all the factories in which the so-called stearine is produced, — that is to say, a mixture of stearic and palmitic acids, — a large percentage of glycerine as a by-product is produced, which in most factories is now utilized by being concentrated and refined. The method which is employed depends on the proceeding by which the fats are decomposed, and the quanti- tative results of glycerine depend on them. The decomposition of the fats can be effected by various methods : as, the saponification with alkalies or alkaline earth like caustic lime (calcic hydrate) ; or sometimes with caustic alkalies ; again, by the saponification with lime, and employment of steam-pressure. Newer methods are those where the separation of the glycer- ine from the fatty acids is effected by the decomposition of the fats by acids, especially sulphuric acid ; then, in place of the acids, water is employed ; and the saponification is effected by superheated water or steam. These methods can be employed wherever we wish to obtain the fatty acids which are used in the stearine-candle manu- facture only : but they are not applicable when it is desirable to get the glycerine also, as at present the case in most facto- ries ; since by the saponification with acids, and the high tem- perature, the glycerine is completely destroyed. But this process has been so modified as to gain the glycerine also. A mere outline of the different methods which are employed in the manufacture of glycerine is here given. Theoretically the different methods can be classed as fol- lows : — a. Saponification with Alkalies, especially Caustic Lime: — 2 C3H5(O.C.8H350)3 + 3 Ca(OH), = 3 Ca(O.C.8H350.) -I-2 C3H5(OH)3. Tri-stearine. Calcic hydrate. Calcic stearate. Glycerine. As we have in the fats, beside stearine, also palmitine, oleine, arachine, and mysestine, these glycerides are decomposed in the same manner like the stearine ; and we obtain a mixture of calcic stearate, palmitate, oleate, mysestate, and arachidate, — lime-soap, — insoluble in water, — and a solution of glycerine. GLYCERINE. I J b. Saponification with Acids, especially Sulphuric Acid: — Palmidne. Sulphuric acid. SCeHj.OCOSO.OH) + C3H5(OH),(OSO,OH) + H,0. Palmitine sulphu! ic acid. Glycerine sulphuric acid. Water. And out of these combinations, by the addition of water, there is produced, — 3C,6H3,0(OH) + C3H5(OH)3 + 4H,S04. Palmitic acid. Glycerine. Sulphuric acid. Description. — By the action of sulphuric acid on glycerides, — palmitine, for instance, — it is decomposed in the first place; so that palmitic sulphuric acid and glycerine sulphuric acid, by the separation of one molecule of water, are formed. The first two combinations, by the action of water, are divided into palmitic acid, glycerine, and sulphuric acid ; which last remains in solution with the glycerine. c. By the saponification with water at a high temperature, and with superheated steam. C3H5(O.C,8H350)3 + 3H3O = aCsHj.OCHO) + C3H5(OH)3. Stearine. Water. Stearic acid. Glycerine. I. The Saponification of Fats with Caustic Alkalies or Caustic Lime. — The oldest method for the production of fatty acids was the one where the caustic alkalies, potash or soda, were em- ployed, as in the operation of the soap-factories, and a potash or soda soap was obtained ; then by the addition of a strong acid — sulphuric or muriatic — the fatty acids were eliminated, and the glycerine separated with the residue waters or lye. But, of all the operations for saponification, the one where caustic lime is employed is the most practical, and is mostly used, as caustic lime is cheap, and lime-soap is insoluble, and separates readily from the liquids. The process is as follows: The fats — tallow or palm-oil — are put into large wooden vats, and melted there after the addi- tion of some water : by the introduction of steam, the tempera- ture is raised to 212° F. 1 8 THE MODERN HIGH EXPLOSIVES. While the material is boiling, fifteen per cent of the weight of fat in lime is added. This lime has to be free from iron, newly burnt (free from carbonic acid), and diluted with water to- a milky consistency ; in which state it is poured into the vat. The saponification in the vat is now assisted by a continual jet of steam, and by an agitating apparatus. The commence- ment of the saponification is noticed by the thickening of the mass, and this happens three to four hours after the commence- ment of the operation ; later on, the small particles of soap conglomerate to small lumps which rise to the surface. After seven to eight hours, the saponification is finished; and we have now in the vat a solid mass, which is lime-soap with some free lime; and the liquid should be entirely free from undecomposed fat. The yellowish or brown liquid is a dilute solution of raw gly- cerine in water, which seems adulterated with foreign matter. A modification of this process is to employ a smaller quantity of lime, but to let the steam act under a pressure of ten atmos- pheres ; and two to three per cent of caustic lime is sufificient to effect a complete saponification. This last process is especially advantageous for the produc- tion of glycerine ; as smaller quantities of water are employed, and the solution of glycerine is more concentrated. In both cases, the lime-soap is decomposed by sulphuric or hydrochloric acid, whereby either gypsum or calcium chloride is formed : the mixture of these fatty acids — stearic, palmitic,, mysestic, arachidic, and oleic acid — is freed from the oil-acid in strong hydraulic presses, and after clearing is employed in the manufacture of candles ; and the liquid separated from the lime- soap is employed for the production of glycerine. 2. Decomposition of Fats by Sulphuric Acid. — Sulphuric acid acts on fats, and produces combinations of the fatty acids and of the glycerine with sulphuric acid ; and these combinations are again decomposed, through the action of water, into fatty acids, glycerine, and sulphuric acid. There are two methods, — the quick and the slow process. The slow process takes place where the saponification is effected by sulphuric acid at a low temperature ; and the more sulphuric acid is employed, and the lower the temperature, the GLYCERINE. 1 9 more time is required to effect the decomposition of the fats ; and the consequence is, that a large portion of the fats is lost, and the production of fatty acids, and also of glycerine, is diminished. When this process was first introduced, thirty-seven per cent of the weight of fat in sulphuric acid was employed, and the operation carried on at a temperature of 185° to 200° F., and required from twenty-four to thirty-six hours. Later on, the quantity of sulphuric acid was diminished, and the temperature raised to 212° and 280° F. ; and, with five and a half per cent of sulphuric acid, the operation was finished in from twelve to eighteen hours. That the chemical operation does not pass off so smoothly as the theoretical formula would apparently indicate, is proved by the deportment of the heated mass. Large volumes of violet -colored fumes are evolved, having a bad smell, containing sulphurous-acid gases and vapors of acro- line ; and these vapors must be conducted by a strong draught into the chimney. The vapors of acroline are produced from the decomposition of the glycerine ; and not alone the glycerine, but also the fatty acids, are attacked, and a black tarry substance is formed, which can only be separated by the distillation of the fatty acids. The loss which is occasioned in this manner may amount to twenty per cent, and is seldom less than twelve per cent. After the saponification, the mass is treated with boiling water, to separate the fatty acids from the glycerine and the sulphuric acid ; and the fatty acids are further treated for the stearic-palmitic acids, and the residuary waters are worked now for the glycerine. The process of the quick saponification, or fractional saponi- fication, is worked in such a manner, that small quantities of fats, having a temperature from 194° to 280° F., are mixed with sulphuric acid for half an hour, and then the mixture is dumped into boiling water. By this means the fatty acids separate, and collect as an oily layer on the surface of the liquid ; and glycer- ine and sulphuric acid remain in solution. This process requires from three and a half to four per cent of sulphuric acid, and the work which required before several 20 THE MODERN HIGH EXPLOSIVES. hours is now done in a few minutes ; but the main advantage is, that only a small loss occurs through the decomposition of the fats and the sulphuric acid : only very little sulphurous acid is evolved, and no smell of acroline is perceptible. A mixture of sulphuric and nitric acid is also employed to prevent the production of the dark-colored products, which can- not well be prevented by the employment of sulphuric acid alone ; and the treatment with this acid-mixture takes place at a temperature of 250° to 260° F., and is finished in a few min- utes. With a hundred parts of fat, four to six parts of the acid- mixture is used, and the glycerine is produced in an unaltered condition. Zincic chloride decomposes fats like the acids ; and 10 ^ to i2 ^ of it is employed at a temperature of 340° to 420° F., when the decomposition can be effected very readily. The zincic chloride can be regained, and only a small portion of it is consumed during the operation ; but this method is not employed in practice. 3. The Decomposition of Fats by Steam. — If fats are treated with superheated steam of 400° F.. its chemical action is such as to decompose them, and to produce fatty acids and glycerine. This proceeding is largely employed, as it gives good results at a low cost. In this process, the fat is mixed with one-third its volume of water, and, by means of a force-pump, driven through a system of vertical pipes, which are heated in a fireplace, and the con- tents of these pipes heated to about 630° F. In this system of pipes, the water and fat act on one another, under a pressure of fourteen to sixteen atmospheres, in connec- tion with a cooling-worm, in which the two liquids condense ; one of them consists of fluid fatty acids, and the other of glycerine dissolved in the water. There are also other kinds of apparatus in use for the decom- position of fats by steam. The Composition of the Glycerine Waters (Lyes). — By the application of one of the preceding processes for the decom- position of fats, we always get liquids, in which, besides water, we get larger or smaller quantities of glycerine. But, in addi- tion to these two bodies, we find in the liquid all those matters GLYCERINE. 21 •which were originally in admixture with the fat, or were pro- duced through decomposition during the saponification. The raw glycerine water or lye has, in most cases, a bad and dis- agreeable smell, and is of a dark brownish color. The liquid which is obtained by the decomposition of lime- soap with sulphuric acid has always a considerable quantity of gypsum in solution; and gypsum will always dissolve with greater facility in liquids which contain glycerine, and for this reason glycerine obtained by this method always contains lime. By the treatment of grease or fats with sulphuric acid, a certain portion of glycerine is chemically decomposed or lost ; and, owing to the decomposition products, the article so ob- tained is generally brownish colored, and it is difficult to obtain it colorless by this method. The best results are obtained by high steam-pressure, and both quantity and quality are satisfactory in a well-conducted operation ; while, since it is a cheap method, the preference is given to it. Most glycerine and stearine factories work at present by this method, and by its application a nearly chemi- cally pure glycerine is obtained. 4. Production of Glycerine from the Lyes of Soap-Manufac- turers. — The production of soap is carried on by most manu- facturers in the following manner : The fat is boiled with a lime solution until a complete saponification is effected, when the lime-soap is converted into soda-soap. This is done by adding salt (sodium chloride), whereby soda-soap is formed, and calcic chloride remains in solution ; and as all soaps (except cocoanut- soap) are insoluble in salt solutions, they are separated by a surplus of salt. In some factories, the treatment is carried on directly with soda solution, and the separation of the soap is effected by the addition of very concentrated caustic solutions. In the stearine-factories, the mass of fats and grease is sub- mitted to a strong pressure ; and the oleine thereby gained is boiled with caustic lye. The lyes or residuary waters of the soap-factories contain, in addition to potassium and sodium chloride, some free alkalies besides the glycerine, and, under favorable circumstances, can be employed for the extraction of the glycerine. Formerly this was done by neutralizing the free alkalies with hydrochloric 22 THE MODERN HIGH EXPLOSIVES. acids and by evaporating the liquid. The salts were produced in a very pasty and sticky condition, through the adhering glycerine. The salt-mixture with strong alcohol will bring the glycerine into solution, and, when heated in a still to 212° F., will distil over the alcohol, leaving as a residue in the still a sirupy liquid of brown color, which is an impure glycerine. In a less costly manner, the waters are treated by heating them in flat pans till they reach a temperature of 400° F. The <^rystals of salt separate constantly during this process, and are drawn to the edge of the pan, and put into baskets which are hung up over the pans, and the water allowed to drip back into the pan. When a temperature of 240° is reached, the liquid is run into a still, where it is further concentrated till the thermometer ■shows a temperature of 412" F. The heating by means of fire is then interrupted ; and a jet of superheated steam is led into the liquid, the steam being so regulated that the temperature does not sink under 412". Since the introduction of the water-saponification, large masses of glycerine are produced, which are comparatively pure ; and the production from the lyes has in consequence greatly diminished. Still, most soap-factories produce what is called raw glycerine, which they sell to the refiners ; and the refiners generally pay for it according to its density. When the glycerine waters are heated in open pans, we get a darker-colored liquid than when the heating takes place in closed vessels ; and pans are used, at present, on the plan of a still. Different methods are employed now ; and Thomas, Fuller, and King boil the liquid to a temperature at which a large por- tion of the salts, like the sodium chloride and carbonate, crys- tallize, and settle at the bottom of the pan. The supernatant liquid is drawn off into another pan, and boiled with a large quantity of fatty acidg (which are a mixture of stearic, palmitic, and oleic acids). To determine how much fat ought to be added, we have to determine first the quantity of salts remaining in the liquid, and add nine times the quan- tity of fatty acids to neutralize the same. By boiling, the fatty acids combine with the alkali, and sepa< GL YCERINE. 23 rate as a soap, which is skimmed off. The remaining liquid is allowed to cool down, and is filtered. A pretty pure glycerine solution is obtained in this manner, which is concentrated, and afterward distilled. PRODUCTION OF PURE GLYCERINE. The first condition for the production of a pure glycerine is the employment of perfectly pure tallow ; as otherwise the for- eign matter will enter into the glycerine solution, and cannot be eliminated. The tallow has to be cleaned before its saponi- fication, and this is effected through a treatment with weak sulphuric acid or a soda solution. Certain organic matters are thereby destroyed, and dissolve in the alkaline or acid solution; and the molten fats float on top of the liquid, from which they are skimmed off into other vessels, to be decomposed. When this decomposition is completely effected, and the manipulation is properly conducted, we receive a raw glycerine, which need only be properly evaporated to give, after its distillation, a pure concentrated glycerine. The Distillation of Glycerine. — This operation can be con- ducted by allowing superheated steam to act directly on the glycerine in the stills. As long as the glycerine contains a large amount of water, we allow the steam to enter the liquid at a temperature of 630° F., and we evaporate the water. If the temperature in the still rises to 618° F., the glycerine itself commences to boil ; and the regulation of the steam has now to be watched with the greatest care, and the temperature in the still main- tained at 600° to 640°. The glycerine then distils over with- out any decomposition. The cooling of the vapors is effected in specially constructed worms which are systematically arranged. A physical law teaches that the boiling-point of a liquid depends on the pressure ; and, the more this pressure is dimin- ished, the lower the boiling-point. This principle was first applied in sugar-refineries, where the evaporation of sugar solutions is effected in vacuum apparatuses, and by pumping out the air, and continual condensation of the escaping steam, a low pressure is maintained. 24 THE MODERN HIGH EXPLOSIVES. To produce by distillation a clear and oaorless glycerine, the stills have such contrivances that the distillation is carried on under a diminished air-pressure ; and as soon as the still contains the requisite quantity of raw glycerine, the exhaust-pump is. put in motion, the steam enters the still, and the evaporation is conducted and finished in -this way in a much shorter space of time. Under the ordinary atmospheric pressure (760 m.m. quick- silver), the glycerine boils at 618° F. ; but under a quicksilver pressure of 500 m.m., it will boil at 464° F. ; but under a pressure of only i2i m.m., it will boil at 388° F. Hence it is advisable to connect the still with a very strong exhaust-pump, so as to maintain an extremely low pressure ; and by the action of a good jet of steam the boiling will take place quite actively, and the distillation be effected in a remarkably short space of time. The Filtering of the Glycerine. — The glycerineobtained in the vacuum apparatus has a light brown or yellow color ; and, to get it in a perfectly colorless state, it ,has to be filtered. To decolorize it, bone-coal or bone-black is employed, which absorbs the coloring substances, and also deodorizes the gly- cerine. Since, however, the glycerine has great dissolving powers for all lime-salts, after filtration it becomes colorless and odorless, but contains quite a percentage of lime-salts in solution ; and to free it from these salts requires a second distillation. The filtration of the glycerine requires time, and, for a sys- tematic arrangement in a large factory and a regular working system, a large number of filters. They are arranged in sets- or batteries, in such a inanner that the glycerine which flows into the first filter, after running through one or more batteries, escapes from the last filter as a clear, colorless liquid. As tO' the arrangement of the filters, it resembles much those em- ployed in sugar-factories for the purification of the sugar- solutions. As the absorbing power of bone-coal is not unlimited, the filters have to be renewed from time to time. The porous bone-coal retains also considerable quantities of glycerine, and this is recovered by two methods : it is washed out with water, resulting in a very dilute glycerine, which in the distillation GLYCERINE. 2$ process is mixed with the fresh inaterial ; or the glycerine is obtained by distilling it directly out of the filter. The bone-coal which has no more absorbing powers is regen- erated in the same manner as the bone-coal employed in sugar- refineries. The coal is washed with water, and the wash-waters are employed again for the decomposition of the tallows, so that the small particles of glycerine which are held in suspen- sion shall not be lost. The washed coal is dried and burnt in iron retorts till the organic matters it contains shall be de- stroyed, and now is fit for use in the filters again. It is well to wash the bone-coal, before using it in the filters, with muriatic acid, which will dissolve all the lime-salts out of it ; and the glycerine obtained by such filters will be free from lime, and require no second distillation. Purification of Glycerine from its Lime Contents. — Glycerine obtained by the saponification of tallow with lime contains a certain percentage of lime, and must be liberated from it. This is done by converting the lime into a carbonate. Into the liquid maintained at 212° F., a stream of carbonic acid is led ; and calcic dicarbonate would form, but for the high temperature which prevents all formation of this salt : only a single carbonate is produced, and the liquid assumes a milky color by the separation of the small crystals of this salt. This carbonate is separated through filtration from the glycer- ine, and is concentrated by evaporation. By this method a glycerine which is comparatively free from lime results ; although it still retains some of it, for calcic car- bonate is soluble in glycerine. In the saponification of tallow by lime, it is best to use little lime ; and a high pressure, for instance, by employing one hun- dred parts of tallow and four parts of lime. In this way, only fatty salts of the lime are formed ; and the dilute solution of glycerine obtained at the end of the operation is compara- tively free from lime. Since the introduction of the process of saponification by water alone, the methods used to clear glycerine of its lime contents have lost their value, as a comparatively high concen- trated glycerine results free of lime, which by the vacuum still and filtering process gives a clear and merchantable article. 26 THE MODERN HIGH EXPLOSIVES. In submitting glycerine to a very low temperature, it freezes and crystallizes ; and it these crystals are separated, and after- ward allowed to melt, they will give a perfectly clear glycerine. THE BEAUJARD PROCESS. A New Process for extracting Glycerine. — A new process foi extracting glycerine from fatty substances has just been pat- ented in this country, which is destined to revolutionize the glycerine industry. As a great deal of glycerine is a by-prod- uct from the candle-works, and the demand for candles being steadily on the decrease by reason of the almost universal use of other illuminating agents, the production of glycerine, it was feared, would not be sufficient to meet the ever-increasing demand. Chemists have, therefore, for a long time been experimenting to profitably extract the glycerine from greases used in soap- making ; but heretofore they have met with but partial success, as the processes thus far proposed have had an injurious effect on the greases, and it was impossible to produce light-colored soaps. By the newly patented process the grease is made lighter, and pure white soap can be produced without additional treat- ment. Another objection to the older processes proposed was the expense attendant upon their application, the cost of the lime and sulphuric acid used also being objectionable. In the new process no lime is used, and only a very small quantity of sulphuric acid when the stock is to be used for the manufacture of candles ; but when used for making soap no chemicals of any kind are required, the principal expense being the manipulation,- which is trifling compared with the value of the product rendered available thereby, the cost of separating the glycerine in a condition of purity suitable for manufacturing and technical purposes being less than the present cost of pro- ducing crude glycerine in the process of candle-making. The process is based, first, on the action produced on all fatty neutral substances by oxygen and hydrogen when in their nascent state ; second, on the property possessed by metallic zinc, when in a condition of proper division, of decomposing, the water when under the influence of heat. CL YCERINE. 2^ In carrying out this process, the patentee takes some pure metallic zinc, and proceeds as follows : In a closed vessel of a •digester, introduce a suitable charge of fatty neutral substances, with about 30^ of its volume of water, when pure metallic zinc, amounting to two or three thousandths of the weight of the fatty substances used, is introduced. This zinc is pulverized or reduced by a file into small particles, and placed in water in a pail or other suitable vessel. The contents of the vessel are stirred to keep the particles of the zinc separated or divided. The contents of the vessel, while under the influence of the stirring, are then introduced into the digester. They will preferably be introduced into the digester in small quantities at a time. They may be advantageously introduced through a funnel having its nozzle furnished with a cock, and located above the level of the charge in the digester. As each quan- tity of the zinc and water is introduced, a sufficient quantity of steam is let into the digester to agitate the charge, and dissemi- nate the zinc throughout the charge. The steam admitted for this purpose is admitted into the lower part of the digester, so ■as to stir up the charge effectually. If desirable, steam may be admitted in this way before any quantity of zinc and water is introduced, and may be admitted in a constant stream until ■all the zinc and water shall have been introduced. After the zinc and water are introduced, the cock of the said funnel is closed ; and steam is let on more fully until the desired pressure within the digester is attained. A slight escape of steam from the upper part of the digester is provided for, so that the in-coming steam will always keep the charge in the digester stirred up or in a state of turmoil. Under the influ- ence of the heat derived from the steam, a portion of the water in the digester is decomposed. The oxygen and hydrogen in their primitive state exercise their action in the fatty substance in dividing it so much more rapidly, that said fatty substance is quickly brought to a state of division. This is aided by the mechanical or stirring action of steam. If the steam is not introduced so as to keep the charge stirred during and after the introduction of the zinc and water, any mechanical contrivance may be employed for stirring or agi- tating the charge. When this division occurs, volatile acids 28 THE MODERN HIGH EXPLOSIVES. contained in the fatty substances are set at liberty. It can easily be ascertained when they are set at liberty, by applying to an escapement of steam from the digester a strip of litmus paper ; for presence of the volatile acids immediately turns that red. A maximum pressure of about one hundred and fifty pounds will suffice for dividing fatty substances such as are employed in stearine-factories. The division will be effected in about four to five hours. In soap - factories, where the fatty substances employed abound less in concrete acids, the division may be effected in about three hours, at a pressure of about one hundred and twenty-five pounds in the digester. After saponification has taken place in the digester, the contents of the digester are blown off into a suitable lead-lined tank ; and when the water has been completely separated, it is run into a receptacle for subsequent evaporation, and the fatty acids are run into another receptacle for further treatment. To sum up, the following are the benefits and new results t» be derived from the use of this process : First and foremost, the low price of metallic zinc almost nullifies the expense, and, moreover, does away with the inconvenience of metallic oxides, which all, in commercial centres, contain chlorides and salts, both soluble in glycerine, which renders the latter improper for manufacturing dynamite. When lime is used in the ordinary process, it is partly soluble in the glycerine : moreover, it con- tains chlorides and salts soluble in glycerine, thus producing impure glycerine, unsuitable, without refining, for use. The calcareous soap obtained by the lime process must be decom- posed by sulphuric acid. The calcic sulphate which results from this treatment necessitates numerous washings, which are not sufficient to eliminate all the fatty ac'ds interposed : thus a considerable expense, due to the use of sulphuric acid, the loss of time, and loss of fatty substance incident to the use of the lime process, is avoided. By this process, time is alsO' economized, owing to the fact that the treatment by the di- gester lasts but about one-half the time of any of the ordinary processes : consequently the same digester is adapted to do double the work ordinarily performed in a given time by a digester. Much time is also saved by this process, because a CL YCERINE. 2(^ plain washing with acidulated water will suffice to eliminate any particles of zinc which might remain in suspension in the fatty acids. The soap-manufacturers generally lose the glycerine, which is carried off with the spent lye. Those who endeavor to extract it by a preliminary saponification in a digester, with the intervention of metallic oxides, not only obtain an impure glycerine, containing a quantity of chlorides and salts, unfitted, without refining, for use ; but they also obtain a soap, the base of which is with difficulty displaced by the lye. The soap ob- tained is incomplete, and dull in color. By this process the manufacturer will, after about three hours treatment of a charge in a digester, at a pressure of about 125 pounds, extract eight to nine per cent of practically pure glycerine ; and the soap obtained will be much more desirable than that obtained by the ordinary processes. Examination of Glycerine. — i. Glycerine diluted with water must not re-act on litmus paper ; i.e., it must not exhibit acid or alkaline re-actions. 2. With sulphuretted hydrogen, no precipitate ought to show (absence of metallic impurities). The following re-actions, 3, 4, and 5, are superfluous if the glycerine, mixed with a mixture of two parts of alcohol and one of ether, gives a clear mixture, not showing any layers. 3. Dilute glycerine, if mixed with solution of caustic potash, and heated on a water-bath, must not get brown ; as otherwise it is impure or adulterated with glucose. Pure glycerine ought only to give a yellowish coloring in this mixture, or rather the coloration of the potash solution. 4. In approaching the above mixture of test 3, with a glass rod dipped in muriatic acid, there should be no formation of vapors. 5. If we take the hot mixture under No. 3, heat it, and add a few drops of sulphate-of-copper solution, it ought not to show any red coloring ; i.e., no separation of sesquioxide of copper should take place. 6. Equal volumes of pure concentrated sulphuric acid, mixed ■with glycerine, give a clear liquid in which, in the act of mixing, there ought to be no development of gas. There will be a dis- 30 THE MODERN HIGH EXPLOSIVES. engagement of air which glycerine always contains ; bubbles may escape, but air-bubbles are easily distinguished from a disengagement of carbonic-acid gas. 7. The mixture with sulphuric acid must not get blackened when heated. 8. The mixture with sulphuric acid ought not, on addition of alcohol and slight heating, to develop a smell like pine-apples, which would show the presence of butyric acid or of other fatty acids. 9. Glycerine diluted with water, and mixed with nitrate of silver and aqua ammonia, left by itself for half an hour, must not show a metallic black precipitate of silver (presence of formic acid, acroline, and similar substances). This mixture must not, however, be heated ; as in that case even pure glycer- ine would show a re-action. 10. Glycerine, diluted with water, ought not to give a pre- cipitate if mixed with nitrate of silver or nitrate of baryta (absence of chlorine, sulphates). 11. The mixture of glycerine with chloride of lime and solu- tion of acetate of soda should be clear, and remain so if left to itself for fifteen minutes (oxalic acid). 12. About one cubic centimetre, heated on a platinum cup gradually, evaporates, and leaves a small residue ; which, on red heating, disappears. Fixed substances remain as residue. Determination of Lime. — This test allows us to distinguish easily the evaporated from the distilled glycerine. The glycer- ine is diluted with twice or three times its volume of water, and ammonio oxalate is added ; and, in the presence of lime, a precipitate of calcic oxalate is formed. The presence of sul- phuric acid, ordinarily as calcic sulphate (gypsum), is detected in adding baric chloride to the diluted glycerine. The produc- tion of a white precipitate indicates the presence of sulphuric acid. If the precipitate is soluble in hydrochloric acid, then it is calcic phosphate which the glycerine has taken up from the bone-coal which had not been treated previously with hydro- chloric acid. Examination for Impurities which were produced during the Distillation of the Glycerine. — Glycerine, which is somewhat acid, may take up and dissolve, during the distillation from CELLULOSE. 3 1 the apparatus, iron or copper, and become impure. Iron can be easily detected by the addition of a solution of sodic nitro prusside or cyanide, or of salicylic acid. In both cases, in the presence of iron, a red coloration is produced ; if copper is present, it is easily detected by the addition of ammoniac hy- drate, as in thick layers the glycerine will show the characteris- tic blue color if copper is present. VI. — THE SACCHARINE GROUP. Before entering upon the study of the various nitra^ted com- pounds, a few words of those bodies which are capable of becoming explosive substances by their treatment with nitric acid will not be inappropriate. The Saccharine or Amylaceous Group. — The substances form- ing this group are numerous : they contain, with a few excep- tions, oxygen and hydrogen in the proportion to form water. The sugars and gums are the only members of the group which are soluble in cold water ; starch and other similar bodies are insoluble in cold, but soluble in hot, water; whilst cellulose is quite insoluble in water, whether hot or cold. There are three leading varieties of sugar, — cane-sugar, or sucrose ; grape-sugar, or glucose ; milk-sugar, or lactose ; and some chemists add a fourth, fruit-sugar, or fructose, while other chemists consider it to be merely grape-sugar. The body which, next to glycerine, plays the most important role in the industry of high explosives, is : — VII. — CELLULOSE (Lignine, Wood-Fibre, CeHioOsV- Cellulose forms the framework of all plants. Its decomposi- tion and re-actions are always the same ; but the properties which depend upon its state of aggregation present the greatest differences, as its texture varies with the plant from which it is extracted. Cotton, linen, hemp, and unsized white paper con- sist of cellulose very nearly pure. The easiest method of obtaining pure cellulose is to wash white cotton, unsized paper, old linen, or elder-pith, with a hot solution of caustic potash or soda, then with cold dilute hydro- 32 THE MODERN HIGH EXPLOSIVES. chloric acid, next with ammonia, washing thoroughly with water after the application of each of these re-agents, and lastly with alcohol and ether : it is often necessary to repeat this series of operations two or three times. To obtain pure cellulose from wood, it is necessary, after boil- ing the wood with potash till the liquid is almost dry, to treat it with chlorine-water, or with a weak solution of chloride of lime, repeating these successive operations several times, in order to free the cellular tissue from the incrusting matter which is so intimately united with it. Cellulose thus purified is white, translucent, of specific gravity about 1.5, insoluble in water, alcohol, ether, and oils, both fixed and volatile. When quite pure it is unalterable in the air ; but as it exists in wood, in contact with azotized and other easily alterable matters, it gradually decomposes in moist air, undergoing a slow combus- tion, and being converted into a yellow or brown friable sub- stance called touch-wood. Cold, concentrated sulphuric acid disintegrates it, and converts it into dextrine, — a substance isomeric with cellulose, — without blackening; if water be then added, and the liquid be subsequently boiled, the dextrine is converted into glucose. Concentrated nitric acid transforms cellulose into gun-cotton. Alkaline liquids when dilute do not act upon cellulose, but when concentrated they gradually destroy its texture. Cellulose in its natural state is not colored blue by iodine ; but after it has been digested for a short time with sulphuric acid it becomes of a fine blue when free iodine is added. This re-action is sometimes serviceable in the microscopic examina- tion of vegetable tissue, cellulose being thus easily distinguished from tissues into the composition of which nitrogen enters. By the prolonged action of sulphuric acid, the property of being- colored blue by sulphuric acid disappears, the dextrine and sugar which are formed not being susceptible of the blue coloration. Cellulose dissolves completely in an ammoniacal solution of oxide of copper, forming a sirupy liquid which may be filtered, after dilution, with an equal bulk of water. It is precipitated from this solution in flakes on the addition of hydrochloric acid. DEXTRINE. 33 VIII. — DEXTRINE (CeHioOj). When gelatinous starch is boiled with a small quantity of dilute sulphuric, hydrochloric, or, indeed, almost any acid, it speedily loses its consistency, and becoipes thin and limpid, from having suffered conversion into a soluble gum-like sub- stance, called dextrine on account of its dextro-rotary action on polarized light. The experiment is conveniently made with sulphuric acid, which may be afterwards withdrawn by satura- tion with chalk. The liquid filtered from the nearly insoluble gypsum may then be evaporated to dryness on a water-bath. The result is a gum-like mass, destitute of crystalline structure, soluble in cold water, precipitable from its solution by alcohol, and capable of combining with lead oxide. When the boiling with the dilute acid is continued for a con- siderable time, the dextrine first formed undergoes a further change, and becomes converted into dextro-glucose, which can be thus artificially produced with the greatest facility. The length of time required for this change depends upon the quan- tity of acid present. If the latter be very small, it is necessary to continue the boiling many successive hours, replacing the water which evaporates. With a larger proportion of acid, the conversion is much more speedy. A mixture of fifteen parts of potato-starch, sixty parts of water, and six parts sul- phuric acid, may be kept boiling for about four hours, the liquid neutralized with chalk, then filtered, and rapidly evaporated to a small bulk. By digestion with animal charcoal, and a second filtration, much of the color will be removed ; after which the solution may be boiled down to a thin sirup, and left to crys- tallize. In the course of a few days it solidifies to a mass of glucose. There is another method of preparing this substance from starch which deserves particular notice. Germinating seeds, and buds in the act of development, are found to contain a small quantity of a peculiar azotized substance, called diastase, formed at this particular period from the gluten of vegetable albuminous matter. This substance likewise converts starch into dextrine and glucose, and at a temperature much below the 34 THE MODERN HIGH EXPLOSIVES. boiling-point. When a little infusion of malt, or germinated barley, in tepid water, is mixed with a large quantity of thick gelatinous starch, and the whole kept at about 71" C. (160° F.), complete liquefaction takes place in the space of a few minutes, from the production of dextrine and glucose. If a greater degree of heat be employed, the diastase is coagulated, and rendered insoluble and inactive. Very little is known respecting diastase itself : it seems very much to resemble vegetable albujnen, but has never been obtained in a state of purity. The change of starch or dextrine into sugar, whether pro- duced by the action of dilute acids or by diastase, takes place quite independently of the oxygen of the air, and is unaccom- panied by any secondary product. The acid takes no direct part in the re-action : it may, if not volatile, be all withdrawn without loss after the experiment. The whole re-action lies between the starch and the elements of water ; a fixation of the latter occurring in the new product, as will be seen on compar- ing the composition of starch and glucose. Dextrine itself has exactly the same composition as the original starch. It was formerly supposed, that, in the action of acids (or of diastase) upon starch, the starch is first converted into dextrine by a mere alteration of physical structure, and that the dextrine then takes up the elements of water, and is converted into glucose, this second stage of the process occupying a much longer time than the first ; but from the experiments of Muscu- lus it appears, that, when the conversion is effected by a dilute acid, both dextrine and glucose are produced at the very com- mencement of the re-action, and always in the proportion of one molecule of glucose to two molecules of dextrine ; whence it may be inferred that the molecule of .starch contains CigHj,,, O15, or CisHjjOis, and that it is resolved into glucose and dex- trine by taking up a molecule of water : — CsHjoO.s + H,0 = CsH^Oe -f 2 CsH.oOs ; Starch. Glucose. Dextrine. and that the dextrine, after several hours' boiling, is completely converted into glucose, which is therefore the sole ultimate product of the re-action. DEXTRINE. 35 When malt extract is used as the converting agent, the starch is first resolved into dextrine and maltose in various propor- tions according to the temperature and other conditions of the re-action ; and the dextrine is afterwards very gradually con- verted into maltose. Dextrine is used in the arts as a substitute for gum ; it is sometimes made in the manner above described, but more fre- quently by heating dry potato-starch to 400° C. (752° F.), by which it acquires a yellowish tint, and becomes soluble in cold water. It is sold in this state under the name of British gum. CHAPTER II. NITRO-GLYCERINE. — ITS MANUFACTURE, CHEMICAL AND PHYSICAL PROPERTIES. I. — EXPLOSIVES. Bodies which possess the property, when heated or set on fire or from some other cause, of being converted from their solid or liquid state into gases in an almost immeasurably short ■space of time, — such gases during this chemical conversion liberating heat, and in consequence highly expanding, and through this expansion exerting a great pressure on their sur- roundings, — are called explosives. This conversion is accompanied by a detonation, which in its proper sense is called an explosion. The explosives are either mechanical mixtures of bodies which contain substances which under certain conditions, through a chemical exchange or decomposition, produce an explosion, or they are chemical preparations. Under the first, we count black-powder or gunpowder ; and under the latter, the explosive nitro compounds. The shorter the space of time in which a certain quantity -explodes, the larger the volume of gases developed by the ■explosion ; and the greater the heat developed, the stronger the explosive, that is to say, the more force is exerted by the gases developed. The explosive bodies are divided into two classes : — 1. Those whose explosion is effected in an immeasurably short space of time ; and we apply to them the term, " shatter- ing compounds." 2. The weaker compounds, which do their work by trajpc- tion, may be called "disintegrating compounds." Black-povv- 36 NITRO-GLYCERINE. 37 der, for example, is a good agent for rending apart the rock, but not a good agent for breaking it up. A cartridge of black-powder, two hundred feet long and one inch in diameter, would require eighteen seconds to consume. The explosion of gunpowder proceeds progressively by com- bustion, and its gases gradually accumulate until the resistance to them gives way. The yielding of the surrounding rocks, in almost every case, takes place before all the powder is burned ; so that any vacancies are filled with gas at the maximum pressure or density, and no effect is lost. But that class called dynamites (i) do not thus explode. Their explosion does not take place by combustion, or pro- gressively : it takes place instantaneously ; and all parts of the charge decompose simultaneously, thus making the initial pressure the maximum one. II. — NITRO-GLYCERINE. It is now admitted that this explosive is the most powerful known to man, being, in fact, " the ideal of portable force." A more favorable opinion of this powerful blasting agent may be created in the public mind by correcting many errors in respect to its properties and to the casualties attending its use. In that hope, these pages have been prepared, showing how science and chemistry have mastered a substance which, at its discovery, was considered uncontrollable. After full knowledge is acquired how to put this terrible substance into such a shape as to permit its transportation over the public highways with safety, and, when it reaches its destination, how to store it without danger ; and is given to the industrious miner and engineer for the operations of blasting in mines, quarries, and railroad work, — confidence will speedily follow. The defects which formerly existed in the different species of dynamites have been eradicated by many improvements ; and at present these compounds possess all the valuable properties of the liquid nitro-glycerine, without its dangers. As a special description of these substances is given farther on, the subject of nitro-glycerine and its chemical and physical properties is here considered. 38 , THE MODERN HIGH EXPLOSIVES. The liquid nitro-glycerine is very little used in blasting oper- ations, but serves as a base in the manufacture of the high explosives, which come into the market under the generic name of dynamite. Historical Notes. — Nitro-glycerine, or blasting-oil, was dis- covered by A. Sobrero, in' the laboratory of Pelouze in Paris, in the year 1847.- Sobrero was the first to notice the explosive qualities of this new body, and he called it pyro-glycerine. For a long time this discovery of nitro-glycerine was attended with no special results. Here and there chemists would prepare a small quantity to study its properties. Meanwhile, pyro- glycerine, under the name of glonoine, found a limited applica- tion for pharmaceutical purposes in the United States ; but even the practical Yankee had not applied as yet this powerful substance to technical uses. In a certain measure, its valuable properties as a blasting agent were overlooked, and also a cer- tain dread existed as to the manufacture of this substance on a large scale. The first man who possessed sufficient courage to produce a large quantity of it at once was the Swedish engineer, Alfred Nobel, in the year 1863 ; and a brave deed it was truly. He discovered a very simple and comparatively safe method for the production of nitro-glycerine on a large scale, and he also dis- covered the means by which this substance is readily exploded. A. Nobel & Co. founded two nitro-glycerine factories, — one in the neighborhood of Stockholm, and another near Lauenburg. Nitro-glycerine very soon found its way as a blasting-agent into Germany, England, Sweden, and America. During the years 1863-65 Nobel took out numerous patents for what he called " Nobel's patent blasting-oil," in different parts of Europe. The blasting-oil was very soon known and liked, and the different factories could not keep pace with the demand. But its glory was only short-lived ; as from nearly all parts of the world the news of some frightful accidents were heralded, caused by premature explosions of nitro-glycerine. Nobel's factory at Stockholm blew up in 1864; in the harbor of Aspinwall, on the Isthmus of Panama, a cargo of this sub- stance en route for San Francisco exploded on the steamer "European," and the steamer was destroyed, and other vessels NITRO-GL YCERINE. 39 and considerable property injured, besides which several lives were lost. Similar accidents happened in England, Sydney, and San Francisco ; and the current literature of those days filled the public mind, by its description of the fearful ravages of this substance, with a dread which up to this day has not been eradicated. In Sweden and Belgium, the manufacture of this substance was prohibited. The favorable opinion of the blasting-oil turned against it ; and a general clamor arose, which asked energetically for a general prohibition of the manufac- ture and use of nitro-glycerine. It required, beyond a doubt, a certain degree of moral courage and energy, under such circumstances to combat public opinion, and to fight for the cause of nitro-glycerine, and not to despair of its ultimate success. The principal merit of Nobel was, that, in spite of the unfavorable circumstances attending the introduction of this substance, he courageously pursued his aim. He made numerous trials in Sweden and near Hamburg, in presence of engineers and chemists, to demonstrate that the numerous accidental explosions were mostly the result of great carelessness, and that nitro-glycerine was no more dangerous than gunpowder. He found that nitro-glycerine dissolved in wood-spirit or methyl-alcohol lost its explosiveness. By adding water to this solution, the nitro-glycerine is separated again in its proper state. He succeeded in diminishing its danger by mixing it with porous substances, and causing its absorption by them ; as, for instance, by infusorial earth. These absorbents saturated with nitro-glycerine are called dynamite, and are exploded by the detonation of a cap, which is inserted into the mixture. Dynamite was applied for the first time for blasting opera- tions in the year 1866, and its use and application in the mining industries have increased wonderfully since that date : moreover, the great improvements which have lately been introduced, in the manufacture of nitro-glycerine and its prod- ucts, have diminished considerably the great risks attending them. Tlie Chemistry of its Production. — As to the chemical con- stitution of nitro-glycerine, it may be remarked, it is not a nitro compound in the same sense, for instance, as gun-cotton or 40 THE MODERN HIGH EXPLOSIVES. tri-nitrophenol, in which hydrogen is replaced through the radi- cal nitryl (NO^), but the nitro-glycerine is actually a glyceride of nitric acid ; for, as in the grouping of the atoms in glycerine, — C3H5(HO)3, — the three molecules of hydroxide (OH) can be re- placed by acid radicals, so it is possible to replace them through nitric acid, and thus are obtained mono-, di-, tri-nitroglycerides, that is to say, combinations in which one, two, or three atoms of hydrogen in the three molecules of hydroxyl (OH) can be replaced by nitryl (NO2). By treating glycerine with nitric acid alone, the three possi- ble nitro-glycerides are obtained, whose compositions are repre- sented in the following formulas : — Mono-nitroglyceride, or glycerine = €3115(011) 2 (O.NO2), Di-nitroglyceride, or glycerine = C3H5(OH) (O. N0j)2, Tri-nitroglyceride, or glycerine = C3Hs(0 . N02)3. Only the last one has any practical value in this treatise ; and, in manufacturing, it is only desirable to produce this. If nitric acid in a very highly concentrated state acts on glycerine, the first result is tri-nitroglyceride ; but by a continuous re-action mono- and di-nitroglycerine are produced, as the nitric acid becomes diluted through the water which separates. C3H5(OH)3 + 3HNO3 = C3H5(ONO^)3 + 3H2O. Glycerine. Nitric acid. Tri-nitroglyccrine. Water. To prevent, by the action of nitric acid on glycerine, the pro- duction of mono- and di-nitroglycerine, it is necessary to get rid of the water which forms ; and that is done by adding the con- centrated sulphuric acid, which takes up the water liberated during the re-action, and, the nitric acid is maintained in a highly concentrated state. Mowbray' s Process for the Manufacture of Nitro-glycerine. — His method was for many years the best employed in the United States. Mowbray was the first who saw the great importance of using chemically pure glycerine, and the purification of the nitro- glycerine from nitrous acid and the adhering nitric acid, and used much care in its purification. NITRO-GL YCERINE. 4 1 The acid mixture was produced by Mowbray as follows : — In a well-ventilated building, 150 feet long, were five .retorts, each 22 cubic feet in content, and each charged with 300 pounds of nitrate and 375 pounds of sulphuric acid. Earthen tubes led the fumes from each retort into a series of four stone jars, which were placed on a wooden frame. Into the first two jars was put 150 pounds of sulphuric acid ; into the third, 100 pounds ; while the fourth remained empty. The nitric acid produced from the nitrates and acid mixtures was con- densed in the three jars, and in that way the acid mixture for the nitrating process was at once obtained. The distillation lasted about twenty-four hours. After that time, the mixture of acids, weighing about 600 pounds, was drawn into carboys, and emptied into a trough of soapstone which held eighteen carboys. For the purpose of clearing the acid mixture of nitrous acid, and also to produce an equal mixture, Mowbray passed a current of compressed air for five minutes through the acid in the soap- stone trough. By the introduction of compressed air, he obtained a perfectly clear and pure acid, which is of importance for the manufacturer, as' the presence of nitrous acid may lead to decompositions and spontaneous explosions. The nitrating house in which this operation was performed measured 150 feet in length. There were nine wooden troughs in this building, containing 116 earthenware pots. Into each pot were put 17 pounds of the acid mixture, and the troughs filled with ice-cold water, or a mixture of ice and salt, to within four inches of the rim of the earthen pots. Above the troughs, along a wooden shelf, there were a number of glass jars, corresponding to the number of stone jars in the troughs; each of the jars containing two pounds of pure gly- cerine, which, by means of a siphon, flows drop by drop into the prepared acid-mixture. Below the shelving, on which the glycerine pots are placed, is an iron tubing, two inches and a half in diameter, through which cold dry air circulates, and penetrates into this mixture by means of glass cubes, sixteen inches long and one-fourth inch wide, while thf, acids and glycerine are mixing. This cur- 42 THE MODERN HIGH EXPLOSIVES. rent of air mixes the acids and glycerine thoroughly, cools the mixture, and frees it from nitrous acid. This process saves material, augments the rendering of the nitro-glycerine, and gives a chemically pure article, as proved by its being colorless, — one which always crystallizes at the s:ime temperature. It takes about an hour and a half for the glycerine to run out of these jars; and, during that time, the greatest care and attention must be exercised. The three workmen who attend to this room move continually, thermometer in hand ; and, when they find the temperature rising in one of the pots, they stir the mixture with the glass tube, through which the air enters. This heating takes place when the flow of glycerine is too active, and the temperature must be decreased. After the conversion into nitro-glycerine is finished, and no more vapors are evolved, the contents of the earthen pots are emptied into a vat, which contains water at 21° Cel., or 68° F. The oil sinks to the bottom, and is covered by six feet of water. It remains for fifteen minutes in this vat, that it may be cleared of its impurities. As the vat extends through the floor into a lower compartment, and the bottom is inclined, the oil can be easily drawn off into another vat. It is washed five times in all, — three times with pure water, and twice with a dilute solution of soda; and finally a current of air is passed through it. The wash-waters are drawn into two barrels, sunk in the ground ; and any oil carried along with it settles in these barrels, and can be recovered. The nitro-glycerine is carried in copper vessels into a maga- zine three hundred yards distant, and put into earthenware crocks, which hold sixty pounds each. These crocks are put into a wooden reservoir two and a half feet deep, which holds twenty of them, and are surrounded by water of 21" Cel., reaching within six inches of the top of the crocks. They remain there for seventy-two hours ; and during that time all impurities which may be in the oil come to the surface as a scum, and may be skimmed with a spoon. After this treat- ment, the nitro-glycerine is chemically p. ire, transparent, and ready for packing. NITRO-GL YCERINE. 43 It is put in tin cans holding fifty-six pounds each, and coated on the inside with paraflRne. These cans are put inside of a flat- bottomed trough, and the oil is poured in carefully from a copper can by means of an India-rubber funnel. To guard against drops of oil being spilled and scattered about, the bottom of the trough is covered with burned gypsum, which absorbs the liquid very quickly. The filled cans are put into wooden vats, surrounded with salt and ice, till their contents are frozen. Afterward, thirty or forty of them are put into small magazines, distant about three hundred feet from the factory, till they are ready for ship- ment. The cans, when they are to be shipped, are packed into fitting boxes which are lined inside with a layer of two inches of sponge. Around the wooden boxes is wound India-rubber tubing for protection from heavy knocks. In summer, the nitro-glycerine is transported by means of wagons, and the boxes are surrounded with ice ; and for railroad transportation specially fitted refrigerator-cars are used. For the storage of ice, two ice-houses are used, having a capacity of two hundred tons each. In their neighborhood is a small house for the engine and boiler. The engine pumps water for the nitro-glycerine house, and also furnishes power for the blower and the India-rubber factory. To insure a uniform current, the air is not allowed to pass directly into the acid-mixture, but goes through a wind-regulator, where it is cleared of its water-vapors. In the neighborhood of the nitro-glycerine factory, is the building for the purification of the India-rubber which is used for the insulating of the copper wires used in blasting operations. As far as the modus operandi is concerned, the work is com- menced at seven a.m., by mixing the acids together, and filling the pots with glycerine. Three men finish this work in one hour. The acids are now drawn off, weighed, and poured into the stone jars. After the acid has properly cooled, the gly- cerine is allowed to trickle slowly into it. This operation is conducted by three workmen. The oil is now poured into the washing apparatus, where two men wash it, while two others clean the stone jars. The flooring in the operating-room is washed, with the greatest care, with water of 15° C. ; as other- 44 THE MODERN HIGH EXPLOSIVES. wise traces of nitro-glycerine may remain on the floor, and by- walking over them cause an explosion. Before concluding the day's work, the operating-room is prepared for the next day's labor. Mowbray's nitro-glycerine was largely used in the Hoosac Tunnel in Massachusetts, which is twenty-five thousand feet long, and is the third tunnel in the world, as to its length. Mowbray proceeds very carefully in his manufacture, as has been shown. For the nitrating, it takes about an hour and a half, seventy-two hours for the cleaning, and forty-eight hours for the crystallizing. This lengthy operation amply repays, by the excellent results of its products, all the care employed throughout the process. Mowbray on the Use of Nitro-glycerine in Tunnelling. — The lineal advance at the Hoosac Tunnel was f 6", instead of 2' 6" as at the St. Gothard, for each blast. At the Hoosac Tunnel, the average of the work may be said to have consumed two to three pounds tri-nitroglycerine per cubic yard of rock in the headings, and from six to twelve ounces per cubic yard at the bench-work and stoping out the roof: this expenditure was decreased in 1874, by greater care in direction of holes and closer supervision by foremen. In blasting the above charges, a very light initial exploder was used, — about eight grains only, of a mixture of chlorate of potash, powdered catechu, and sulphur, confined in a copper capsule, — an initial explosive force neither suited to the explo- sive used, nor, in the opinion of the author, capable of devel- oping perfectly and completely the force stored up in nitro- glycerine or dynamites ; the impression of the blasters being, that, if an explosion followed the electric spark, then the explo- sive must have developed its full force. Mr. Mowbray holds that a weak cap will cause an imperfect detonation of the nitro- glycerine ; that part will burn, part will explode, and part will volatilize ; and thinks heavy charges of fulminate in the ex- ploder would save twenty per cent of the explosive wasted by an incomplete detonation. Careful observations of exploding force at the east end of the Hoosac Tunnel convinced Mr. Francis Shanley, that when nitro-glycerine was poured into a drilled hole, without using a NITRO-GL YCERINE. 45 tin cartridge, the blast gave thirty per cent better results than when the same quantity of nitro-glycerine was enclosed in an inch-and-a-quarter tin cartridge ; such was the cushioning effect ■of the tin cartridge backed by one-fourth inch annular space of air. At the Hoosac Tunnel, Mowbray bottomed 12' holes with nitro-glycerine ; while, at St. Gothard Tunnel, they only could bottom 40" holes. In March, 1874, at the Hoosac Tunnel, central shaft division, 3,044 cubic yards of the hard, tough tunnel rock were taken out with 2,000 pounds of Mowbray's mica powder, or over one and a half cubic yards per pound of powder. At the Hoosac Tunnel, the cut is nine feet in height by nine in width ; and twelve holes, each about nine or ten feet deep, were fired simultaneously by electricity. Nobel's Process for producing Nitro-glycerine. — In most of the European and American dynamite-factories, an apparatus is employed, allowing the production of large quantities of nitro- glycerine at a time. In the hands of a practical chemist, this proceeding offers at the same time great safety and rapidity of execution. The acids are previously mixed, generally twenty- four hours ahead, so as to allow them time to cool ; and a mixture of about 1,000 pounds of sulphuric acid 66° Beaum^ and 500 pounds nitric acid of 48° Beaume, is introduced into the apparatus, — which is a large, lead-lined, wooden tank, — just before the operation. There should be a space between the lead and the tub, so as to form a water-jacket, for the free circulation of the cold water. Lead worms are at the bottom and sides of the lead tank, serving for the circulation of the water. A mechanical contrivance is arranged inside of the tank, to keep the mixture agitated ; and after it is set in motion, the glycerine is allowed to flow in a very fine stream into this acid mixture. For 1,500 pounds of acid mixture, 214 pounds of glycerine are used. The thermometer plunged in the mixture must be closely watched, and the temperature, owing to the strong chemical re-action now going on, should range from 72° to 80° F., but not go beyond the latter : should the mixture show a tendency to go beyond 80°, the flow of glycerine must be stopped, and the agitator run at a greater speed. While 46 THE MODERN HIGH EXPLOSIVES. the operation goes on, water of a temperature of 50° F. ought to circulate freely through the worms and the water-jacliet ; and the colder the water, the better for the operation. If, for any causq, the temperature rises above 80", and it is im- possible to reduce it, if danger of firing the mass is appre- hended, a large discharge-faucet, of four inches in diameter, must be opened, and the whole mass discharged into a large vat, or drowning-tank, three-quarters full of cold water. Where the operation in the nitro-glycerine mixer proceeas regularly, the whole 214 pounds of glycerine are allowed to flow in steadily; and when the operation is finished, the' whole mixture is run into a large vat half full of water. The nitro-glycerine mixer has a light wooden cover, which fits tightly ; and through a lead tube the nitrous gases evolved during the operation are conducted outside the building. This operation may take from an hour to an hour and a half. After the mixture of acids and nitro-glycerine is emptied in the large washing-tank, the nitro-glycerine, owing to its higher specific gravity, sinks to the bottom ; and the dilute acids are drawn off through a siphon. The nitro-glycerine is now washed two or three times with clear cold water, and once with solution of alkalies — soda preferred — so as to destroy the last traces of acids. After this washing, the nitro-glycerine ought not to redden litmus paper. Any one inexperienced in the mixing of nitro-glycerine should not attempt it, even in a laboratory, except under the direction of an expert ; for only an experienced person ought to under- take this difficult task. Farther on, under another head, an apparatus for the produc- tion of nitro-glycerine will be described more fully. The Properties of Nitro-glycerine. — The pure nitro-glycerine, that is, nitro-glycerine which is free from acid and water, is a colorless liquid, — or slightly yellow, owing to coloring-matter contained in the glycerine used in its manufacture, — and of a sweetish, burning taste, and without any odor. The specific gravity of pure nitro-glycerine is 1.6 at 60° F. Nitro-glycerine is insoluble in water. It mixes in all propor- tions with ether and methyl-alcohol. Before it was known how to convert nitro-glycerine into dynamite, the oil was dissolved NITRO-GL YCERINE ^J in methyl-alcohol ; and in this solution the substance lost its explosive properties. On addition of water, the nitro-glycerine separates again from its solution in methyl-alcohol, retaining all its explosive properties. In cold alcohol the nitro-glycerine is not very soluble ; but when heated to 120° F., it dissolves readily. It evaporates easily at 212° F. without decomposing; and, in its pure state, it does not decompose of its cwn accord. When exposed to a temperature of about 10° F., it crystal- lizes, and a temperature of 30° is sufficient to convert it into the crystallized state. It can be said that the nitro-glycerine, when exposed to temperatures from 35° to 14° R, can be converted from the liquid to the frozen state ; and in this respect various nitro-glycerines act differently. Some nitro-glycerines require a temperature of about 10° F., and from ten to fourteen days, till they solidify; whereas others require still different time, sometimes more and sometimes less. When nitro-glycerine is exposed for any length of time to a temperature of 212" F., it will show a great resistance to freez- ing. Unless perfectly pure, it rapidly changes, becoming of an orange color, evolving fumes, and seeming to become a wholly different compound, difficult, when thus chinged, to congeal, except at a much lower temperature than 45° F., and is more readily exploded. A very small amount of impurities is sufficient to prevent the crystallization ; but when the nitro-glycerine is brought quickly to the freezing-point, it crystallizes into a white-yellow, non-transparent mass. The frozen oil thaws out at 42° F. It was supposed for a long- time that nitro-glycerine expands, by freezing, one-sixteenth of its volume ; whereas the nitro-glycerine prepared after the Mowbray system is said to contract one-twelfth of its original volume. It has been lately established that the density of Nobel's oil is 1.599, ^i^d of ^he frozen, 1.735 > ^^'^ consequently a contrac- tion in volume of ^^^ is the result. This fraction agrees exactly with the one obtained by Mowbray, and therefore the physical deportment of Nobel's oil is exactly similar to Mowbray's. Even very small doses of nitro-glycerine are poisonous. 48 THE MODERN HIGH EXPLOSIVES. When one drop of nitro-glycerine is swallowed, it produces dizziness, weakness of the eyesight, headache, weakness and sleepiness, and a strong burning taste in the throat. An ad- ditional drop or two of it introduced in the throat produces a considerable increase of these symptoms, like unconsciousness, dizziness, trembling, and a very heavy headache, with great sensi- tiveness against light, a heavy and hot, feverish feeling followed by chills, and a general sensation of uneasiness, but not cramps and vomiting: the effects generally pass away in a day or so. Workmen who use nitro-glycerine for blasting get headaches very easily. This is explained from the fact that nitro-glycerine penetrates easily through the skin, and gets into the blood.' To avoid the direct contact of the skin with the nitro-gly- cerine, the workmen are provided, especially in the preparation of dynamite, with India-rubber gloves. But men very seldom keep them on ; and, after a few days' use, they generally discard them, as they are troublesome in working. As an antidote for nitro-glycerine poisoning, black coffee is recommended ; and for external use, rubbing with potash solution and hydro- iodic acid, which is said to decompose the nitro-glycerine. To detect the smallest quantities of nitro-glycerine, aniline and concentrated sulphuric acid are used as re-agents: after the addition of both, in the presence of nitro-glycerine, a purple color- ing is produced, which, on adding water, turns green. Nitro- glycerine decomposes very easily by drying in a warm room with rarefied air. It is instantly decomposed when dissolved in alco- hol. By adding an alcoholic solution of caustic potash, the re-action is so violent as to eject the mixture from the test-tube. Nitro-glycerine in contact with the following salts : nitrates of lime, cobalt, soda, baryta, and potash ; chlorides of calcium, of barium ; perchloride of iron, carbonate of lime, sulphates of potash, lime, and soda, — was found unchanged after two years' exposure. Incompatibles. — Nitrate of silver precipitates black oxide of silver. Nitrate of copper gives a precipitate of peroxide of copper ; the nitro-glycerine remaining, however, bright and apparently unchanged. ^ Aceiaie of morphine is a good antidote for nitro-glycerine poisoning, but should be given under a doctor's advice. NITRO-GL YCERJNE. 49 In a solution of nitrate of mercury, there appears a white film and a bubble of protoxide of azote, apparently adherent to the nitro-glycerine. Muriate of ammonia seems to divide the nitro-glycerine into two liquids, — a light film, and a bubble of protoxide of nitrogen, apparently adherent to the nitro-glycerine ; the light film, in this case, being supernatant, and the heavier liquid subjacent. The action of chloride of mercury (calomel) is but very slight. Protochloride of tin forms a precipitate of peroxide of tin ; the residuary nitro-glycerine reflecting light powerfully, and as brightly as a diamond. Bi-chromate of potash is partly reduced to chromate. Sulphate of copper forms a very slight precipitate of oxide of copper, apparently in the residuary nitro-glycerine. Sulphate of iron decomposes it, giving a voluminous precipitate with evolution of nitrous fumes. Sulphuret of ammonia decom- poses it with precipitation of sulphur. Acetate of lead, chlo- rine water, ferrid cyanide of potassium, cyanide of potassium, sulpho-cyanide of potassium and of mercury, nitro-prusside of sodium, decompose it, also the sulphurets of iron and potassium. The action of tin, iron, and lead, slowly decomposing the nitro-glycerine, especially in the presence of an acid, indicates that metals having an affinity for oxygen are the most active in promoting decomposition, evolving at the same time nitrous fumes, or protoxide of nitrogen, whilst the residuary nitro- gl)xerine does not seem to be affected. With sulphuretted hydrogen, as with sulphuret of sodium, potassium, and ammo- nia, the action is prompt ; and if these re-agents be added in sufficient quantity, the nitro-glycerine is wholly decomposed, sulphur being precipitated. Professor C. L. Bloxam publishes an article under the title " Reconversion of Nitro-glycerine into Glycerine " (" Chemical News," 47, 169, April 13, 1883). He states that the following experiments of this subject appear to possess some interest at the present moment : — I. Nitro-glycerine was shaken with methyllated alcohol, which dissolves it readily ; and the solution was mixed with an alcoholic solution of KHS (prepared by dissolving KHO in methyllated spirit, and saturating with H^S gas). Considerable rise of tem- perature took place, the liquid became red, a large quantity of 50 THE MODERN HIGH EXPLOSIVES. sulphur separated, and the nitro-glycerine was entirely decom- posed. 2. Nitro-glycerine was shaken with a strong aqueous solution of commercial K^S. The same changes were observed as in (i), but the rise in temperature was not so great ; and the liquid became opaque very suddenly when the decomposition of the nitro-glycerine was completed. 3. The ordinary yellow solution of ammonium sulphide used in the laboratory had the same effect as the K^S. In this case» the mixture was evaporated to dryness on the steam-bath, when bubbles of gas were evolved, due to the decomposition of the ammonium nitrite. The pasty mass of sulphur was treated with alcohol, which extracted the glycerine subsequently recov- ered by evaporation. Another portion of the mixture of nitro- glycerine with ammoniac sulphide was treated with excess of PbCOj and a little plumbic acetate, filtered, and the ammoniac nitrite detected in the solution. The qualitative results would be expressed by the equation C3H5(N03)3 -j- 3NH^HS = CjHj (OH)3 -\- 3NH4NO2 + S3, which is similar to that for the action of potassium hydro-sulphide upon gun-cotton. 4. Flowers of sulphur and slaked lime were boiled with water till a bright orange solution was obtained. This was filtered, and some nitro-glycerine poured into it. The reduction took place much more slowly than in the other cases ; and more agi- tation was required, because the nitro-glycerine became coated with sulphur. In a few minutes, the reduction appearing to be complete, the separated sulphur was filtered off : the filtrate was clear, and the sulphur bore hammering without the slightest indication of nitro-glycerine. This would be the cheapest method of decomposing nitro- glycerine. Perhaps the calcium sulphide of tank waste, obtain- able from the alkali-works, might answer the purpose. The Explosion of Nitro-glycerine, and the Gases formed thereby. — Nitro-glycerine explodes when heated to 306° F., or from the effect of a violent blow, or by the quick and strong pressure which the explosion of a fulminating cap exercises when in contact with it. In all these three cases, it is the heat produced by the concussion, which causes the explosion. If nitro-glycerine is carefully heated, it commences to evolve NI TRO- GL YCERINE. 5 I nitrous acid at 230" F. It is said that nitro-glycerine through gradual heating can be completely evaporated without causing an explosion. But gases formed by its combustion are materially different from those formed by its explosion. They are much more offensive to the smell, and injurious to health. Sometimes the cap, failing to detonate the high explosive, sets it on fire. If this occurs in a mine not well ventilated, the smoke is almost intolerable ; while the gases of complete explosion are innocu- ous. Chemically, the gases resulting from the burning of nitro- glycerine differ materially from the gases which result fromi the explosion of nitro-glycerine. A very important property of nitro-glycerine is, that the tem- perature at which it explodes differs from the temperature at which it takes fire. This property is of great practical utility ; and, if nitro-glycerine is set on fire, it burns with difificulty, but does not explode, as it may burn up before reaching its explod- ing temperature. It is hardly to be presumed that large quan- tities of nitro-glycerine set on fire would burn away harmlessly, as the burning portion would heat the unburnt one to the explosion temperature. If nitro-glycerine is exposed to a gradual pressure, it will not explode, but a violent blow will explode it. It is said, that if a small quantity be put on an anvil, and struck with a hammer, only the particles struck will explode, and the explosion will not be propagated throughout the whole mass ; and, further, that a bottle containing nitro-glycerine can be thrown against a rock without exploding. Even at a late date, the impression existed that frozen nitro- glycerine is more sensitive to blows and concussions than the liquid ; but this theory has been entirely disproved by late ex- periments, and especially by Mr. Mowbray's production of frozen nitro-glycerine on a large scale. If nitro-glycerine is not per- fectly pure, it undergoes, like impure gun-cotton, a spontaneous decomposition, from which explosions may result. There is formed, through oxidation, glyceric and oxalic acid. The de- composing nitro-glycerine is colored green, forming nitrous acid, hypo-nitrous acid, nitric oxide, and carbonic acid. As nitro- glycerine is generally kept in well-stopped bottles, the gases 52 THE MODERN HIGH EXPLOSIVES. which evolve through decomposition cannot escape ; and hence they exert a strong pressure on the nitro-glycerine. Under these circumstances, the least concussion or a slight shock are sufficient to cause an explosion. To recognize such a decomposition, a piece of litmus paper is inserted into the nitro-glycerine ; and, if it colors red, it shows that decomposition is taking place. Greenish-colored oil ought to be buried. When nitro-glycerine explodes in a closed space, it exerts a tremendous pressure. This is the result of the large quantity of gases which are developed, and from the high temperature produced, by which the gases are expanded eight times their original volume. By the explosion, carbonic-acid gas, hydro- gen, nitrogen, and oxygen are formed. One hundred grams nitro-glycerine give by burning the following : — Water 20.0 grams. Carbonic acid 58.0 " Oxygen 3.5 " Nitrogen 18.5 " Total loo.o One kilogram of nitro-glycerine gives, on exploding, 710 litres of gases ; and one litre of nitro-glycerine gives, owing to its high specific gravity, 1,135 litres of gases. But the gaseous mixture is, as stated, expanded, owing to its high temperature, to eight times its volume. According to Nobel, one litre of blasting-oil gives 1,298 litres of gases, which at the moment of explosion are expanded to 10,400 litres. Consequently, where one litre of blasting-oil fur- nished 10,400 litres of gases, one litre of gunpowder furnishes only 800 litres of gases. The force of the blasting-oil stands in the following proportion to the force of gunpowder : — According to its volume, as 1 3 to i ; According to its weight, as 8 to i. If we can imagine the enormous gas quantity of 100,000 litres, which can be produced out of ten litres of oil, then we can also conceive that nothing can resist such an enormous NITRO- GL YCERINE. 5 3 gas pressure. The marvellous rapidity with which such an explosion takes place has been demonstrated by the recent experiments of the Austrian Technical Military Committee. According to their researches, a dynamite cartridge 200 feet long exploded in less than one hundredth of a second. The chemical examination of nitro-glycerine offered hereto- fore great difficulty, but this is now examined in rarefied air ; and, if it is heated in a vacuum, it will boil at a much lower temperature, and will evaporate before it reaches its exploding temperature, — about 380° F. Various Notes. — The explosive force of nitro-glycerine un- doubtedly results from the sudden production of watery vapor, CO'', and nitrogen gas at a very high temperature, by the union of the oxygen present in the nitric acid, with the hydrogen and carbon of the glycerine ; in other words, the oxygen of the nitric acid plays the part in nitro-glycerine which the oxygen of the nitric acid in nitre plays in ordinary gunpowder. Now, in tri-nitroglycerine, or trinitrin, there is a slight excess of oxygen present, while in di-nitroglycerine there is a considera- ble deficiency : hence what we may call the combustion of the carbon and hydrogen is incomplete in the latter case ; and, the combustion being imperfect, the force developed is therefore less, just as in gunpowder which contained too small a propor- tion of nitre. By mixing nitro-glycerine with gunpowder, gun-cotton, or any other substance developing a rapid heat, nitro-glycerine, being an oil, fills the pores of gunpowder, and is readily heated by the latter to the degree of its explosion. Gunpowder treat- ed in this way can take up from ten to thirty-five per cent of nitro-glycerine, and develops a greater power with a diminished quickness of explosion. Nobel, in following up his idea of "an impulse of explosion" put his main charge of gunpowder mixture in a tube, and sur- rounded it with gunpowder, setting fire to the gunpowder, and, by its explosion, exploding the main charge. This seems to be the first instance of using a typical "exploder." The process Nobel used was as follows : He first filled a zinc tube with gun- powder ; then poured in all the nitro-glycerine it would hold, and corked it. This cartridge he put into the bore-hole, cork 54 THE MODERN HIGH EXPLOSIVES. downward, and then filled the space above it with gunpowder ; inserted the fuse into the gunpowder, and tamped as usual, except that the blows on the tamp next to the charge were very light. The fire of the fuse exploded the gunpowder, and this explosion was sufficient to cause the detonation of the nitro-glycerine mixture in the cartridge. The Introduction of Caps. — Their introduction completed the practical application of nitro-glycerine as a blasting-agent, and it remained simply to improve the methods of firing. Now, it may be asked how gunpowder, which is an igniting explosive compound, can be thus applied in effecting the detonation of a detonating compound. The rationale of the process is this : Nitro-glycerine, when fired by an exploder composed simply of gunpowder, undoubtedly detonates ; but complete detonation is not in general effected. The explosion of the gunpowder heats by impact the nitro-glycerine immediately contiguous to it; this portion of the nitro-glycerine is thus exploded or detonated, and its detonation is propagated through the mass of the nitro- glycerine charge. But experience showed that great heat and pressure were requisite to effect a complete detonation ; so that subsequently Nobel caused regular fulminating caps, fitted for this purpose, to be made ; and these have since been the only kind of exploders in general use. CHAPTER III. THE VARIOUS HIGH EXPLOSIVES PREPARED WITH NITRO-GLYCERINE, AND THEIR PROPERTIES. DYNAMITE, OR GIANT-POWDER. Composition and Properties of Nobel's Dynamite. — In the factories working under Nobel's patent, the different grades of dynamite have the following composition : — Absorbent. Dynamite No. i . Dynamite No. 2 . Dynamite No. 3 . Dynamite No. 3B 25% 70% The absorbent for dynamite No. i is pure kieselguhr ; the absorbent for Nos. 2, 3, 3B, is a mixture of nitrate of potash, wood-fibre, rosin, soda, and kieselguhr. Dynamite No. i has, in a soft condition, a light-orange or yellow-brown ; in a frozen condition, a white or dirty white color. The specific gravities of the different grades of dynamite are : — Dynamite No. i . Dynamite No. 2 . Dynamite No. 3 . Dynamite No. 3B. In the Loose. In the Compressed Condition. 55 56 THE MODERN HIGH EXPLOSIVES. It is generally packed in paper {farchemin); making rolls of from J, i, i", to 3" in diameter, and of any length required by customers. The cartridges are packed in wooden boxes con- taining twenty-five or fifty pounds, with layers of sawdust between the different layers of cartridges. The rapid increase in the use of dynamite through Europe is mainly due to the Austrian Government commission, which, at the request of the secretary of the interior, made a very exhaustive examination of this material ; and, upon the results of these experiments demonstrating the safety of dynamite against fire and percussion, its import and transportation were allowed on the railroads. Austria was the first nation which, with great foresight, rec- ognized immediately the immense value of this new blasting material, and acceded to the wishes of the engineers by allowing its transportation. DYNAMITES No. i. ' Infusorial earth has so far been found to excel all other sub- stances used as absorbents ; for it absorbs the nitro-glycerine, and holds it by capillary attraction. This earth, ox guhr, is a silicious limestone, composed of small shells, every one offering a cavity in which the nitro-glycerine lodges. Originally it was understood that dynamite was guhr satu- rated with nitro-glycerine. To-day by dynamite is understood every explosive body which contains nitro-glycerine in absorp- tion. The numerous varieties of dynamites are divided into two very distinct classes ; namely, those which contain chemically active absorbents, and those which contain chemically inactive absorbents. To the last belongs the guhr, or kieselguhr dyna- mite ; since this absorbent exerts no chemical action whatever in the explosion of the nitro-glycerine it contains, remaining behind as an unaltered residue. Totally different are the dynamites with chemically active absorbents, taking part under all circumstances with their chemical components in the explosion, and thus changing the composition and active force of the explosive gases of the nitro- glycerine. DYNAMITE, OR GIANT-POWDER. 57 The dynamites with chemically active absorbents modify the too-rapid explosion of the nitro-glycerine in dynamite No. i, and convert the violent breaking action of its gases into more of a pushing or propelling force. At the same time, these dynamites are less dangerous to manipulate than the guhr dynamites, as they contain less oil. Under Dynamite No. 2, more will be said on this subject. Dytimnite with Chemically Inactive Absorbents. — Kieselguhr Dynatnite. — It is said that the following fortunate occurrence led Nobel to the discovery of this dynamite. This infusorial earth was used for a long time in the packing of the tin cans containing nitro-glycerine. Through the leaking of a can, it was discovered that this earth had great absorbing power ; and trials proved that the nitro-glycerine, although absorbed by this earth, retained completely its explosive qualities, while its tendency to explode was greatly diminished. Other reports, again, say that mining-engineer Schell at Grund, near Klausthal-am-Harz, was the first one who used nitro-glycerine mixed with a light porous earth, employing it in his mine. However this may be, Nobel first introduced dynamite in practice. The Manufacture of Kieselguhr Dynamite. — The kieselguhr employed in the manufacture of dynamite is found in large deposits at Oberlohe (Province Hanover). It should not con- tain moisture, organic matters, or grains of quartz. To rid it of moisture and organic matters, the guhr is burnt in a kiln, and afterwards ground up, and passed through sieves. Fifty pounds of this guhr are mixed with one hundred and fifty pounds of nitro-glycerine in a wooden trough, and the mass thoroughly mixed by kneading it as bread is kneaded. In half an hour the mixture is completed ; and the mass is placed in a coarse sieve, being squeezed through the meshes by the palm of the hand. It is now dynamite, and ready to be put in cartridges. The cartridges are small paper cylinders, of different length and diameter, into which the dynamite is pressed. A dynamite-factory has ordinarily about ten small cartridge- houses, in each of which two or three men are at work ; one cartridge-house being separated from the other by an earth wall. 5 8 THE MODERN HIGH EXPLOSIVES. These houses are generally light structures, and in winter must be kept at a temperature of about 60° F. The floors are covered with loose sand. In the manufacture of dynamite, the mixing of the kieselguhr with the oil, and the filling of the cartridges with the powder, are very dangerous. Accidents in its manufacture happen oc- casionally, and the greatest care and attention are required to avoid them. It is mainly because of careless manipulation that these misfortunes happen ; and they can, in a certain measure, be avoided by strict regulations in the manufacture and use of this explosive. Properties of Dynamite. — The dynamite is a pasty, plastic mass, of 1.4 specific gravity, and of a yellowish-red color, unc- tuous to the touch, and without any odor. It can be exploded by means of a cap, or by contact with red-hot metal, or again by rapid heating to a high temperature, or by means of a heavy blow or concussion. Brought into contact with a burning match or fuse, it will burn without exploding, similar to damp powder : hence nitro-glycerine compounds do not explode from the application of fire (unless in large quantities), but by the application of force. Whether this results from shock, jar, blow, percussion, concussion, or vibration, or from the heat produced by these, one thing is certain : force is necessary in some form to cause detonation, whereas in gunpowder-explosion it is not essential. This force is applied, not gradually or slowly, or to a part of the charge at a time, but at once, and suddenly, and to all parts of the charge simultaneously. Perhaps it may be said that this cannot be strictly or theoretically true where a small exploder is used in a large charge ; for the exploder cannot affect directly the entire charge, but explodes a part of it, and this explosion explodes the balance. It is only essential to know that the explosion is produced by force, whether applied directly by the exploder, or indirectly by propagation. In order to effect the explosion of nitro-glycerine at all, whether in the liquid or powder form, a certain degree of this force is requisite ; and, when the proper degree of force is applied to its particles, they explode, however situated. The fact that these particles are separated one from the DYNAMITE, OR GIANT-POWDER. 59 Other is of no consequence, as long as they are made to feel the requisite force. For example : If a thin film of the oil be placed upon the face of an anvil, or on sheet metal, and be struck so as to com- press the particles of the oil, they explode. Now, if we have a series of these plates one above the other, to any extent, with oil between them, and a blow be struck upon the top of the pile, all the nitro-glycerine between the plates throughout the entire pile will be exploded, and simultaneously ; yet the charge thus exploded was divided into as many wholly separate parts as there were plates. On the other hand, if gunpowder had been placed between the plates instead of nitro-glycerine, and fire had been applied at the top of the pile, the explosion would have been limited to the burning of the powder between two plates only. Suppose now, plates of India-rubber, or wood, or cloth, or leather, or any other compressible material, are used instead ■of the rigid plates of iron. What is the effect 1 A blow upon the top of the pile does not produce the per- cussive, sharp ringing, and violent effect requisite to explosion. The blow is deadened, the nitro-glycerine is cushioned and protected, and no explosion follows as in case of the iron plates. Here is the whole secret of the dynamite invention. When an absorbent is used, it acts similarly to these soft plates in separating, cushioning, and protecting the nitro-glycerine, and making it safe against mechanical blows; but when sufficient force is applied to solidify the absorbent, as when an exploder is used, it acts like the iron plates in communicating the force to the different parts of the charge. The absorbent renders the oil less sensitive ; that is to say, more force is required to explode the nitro-glycerine when in the powders than to explode it in the liquid form. The kieselguhr is considered as (Ae absorbent />ar excel- lence, as every particle or molecule of it makes a separate and distinct receptacle for the liquid. Under the microscope, each particle, infinitesimally small though it be, shows a cavity, in which the nitro-glycerine settles and is well protected. While in the fluid form, it is compact and incompressible, 6o THE MODERN HIGH EXPLOSIVES. and a slight force will give it the requisite compression ; but when in the powdered form, it is cushioned by the absorbent, and this cushion has to be compressed and made solid ; which requires additional force, precisely as it requires a more forcible blow to drive a nail whose head is cushioned, and the cushion must be compressed to solidity before the nail will start. Notwithstanding, however, the explosion is more difficult when the nitro-glycerine is thus cushioned, yet when the force is sufficient to affect it all, the decomposition takes place, pro- ceeds in the same way, and is accomplished in substantially the same time, as when not so cushioned ;. and, therefore, the intrinsic power developed by the nitro-glycerine in the powder is substantially the same as when the same amount of it is exploded in the fluid form. Thus we find, from the peculiar nature of nitro-glycerine, a powerful powder can be made, and at the same time be ex- tremely difficult to explode. It is, therefore, comparatively safe. For instance : A powder made of fifty per cent of nitro- glycerine, and fifty per cent of infusorial earth, is very dry, and cannot be exploded except by a triple-force exploder. On the other hand, a powder made of fifty per cent of nitro-glycerine, and fifty per cent of fine sand, is very wet and leaky, and explodes almost as easily as the liquid oil. Nevertheless, the earth-powder is in every way as strong as either of the others. This confirms the position, that a powder which is very dry and difficult to explode, and therefore safe, is substantially as good as a wet and therefore dangerous one, when the propor- tion of nitro-glycerine is the same in each. From what has been already said, it is plain these powders may be so made as to be either safe or unsafe, according to the proportion of oil they contain. But it must be borne in mind, that this proportion is to be measured not arbitrarily by per- centage merely, or weight, but relatively also, according to the absorbent capacity of the solid substances used. Of course, different substances have different absorbent capacities. Some will hold safely seventy-eight per cent of nitro-glycerine, while others will not safely hold two per cent. Wetness or dryness, then, is the true test of safety. If it leaks, it is dangerous ; but if not, it is safe. DYNAMITE, OR GIANT-POWDER. 6 1 Here it may be asked whether a powder, which is as damp with nitro-glycerine as it can be without leaking, is not danger- ous ? A moment's thought will settle this, as it has been settled by experience. All mixtures so fully saturated as to have no vacancies will leak ; and the fact that a mixture does not leak shows that it has pores, interstices, and vacancies ; that it is not compact like the liquid, but compressible and yielding; and this shows it to be safe. Its safety does not depend so much upon the amount of vacancies in the powder, as upon the fact of their existence at all. A slight compressibility destroys the fatal rigidity, and hence gives safety. Infusorial earth with eighty per cent is saturated, and almost as compact as pure nitro-glycerine, and almost as dangerous; while with seventy-five per cent, it is comparatively safe for the ordinary temperature. The danger lies in the escape of the liquid, and the oil drained from powder is as dangerous as if it had never been in it. From this it follows, that no leaky powder should be trans- ported at all, but should be classed with liquid nitro-glycerine. Hence, to determine whether a powder is dangerous or safe, is the simplest of all things ; for, if it will leak, it is dangerous : if not, it is safe. Whether it is leaky, or not, is settled by an examination ; and it would be folly to rely on the proportion by actual weight of the ingredients used, because, with the same proportions, but with absorbents of different capacity, one powder would be dry and safe, and another wet and dangerous. J Temperature. — Other things being equal, both nitro-glycer- ine and its compounds explode more readily as the temperature is increased. At any temperature below 30° F., frozen nitro-glycerine will not explode from any ordinary cause ; and, even at 32° F., it explodes with great difificulty. Hence the means employed mainly by Mr. Mowbray for making his nitro-glycerine safe for handling and transport is to freeze it. Nevertheless, frozen nitro-glycerine can be exploded. To accomplish this, all that is necessary is to intensify the means. Use a sufficiently strong exploder, or confine the ex- 62 THE MODERN HIGH EXPLOSIVES. plosive, or employ both means, and it can be exploded at any temperature. So much for the effect of cold : the other extreme is about 360° F. At this temperature, it either burns or explodes. If free from all pressure, jar, vibration, or force in any form, it burns : otherwise it explodes. Placed in a film on tin, and held over a spirit-lamp, it smokes away, or takes fire, and is consumed. But heated to this tem- perature when of any considerable depth, say over a quarter of an inch, it explodes. (This is a dangerous test.) When heated to any degree less than this, it is exploded by a cap, or blow, or jar, or vibration, with an ease proportionate to the temperature. At 350°, the fall upon it of a dime will explode it. Temperature has another special influence on the explo- sives ; to wit, they are more liable to leak as their temperature is raised. A powder which would be dry and safe at 50° may be leaky at 100°. The powders, therefore, should be made with reference to the highest temperature to which they are to be exposed ; and when tested, they should be at this tem- perature. Confinement and Compression. — Nitro-glycerine and its com- pounds are, as a rule, more easily exploded, the more closely they are confined, and the more they are compressed. If they are enclosed without pressure, and an exploder applied, the enclosing aids the exploder in applying the pressure : so that a charge, with a certain exploder which will not explode it in the open air, may be detonated by this same exploder in a drill- hole, or under water. Also, if they are not only tightly but also strongly enclosed, as in gas-pipes, with a cap screwed on each end, and set on fire by a fuse through a small hole, or otherwise, they will explode ; the gases from the combustion causing a pressure on the part of the charge not burned, which, unless they escape, will finally be sufficient to cause explosion. Compression of the charge makes it more sensitive. For instance, let an iron tube be filled with nitro-glycerine : then a blow, which will not cause explosion when struck against the upper end of this tube, will cause explosion when struck against DYNAMITE, OR GIANT-POWDER. 63 its lower end : the difference being, that the lower part of the charge is under pressure from the upper part. But this pressure from superincumbency has no material in- fluence on the powder, for reasons too obvious to be mentioned. On the other hand, if spread upon an anvil, and struck, onlv that portion which is hit explodes : the balance does not, because it is not sufficiently confined, or is not so located as to receive the requisite blow or pressure from that part which does explode. The reason why a small quantity of nitro-glycerine in a large mass of absorbent cannot be exploded at all is, the absorbent cushions the liquid so deeply that the requisite pressure is not felt. The practical lesson from these facts is, that the powder for transportation ought not to be packed in strong and tight vessels. Metallic Cases. — The rigid character and peculiarly forcible vibration of steel and iron, and especially when in the sheet form, seem to be particularly favorable for the explosion of nitro- glycerine and its compounds. A cause insufficient to explode a charge in wood or paper will explode.it in iron. Place a three-inch cartridge of dynamite at the bottom of a hole bored in a log, and fire • three inches of gunpowder well tamped above it, and the dynamite will not explode ; but the same charge in iron casing explodes. Strike nitro-glycerine in a leather bag, and it will not explode from a blow which will explode it in a tin vessel. { Nobel deemed it of great importance, that the solid form of dynamite permitted it to be packed in wood ; the more so, be- cause the metallic vessels, in which the liquid was carried, were so dangerous^ Mr. Mowbray gives an instance of explosion caused by vibra- tion which is very instructive. A small can containing four pounds of nitro-glycerine, left by a blaster about three hundred and fifty feet from the header in the Hoosac Tunnel, was placed under the iron rail leading from the vicinity of the blast : the upper part of the can was in contact with the rail. When the charge of sixteen holes was fired in the heading, the nitro-gly- cerine in the can exploded also. This was undoubtedly caused 64 THE MODERN HIGH EXPLOSIVES. by the vibration along the rail ; and, as no heat could have been produced by the vibration alone, it affords a striking instance of the explosion of nitro-glycerine by induced concussion. The chances are, that, if the oil had been in wood or paper, it would not have exploded. This shows the danger in using metallic cases for the trans- portation of nitro-glycerine and its compounds. Thawing and Enclosing. — So far as known, there are but two ways in which there is any danger from fire. One is where the powder is completely enclosed in some strong vessel, and set on fire, as already explained ; the vessel being much stronger than any in which the powders are ever transported, and so tight that the gases cannot escape as fast as they form. There is no practical danger from this source in transporta- tion. The other is in roasting, toasting, and baking the powder when frozen. When frozen cartridges are put into a hot oven, upon stoves or boilers, or in kettles over a fire, and allowed to remain long enough to thaw, they soon become so hot as to smoke: the result is, in about nineteen cases out of twenty, the powder takes fire, and burns up, or all the nitro-glycerine is evaporated, and they are ruined. But, in the twentieth case, there will be an explosion. If all the powder is equally exposed to the heat, since the evaporation commences long before the exploding-point is reached, the powder is weakened, and the explosion is correspondingly weak, — often a mere pop or puff. But if there is a large quantity of powder, some of which is thus heated, and the balance left unaffected, the explosion may extend to the full-strength powder, and be accordingly violent. Experimental Tests. — Heretofore the question has never been raised, whether these powders are abundantly safe from explo- sion by fire, or not ; but, as has been shown, the burning powder will heat the powder not ignited to its exploding temperature. When in large quantities the burning powder will heat the unburned portion to its exploding temperature, and cause its explosion. Still, the following incidents show the tendency of this explosive : — DYNAMJTE, OK GIANT-POWDER. 65 The steamer " Streeter " took fire from its furnace, and burned to the water's edge on Lake Erie, consuming eight thousand pounds of giant-powder on board without explosion. The Marysville (Cal.) Railroad depot burned down in 1877, and six hundred pounds of dynamite were stored there with other quantities of freight. The firemen and hundreds of spec- tators surrounded the burning building, not knowing that any powder was consumed during the conflagration : still, the Cen- tral Pacific Railroad Company paid for the powder which was consumed there. If set on fire in piles, large or small, either loose or in cart- ridges, it burns up rapidly, like chaff when loose ; but, when in cartridges, it burns slowly, like rosin, tar, or sulphur. Set fire to one end of a cartridge, and it burns like a Roman candle, without the pop, and with less speed. When partly burned, it may be extinguished by water. Packed for transportation in boxes of inch boards, strongly nailed, and set on fire by a fuse through a gimlet-hole, its gases force the boards apart, and the flame issues. A box of one hun- dred pounds is burned in from two to five minutes, according to the composition of the powder. The following experiments have been repeated many times : — A minute quantity is placed on an anvil, and struck with a hammer. A snapping sound is produced, like the breaking of a stick ; and only the particles between the points in contact are exploded, while the balance is scattered. If the quantity be increased, and the blows repeated until the powder is made solid, a greater quantity can be exploded ; but if the quantity is so large that the blows are deadened, and the percussive action prevented, there will be no explosion. Pounding it upon wood will not explode it. A box of it thrown from any height upon rocks will be broken in pieces, but no explosion can be thus caused ; and even heavy weights can be dropped upon it. Actual Experience. — Its transportation has taken place by all the ordinary means, — on vessels, vehicles, backs of mules and horses, over mountain roads and trails of the worst de- scription ; and instances are known where a mule packed with with dynamite fell from a trail over a steep declivity. The ani- 66 THE MODERN HIGH EXPLOSIVES. mal was killed ; but the boxes of powder broke open, and did not explode. It has met with such treatment as would naturally befall an article supposed to be safe in every respect, and has been handled correspondingly roughly. But, in spite of all this, it is recommended to those who have to handle it, always to bear in mind that it is a high explosive. \ Authority. — Men of science, experts in explosives, men in charge of works requiring their use, committees on behalf of transportation companies, military gentlemen, and government commissions, besides numerous others, have examined the sub- ject, and reported upon it, some of them elaborately. A brief summary of the conclusions arrived at is here given : — 1. These powders are the most powerful of all the disrupting agents now in general use. 2. When properly made, and economically transported, they are, for hard rock-work and sub-aqueous work, by far the most economical explosives in use. 3. They are the safest of all explosives, both in transportation and use, many times safer than gunpowder, and when properly made, and with a few simple precautions, are as practically safe for transportation as if they were wholly inexplosive. 4. There is no good reason why, under proper regulations, they should not be transported in freight conveyances as freely as any ordinary merchandise. Proper Regulations for their Transportation. — As liquid nitro- glycerine is known to be dangerous, its transportation on public conveyances ought to be forbidden. 2. Leaky powders ought to be classed with liquid nitro- glycerine, and wholly debarred from transportation in like manner. 3. The dry and safe powders ought to be carried on all public freight conveyances. 4. The powders ought not to be packed in metallic cases. 5. Large percussion-caps, electrical exploders, gunpowder, or other things whose explosion by fire will detonate the powders, ought not to be transported in conjunction with them, and especially should be kept out of the same freight-car. DYNAMITE, OR GIANT-POWDER. 6/ 6. Let dynamite go by itself in a separate car. 7. Let each package be marked on the outside with the name of the contents, so as to be legible to those who handle it. DYNAMITE No. 2. Discussion of its Properties.^ — With regard to dynamite No. 2, and the other nitro-glycerine mixtures in which some lower explosive compound is substituted for part of the nitro- glycerine, acting at the same time as an absorbent, Mowbray says : ^ — "To couple nitro-glycerine with chemicals such as nitrate of potash, nitrate of soda, chlorate of potash, mixed with carbonaceous matter, which require an instant's time to develop into gases, would be like attempting to quicken the electric current by coupling it to the velocity of a locomotive. . . . Under the usual conditions of blasting, the confinement of tamping with clay is insufficient to retain the explosive force of the nitro-glycerine until its tardy neighbors, resin, paraffine, saltpetre, chlorate of potash, nitrate of barytes, et id genus omne, have developed their force ; or, to recall the simile of the electric current, the sounding-board fifty miles away is giving the signal before the first puff of steam has reached the blast-pipe. Give four men a weight to lift which requires the united force of all of them to raise, the exertion of force by any one later than that of the others wastes the forces of all." On this same question, Andr6 says,3 — " Numerous attempts have been made to substitute combustible and explosive absorbent media for the incombustible silicious earth used in the preparation of dynamite. The purpose of this substitution is to increase the strength of the explosive by rendering the absorbent matters, which in dynamite are wholly inert, themselves explosive, to insure perfect combus- tion when the charge is fired, and to prevent the formation of noxious gases. The first of these objects is unattainable in the direction in which it is usually sought. No two explosive substances generate their gases with the same degree of rapidity ; and it is obvious, that, if any two be mixed as inde- pendent explosives, the resulting compound cannot exceed in strength that of the more rapid substance, since the tardy forces of the other can take no part in the work done.'' * From Drinker on Tunnelling, p. y^ ; published by John Wiley & Sons. ^ On Tri-nitroglycerine, p. 85. ^ On Coal-Mining, p. 198. On p. 200, however, Mr. Andr^ quotes Mr. Linford's opinion to the effect that the explosive dope in Brain's blasting-powder adds effective strength. 68 THE MODERN HIGH EXPLOSIVES. " Thus we see it is argued, that it is more than questionable whether the mixture of explosive salts with nitro-glycerine, as part of the absorbent, results in giving a compound of any- greater effective strength than the same quantity of nitro-gly- cerine mixed with silicious earth would have. It is allowed that the salts certainly have explosive force ; but, the essential char- acteristic of nitro-glycerine as an explosive being its " quick- ness," the advocates of this theory assume that its effect is practically expended before that of its associates is fairly begun, and, if so, that their force is either spent through the spaces opened by the nitro-glycerine, or, if the latter have failed of full effect, that the following force, so greatly mferior in strength, can do but little. '■ But the natural query arises : If these salts used m the bases of the various lower dynamites do not add to the effective strength of the compound, why admix them .■' One reason simply is, that an admixture of forty per cent nitro-glycerine or less with infusorial earth alone is absolutely non-explosive." It is an established fact that No. 2 and No. 3, or lower grades of dynamite, are manufactured containing as low as twenty per cent of nitro-glycerine, and even less ; and that these grades of dynamite are only rendered detonable by the admixture of ex- plosive salts ; and, therefore, the presence of these explosive salts does serve to perform a useful function. Again quoting from Mr. Drinker (p. 74), he says, — "The question that remains, then, simply is : Do these com- bined salts in the base act passively, or actively, when the explo- sion takes place .' That is to say, do they, by their presence in the base, simply afford an absorbent for the liquid nitro-gly- cerine, which, by its nature, does not secrete the absorbed nitro- glycerine so closely as kieselguhr (or infusorial earth) alone does ? or do they themselves participate in and augment the force developed when explosion is effected .-" Were the former object the only one sought by the admixture of salts in the base of No. 2, it would be open to question whether this object could not be attained at less expense by the substitution of cheaper components than soda, nitre, or saltpetre, etc., yet having the same carrying (if we may so express it) character- istics. But this object is not the only one subserved by the DYNAMITE, OR GIANT-POWDER. 69 admixture of nitro-glycerine with explosive salts as absorb- ents-. " We propose now to show, and it is submitted that the proof is based not on theory alone, but on facts, that not only do these salts in the base add appreciable strength to the explosive force of a nitro-glycerine compound, but they, in fact, add great strength to it ; that the theory that their action is nil is errone- ous, and founded simply on the plausible theoretical deductions and reasoning which we have above given ; further, that this theory that they do not add strength is not in accordance with the facts, nor based on fact." And again (p. 75) : — "Now, let us bear in mind that the question simply is, whether a mixture of nitro-glycerine (which is essentially a detonating explosive compound), with an igniting explosive compound, will develop greater effective strength than the sum of the forces developed by the same compounds fired separately. We will show that a resulting force far greater than the sum of these forces is developed. Suppose we simply take nitro-glycerine and gunpowder : they are the leading types of the two classes. On this point. Professor Charles F. Chandler of Columbia Col- lege, New York, has said," — " ' Where gunpowder explodes in the ordinary manner, the explosion is slow and progressive, and produces a temperature much lower than that produced by nitro-glycerine. But when the gunpowder is exploded by nitro- glycerine, its explosion becomes instantaneous; it becomes detonative; it oc- curs at a much higher temperature, produces a much larger volume of gas, and consequently develops a very much greater force than when exploded alone consequently the force developed by the explosion of a mixture of gunpowder and nitro-glycerine is equal to the sum of the forces developed by the nitro-glycerine and by the gunpowder when detonated, which last force is very much greater than the force of the gunpowder when exploded alone.' " (The foregoing opinion was directly on the following point : viz., 'If a given quantity of gunpowder explodes with a certain force, and a given quantity of nitro-glycerine explodes with a certain force, if the same quantity of nitro-glycerine and powder be mixed together, and exploded by concussion, will the ■ Testifying as expert in the case of The Atlantic Giant-Powder Company vs. Treat S. Beach, et nl. (1875). ^0 THE MODERN HIGH EXPLOSIVES. mixture explode with a force much greater than the sum of the force of the explosion of the two parts ? ') " And again (Drinker's "Tunnelling," p. "jG) : — " On the general question, Professor Chandler says further, — " ' The force exerted by an explosive agent when it explodes depends, first, upon the absolute quantity of gas produced, and, second, upon the increased quantity of gas due to the expansion, or increased volume, due to the high temperature. The expansion is in proportion to the temperature ; the tem- perature, however, varies with the manner of the explosion, while the absolute number of heat units developed by a chemical re-action, as an explosion, is fixed. The temperature depends entirely on the time during which the re-action takes place. A pound of wood produces just as much heat when it undergoes oxidation or decay in a forest, as when it is burned rapidly in a fireplace ; but years elapse before the slow decay is complete, and the most delicate thermometer would hardly detect any increase in temperature during the combustion. With the aid of the bellows, the combustion in the fireplace is completed in a few moments, and a white heat is produced. Now, in the ordinary explosion of gunpowder, we have a comparatively slow combustion ; a large amount of the gunpowder escapes combustion, or fails to undergo com- bustion until it is too late for it to accomplish any practical result in moving a projectile or in shattering rocks. Moreover, owing to the slowness of this combustion, a lower temperature is produced ; and consequently the volume of gas at the moment of explosion is much less than it would be did the explosion take place more rapidly, and develop a higher temperature. When gunpowder is mixed with nitro-glycerine, and exploded, the combustion is much more rapid. It is called, by investigators of explosives, a detonation, to distinguish it from an ordinary explosion. Gunpowder undergoing deto- nation produces a much greater effect, therefore, than when exploded by itself in the ordinary manner: first, because it produces a much higher temperature ; second, because it is more completely burned.' "As to the amount of gunpowder unconsumed when gun- powder alone is fired, the experiments of Bunsen and Schischkoff showed that the waste in gunpowder is about sixty-eight per cent of its own weight, only thirty-two per cent being utilized ; that is to say, while about one-third of the weight of gunpow- der appears, after the explosion, in the form of gas, carbonic acid, carbonic oxide, and nitrogen, about two-thirds the weight appears in the form of solids, sulphate of potash, carbonate of potash, hyposulphite of potash, unchanged nitrate of potash, and sulphide of potassium, — all of which compounds are solid at a red heat, but assume the form of gas at a considerably higher temperature. DYNAMITE, OR GIANT-POWDER. "Jl "This supposed utilization (if it may be so called) of the ordi- narily unconsumed proportion of gunpowder, that is effected when it is fired in conjunction or combination with nitro-gly- cerine, is of course only one theory to account for the fact, that, in combination with nitro-glycerine, gunpowder does undoubt- edly, in spite of all theories to the contrary, develop enormously greater strength than when fired alone. Professor Chandler says : — " ' This is not the only possible explanation of the fact. It is known that very high temperature destroys chemical compounds, dissociating their ele- ments. It may be that the temperature which prevails when gunpowder is exploded by nitro-glycerine is sufficient to separate tlie elements contained in the potash salts combined with it, and thus greatly increase their volume.' " Now, the above discussions give theories on either side of this question ; but the tunnel-man, as a general rule, is not so much interested in theories as in facts. The question is. What is the fact in this matter ? Do explosive dopes or absorbents, when mixed with nitro-glycerine, add to its effective, disruptive strength, or do they not } To practically test the question, the author of this work requested permission of the Atlantic Giant- Powder Company to make a set of trials at their works at Drakes- ville, N.J. The permission was cordially acceded, and the trials were made in June, 1877. They were of three kinds, and will be described in order. "The first experiment was made with a block of iron, hav- ing on its top surface a socket or hemispherical bore hollowed out, this socket having a diameter of four and a half inches. In this hollow an iron ball exactly fitted. When the ball was in place, of course half of it projected above the block. A channel cut in the block down the side of the hollow allowed the introduction of a fuse below the ball, without, however, pre- venting the latter from resting solidly in place. At the bottom of the socket (if we may so term it) was a powder-chamber one inch and an eighth in diameter and about one-quarter of an inch deep. In this chamber, four pennyweights ' of common black blasting-powder were placed, the ball placed over it, and the ^ One pennyweight "=■ 1.535 grams. 72 THE MODERN HIGH EXPLOSIVES. '■ Next, a mortar such charge ignited by a piece of common safety-fuse. Result : On ignition of the charge, it did not throw the ball out of the socket, but raised it sufficiently to allow the gases to puff out. Second, twelve grains ' (by weight) of nitro-glycerine were ex- ploded in the same manner under the ball (except, of course, that in this case an exploder was attached to the end of the fuse, in order to explode the nitro-glycerine) ; and the ball was thrown twenty-five feet vertically in the air. Third, four penny- weights of the same blasting-powder and twelve grains of nitro- glycerine were together, by means of an exploder, fired under the ball : the ball was thrown up seventy-five feet. Now, it will be observed that the amounts of powder and nitro-glycerine used in the compound were the same as when they were used in separate charges. as is shown in section in Fig. i was used. This mortar was of cast iron, its bore four inches in diameter, with a steel disc three inches thick shrunk into the bottom so as to leave the bore six inches deep. The shot exactly fitted the bore, was seven inches long, and weighed twenty-eight and a half pounds. "At the centre of the inner end of the shot was a hollow cavity for the charge. Above the powder-cav- ity, there was a recess, into which the exploder fitted, so as to leave the fulminate 'of the cap in the powder-chamber. From the cap, through the centre of the shot to the outer end, was a small hole for the electric wires. This mortar was strengthened by heavy wrought-iron bands shrunk on it, and it was bolted at an angle of forty-five degrees to foundation-timber placed in the ground. In charging the mortar, the wires of the exploder were passed through the shot, and the cap drawn to its place. The charge was then placed in its chamber, and held in place by a disc of thin paper pasted over it, within a recess prepared for it as shown ' One grain = .0625 gram. DYNAMITE, OR GIANT-POWDER. 73 in the figure. The shot was then lowered to its place in the mortar, great care being taken to have the shot and the bot- tom of the bore in close contact. The slightest opening be- tween them was found to seriously affect the result. The charge was fired by a friction battery, and the distances to which the shot was thrown carefully noted from a series of distance-stakes along the line. "In this mortar, trials were made with various nitro-glycerine compounds as follows : — (i) Charge = 5 dwts. No. 2 dynamite. Ball thrown 620 feet. {2) Charge = 48 grains nitro-glycerine (this being the amount of pure nitro- glycerine contained in combination in 5 dwts. of No. 2 dynamite). Ball thrown 358 feet. (3) Charge = j dwts. rifle-powder (Hazard's American sporting-powder, $1 per lb.). Ball thrown 248 feet. (4) Charge = 5 dwts. XX dynamite. (This dynamite was composed of only 4 per cent of nitro-glycerine, with an explosive base.) Ball thrown 256 feet. "The latter two experiments were simply to show that a dynamite holding a very small percentage only of nitro-glycerine will, when mixed with an explosive base, give a blasting-powder exceeding the best rifle-powder in strength. It is, however, with the main experiments, i and 2, that we are here concerned. As to tests of this nature made in a mortar, it has been objected that they do not give accurate results, on the general ground that explosive compounds, when fired, develop, according to their nature, either mainly projectile or disruptive effects. Thus, in order that a ball of a given weight should be set in motion by a given total force, that force must be applied during a definite interval of time ; if the same total force is ap'plied during a less time, it cannot produce the same velocity, but will be expended, as is all arrested motion or force, in heating the substances by which the motion is arrested. Thus, when a rapidly exploding material is fired in a mortar of the above description, a large part of its force is consumed in heating the shot and mortar in the same manner that a bar of iron is heated when violently struck with a hammer. On the other hand, an explosive which developed the same total force, but burned a little more slowly. 74 THE MODERN HIGH EXPLOSIVES. would expend relatively all its force in giving motion to the ball, as, during the passage of the ball from its seat to the mouth of the mortar or cannon, it would be impelled by a constantly accelerating force induced by the more complete combustion of the explosive. Again, an explosive developing the same, or even greater total force, but exploding quicker, would produce less projectile velocity in the ball ; while, again, this very sud- denness, which is unfavorable to the maximum projectile effect, would be favorable to bursting or fracturing results, since the resisting forces which are there to be overcome also involve the element of time. In other words, this reasoning, on general grounds, would tend to indicate that the mortar test is a proper measure of ballistic force, but not so accurate a gauge of dis- ruptive force in explosive compounds not similarly constituted. But the application of this reasoning is seen best in gunnery proper, where the distance traversed by the ball from breech to muzzle is of moment. With a mortar such as is above described, where the diameter of the bore is four-sevenths of the length of the bore, the charge of explosive is so small relatively to the bore of the mortar, and the retention of the gases so slight (comparatively speaking), that the test may be taken as an approximate indication at least. Moreover, in the first set of tests with the hemispherical socket and ball, the same comparative result, it will be remembered, was reached with no bore whatever. There, as soon as the ball was raised from its seat the smallest fraction of an inch, the gases had a vent. In order, however, to test the question from a wholly different standpoint, a third apparatus was tried, which we will term a pressure-gauge. It consisted, as shown in Fig. 2, of a vertical steel pin C, six and three-fourths inches long, an inch and a half in diameter, enlarged at the top to four inches. This pin weighed eight and a half pounds ; and it slid vertically in an iron block E, which block was bolted by G G to an iron foundation F, weighing some twelve hundred pounds. The pin rested upon a small truncated cone D of lead, which itself rested upon the foundation. Great care was taken to have the lead cones homo- geneous in purity, and of exactly the same dimensions. The machine was operated by charging the same ball or shot that DYNAMITE, OR GIANT-POWDER. 75 cSi- Mr-i, Fig.2 ^f^ was used in the mortar experiments. It was then placed, A, upon the steel pin, and fired in the manner already above de- scribed in the mortar experiments, through the wires B B. The comparative strength of the different compounds tested was measured by the compression of the lead effected at each shot. " Repeated trials with this press- ure-gauge showed conclusively, that not only the compression of the lead was far greater when an explosive base was used in conjunction with nitro-glycerine than the sum of the compressions effected by the same amounts of nitro-glycerine and base when fired alone, but so much greater that there could be no question of the principle estabhshed.' " These tests, in June, 1877, were conducted by Mr. Drinker. In order, however, to substantiate the results obtained, he arranged to re- peat them in September, 1877, in the presence of Professor P. W. Frazier, professor of mining and metallurgy at the Lehigh University ; Mr. Frank L. Clerc, chemist to the Le- high Zinc Works ; and Mr. Frank P. Howe, mining-engineer. These gentlemen were so kind as to give their assistance as experts ; and the second set of experi- ments were made under the auspices of the Lehigh Univer- sity, the university apparatus, scales, etc., being kindly ten- dered. "This time, the ball-and-socket and the mortar tests were omitted, the pressure-gauge being alone used. It was arranged precisely as above described. :\ i2i] P/essure Gauge. " Mr. T. Shaw, of Philadelphia, makes differential mercury column gauges registering explosive force up to 40,000 pounds per square inch. These gauges are used for black- j)Owder ; ordinary blasting giving 22,000 pounds, and sporting grades 40,000 pounds. y^) THE MODERN HIGH EXPLOSIVES. " The tests in detail were as follows ; ' the measurements being in inches and decimals of an inch (i inch = 2.54 ctm.), and the weights in grams and decimals of a gram (i gram = 0.0352758 ounce avoirdupois). "The small truncated cones of lead averaged in diameter at top, 0.815"; at bottom, 0.797"; mean diameter = 0.806". The height of the cone was in each case carefully measured, before and after compression, by a micrometer screw measuring to thousandths of an inch. "Each separate test was repeated a sufficient number of times to eliminate errors of accident. The average results only are herewith given. " I. The first trial was to test the strength of the exploder or cap used in all subsequent experiments with nitro-glycerine or its compounds. Charge, one exploder. Mean height of lead before firing 0.929" Mean height of lead after firing 0.754" Compression 0.175" " II. The second trial was to test whether in ordinary No. i dynamite (or giant-powder), composed of seventy-five per cent nitro-glycerine and twenty-five per cent infusorial earth, there was any appreciable loss of power by the absorption of the nitro-glycerine in the infusorial earth. (A) Charge, 1.5 grams No. i dynamite. Mean height of lead before firing 0.932" Mean height of lead after firing 0.194" Compression 0.738" " Next, the amount of pure nitro-glycerine contained in 1.5 grams No. i dynamite was taken. (B) Charge, seventy-five per cent of 1.5 grams = 1.125 grams. Mean height of lead before firing 0.933" Mean height of lead after firing 0.180" Compression o753" ' It will be observed, that, in the experiments in June, troy weights were used. In September, the metric weights from the university were adopted. DYNAMITE, OR GIANT-POWDER. jy Therefore, (C) Compression exerted by No. i dynamite 0.738" Compression exerted by nitro-glycerine alone . . . 0.753" In favor of nitro-glycerine alone 0.015" "This difference is very small; still, it would appear suffi- cient to indicate, if not a practical, a positive and appreciable diminution of the effective power of the nitro-glycerine by the absorbent. Practically, about seventy-five has been found, bv long practice, to be the highest percentage of nitro-glycerine that can be held by kieselguhr without exudation ; and it may be assumed, for all practical purposes, that the full effect of the nitro-glycerine is attained. "III. The third trial was with the same percentage (75) of nitro-glycerine as in II., but with an explosive base or dope substituted for the twenty-five per cent of kieselguhr. Charge, 1.5 grams. Nitro-glycerine 75 per cent. Nitrate of potash (saltpetre) 20 " Sawdust 5 " "The nitrate of potash was finely divided, and had been care^ fully dried. The sawdust was of pine, and it also had been dried. Mean height of lead before firing 0.932" Mean hfeight of lead after firing 0.162" Mean compression 0.770" We therefore have from II. (A) Mean compression 0'738" III. Mean compression 0.770" In favor of III 0.032" " Where one is dealing with explosive compounds, we must remember that their manufacture is simply a question of syn- thetic chemistry, and that, given certain explosive re-agents, that mixture of them will develop the greatest effective force in which the several constituents are combined in such propor- 78 THE MODERN HIGH EXPLOSIVES. tions as to leave no excess of one re-agent over another. Re- peated trials seem to have established, as to the explosive dope, that, where sawdust and saltpetre are used, the best proportions are one of sawdust to from three to four of saltpetre. In the tests made in June, the author used one of sawdust to three of saltpetre ; in September (the tests we are now describing), one of sawdust to four of saltpetre was used, and the results obtained were very close to each other. Theoretically, the proportion of one to three seems the more correct ; for, assum- ing the ideal re-action to be : — 48(KN03) + 5(C.,H3oO:o) = 24(K,C03) -^ 36CO, -H soH.O -1- 48 N, we see that a theoretically perfect mixture (if the above re- action be correct) would call for 4848 parts saltpetre to 1620 parts sawdust, giving a proportion of three to one. "IV. (A) Charge, 1.5 grams. Nitro-glycerine 40 per cent. Nitrate of potash 48 " Sawdust 12 " Mean height of lead before firing 0.930" Mean height of lead after firing 0.227" Mean compression 0.703" "Next, the amount of pure nitro-glycerine contained in 1.5 grams of the above mixture IV. (A) was taken. e> (B) Charge, forty per cent of 1.5 grams — 0.6 gram. Mean height of lead before firing 0.930" Mean height of lead after firing 0.329" Mean compression 0.601" We therefore have from IV. (A) Mean compression 0.703" IV. (B) Mean compression 0.601" In favor of IV. (A) 0.102" DYNAMITE, OR GIANT-POWDER. 79 " It was thus evident that great effective strength was added by the admixture of the dope. Moreover, this compression of 0.102" is, in fact, much greater than it relatively appears to be : for we must remember that the compression effected is not in direct proportion to the force exerted ; that is to say, if a cone of lead were struck and compressed by a certain force, and then a similar cone were struck with a force twice as great, the compression effected in the latter case would be less than double that shown in the former case, for the resistance would be greater as the molecules became more closely compressed. " The next trial was suggested by Mr. Clerc on the ground, 'Given an explosive compound composed as in IV. (A) of Nitro-glycerine 40 per cent. Nitrate of potash 48 " Sawdust 12 " what relation, in point of effective strength, does the dope bear to the nitro-glycerine t ' After several trials with different weights of pure nitro-glycerine, it was found that a charge of 0.900 gram of pure nitro-glycerine £-ave practically the same compression as a charge of \.^ grams of the mixture IV. (A) ; thus : — "V. Charge, 0.900 gram pure nitro-glycerine. Mean height of lead before firing 0.929" Mean height of lead after firing 0.229" Mean compression 0.700" or IV. (A) Mean compression . . . . : 0.703" V. Mean compression 0.700" Difference 0.003" " Three thousandths is so small a difference that it may be disregarded : indeed, exact equivalent results would not be any more reliable. We therefore see, that the proportions of pure nitro-glycerine in IV. (A) and V. are as 6 : 9, while in IV. (A) the nitro-glycerine does two-thirds of the work; in other words, that an explosive dope composed of one of sawdust to four of saltpetre, when mixed in the proportion of forty parts of nitro- glycerine to sixty of dope, adds one-half to the effective strength 8o THE MODERN HIGH EXPLOSIVES. of the nitro-glycerine. This compound is the ordinary com- mercial giant-powder (or dynamite) No. 2. The sulphur and rosin described before by Capt. Alex. Mackenzie as being used in the manufacture of No. 2 dynamite are now discarded. Sawdust and saltpetre are the only constituents of the dope ; the sawdust giving the carbon, and the saltpetre the oxygen necessary, while the nitro-glycerine present avoids the need of the sulphur ordinarily added to promote combustion." Mr. Drinker then gives a test to demonstrate the difference between the XX powder (now manufactured by the Giant- Powder Company, and containing only six per cent of nitro- glycerine) and black powder. The fallacy of such a test is apparent when we consider that in one instance we have a deto- nating compound (the XX powder), which will exert its force downward, and compress the lead according to its ratio of vol- ume of gas developed, quickness of explosion, etc. ; but it is questionable whether the black powder is even partially deto- nated in this case, not being under pressure : and, although its ballistic effect may be equal to the XX powder, its disruptive qualities could never be established by such a test ; since its explosion, or development of force, would not act downward like dynamite, but certainly, as in this case, seek the line of least resistance, which is upward, through the free vent. The foregoing tests, of course, demonstrate very fully that an explosive dope adds effective strength to a nitro-glycerine compoimd. Again from Mr. Drinker's " Tunnelling," p. 84, the following extract is made : — " Next, a trial was made with the XX powder that has since been largely introduced by the giant-powder companies. This explosive is substantially founded on the principles described in the patent No. 183,764 of Egbert Judson. In it a very low per- centage (six per cent) of nitro-glycerine was used. The object of the trial was to see the strength added by the explosive dope, and also to compare this XX dynamite with ordinary rifle-powder. "VI. (A) Charge, 1.5 grams XX powder. Mean height of lead before firing 0.933" Mean height of lead after firing 0.335" Mean compression 0.598" DYNAMITE, OR GIANT-POWDER. 8 1 "Next, the amount of pure nitro-glycerine contained in 1.5 grams of XX powder was taken. (B) Charge, six per cent of 1.5 grams = 0.09 gram. Mean height of lead before firing 0.931" Mean height of lead after firing 0.668" Mean compression 0.263" (C) Charge, 1.5 grams "American Sporting Powder," of the Hazard Powder Company, fired simply with Bickford fuse without exploder. Mean height of lead before firing 0-933" Mean height of lead after firing 0.876" Mean compression o-of?" (D) Same charge as (C), except that, instead of being ignited by a fuse, it was fired by an exploder with battery. Mean heig!.it of lead before firing 0.933" Mean height of lead after firing 0.516" Mean compression 0417" " From these four tests, VI. (A), (B), (C), and (D), we see, first, that as between (A) and (B) : — (A) Mean compression 0.598" (B) Mean compression 0.263" In favor of (A) 0-335" "Now, the compression produced by the best rifle-powder is, we see by (C), only 0.057 when it is fired by fuse; but when fired with an exploder as in D, it is probably in a measure deto- nated, and we then obtain an effect of 0.417. Comparing (A) and D, we have : — (A) Mean compression 0.598" (B) Mean compression 0417" In favor of (A) 0.181" But it is hardly necessary to call the attention of the reader to the fact that the best rifle-powder is many times stronger than ordinary blasting-powder ; moreover, that a small quantity of rifle-powder (1.5 grams), fired by an exploder, would be deto- 82 THE MODERN HIGH EXPLOSIVES. nated under the most favorable circumstances : yet even here we see the XX powder developing far greater strength, though the percentage of nitro-glycerine is only six. It is claimed that this new XX brand of dynamite can be manufactured at a much lower cost than black blasting-powder, and that it will do far greater work ; and these tests appear to substantiate such a conclusion as to the question of greater strength. " The above six trials appeared to so conclusively demonstrate the fact that an explosive dope does add effective strength to a nitro-glycerine compound, that it did not seem necessary tO' pursue the question farther. " Before concluding the trials, however, a set of successive tests were made, with gradually increasing charges of pure nitro-glycerine, to establish the pressure exerted by the several amounts of nitro-glycerine taken. This was done with the fol- lowing results : — I. 0.200 gram nitro-glycerine gave a mean compression of . . 0.406" II. 0.400 gram nitro-glycerine gave a mean compression of . . 0.516" III. 0.600 gram nitro-glycerine gave a mean compression of . . 0.601" IV. 0.700 gram nitro-glycerine gave a mean compression of . . 0.644" V. 0.800 gram nitro-glycerine gave a mean compression of . . 0.672" VI. 0.900 gram nitro-glycerine gave a mean compression of . . 0.700" VII. i.ooo gram nitro-glycerine gave a mean compression of . . 0.730" Mean height of leads before compression was 931". "VII. Charge, 0.200 gram pure nitro-glycerine. Mean height of lead before firing 0.933" Mean height of lead after firing 0.527" Mean compression 0.406" "VIII. Charge, 0.400 gram pure nitro-glycerine. Mean height of lead before firing 0.930" Mean height of lead after firing 0.414" Mean compression 0.516" "IX. Charge, 0.600 gram pure nitro-glycerine. Test No. IV. (B), above, showed the mean compression with this charge to be 0.601". DYNAMITE, OR GIANT-POWDER. 83 "X. Charge, 0.700 gram pure nitro-glycerine. Mean height of lead before firing 0.929" Mean height of lead after firing 0.285" Mean compression 0.644" "XI. Charge, 0.800 gram pure nitro-glycerine. Mean height of lead before firing 0.933" Mean height of lead after firing 0.261" Mean compression 0.672" "XII. Charge, o.goo gram pure nitro-glycerine. Test No. 5, above, showed the mean compression with this charge to be 0.700"- "XIII. Charge, i.o gram pure nitro-glycerine. Mean height of lead before firing o-93i" Mean height of lead after firing 0.201" 0.730" Again (p. 96, Drinker's " Tunnelling ") we find : — "Sarrau," in some more recent experiments, has taken the ground that the force of any explosive substance is nearly pro- portional to the product of the heat of combustion, by the weight of the permanent gas produced by the combustion ; and has, from experiments, prepared the following table : — Name of Substance. Relative Force. Saltpetre powder Chloride of nitrogen Mixture of 55 parts picrate of potash and 45 parts saltpetre Mixture of equal weights of picrate and chlorate of potash Picrate of potash Gun-cotton Nitro-glycerine 1. 00 1.08 1.49 1.82 1.98 3.06 4-SS ' Recherches Th^oriques sur les Effets de la Poudre et des Substances Explosives. 84 THE MODERN HIGH EXPLOSIVES. " Detonation may be defined to be the instantaneous explosion of the whole mass of a body. Thus, when gunpowder is fired in the usual manner, true combustion takes place, which goes on with comparative slowness from the surfaces of the grains toward their interiors. On the other hand, when nitro-glycerine is firqd by means of fulminating mercury, the whole mass ex- plodes simultaneously or nearly so." On p. 97, Drinker's "Tunnelling," we find the following: — " The various explosive compounds, according to their work in blasting, can clearly be divided into the two classes of : — " I. Slow, or rending, compounds. " 2. Quick, or shattering, compounds. "A slow or rending compound is therefore distinctively one in which the transformation of the substance into gaseous form is slow, and where the explosive force is exerted by degrees as the gases are developed ; and these compounds are the ones in which the greatest effect produced is not invariably at the exact point at which the explosive is located, — i.e., the gas, being slowly evolved, will tend to concentrate its strength, and act in the line of least resistance ; and the pressure upon the con- taining body can in no part be greater than that which is exerted on the part which yields, — i.e., it can never be greater than the resistance of the least resistant part. This class of explosives is, of course, especially applicable in quarries, etc., where the material is required to be blasted in certain shape, or in large blocks. Gunpowder is its prominent type. "A quick or shattering compound is, on the other hand, one where the transformation of the substance into gas occurs prac- tically instantaneously, and the full force of the enlarged volume is at once exerted in all directions, and upon every part of the containing body, because motion requires time ; and, as no time is allowed for the less resistant part to yield by moving away before the pressure of the fluid, it follows that the whole force of the latter must be exerted upon all alike : the rock is there- fore not only blown out in fragments to the full depth of the hole, but is violently strained and shattered in the immediate vicinity of the hole, even where the resistance is greatest ; so we see that these shattering explosives are of course of especial value in tight headings driven through hard rocks. Of this class, nitro-glycerine is the distinctive type. DYNAMITE, OR GIANT-POWDER. 85 "Between gunpowder and nitro-glycerine as extremes, the other explosives in use range according to their strength ; and we must remember, in studying their practical application to blasting, that, in choosing the best explosive for a particular piece of work, and in different parts of the same work, many circumstances must be taken into consideration : whether the material to be blasted is homogeneous in its character; whether it be a hard, soft, or loose rock ; and whether time (as in most railroad-tunnels) is an essential element in the problem. In the same piece of work, different explosives can generally be used to advantage in the different workings, with economy of both time and money ; as, in a tunnel, the heading often requires a quick, and the bottom a lifting, force. For this reason, it will not do to assume that one explosive is practically a better one than another, in the ratio in which it may be said to exceed it in power. No general comparison can be made, or empirical rule laid down ; but good judgment in this as in other engineering problems must be exercised." FORCITE. The Method employed in Continental Dynamite -Works for the Mamifaciure of Nitro-glycerine. — In factories where about 1,200 pounds of nitro-glycerine are prepared daily, the following method is employed : — The chemist mixes, in a large lead vat, 650 pounds of nitric acid (specific gravity 1.50), and 1,300 pounds of sulphuric acid (specific gravity 1.83) ; and, after remaining twelve hours, this mixture is carried through a lead tube into the nitro-glycerine apparatus. (The acid-mixing tank is generally located outside the building, and on a higher level than the nitro-glycerine apparatus.) The nitro-glycerine apparatus is composed of a cast-iron vessel (see Fig. 3), surrounded with a water-jacket, and, to better cool the mixture, is further provided with two large lead worms, through which a rapid current of water cir- culates. To this acid mixture, 310 pounds of glycerine are gradually added. The flow of glycerine is regulated by means of a faucet from the glycerine reservoir, which is generally placed on the roof of the building. 86 THE MODERN HIGH EXPLOSIVES. The following cut will give a clear idea of the apparatus which has been in general use by a great many factories, and given entire satisfaction. Nitro-glycerine Apparatus. — a a is the iron vessel ; b is the agitator-screw ; c is the agitator screw-shaft ; d is the stone- ware faucet for emptying the apparatus ; e is the fau- cet and glass tube through which the communication between the apparatus and the glycerine-tank, /, can be established or cut off ; /, glass tubes through which the nitrous fumes are con- ducted outside of the build- ing ; h, j, k, supports for the shafting and gearing ; o, p, bevel gearing ; n n, transmission - pulleys ; m, entrance of lead worm, or cooling-pipe ; r, outlet of lead worm, or cooling-pipe ; ti, entrance to the water- jacket surrounding the iron tank; v, outlet for the wa- ter-jacket surrounding the iron tank ; t, the thermometer. As soon as the acids are introduced into the iron tank a a, and before the glass faucet e is turned so as to allow the gly- cerine to flow very slowly into the acids, fresh water is made to circulate continually in the space between a a and s. s repre- sents a wooden tank in which the iron tank is enclosed ; the latter resting on supports, so that the water circulates around the bottom and sides. The water is turned on also into the lead worms at m. The thermometer is now watched ; and, the instant before the glycerine is allowed to flow in, the screw is set in motion by hand or steam power. The temperature should never ex- ceed 28" Cel., or 80° F. Should this, however, occur, the flow of glycerine is stopped, and the screw turned more rapidly. Fig. 3. — Nitro-glycerine Apparatus. FORCITE. 87 Should the temperature still increase, let the operator not lose Jiis presence of mind, but open the faucet d, and discharge the contents of the apparatus into a large tank filled with water. The faucet d ought to be of large dimension, — at least a 2i-inch opening, — so that the discharge shall be as rapid as possible. A practical operator knows how to regulate the flow of the glycerine ; and, if the operation proceeds without any disturb- ance, all that he need do is to watch closely the thermometer, and that the screw works steadily, so as to perfect the mixing. With water at 15° Cel, or 55° F., the operation usually requires three-quarters of an hour ; and on watching the fumes which disengage through /, the operator can also tell if the operation is properly conducted. •The faucet d is now opened ; and the contents flow into a very large wooden tank, six feet high and twelve feet in diame- ter, three-fourths full of water ; and the mixture now is rapidly agitated with wooden rakes. The nitro-glycerine, owing to its higher specific gravity, will precipitate to the bottom of the vat, and is drawn off by means of faucets into a series of tubs (see Fig. 4), where it is washed, first with water, and then with Fig. 4. — Apparatus for the Washing of Nitro-glycerine. a weak solution of carbonate of soda heated to 70° Cel, or 158 F. ; and this washing is continued until the nitro-glycerine 88 THE MODERN HIGH EXPLOSIVES. fails to redden litmus paper. It must not show the least trace of acid. This last is very important. Generally, large factories have two apparatus under the same roof, and the operation is generally carried on in the earlier part of the day. The Washing of Nitro-glycerine. — A A' A" are washing- tanks ; B B' B", glass tubes through which the water flows out ; CC C", faucets to allow the nitro-glycerine to flow out ; D D' D" , tubes and faucets to turn on the water under pressure which enters through sprinklers into the vats, so as to be distributed through the nitro-glycerine, and wash it thoroughly. The nitro-glycerine, after falling to the bottom of a large tank,, on being discharged from the mixing apparatus, is drawn off into- this washing-apparatus; and the faucets D D' D" are opened, and the water-sprinklers distribute it in fine jets throughout the mass. It then rises to the surface, and flows through B to A' , and thence through B' to A" , till it escapes through B" . When the washing is completed, the nitro-glycerine is drawn off through C, C, and C". The System employed by the Forcite Company to Manufacture Nitro-glycerine. — Mr. Mowbray was the first to recognize, in this country, that compressed air effected most thoroughly the mixture of acids and glycerine, and also accelerated the opera- tion, as the compressed air in expanding absorbed heat. Mr. Nobel also used this method in his factories in Europe ; and he confided to the engineer Liedbeck the task of studying the details, and of constructing an apparatus to further this method. Mr. Liedbeck delivered the glycerine into the acid mixture in the form of a shower, and effected the mixing at the same time by means of compressed air, and succeeded in increasing the rendering of the nitro-glycerine. This system, completely modified by the Swedish engineer K. I. Sundstrom, was adopted in the factories of the forcite- company. A description ,of their manner of working is given here. The acid mixture is made in a leaden vat, and allowed to stand twelve hours to permit it to cool sufficiently. For every opera- tion, six hundred pounds of nitric and eleven hundred pounds of sulphuric acid are employed. When cooled as above, the acids are charged into the nitro-glycerine apparatus, the water FORCITE. 89 circulating in it through six lead worms and in a water-jacket around it. The glycerine runs into it by means of a special Fig. 5. — Nitro-glycerine Apparatus of the Forcite Company. injector, which works by compressed air. Two hundred and forty pounds of glycerine are required for a charge, and the operation takes an hour and a half. The thermometer is con- stantly watched as before. 90 THE MODERN HIGH EXPLOSIVES. When all the glycerine from the vessel / has flowed into the mixing-apparatus a, into which it is injected by me'ans of the injector i, the contents of a are discharged into the separator b made of lead ; and the nitro-glycerine after a few minutes will collect on the surface of the acid mixture, where it is skimmed off by means of a dipper as it rises to the surface, and is poured into the washing-vessels c, c, where it is washed with cold water. After running into the tank d, it is washed with a solution of carbonate of soda till it shows an alkaline re -action with litmus paper, and is then passed through the cotton filter into the tank /, from which it is taken for further use. In the course of the mixing in the apparatus a, if the tempera- ture rise above 28° Cel. or 80° F , the contents are discharged into a large tank e, three-fourths full of water ; and this is also done when the temperature rises in the separator b. The resting acids from the separator b are now allowed to flow into a lead chamber, or rather a species of tower, to destroy the last traces of nitro-glycerine (see Fig. 6). Apparatus for the Detiitrification of the Resting Acids ivhich still con- tain Nitro glycerine. — a is the lead cylinder soldered to the top b and to the bottom c, and is lined with refractory bricks laid in a mortar composed of refractory clay and tar. The acid enters by the lead tube /, and the nitrous gases escape by the earthenware pipe e. h is the entrance for the steam. g is the escape for the denitrified acids. The cylinder a is filled with large masses of quartz. Fig. 6. — Apparatus for the Denitrifica- ™, tion of the Resting Acids. ^ "^ nitrous-acid vapors cscape by e into a condensing-tower ; and the sulphuric acid runs by the tube g into an iron retort, there to be concentrated and again employed in the manufacture of nitro- glycerine. This regained acid is serviceable in the manufacture of nitro FORCITE. 91 Fig. 7. — Cartridge-Machines. glycerine, but, containing some iron, cannot be employed in the manufacture of nitric acid, as the sulphate of iron decomposes a part of the nitric acid. The mixed acids enter by b, and the steam which decomposes the nitrD-glycerine enters at h. Cartridge- Machines. — The ordinary cartridge-machines for No. I dynamite are made of an iron cylin- der c with a wooden pis- ton b. The machine is screwed to a table, and put in motion by the lever a. Dynamite is introduced by the fun- nel d, and comes out in pretty solid cartridges at e, of cylindrical shape ; and they are cut into the required sizes. Qualities of Forcites. — Forcite is a mixture of nitro-glycerine with other bodies which in themselves are also explosive, but is entirely different in its preparation from dynamite. No. I Forcite. — The type mostly in use, and which possesses the most excellent qualities, is the No. i, invented by the Swed- ish captain John Malcolm Lewin. It contains from sixty-five to eighty-five per cent of nitro-glycerine. The physical appearance of forcite is that of India-rubber, and it is very plastic. There are different grades of forcites, varying from those containing a large amount of nitro-glycerine to those containing only twenty to twenty-five per cent of it. Forcite has been exposed for several hours to a temperature of 125° F., without showing any signs of exudation. To explode it, quadruple-force caps are employed, as single- force have not sufficient power to always cause its explosion ; showing that the powder is not so sensitive to percussion, or to a blow, as the dynamites. Owing to its plasticity, it can be classed under the same head- ing as the gelatine dynamite manufactured in A. Nobel's 92 THE MODERN HIGH EXPLOSIVES. Continental dynamite works, to which substance it bears great resemblance. As to the use and application of forcite, very little can be added ; as the same rules which were laid down for dynamite may also be applied to this explosive. CHAPTER IV. OTHER VARIETIES OF HIGH EXPLOSIVES. DIFFERENT DYNAMITES WITH CHEMICALLY ACTIVE ABSORBENTS. To these belong lithofracteur (Colonia powder). Brain's blasting-powder, lignose, dualine, Vulcan powder. Atlas powder, dynamite nos. 3 and 4, blasting gelatine. I. — LITHOFRACTEUR. This compound, invented by Engel, and manufactured by Krebs Brothers & Co., in Koln (Germany), enjoys the reputa- tion of being as effective as Nobel's kieselguhr dynamite. In a hundred parts of lithofracteur, fifty-five parts of nitro- glycerine are contained ; and although this is by twenty parts less than is contained in dynamite No. i, the manufacturers claim that it produces the same effects, owing to the nature of its absorbents and the complete burning of the nitro-glycerine. The resulting gases are only carbonic acid, nitrogen, hydrogen, and a small quantity of sulphurous acid ; and there are no vapors given out injurious to health. The forty-five parts of admixture in lithofracteur contain only twenty-one parts of infusorial earth, and twenty-one parts of other absorbing, substances, which not only act as absorb- ents, but by the explosion are converted entirely into gases of high tension and temperature. These substances are carbon, prepared bran, prepared wood- pulp, nitrate of baryta, bicarbonate of soda, oxide of manga- nese, and sulphur. They are taken in such proportions as to 93 94 THE MODERN HIGH EXPLOSIVES. develop by their explosion the highest temperature and the greatest volume of gases. The addition of bicarbonate of soda has a twofold object to accomplish. It is a preventive, during storage and manufac- ture, of spontaneous decomposition, which would be possible in nitro-glycerine,. if through neglect it were not freed entirely from acids. Such traces of acids, if present, would be neu- tralized by the presence of bicarbonate of soda. When litho- fracteur is exploded, the bicarbonate of soda is decomposed, through the enormous heat developed, into free carbonic acid and caustic soda, thereby augmenting the quantity of expansive gases, and consequently the force of the powder is increased. If the composition of lithofracteur is considered, it appears that approximately the same substances are contained as in ordinary black powder, mixed with dynamite. Instead of nitrate of potash, it contains nitrate of baryta. It is said that lithofracteur is rather insensible against per- cussion. For instance, a bullet fired into a lithofracteur cart- ridge did not cause its explosion ; and a box containing five pounds was dropped from a height of fifty metres, and did not explode. But, when placed between two pieces of iron, this substance was exploded by a blow. II. — COLONIA POWDER. This explosive resembles very much the Vulcan powder, manufactured heretofore by Mr. R. W. Warren, and at present by the Vulcan Powder Company of San Francisco, Cal. The Colonia powder was brought first into commercial notice by Wasserfuhr, in Koln. When freshly made, it shows very good results. By prolonged storage it shows a defect, from the fact that the nitro-glycerine separates, especially when prepared with nitrate of soda, which is very hygroscopic ; and, to avoid this difificulty, the carbon is replaced in part or en- tirely by paper-pulp, which possesses good absorbing qualities. III. — BRAIN'S BLASTING-POWDER. This powder is composed, to the extent of sixty per cent, of a dry mixture, containing chlorate of potash, nitrate of potash, DIFFERENT DYNAMITES. 95 wood-coal, and wood-pulp, and of forty per cent of nitro- glycerine. This powder gave very satisfactory results, but, owing to the admixture of chlorate of potash, is to be considered a very dangerous compound. IV. — LIGNOSE. The three compounds which have been enumerated may be considered as mixtures of nitro-glycerine with variable ingre- dients of blasting-powders ; whereas the following are mixtures of nitro-glycerine with wood-fibre, or of nitrated wood-fibres with nitro-glycerine, to which a nitrate is added. When lignose was first brought into the market, there were anticipations, it would quickly replace black powder, especially for blasting-operations in medium hard rock. For that pur- pose, wood-pulp was simply saturated with nitro-glycerine. It was first employed in the mines of Silesia ; but its intro- duction met a speedy end by its objectionable features, which were mainly its obnoxious gases, and its great sensitiveness, which occasioned several severe accidents. In addition to these it is also very hygroscopic. v. — DUALINE. This explosive was discovered in this country by Lieut. Ditt- mar, of the artillery ; and is a mixture of sawdust and nitro- glycerine, or of wood-pulp which was either treated with a mixture of nitric and sulphuric acids, or saturated with a solu- tion of nitrate of potash. Dualine is of a brownish-yellow color, of the specific gravity 1.2. In open air it burns without exploding. Owing to its light specific gravity, it is more voluminous than dynamite ; and consequently the bore-holes for it have to be much larger. August Beckman, near Stockholm, manufactured sebastine and serranine, which much resemble dualine. The different varieties of high explosives which are in the market in the United States are mostly a mixture of nitro- glycerine with an explosive base ; and it is useless to enter into a detailed description of them, as a practical test will very soon 96 THE MODERN HIGH EXPLOSIVES. convince every miner or engineer which powder will answer his purposes the best. VI. — EXPLOSIVE GELATINE.' "This, the latest compound devised by Nobel, has not yet made its appearance in our market. Various efforts were made, immediately after its announcement in Europe, to import a sample for trial ; but the shipment across the ocean could not be arranged. Facilities for manufacturing the material in bulk are lacking at Willet's Point ; and it therefore had received no experimental study when this report was ofificially transmitted to the Board of Engineers in December, 1880. Since that date, a sample (about a hundred pounds), made by Professor Hill of the Naval Torpedo Station at Newport, has been kindly presented to us by Capt. Ramsey ; and to his courtesy I am thus indebted for the opportunity of making the following sup- plementary experiments in time for insertion before this book has passed through the press. Both the Atlantic and Pacific Giant-Powder Companies are now taking steps to manufacture explosive gelatine for the market ; and hereafter there will probably be no diiificulty in continuing and extending the trials needful to determine whether or not it should supersede dyna- mite No. I in our torpedo-service. " The sample prepared by Professor Hill consisted of eighty- nine per cent of nitro-glycerine, seven per cent of collodion (gun-cotton), and four per cent of camphor. It was forwarded in slabs wrapped in oil paper, each weighing about ten pounds. Being received in midwinter, it remained frozen in the maga- zine until April 18, 1881, — a whitish, opaque solid of about the consistency of cheese. Small pieces in this state, lashed to a service low-tension fuse primed with twenty-four grains of fulminate of mercury, failed to explode; and the same result followed when three of "Tihe fuses were fired simultaneously in contact. " In April the slabs were moved to a wooden shed, with the papers unwrapped; and, under the influence of the sprino- ' From Report upon Experiments and Investigations to develop a System of Submarine Mines for defending the Harbors of the United States. By Lieut.-Col. H. L. Abbot U.S A NITRO- GELA TINE. 97 weather, they soon began to thaw, changing in appearance into a thick, semi-transparent jelly of a pale-yellow color. The sub- stance in this condition possessed considerable toughness, but could be easily cut with a knife, and rolled in strips. Its specific gravity was about 1.6, or nearly that of dynamite No. i compacted in cartridges. A couple of ounces laid on a zinc plate, and exposed for about six hours to a hot sun, when the thermometer in the shade indicated 90° F., softened sufficiently to flatten by gravity, but no oil exuded ; and when ignited by a match, the mass burned like gun-cotton, with a strong hissing flame. A small piece plastered upon the copper cap of a ser- vice-fuse exploded with a loud report, indicating an increase in sensitiveness. " In only one instance (May 10, 1881) was any important exu- dation of nitro-glycerine noted, when about half a^ dozen drops appeared by the side of one of the thawing slabs : but the surface of the mass in this condition was usually oily ; and by absorbing with paper, and striking with a hammer, a sharp explosion could be obtained, proving the presence of free nitro- glycerine. Handling the jelly always produced the customary nitro-glycerine headache. "The following experiments were made upon the gelatine, when unfrozen, to test the effect of violent concussion. " A slice, half an inch in thickness, was suspended in paper, and pierced by a bullet from a regular Springfield rifle fired at twenty-five yards ; result, nil. This experiment was repeated without explosion, when the gelatine was backed by an inch board. The range was then increased to forty-five yards ; and the bullet was driven with a like result through the explosive, and flattened on a half-inch plate against which it was resting. P"inally, a ten-pound slab was lashed to a vertical board one inch thick, and was pierced by a service-bullet at a range of a hun- dred yards. The ball thus traversed about three inches of the gelatine without effect. In all these trials, the explosive was in its semi-transparent, jelly-like condition. "To test its tendency to sympathetic explosion, a few experi- ments were carried out. Half-pound cartridges wrapped in paper were submerged five feet below the water-surface, at distances of fifteen, ten, five, and three feet from a fuse-can 98 THE MODERN HIGH EXPLOSIVES. containing one pound of dynamite No. i. Detonating the latter produced no effect upon the explosive gelatine. Under like conditions, dynamite No. i explodes up to a range of twenty feet. "These experiments, confirmatory of those reported abroad, show that the new explosive possesses much less liability ta accidental detonation thaa dynamite No. i, an advantage which, in military operations on land, can hardly be over-estimated. " This explosive gelatine proved to be wholly soluble in ether, and in a mixture of ether and alcohol ; but in alcohol alone it dissolved with difficulty. Unlike its operation with other nitro- glycerine compounds, this process did not separate the oil from the base. "By evaporation, or by the addition of water, a white mass was precipitated, which resembled thick flour-paste in appearance. When subjected to moderate heat, a tendency to very gradually resume the semi-transparent appearance was developed. " Water produced no exudation of nitro-glycerine ; another important advantage over dynamite No. i, from which, as already stated, it abstracts the nitro-glycerine to a greater or less extent, depending upon the compactness of the material. After several hours submergence, however, the color changed to the opaque white characteristic of the precipitation from ether, etc." The following statement respecting this explosive is from vol. iv., No. 12, Occasional Papers of the Royal-Engineer In- stitute, being extracts from the "Revue d'Artillerie " for 1879,, translated by Capt. H. Tekyll, R.E. : — " Explosive gelatine is a peculiar description of gun-cotton, entirely soluble in nitro-glycerine, and forming with it a gelatinous or gummy substance more powerful than nitro-glycerine, scarcely affected by water, and giving out no. trace of nitro-glycerine under the strongest pressure. " It can be rendered insensible to mechanical action, while retaining its. power, by mixing it with certain substances soluble in nitro-glycerine, such as benzine, etc. " It is composed of ninety-three per cent of nitro-glycerine, and seven per cent of soluble gun-cotton. " The experiments demonstrated its insensibility to shock, to friction, and to the pressure or action of water; and, further, that to produce complete explosion in a free state, and to develop the great force corresponding to its^ NITRO-GELA TINE. 99 chemical composition, it would be necessary to use, even in its soft state, a peculiarly powerful detonator. " One gram of fulminate of mercury was insufficient to detonate a charge in a soft state contained loosely in a tin case. Fragments of gelatine as large as a pin's head, or even as a small pea, were found scattered about after the explosion. " Under the blow of a pile-engine, the gelatine was insensible to a blow of 3.5 kilogrammetres ; while dynamite instantly explodes under one kilo grammetre. " The gelatine is unaffected by submersion in water, even at a temperature of 1 58° F., and showed no trace of exudation after eight days, at a tempera- ture of 113° F. " From these properties it would appear verj' superior to dynamite for military purposes, provided a sufficiently powerful primer can be made to insure complete detonation. " A new explosive, suitable to all requirements, has been prepared from this substance, and may be termed 'gelatine explosive-de-guerre.' It is pro- duced'by adding to the gelatine a small preparation of camphor, a substance highly soluble in nitro-glycerine. '• A very small proportion of camphor renders the explosive insensible to blows, even of projectiles at short range : it also enables it to resist the action of water, and imparts to it an explosive force far superior to dynamite or compressed gun-cotton. '■ For complete detonation a special primer is needed, of extra power, composed of a mixture of nitro-glycerine, with a description of nitro-cellulose prepared in a particular manner. " The composition of explosive gelatine-de-guerre is : — Camphor 4 Explosive gelatine 96 100 " Explosive gelatine consisting of — Nitro-glycerine 90 Soluble gun-cotton 10 100 " In appearance it is gelatinous, elastic, transparent, and pale yellow in color. Its density is 1.6; it can be cut with a knife ; and under the severest pressure it shows no trace -of nitro-glycerine. At a temperature of 122° F. to 140° F., it softens a little, but seldom becomes greasy. •' When inflamed in the open air, it burns like dynamite, or dry compressed gun-cotton. "Two hundred grams were placed in a tin cylinder six inches long. When ignited with a slow-match, penetrating the middle of the charge, it burned quietly with a long, yellow flame, though the case was covered with a metal cover. When half the charge was burned, the cover was simply raised by the pressure, without any explosion taking place. lOO THE MODERN HIGH EXPLOSIVES. " A composition of ten parts of camphor and ninety of explosive gelatine may be exposed for a week to a temperature of 1 58° F., without showing any signs of decomposition. 4.4708 grams of the same composition, in a watch-glass, were exposed for seven hours a day, during two months, to a temperature of from 104° to 122° F. No decomposition took place, — merely a partial volatilization of camphor and nitro-glycerine. After the experiment, the specimen still weighed 4.1239 grams: so that the loss of weight amounted to only 0.3469 grams, or 7.7 per cent. As nitro-glycerine becomes volatile at 104°, part of the loss is accounted for: so that half the camphor in the composition can scarcely have evaporated, though the cir- cumstances were exceptionally favorable for evaporation. " Experiments are needed to determine the rapidit)- of evaporation of the camphor, and the effect of its volatihzation on the properties of the composi- tion. The preservative action of camphor, especially at exploding tempera- tures, is extremely notable. Thus pure explosive gelatine, slowly heated, detonates at 400° F., or rapidly at 464°. If ten per cent of camphor is added, it will not detonate at all when slowly heated, but becomes diffused in sparks. " When heated rapidly, it explodes at a temperature too high for measure- ment by ordinary apparatus. Mixed with ten per rent, pr even four per cent, of camphor, this substance will not explode at the same temperature as gun- powder, — viz., 570° to 600° F., — but simply burns, producing sparks. " It may be inferred from the above, that its liability to explosion from a blow would be equally slight, especially having regard to the elastic, gelatin- ous consistency of the material. " It requires a peculiarly powerful fuse to insure the certainty of detona- tion. The inertness of the composition increases rapidly with the propor- tion of camphor. With the addition of only four per cent, detonation cannot be insured with two grams of fulminate of mercury, a primer of compressed gun-cotton, or a mixture of seventy-five parts of nitro-glycerine with twenty- five of gun-cotton, as used in the Austrian service. ^ "A special primer is therefore required. It is composed of sixty per cent of nitro-glycerine and forty per cent of a nitrous substance obtained from cellulose by a peculiar process. Owing to the composition of cotton, it is impossible to obtain from it tri-nitro-cellulose. In Abel's process, much of the cotton is only partially nitrogenized, and some not at all ; while Lenk's method is still less efficient. " If sulphuric acid be made to act upon cotton, a white powder is obtained, named hydro-cellulose. This substance is extremely susceptible to the action of nitric acid. The result is, as regards explosive force, a highly nitrogenized description of cellulose. " This new gun-cotton appears in the form of a fine powder resembling flour, but exhibits under the microscope the specific structure of cotton. It is not a great absorbent of nitro-glycerine, like Abel's or Lenk's cotton, which are divided Ijy mechanical means; neither does it share their property cf becoming gelatinous with this liquid. NITRO-GELA TINE. lO I "Tne mixture of sixty per cent of nitro-glycerine with forty per cent of iiitro-hydro-cellulose yields a soft, white, soapy, and entirely homogeneous substance. Twenty grams can be placed in an Austrian cartridge, which will hold but fifteen to seventeen of the regulation composition; and thus furnishes a primer capable of exploding gelatine explosive-de-guerre, and surpassing in detonating power all known exploding agents." Decomposition of Explosive Gelatine.' — The great force and stability of freshly made camphorated explosive gelatine is such as to make it peculiarly a favorite for torpedo charges, provided its stability after long periods could be as safely depended upon. A large number of experiments have been made with this object in view ; and, unfortunately, the results have not been at all favorable. It has been suggested that possibly the cause of its rapid decomposition is due to the presence of free acid in the soluble gun-cotton. (The question of decomposition of explosive gelatine has not been explained as yet, but it may be due to its mode of man- ufacture; for, since the nitro-glycerine has to be raised to a certain temperature during its conversion into gelatine, may not this temperature be sufficient to start a slow decomposition i") ^ , So far, experiments certainly show that explosive gelatine is not a safe agent after some months' exposure to ordinary atmospheric re-actions. ^ To test the Action of Water on Explosive Gelatine. — Several samples were placed in distilled water, and left at a temperature of 65° to 75° F. After twenty to twenty-five days, the water gave a slightly acid re-action ; and, after two months, a strong acid re-action, and the samples had grown thin and soft, and were covered with a white, waxy substance. Several samples, of ten ounces each, were placed in beakers, and covered with distilled water, and placed in the heater at 113° to 122° F. ' From ii report of the Chief of the Bureau of Ordnance, Navy Department, Wash- ington, 1SS2. ^ Author's remark. 3 Explosive gelatine prepared with a perfectly soluble gun-cotton ought not to deteriorate or decompose, and it may be that an imperfectly nitrated cotton may cause the difficulty e.xperienced with this substance ; and various opinions exist as to its stability, which will require further experimental study and investigation. — Author's remark. 102 THE MODERN HIGH EXPLOSIVES. After from three to five days the water gave an acid re-action, and was changed as often as acid could be detected. After twenty days rapid decomposition began in the same samples, and after thirty days they were all decomposed. The explosive gelatine continued to decompose rapidly after being removed from the heater, and gave very strong acid re- action to water, even when the samples were frozen. These samples, after decomposing, were found to be coated on top with a white, waxy substance ; and the bottom and sides were of a greenish color. The interior of the samples consisted of a hard white sub- stance, and large amounts of free nitro-glycerine were found in the bottoms of the beakers. These samples, being dangerous, were not further examined, but were exploded by detonators of thirty-five grains fulminate each. The explosions were very violent and sharp, resembling those produced by liquid nitro- glycerine. Storing Explosive Gelatine. — Twenty-four pounds of explo- sive gelatine of the following composition : — Nitro-glycerine 88.80 Soluble gun-cotton 7.20 Camphor 4.00 100.00 prepared by Professor Hill during the fall of 1880, together with two hundred and fifty-six pounds of the same composition made during fall of 1881, were stored in lots of from ten to twenty-five pounds each. The gelatine was wrapped in parafifined paper, and placed in wooden boxes. Each box contained from ten to thirty-five pounds. On Oct. 11, 1881, these boxes were placed in a light wooden building. The covers of the boxes were so arranged as to permit free circulation of air over the gelatine. Test- papers were placed over each box to detect any acid given off by the decomposition. After three days the test-papers showed slight acid re-action, but no signs of rapid decomposition were shown during the fall or winter. Samples of two pounds each, from the explosive gelatine, stored as above described, were kept in a building similar to NITRO-GELATINB. IO3 the one in which the boxes were placed. These samples were inspected daily. They all gave off acid fumes slowly, but did not show exudation of nitro-glycerine, or signs of rapid decom- position. After thawing in the spring, they were soft and waxy ; and that made during the fall of 1880 was of a dark color, and showed strong acid re-action on test-papers in twenty-four hours. This sample was destroyed June 13, 1882. The samples taken from that made during the fall of 188 1 were removed to a cool underground magazine on June 16, 1882, where they continued to give off acid fumes, but showed no signs of very rapid decomposition. On Sept. 16, 1882, they were packed in silicious earth, to absorb any nitro-glycerine that might be upon the surface. The explosive gelatine was removed on June 10, 1882, from the boxes. That made during the fall of 1880 was badly decom- posed. It was of a dark color, containing green streaks, was soft and waxy, and the surface was covered with liquid nitro- glycerine. This decomposed gelatine was washed in a large volume of water, when the water became very strongly acid, and was re- placed by fresh water. After the greater part of the acid had been removed, the gelatine remained in one soft mass in the bottom of the jar. It was placed in a wooden box, and exploded under ten feet of water. The gelatine made in 1881 was found on June 10, 1882, to be very soft ; and the surface was oily, showing exudation of nitro-glycerine. It was removed to a cool underground maga- zine, and inspected daily. It remained soft, and continued to give off acid fumes, but showed no signs of rapid decomposition. This was exploded in torpedoes during June, July, and August, 1882. Details of some Experiments made in Austria on Explosive Gelatine. — The behavior of nitro-gelatine when fired into at twenty-five metres distance. It contained different proportions of camphor, was either plastic or frozen, and was exposed for several days to a temperature of 30° to 40° C. The gelatine was placed in an iron box of five millimetres. Fig. 8 shows the dimensions of the box and its cover. Fig. 9 shows the arrangements made for these experiments. I04 THE MODERN HIGH EXPLOSIVES. The gun was at a distance of twenty-five metres, and of the Wemdl pattern. First shot (soft gelatine with four per cent of camphor). The ball tore off the cover, no explosion. The explosive was scattered about, and the ball was covered with it. The gelatine was then gathered up, and replaced in the original box. Second, third, and fourth shots. Same results : no explosion, no inflammation. a o[o oE lolo go ZLOin lojo go Fig. 8. Fifth shots. The gelatine used in this trial contained only one per cent of camphor. There was no explosion, no inflam- mation. Sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth shots. Same result. At the thirteenth shot a report was heard, proving only a small local explosion, as about five-sixths of the gelatine used was scattered about, and the inspection of the post //"showed that it was not affected ; so that only a very small portion could have detonated. Fig. 9. H, wooden beam supporting the box ; E, iron plate ten millimetres thick ; B, box contain- ing the explosive. The trials were continued with frozen gelatine. Fourteenth shot (gelatine with four per cent of camphor). The iron plate H was replaced. Explosion ensued, and the target was destroyed. NITRO-GELA TINE. 1 05 Fifteenth shot (gelatine with one per cent of camphor). The iron plate was taken away. Incomplete explosion resulted. Sixteenth shot. A thin board was placed in front of the tar- get. No explosion resulted. From these facts the following conclusions were drawn : — 1. Explosive gelatine, under the worst conditions, — that is to say, when lying on an iron plate, when it contains four per cent of camphor, and when not frozen, — will resist the percus- sion of a rifle-ball. 2. Nitro-gelatine, when frozen, will explode when struck by a ball. 3. When a board is placed before it, it will not explode. 4. Gelatine placed against wood, instead of iron, as long as it contains over two per cent of camphor, is insensible to the repeated blow of rifle-balls fired into it, and seems to offer suffi- cient security against percussion. The important question to decide now was : In case the cam- phor, which is very volatile, evaporates easily from the gelatine, is not this substance rendered very sensitive again .■' Small pieces of gelatine, twenty-six millimetres thick, were placed on a sieve, which was suspended, so that there should be a free circulation of air around them, and was exposed for forty-eight hours to a temperature of 40° Cel. Some iron boxes were now charged with this material. Seventeenth shot. This gelatine, which contained four per cent of camphor, was placed against an iron plate. No explo- sion nor inflammation ensued. Shots eighteen, nineteen, and twenty were fired into gelatine containing one per cent camphor, placed against iron. No explosion occurred. These trials were evidently more satisfactory than those executed in the United States, where it was demonstrated, that, after a certain lapse of time, there was a considerable loss of camphor, and that the gelatine becomes more sensitive in con- sequence. Twenty-first shot. Was the most conclusive of all. The box containing the gelatine, without any camphor, was fixed against a wooden post. There was an explosion, and the target was completely destroyed. io6 THE MODERN HIGH EXPLOSIVES. This last trial was a complete corroboration of all which had been said before. Trials as to the Transmission of the Explosion of One Charge to Another placed in its Vicinity. — The object of these trials was to demonstrate that the explosive gelatine is not so sen- sitive as ordinary dynamite to the effects of explosions which take place in its vicinity. This property is of very great im- portance in an explosive intended for torpedo charging. The following figure shows how these trials were made. px~ Fig. io. Z., Z,„ the charges ; E, E^, the iron plates. The charges Z and Z, weighed one kilogram each, were six- teen centimetres high, and eight centimetres diameter. They were tied down with strings to the iron plates. The ordinary primers were used. In the first trial, the gelatine with four per cent of camphor was used. The two cartridges were twenty-five centimetres apart from each other. The cartridge L was exploded, and broke the iron plate E. The cartridge Z, was all broken to crumbs, but did not take fire ; and the iron plate E^ was intact. (The author did not witness these trials.) In the second trial, the gelatine was replaced by ordinary seventy-five per cent dynamite. The cartridges were twenty- five centimetres apart ; but in firing Z, the cartridge Z, went off also, and both iron plates E and E, were broken. CHAPTER V. PYROXYLINE, GUN-COTTON, NITRO-CELLULOSE. GUN-COTTON. History. — Nitro-glycerine and gun-cotton were discovered nearly at the same period. They are related in their produc- tion and in their properties ; but their progressive history is entirely different, and a short sketch will not be amiss here. The discovery of gun-cotton, by Schonbein, was hailed with delight by practical and scientific men ; and immediately after its discovery a great many experiments and trials were made with it on a large scale all over Europe, not alone by individuals, but by the different governments, who were inclined to adopt the new explosive for war purposes. But these sanguine ex- pectations, which everybody seemed to have at the outset, were not realized ; and all the trials were finally abandoned. In France, as early as the 3d of February, 1846, the secre- tary of war appointed a commission, under the direction of the Duke of Montpensier, which included among its members some of the ablest men in France, like Piobert, Morin, and the great chemist Pelouze, who conducted all the experiments themselves. The result of their trials, extending over a period of three years, during which they entered carefully and extensively into the nature of the explosive, was a verdict of "Not favorable." The causes of their unfavorable verdict in 1849 were the numerous decompositions and spontaneous explosions, which had, as a consequence, loss of life ; and all further trials with gun-cotton were abandoned in France. They concluded their report in the following words : — " I. Fire-arms {armes de guerre). In the present state in which this new material is produced by chemists, manufacturers, and artillery officers, it is 107 I08 ' THE MODERN HIGH EXPLOSIVCS. useless to continue to experiment witli it in respect to its application to fire- arms. " 2. Military mines {mines militaires). For war purposes, in destroying bridges and fortifications. As for its application in military mines, it would be impossible to furnish it to the military service, except in a wet state, by reason of the danger which its conservation presents in the dry state. Should it be even adopted in that wet condition, — which would have, as a conse- quence, the great danger to which our soldiers would be exposed by drying it, before its -jse, — we do not see that it offers any advantages, or even any saving, over black-powder." Much shorter than in France were the experiments made with it in Russia. After a few unimportant disasters during the first trials, the transport and sale of gun-cotton were pro- hibited throughout the empire. In England they were more persevering, and the experiments were continued till 1854; but they were abandoned also, in consequence of spontaneous explosions, causing serious loss of life. In Prussia the experiments were continued during a period of eight years, but they were abandoned on account of an ex- plosion in a drying-chamber. More persevering, and somewhat more fortunate, was gun- cotton in Austria ; and the results obtained there led to its revival in England. It is owing to the Austrian, Baron von Lenk, who introduced an improvement in the process of its manufacture, that this explosive ever acquired any standing at all ; as the gun-cotton prepared after Lenk's process is said to possess more stability, so that it can be kept in store during a certain length of time withoat decomposing. In consequence of these favorable results, the Austrian Government appointed a commission in 1852. This commission continued during ten years its labors in a very searching and exhaustive manner, not only in regard to its manufacture, but also as to its action when transported, or when kept in store, and its action in fire-arms, small and large. Its effect as a blasting-agent was also exten- sively examined, and resulted in the following report : — " Gun-cotton can be used as charges for heavy ordnance, small arms, and other hollow projectiles ; and it is also adapted for conduits and mines in military warfare ; and, as a blasting-agent, it is better than gunpowder." GUN-COTTON. 109 Based on this report, the Austrian Government ordered, in the spring of 1862, the equipment of thirty batteries of ord- nance ; and three artillery regiments were appointed to be drilled into the use of the new explosives on a large scale. The reports upon this new artillery material were very favor- able, and the admirers of gun-cotton had now a full right to expect its complete victory. But the change came soon. On the 30th of July, 1862, a small magazine exploded on the Simmeringer Haide (the military drill-ground near Vienna), which contained twenty-eight hundred pounds of gun-cotton. Very soon afterwards, on the isth of September, in a factory, while twisting some gun-cotton into a rope, it took fire, and communicated to a barrel filled with gun-cotton, which exploded, and killed two men. These two accidents destroyed the confi- dence of the Government, and the Imperial Commission came to the conclusion that the gun-cotton produced up to that period did not possess the requisite stability for war purposes. In September, 1862, it was ordered that the thirty gun-cotton batteries should adopt gunpowder again, and gun-cotton should be used only for shrapnel. In the summer of 1865 a large magazine, containing between fifty thousand and sixty thousand pounds of gun-cotton exploded : there being no doubt as to the origin (spontaneous combustion), as all military magazines in Austria are kept most carefully guarded, this disaster resulted in the speedy abandonment of its further use, the cessation of its manufacture, and an imperial order for the destruction of all gun-cotton stored anywhere in the Austrian Empire. After its abandonment in Austria, gun-cotton found an asy- lum in England ; and although Von Lenk's persevering efforts to improve its manufacture, and devise modes of application of it, were not crowned with success, they have contributed vastly to secure to this material an important position in England, where it enters largely into consumption as a blasting-agent. Manufacttire of Gim-Cotton.— The transformation of cotton fabrics, paper, and other forms of cellulose, into explosive sub- stances, by the action of strong nitric acid, was discovered by Pelouze in 1838; but Schonbein (in 1846) was the first to con- vert cotton-wool into the explosive body known as gun-cotton. Schonbein found, that when ordinary cotton-wool, well cleansed no THE MODERN HIGH EXPLOSIVES. and carded, was steeped in a mixture of very strong sulphuric and nitric acids, the result was its transformation (almost with- out change of appearance) into the curious inflammable material now known as gun-cotton. Soon after this discovery, many re- searches were instituted into its nature and preparation by many Continental chemists. Experiments were made on its applica- tion as a propelling anu mining agent ; and its manufacture upon a considerable scale was set on foot by Messrs. Hall, the well-known gunpowder-makers at Faversham, Eng. Unfortu- nately, however, a most disastrous explosion occurred at the works ; and the manufacture of gun-cotton on any considerable scale was consequently abandoned. This was in 1847, and from that time until 1854 little or nothing was added to the knowledge already possessed as to the nature and properties of the material. The chief objections to gun-cotton, as first prepared by Schonbein, are said to have been : first, its variable composi- tion ; second, its looseness of texture, which prevented it from having the character of grains of gunpowder, so that, in its application for propelling purposes, one and the same degree of rapidity of combustion must exist for every nature of fire-arm, whether large or small ; third, the dangerous character of its manufacture ; fourth, the low temperature of its ignition ; and, fifth, the corrosive nature of the vapors evolved by it. Manufacture. — The following is an outline of the process of manufacture of gun-cotton as practised by Von Lenk : The cotton, in the form of loose yarn of different sizes, made up into hanks, purified from certain foreign vegetable substances by treatment for a brief period with a weak solution of potash, and subsequent washing, was then suspended in a well-venti- lated hot-air chamber until all moisture had been expelled, when it was transferred to air-tight boxes or jars, and at once removed to the dipping tank or vessel, where its saturation with the mixed acids was effected. The acids, of the specific gravity prescribed by Schonbein, are very intimately mixed in a suit- able apparatus in the proportion originally indicated by that chemist; i.e., three parts by weight of sulphuric acid to one of nitric acid. The mixture is always prepared some time before it is required, in order that it may become perfectly cool. The GUN-COTTON. Ill cotton is immersed in a bath of the mixed acids, one skein at a time, and stirred about for a few minutes until it has become thoroughly saturated with the acids ; it is then transferred to a shelf in the dipping-trough, where it is allowed to drain, and slightly pressed to remove any large excess of acid ; and is afterwards placed in an earthenware jar provided with a tightly fitting lid (which receives six or eight skeins weighing from two to four ounces each). The cotton is lightly pressed down in the jar : and, if there be not sufficient acid present just to cover the mass, a little more is added ; the proportion of acid, to be left in contact with the cotton, being about ten pounds and a half to one pound of the latter. The charged jars are set aside for forty-eight hours in a cool place ; and, moreover, they are kept surrounded by water to prevent the occurrence of any elevation of tem- perature, and consequent destructive action of the acids upon the gun-cotton. After forty-eight hours the excess of acid is removed from the gun-cotton in a centrifugal machine. The cotton is now thoroughly washed in water, and then immersed in a rapid stream, where it is left for two or three weeks undisturbed. It is then washed by hand, and immersed for a short time in a dilute boiling solution of potash. It is once more returned to the stream for a few days, then washed by hand, and finally dried by exposure to the air at a temperature of about 80° F. Mr. Abel has communicated to the Royal Society the results of very extensive and very numerous experiments with gun-cotton prepared at Waltham Abbey, at Stowmarket, and in Austria, the results of which have fully established the character of gun- cotton when manufactured according to Von Lenk's process, and have explained the reasons why conflicting results were furnished by the earlier products of manufacture. He has, moreover, pointed out one or two very simple measures, the adoption of which, he says, insures the preservation with per- fect safety of reserve stores of gun-cotton. The weight of gun-cotton required to produce equal effect, either in heavy ordnance or in small arms, is to the weight of gunpowder in the proportion of one to three ; so it seems, that, for equal weights, gun-cotton would exert three times the force as com- 112 THE MODERN HIGH EXPLOSIVES. pared with gunpowder ; but, regarding its cost of manufacture, it must be at least five times as high as gunpowder. The general properties of gun-cotton as an explosive agent are as follows : When raised to a temperature varying between 270° and 400° F., it burns with a bright flash and large body of flame unaccompanied by smoke, and leaves no appreciable residue. It is far more readily inflamed by percussion than gunpowder. The products of its combustion in air redden lit- mus paper powerfully : they contain a considerable proportion of nitric peroxide, and act rapidly and corrosively upon iron and gun-metal. Its explosion in the loose carded condition resembles that of the fulminates in its violence and instanta- neous character. In a confined space, the effects of its explo- sion are highly destructive as compared with gunpowder, being as one to three; but, strange to say, the projectile force exerted by it in arms is comparatively small. Mechanical means have therefore to be resorted to for the purpose of modifying the rapidity of its decomposition ; and it is with this object in view that Von Lenk manufactures the cotton into yarn of different sizes previous to its conversion into gun-cotton. By winding, plaiting, or twisting into rope these threads, or yarns, of gun- cotton, he has, to some extent, succeeded in effecting modifica- tions in the explosive effects of the material ; but experiments instituted by the committee on gun-cotton have shown that these modifications of the mechanical conditions of gun-cotton do not serve to modify the rapidity of its explosion when under considerable pressure, as in the bore of a gun, sufficiently to reduce the action of the material to that of a safe propelling agent. Much more promising results have been obtained with a different system of mechanical treatment, which has been recently devised by Mr. Abel, and consists in reducing the gun-cotton to fine pulp by ordinary paper-making machinery (Hollander), and then converting it by pressure into uniform masses, the form, extent of surfaces exposed, and density of which, may be greatly varied. This mode of working gun-cotton affords the means of moder- ating its explosive action in other ways ; namely, by intimately mixing the finely divided gun-cotton either with ordinary cotton or other oxidizing salts, nitrate of potash, nitrate of baryta GUN-COTTON. II3 ^the latter composition known as tonite powder). Gun-cotton and its mixtures are used to some extent in England, both for mining and sporting purposes, and are manufactured at Stow- market. Gun-cotton would, no doubt, have played an important role in our mining-industries, had it not been for the discovery of nitro-glycerine ; the properties of this substance being by far superior to gun-cotton when made into nitro-glycerine powders called dynamite, which material, owing to its cheap- ness, superior strength, and other advantages, has taken the first rank as a blasting-agent. COMPRESSED GUN-COTTON. Through the systematic study of Abel, an eminent chemist, this material has now attained quite a position in England, as, by means of his analytical and synthetical researches, he has found the causes of the instability observed in that substance, and has traced its occasional liability to undergo spontaneous combustion to the presence of minute quantities of foreign sub- stances of comparatively unstable character produced by the action of nitric acid upon resinous or fatty substances retained by the cotton fibres. Some parts of his mode of manufacture may be considered comparatively safe, as he carries it on with the material in a wet — therefore uninflammable — -state. His mode of convert- ing it into a minute state of division, which allows of a more perfect cleansing, and then its conversion into highly com- pressed masses, are the main features of his mechanical modi- fications : otherwise, he admits, one has only to follow Von Lenk's plan, and adhere to his rules. Manufachire. — The process of manufacture as pursued by Prentice & Co., or the Liverpool Cotton Company, is as follows : — Clean cotton-waste, picked as free as possible from foreign matter, is brought into a uniform and open condition by being passed through a carding-engine. The rolls thus obtained are dried in a triple cylinder by means of a steam-jacket. 1 14 THE MODERN HIGH EXPLOSIVES. When completely dried, it is placed in large tins, and carefully- covered. After standing in these till quite cold, the cotton is weighed out in quantities of one pound each, and carried by a boy to the dipping-vessel. Here each pan is charged with about twelve gallons of a mixture of three volumes of sulphuric acid, 1.84 specific gravity, and one volume of the strongest nitric acid ; the whole being kept cool during the action by currents of cold water, which circulate around the vessel. In this mixture the cotton is dipped ; and, after it has been in about three minutes, the workman lifts it on to a grating, just above the acids. Then, with a movable lever, he gently squeezes it until, roughly speaking, it retains about ten times its weight of the liquid. Thus saturated with the acids, it is allowed to remain in well- covered earthenware pots for twenty-four hours ; the pots, during this time, standing in a shallow trough containing water to keep down the temperature, sufficient acid being added to cover the cotton. The chemical change in the cotton is now complete, and the further processes are for washing and pressing. First, the large excess of acid is driven off by a centrifugal machine ; and the waste acid is caught by a jacket surrounding the revolving portion of the machine, and collected in a receiver. These machines are on the principle of the wringing-machines employed by laundries to dry clothes (whizzer). On leaving the centrifugal machine, the gun-cotton has to be washed. This operation also requires great care, because the acids which the gun-cotton yet retains would give rise to a considerable development of heat if mixed slowly with water. At such an increased temperature, the gun-cotton would be decomposed, or " fired " as it is technically called. Therefore it has to be brought at once in contact with a large body of water. To perfect the washing, the cotton is subjected to the action of water for one, two, or three weeks, and afterwards boiled in large vats by the injection of steam. By this latter operation, the less stable compounds are destroyed and e.xtracted, and the purified gun-cotton is transferred to the beating-tanks. This is a simple contrivance for converting the gun-cotton GUN-COTTON. II5 into pulp. It is a machine similar to the one used in paper- mills, and called Hollander. The pulp is now removed from the tank to a poacher, where it is agitated with a large quantity of water by a wheel ; and here it has to be washed till it answers the heat-test, which the chemist now applies. When his report is favorable, the pulp is transferred to a vat, and mixed with a small quantity of caustic soda. The further processes of abstracting the water, and moulding the pulp into cartridges or other shapes, are performed by hydraulic pressure or other pressing-machines, which are very ingeniously arranged ; and great credit is due to the manufac- turers for the nice and elaborate machinery they have adopted for the treatment of their products. Where the cartridges are made under light pressure, they are put on perforated trays, and dried in chambers heated with hot air. In establishments where the gun-cotton is mixed with oxidiz- ing salts, these are mixed in regular gunpowder incorporating mills, of light but very elegant pattern. The great difference between the process of manufacture described above, and that of Von Lenk, consists in the intro- duction of the pulping-operation devised by Abel. This im- provement admits of very searching purification, and also of more reliable testing, and of the subsequent compression. Properties. — Before it has been reduced to pulp, gun-cotton has the same appearance as the original fibre , but it is harder to the touch. It has neither taste nor smell. It is insoluble in water, ether, or alcohol. Dilute acids and alkalies have no action upon it, but a lower substitution product is formed by the action of nitric acid of the specific gravity 1.45. Strong sulphuric acid dissolves it with difficulty. Caustic potash dissolves it. Much uncertainty prevailed for a long time, as to whether gun-cotton was liable to spontaneous combustion, or not. It had been used in Austria for twelve years, where it underwent the severest tests, and was held by the best authorities to be perfectly safe ; but it was at last rejected on account of its instability, and also other governments abandoned it after Il6 THE MODERN HIGH EXPLOSIVES. experimenting with it extensively. Professor Abel, in his valu- able researches, ascribes the reason of its decomposition to be mainly due to impurity, generally- resulting in the process of manufacture, from the action of the acids on resinous matter in the imperfectly washed cotton ; and certainly the experience of the last few years speaks in favor of his theory, as no acci- dents from that score are on hand. It is only in late years that the true cause of chemical insta- bility, which belongs to the whole class of nitrated organic compounds, has been clearly defined ; it being the life-question of our modern high explosives. After their nitration, a certain portion of acid — sulphuric, nitric, and hypo-nitric. — always adheres to those compounds, more or less, according to their form and structure. From a liquid explosive substance like nitro-glycerine, the acids are easily washed out by churning it with water first, and then with alkaline solution. But a granular, fiocky, or fibrous mate- rial, like cotton, retains the acids with far greater tenacity, par- ticularly the nitrous and hypo-nitric acids, which every nitrated organic compound has a strong tendency to retain. It is quite clear, that, if there is hypo-nitric acid present, that highly corrosive material, which attacks almost every organic compound, even at the ordinary temperature, must be removed : if not, it will slowly but surely lead to an incipient decomposi- tion, which, acting on a nitrated substance, sets free portions of di-oxide of nitrogen or hypo-nitric acid. From nitro-glycerine the corrosive acid is washed out with the utmost facility ; and, from the moment when the importance of that operation became fully appreciated, it has never been neglected. Hence the chemical stability exhibited by dynamite under all conditions of climate. Although nitro-glycerine has exhibited, upon the whole, greater chemical stability than gun-cotton, yet it acquires that ■superiority only after being thoroughly purified from acid at the factory. When it contains free hypo-nitric acid, it cannot be stored at all in hot weather ; and, even during the course of its manufacture, it has several times given rise to a decomposi- tion, ending with explosion and loss of life. The instability of the crude article contrasts so strongly with the stability of GUN-COTTON. 11/ the pure nitro-glycerine in dynamite as to remove every trace of doubt regarding the decomposing influences of the adhering acids. Fumes. — Amongst the most grievous complaints of miners, about modern explosives, is the poisonous nature of the fumes emitted, which exposes them to most serious inconveniences. The gaseous products of the explosion of gun-cotton differ from those of nitro-glycerine, as gun-cotton lacks 24.24 parts of oxygen in 100 for the complete conversion of its carbon into carbonic acid,- consequently we have the following to be the percentage composition of the resulting gases : — Carbonic oxide 28.55 Carbonic acid 19.11 Marsh-gas 11. 17 Nitric oxide 8.83 Nitrogen 8.56 Aqueous vapors 21.93 98.15 The large amount of carbonic oxide is very deleterious, and even dangerous, when pure gun-cotton is exploded in a close place. It is very clear, to my mind, why English manufacturers have adopted the admixture of oxidizing salts (saltpetre, nitrate of baryta) with gun-cotton, as the oxygen contained in the salts effects a more complete combustion, rendering the resulting gases less obnoxious than those resulting from pure gun-cotton. Gtm-cotton in Mining Operations. — In the compressed form, gun-cotton is susceptible, like nitro-glycerine and its prepara- tions, of explosion through the agency of an initiative detona- tion (cap). Compressed gun-cotton may, therefore, be applied with the same facility as dynamite and analogous substances in all mining and blasting work. On the whole, the mixture of gun-cotton and salts is not as sensitive to concussion as dyna- mite, consequently an extra strong cap is required to detonate it. As the highest nitrated product of cellulose (penta-nitro) still demands 24.24 parts of oxygen for the conversion into carbonic acid of the carbon in 100 parts, it is evident that the most explosive gun-cotton producible must be inferior in explosive I 1 8 THE MODERN HIGH EXPLOSIVES. power to nitro-glycerine, which contains a very slight excess of oxygen. Some authorities claim, that, in spite of the high state of compression to which English manufacturers have brought it, its strength is much less than dynamite. Here, also, it is clear why the English manufacturers have adopted the use of an admixture of oxidizing salts as stated before ; but the question will present itself. Is not the quick- ness of the explosion less rapid through this admixture than with pure gun-cotton ? Where great local action is required, nitro-glycerine or dyna- mite competes advantageously with those substances. Some careful comparative experiments made by the German engineer corps, at Graudentz, with Nobel's dynamite and Abel's com- pressed gun-cotton (made at the English government works), demonstrated that dynamite produced somewhat greater local or shattering effects than gun-cotton. The plastic condition of dynamite and similar preparations gives them an advantage over the rigid, compressed gun-cotton in blasting operations, as plastic powders may be inserted more readily into rugged and uneven bore-holes, and may be made, by application of pressure, thoroughly to fill the part charged. Every miner is aware of the importance of having his charge well home in the bottom of his hole, filling the whole cavity. And this can only be accomplished with a plastic powder. The increased effect derived from this mode of applying plastic explosives is far greater than is generally believed. Volume for volume, it is impossible to put the same weight in a bore-hole for a certain given space ; or, in other words, if one has a cartridge of dynamite, say one inch in diameter and four inches long, and one of compressed gun-cotton of the same size, the dynamite cartridge will weigh more. Consequently one has more explosive material in the same space, owing to the higher specific gravity of dynamite ; and, as a consequence, larger bore-holes are required when using gun-cotton, which increases the cost of mining. The cartridges of compressed gun-cotton are rigid, stiff; and e\ery miner knows there should be no air-chamber round the charge, for the expansion which it causes not only lessens tl-;c power in proportion to its dilution, but actually decreases GUN-COTTON. 119 the tension of the gas in a much greater measure. Stiff cart- ridges cannot be introduced into a bore-hole without leaving a considerable air-chamber round the charge, particularly as bore-holes generally deviate a great deal from the circular shape. It is difficult to calculate, even approximately, the relative proportions of the unoccupied space and the charge ; but cer- tainly the loss will amount to considerable. When a loose mass of gun-cotton is ignited in the air, it burns rapidly away without any explosive effect ; but, if the ignition takes place in a closed chamber, the gases first produced immediately penetrate the mass of the cotton, and the whole is instantaneously decom- posed. According to some authorities, gun-cotton will not explode below a temperature of 280° F. Gun-cotton has the great advantage over dynamite, that it •does not freeze, and therefore needs no thawing out, which is appreciated in cold climates. It does not suffer from exuda- tion, and, when properly made, has good keeping qualities. One great advantage, again, of nitro-glycerine and its prep- arations is, that they remain unaltered under water, and can be iised in wet bore-holes with the same facility as in dry holes ; whereas, although compressed gun-cotton when containing ten per cent or fifteen per cent of water can be exploded, it requires a very strong exploder or a dry primer to accomplish it. Con- sequently, for work under water, dynamite is preferred. The cost of these two materials also differs greatly : the expense of producing gun-cotton must be twenty per cent or twenty-five per cent higher than dynamite ; therefore, when the question of competition arises, the latter has the advantage. In the last six or seven years, there have been brought for- ward in England (since Abel perfected his system of reducing gun-cotton to a fine state of division, and compressing it) several special preparations of gun-cotton, for which peculiar merits are claimed by their advocates. One of those prepara- tions, manufactured by the Gun-Cotton Company, is a mix- ture of finely divided gun-cotton and saltpetre. Another, the Tonite Company, at Faversham, mixes gun-cotton with nitrate of baryta. Which of these is the best, practical experience alone can form the estimate. 120 THE MODERN HIGH EXPLOSIVES. NITRO-CELLULOSE (KOLLOXYLINE, COLLOXYLINUM). This substance is not to be confounded with gun-cotton, which is not soluble in alcoholic ether. Preparation. — Clean, carded cotton is washed in a solution containing three to four per cent of carbonate of soda, and is afterward dried. It is then converted into kolloxyline, by sim- ply dipping it into weak nitric acid, of 1.400 specific gravity. If such an acid is not at hjihd; it may be replaced by a mixture of weak nitric acid and concentrated sulphuric acid. This mix- ture dissolves the cotton-fibres. The time necessary for the conversion of cotton into kolloxy- line depends on the state of concentration of the nitric acid. The more the latter is concentrated, the easier the formation of kolloxyline proceeds. After the kolloxyline is formed, the acid has no decomposing effect. The temperature of the acid mixture must be moderate be- fore the cotton is dipped in it. A temperature of 30° C, or 80° F., shows no peculiar influence on its formation, as to the weight and result we obtain. Several degrees over this tem- perature will produce other nitro-compounds of the cellulose, and more soluble in alcohol ; but in alcoholic ether they are less soluble, or else form a turbid solution, or perhaps the cotton will only swell up in alcohol without dissolving. The following table shows the results to be obtained by acid mixtures, in which the specific gravity of the nitric acid is gradually decreased, and the mixing proportions are constantly changed. All of these mixtures gave an excellent kolloxyline, and a result of 135 per cent to 140 per cent of the cotton employed. If the acid mixed is not sufficiently cooled down before inserting the cotton, the result will decrease to 125 or 115 per cent. According to the degree of concentration of the nitric acid, the temperature of the acid mixture, and the time of action on the cellulose, different grades of nitro-cellulose are obtained, which are distinguished from gun-cotton proper by their solu- bility in alcoholic- ether. NITRO-CELL UL OSE. 1 2 1 Two parts cotton require (temperature being 27° to 36° F.) : — Nitric Acid. Specific Gravity. Sulphuric Acid of 1.833 '0 1.840 Specific Gravity. The formation of Kolloxyltne is finished after II parts. 1.460 II parts. S hours. 12 " 1.450 12 " 6 « I2J « 1.440 13 " 7 " 13 " 1.430 14* " 8 " 14 " 1.420 16 " 9 " IS " I.4IO 17 « 10 " 16 •' 1.400 18J " 12 « 17 « 1.390 20 " IS " 18 " 1.380 22 " 20 " The acids are mixed in a glass bottle ; and when the tem- perature has decreased to about 20°, the mixture is poured into a glass jar, the cotton inserted, and pushed under the acid, with a glass rod, till it is completely saturated, then a cover is put over it, and, for the time indicated above, put in a cool place, from 27" to 36" F. After the mixture has stood the proper time, the acids are drawn off, and the vessel is about three-fourths filled with clear water, and the mixture stirred several times, when the water is decanted, and fresh water added. The kolloxyline is disinte- grated, and washed again (and the last washing is generally done with distilled water), till the wash-waters show no more acid re-action. We press out the kolloxyline with our hands, disintegrate it, and lay it on blotting-paper to dry, in a warm place. As kolloxyline puffs up at a temperature beyond the boiling point of water, it is advisable to dry it at a moderate temperature. The washing-out has to be done with care, and attention paid to any existing lumps. If not properly washed, the product after drying will show yellow spots. The last wash-waters ought to be warm. Kolloxyline is preserved in glass bottles, in a cool place. In packing collodion-cotton, a warm temperature has to be avoided, also heavy concussion, and approach of a flame. 122 THE MODERN HIGH EXPLOSIVES. COLLODION (KOLLOD). Collodium is a solution of koUoxyline in alcoholic ether. Preparation. — Ten parts kolloxyline are mixed in a flask with thirty parts alcohol ; then a hundred and eighty parts ether are added, and the mixture is agitated. The solution, after settling, is decanted. The kollod of the photographers is a solution of one part kolloxyline, in ten parts alcohol and fifteen parts ether. Properties. — Kollod forms a neutral, sirupy, clear, or color- less fluid, which takes fire easily on the approach of a flame, evaporates readily in the air, and, if applied to the skin, sticks firmly, and forms a coating like varnish, which contracts the membrane. Preservation. — The kollod is kept in a tightly corked bottle, in a cool place, with the same precaution as ether. If it gets gelatinous and thick, it is wetted with ether, and transformed again into a sirupy consistency. Use. — It is used in medicine for healing skin-wounds, and is applied with a camel's-hair brush. It is also used to coat sub- stances for the purpose of making them impervious to water, and polished fine instruments are covered with it to protect them from rust. Kolloxyline is not only soluble in alcohol, alcoholic ether, but also in glacial acetic acid, aceton and methyl alcohol. P enta-nitrocellulose is proxyline, gun-cotton proper. The other nitro-compounds of cellulose are only of chemical interest ; they are the di-nitrocellulose and the tetra-nitro- cellulose. J. M. Eder speaks of a mono-nitro and hexa-nitro cellulose. Those nitro-celluloses which are soluble in acetic ether, he calls collodium-pyroxyline ; but he has not as yet succeeded in pre- paring the mono- or hexa-nitrocellulose. I. By the action of nitric-sulphuric acids on cellulose, nitro- compounds are obtained, whose composition and properties differ according to the quantity of acids used, the quality of cellulose employed, the time the acids acted, and the height of temperature of the acid mixture. COLLODION. 123 2. There are four nitro-compounds of the cellulose : — Penta-nitrocellulose . . . 41.89 per cent N O^ Tetra-nitrocellulose . . . 36.50 " " Tri-nitrocellulose .... 30.06 " " Di-nitrocellulose .... 22.22 " " 3. These compounds can be prepared in a fibrous or pul- A-orulent form. 4. The percentage of nitrous acid grows in the nitro-cellulose in proportion to the quantity of sulphuric acid used, the degree of concentration of the sulphuric acid, the time of the action of the acids, and their temperature. 5. The increase in temperature of the acid mixture not only increases the contents of the product in nitrous acid, but also facilitates the percolating of the cellulose, alters its structure, and gives to the pyroxylines and their solutions other physical properties. 6. The products which are obtained through the nitrating of the cellulose are mostly mixtures of these different products, which, with the exception of the penta-nitro-cellulose, are very difficult to prepare by themselves, and can only be incompletely, dissolved out, or separated from one another. 7. Nitro-compounds of cellulose with more than 41.89 per cent NO2 contain nitric acid in the pores, which is not prop- erly washed out ; those which contain less than twenty-two per cent NO2 are mixed with non-nitrated cellulose. 8. Through highly concentrated nitric-sulphuric acid, the dif- ferent kinds of cellulose are changed into an even compound ; but by weaker mixtures they are differently nitrated. 9. The more readily a fibre is parchemined by the action of sulphuric acid, the more difficult it will become to nitrate the same ; and, the less sulphuric acid acts on the same, the more nitric acid comes into play. 10. Through the partial reduction with boiling solution of sulphate of iron, and coloration with iodine solution, the pyr- oxylines which are strongly parchemined are distinguished from those not parchemented. 11. The solubility of the nitro-cellulose varies with its com- position and structure. 124 THE MODERN HIGH EXPLOSIVES. Di-nitro-cellulose is -insoluble in alcohol and alcoholic ether^ Tri-nitro-cellulose is soluble in alcohol and alcoholic ether ; quite readily in the last. Tetra-nitro-cellulose is insoluble in alcohol, and difficult in alcoholic ether. Penta-nitro-cellulose is insoluble in both. The last two are soluble in aceton and acetic ether, not in acetic acid. Tri-nitro-cellulose with a little tetra-nitro-cellulose is soluble in alcoholic ether. This is the pharmaceutical collodion.' 12. Through the impregnation of cotton with gelatine, or by the addition of gelatine to the acid mixture before the nitrating takes place, it is possible to obtain the conditions necessary for the preparation of a pulverulent pyroxyline. TONITE. There is a form of gun-cotton known as tonite, or cotton- powder, which is said to possess rather peculiar properties. It is tolerably well known as a marketable commodity, and manufactured on a large scale near Faversham.^ Tonite con- sists of finely divided or macerated gun-cotton, compounded with about the same weight of nitrate of baryta. The gun- cotton itself is mainly common cotton-waste steeped in nitric acid ; and on the excess being forced out by a hydraulic press, or otherwise, it is left some time for digestion, in vessels of clay. Necessarily, while in the moist state, the fibres are macerated or disintegrated between crushing-rollers. In order to give this substance what is to be complete chemical stability, it is subject to washing processes, the rationale of which is a secret of the maker, and which complete the manufacture of the gun-cotton. Tonite consists of this macerated gun-cotton, intimately mixed up between edge-runners, with about the same weight of nitrate of baryta. This compound is then com- pressed into candle-shaped cartridges, formed with a recess at one end for the reception of a fulminate-of-mercury detonator. ^ All kinds of gun-cotton are soluble in nitro-benzol. ^ There is also a factory of this substance in San Francisco, Cal. TONITE. 125 In the fact of its being easily fastened to the safety-fuse, it contrasts very favorably with soft, plastic dynamite. Amongst the advantages said to result from the use of the nitrate are, that it contains a great amount of oxygen in a very small vol- ume, and that it explodes readily under the detonator, while its great density makes it slow to the influence of ordinary com- bustion. By the employment of nitrate of baryta, it is claimed that this explosive cannot merely be made much cheaper than ordinary gun-cotton, but that the same weight is about thirty per cent stronger. It may seem incredible, but a tonite cart- ridge is no more liable to catch fire than a piece of soap, which it resembles : ' its great density causes it to burn very slowly if set fire to, and so slowly that all danger from a too-violent generation of gases is obviated. While, therefore, the rail- ways of England absolutely refuse to carry dynamite and com- pressed gun-cotton, they regularly take tonite on the same footing as gunpowder. The tonite cartridges are generally waterproofed. The density is such that it takes up the same space as dynamite, and two-thirds of gun-cotton. There can be no doubt that much original chemical thought has been practically applied by the officials of the Cotton-Powder Com- pany ; and they claim, probably with justice, to have taken a lead in the introduction of processes for the purification of nitro-compounds, — in other words, to have given them suffi- cient chemical stability to obviate those dangerous internal changes subsequent to manufacture, at the bottom of so many disasters. » Claim of the manufacturer. CHAPTER VI. FULMINATING COMPOUNDS. FULMINATES. The fulminates are all salts of fulminic acid (C^H^NjOj), and are easily exploded, while some are excessively sensitive to percussion. Their explosions are very sharp, from the extreme rapidity of their decomposition ; but, from the small amount of gas given off, the force exercised is not very great. The explosive force of fulminating mercury, however, is not much greater than that of gunpowder; but it is much more sudden in its action. The readiness with which this compound may be fired makes it an excellent means for exploding other substances, as it is essentially a detonating-powder. It is therefore, as we have seen, a requisite for exploding gun-cotton, nitro-glycerine and its compounds, etc., and is, from this cause, of special interest to the tunnel-man and miner; since through its agency the great force of these high explosives is fully brought out. When prop- erly made, fulminate fuses and electric exploders are perfectly safe ; but, unless care is taken in the manufacture, they may be quite dangerous. They are all of the same general type, and are substantially prepared by placing a small quantity of sensitive powder or priming in the cap, and inserting the extremities of the wires in this priming. From fifteen to twenty-five grains of fulminating-powder were added in the early types ; and the spark, on passing through, ignited the sensitive powder, which again fired the fulminate, while the detonation of the latter fired the charge. The com- 126 FULMINA TES. 1 2 7 mercial caps in general use may be assumed to contain, as a rule, not more than from six to eight grains of fulminate. When improperly made, fulminating-caps are, of course, a fruitful source of danger and loss. Many of the cases, however, in which unexpected explosions of caps occur, and are set down to defects in the exploders, arc clearly attributable, on investigation, to ignorant handling. Others, however, occur which seem unaccountable, unless explainable by the theory of the decomposition of the fulmi- nate : viz., accident at Musconetcong Tunnel, 1874; accident at Sutro Tunnel, 1879. Mr. Mowbray says, with regard to exploders, that the im- portant points to secure in their manufacture are " uniformity of composition ; that they shall not offer too great resistance to the spark ; that they shall not be so sensitive as to explode, either from the ambient electricity of the atmosphere, or from the electricity pervading a tunnel, caused by the friction of the air from the compressors when it escapes through the vulcanized rubber of the connecting-pipe." As to the practical danger of disregarding this source of electrical action, Mowbray says, — " This source of electricity, I believe, caused an accident, March, 1873, at the Hoosac Tunnel, which killed a man : and it was followed by another, similar in every respect, a fortnight afterward ; for, as a blaster who was charging the holes on the last occasion observed, ' The moment I touched the bare wire (after the insulated portion had passed through my hand), pre- mature explosion ensued.' It had been the custom, after withdrawing the drilling-machine, to allow a pretty free discharge of compressed air for ven- tilation ; and, assuming a man in his rubber boots was an insulated jar, the hands, face, etc., would serve as collecting points ; while the electricity devel- oped by the moist vesicles of the cold expanding air rushing through a pipe from a reservoir charged up to fifty or sixty pounds per inch would closely resemble the hydro-electric machine, and develop considerable electricity. The blaster, not aware that he is a walking charge of electricity, proceeds to his work, inserting cartridge after cartridge of nitro-glycerine, until he comes to the last, which is armed with the electric fuse. The moment his hand touches one of the naked wires, the current passes through the priming, and explosion follows. " Let a blaster, before he handles these wires, invariably grasp some metal in moistened contact with the earth, or place both hands against the moist walls of the tunnel. Before taking the leading wires to the electric-fuse 128 THE MODERN HIGH EXPLOSIVES. wires, let the bare ends of the leading and return wires be brought first into contact with themselves, and then into contact with the moist surface of the tunnel, or some metal in good connection with the ground ; and, before inserting the armed cartridge, let him unite both of the uncovered naked wires, and touch them to a metal surface having good ground connection. Above all, do not ventilate by allowing a free blast of air through a rubber connecting-pipe, until after the electric connections have been made, and the blast fired." A case in point happened, where a blaster was walking into the tunnel with a number of caps slung over his shoulder, the caps hanging down his back, and the ends of the wires being in his hands. Suddenly several of them exploded, damaging his shirt considerably, but not injuring the man seriously. A very serious accident happened at the Sutro Tunnel, where the electric exploders were kept in a separate wooden building. Several bunches of these were hanging on wooden pegs on the wall ; and, as a young gentleman employed as electrician of the company walked into this room, a bunch of them exploded, maiming and wounding him very seriously. He claims that he was not within ten or twelve inches of the exploders ; and the explosion is, in consequence, unaccountable. It is a well-known fact, that throughout that portion of Nevada which is a high and dry country, there is a great deal of ambient electricity in the atmosphere, which collects in the body of man and animal ; and sparks can be drawn from any por- tion of the human body on certain days, when the atmospheric condition is favorable. During the spring of 1877 Mr. A. Sutro instituted a series of experiments at the Sutro Tunnel, to test whether the elec- tric exploders used there were capable of being readily fired by electricity communicated from the human body. Repeated trials tended to prove the great danger that may be incurred by carelessly handling them after the ends of the wires have been stripped of their gutta-percha covering. It was found that a man moving briskly across a carpeted floor, and rubbing his feet on the carpet, — in fact, sliding, — became so charged, that, under favorable circumstances, caps were repeatedly fired by sparks from the ends of the finger. This emphasizes the fact that the ends of the wires should not be stripped until the caps FULMINATE. 1 29 are really required for use ; that is to say, they should not be stripped, for instance, several days ahead, and a body of such unprotected caps left lying around, as is often done. FULMINATE. This is polymeric with the cyanates and cyanurets, but dis- tinguished from them by the property of detonating violently when heated or struck. Howard first showed that nitrate of mercury or nitratte of silver, heated with alcohol and an excess of nitric acid, yields a peculiar, crystalline, easily detonating precipitate ; viz., fulminating mercury, or fulminating silver. Fulminic acid, or fulminate of hydrogen, has not been ob- tained ; and the only fulminate of which a satisfactory analysis has been made is the silver salt, which, according to Gay Lus- sac and Liebig, contains 7.92 C, 9.24 N., 72.19 Ag., 10,65 O. This is the formula of cyanate of silver. But there is no doubt the formula of fulminate of silver is a multiple of this, and most probably CjNjAg^O^ : for, in the first place, the ful- minates are formed by the action of nitric acid and a nitrate on alcohol, which is a two-carbon compound; secondly, many of the re-actions of the silver salt show that one-half of the silver is in a different state from the other half ; and, thirdly, several double fulminates are known, including a fulminate of silver and hydrogen, C^NjAgHO^ ; hence Gay Lussac and Liebig assigned to neutral fulminate of silver the formula, CyjAg^Oj, supposing it to be derived from a di-basic fulminic acid, Cy^H^Oj. This view is supported by the fact, in many re-actions of fulmi- nating silver, hydrocyanic acid is produced. The formation of the fulminates by the action of nitric acid upon alcohol, together with their explosive properties, induced Laurent and Gerhardt to regard them as compounds containing nitril, NO^, a radicle which is frequently introduced into organic molecules by the action of nitric acid, and almost always imparts to them more or less of an explosive character ; they accordingly represented fulminating silver by the formula QN(N02)Ag2. Decompositions. — Finely divided zinc, copper, or silver (the last in contact with platinum-foil), boiled in water with fiilmi- 130 THE MODERN HIGH EJCPLOSIVES. Dating mercury, decomposes that compound, yielding metallic mercury and fulminate of zinc, copper, or silver. Preparation of the Fulminate of Mercury (C^AgN^Oj). — The room in which it is to be prepared should be large and well ventilated. The required quantity of mercury is weighed out on a fine scale, in a porcelain cup ; and the exact quantity of nitric acid required to dissolve it is measured, and poured into a glass beaker with a long neck ; the quicksilver is added, and the solution then completely effected oh a sand-bath. As th6 fumes are poisonous, they have to be conducted into a chimney connected with the sand-bath ; and the men employed in mak^ ing this preparation are furnished with respirators. When the quicksilver is dissolved, the solution is allowed t» cool. After cooling, the nitrate of mercury is transferred into a large glass balloon, and eighteen times its volume of alcohol: is added. ' Acid carboys can be used for this operation, and are con-; nected, by means of glass tubes, with a certain number of Woulfe's bottles, which absorb the vapors formed by the opera- tion. These bottles are surrounded b}' a constant stream of cold water. The condensation from the Woulfe's bottles is per- mitted to flow constantly, and pass through a tub containing lime ; and since these condensations are composed of acid, alcohol, and their decomposed products, the acids are thereby neutralized. They are then collected into a second tub, and conducted to a still for the recovery of the alcohdl, by which means about one-fourth of the alcohol employed is here regained. The production of the fulminate is accomplished as fol- lows : — The carboys, or large balloons, now contain the required quantity- of alcohol; and in the dissolving-bottles is the mer- curial solution which is to be poured into the alcohol. This is. done through a very narrow and long funnel, in such a manner that it falls into the centre of the alcohol ; and this precaution is very essential to prevent uneven heating,, which would burst the bottle. As soon as the quicksilver solution is poured into the balloon,, and the cooling-bottles are connected, and the joints well luted with clay, a re-action is at once established ; and a large voluriiei FULMINATE. I31 of heavy, thick fumes is developed, which fills the balloon and the condensing-apparatus. • When the re-action is once in progress, it is not necessary to watch it any more ; for it will proceed undisturbed and quietly. The large balloons with the fulminate are allowed to cool off, and at the bottom the fulminate collects in grayish needles. The acid mixture remaining above the fulminate is drawn off ; and through its evaporation oxalic acid is recovered, which is employed in dyeing-works. The fulminate remaining at the bottom of the balloons is now carefully washed with water, to purify it, and then collected, and stored in earthen or wooden vessels, under water ; since, in its moistened state, it is completely safe. Properties of the Fulminate of Mercury. — Like all quick- silver compounds, it is very poisonous, and is characterized by its great explosiveness. From a moderate blow, or a light fric- tion with hard bodies, or when touched with strong sulphuric or nitric acid, it explodes with a reddish flame. Its gases of explosion are nitrogen, carbonic oxide, mercurial vapors. If touched with a burning body, it explodes ; or, from an electric spark, when heated to 360° F., it explodes. Damp fulminate explodes with moderate violence, but very damp fulminate does not explode at all. When containing from five to thirty per cent of water, those particles only ex- plode which are directly exposed to a blow. Dry fulminate always explodes by a blow if between two pieces of iron, or between iron and copper, but will not always explode between marble plates, hardly ever when placed be- tween iron and lead, and never when between wood and wood. The larger the fulminate crystals are, the easier they explode. The property of fulminate of mercury to explode from a blow is utilized in its application for filling caps ; but it is never used alone, but always with admixtures, as its action is too rapid, and it will attack metals. It is therefore mixed with gunpowder, nitrates, and sulphur. Those admixtures serve to modify the rapidity of its decomposition, and to increase the volume of its gases. Such mixtures as are utilized in the manu- facture of caps are called the filling. 1$2 THE MODERN HIGH EXPLOSIVES. FULMINATES OF SILVER. The neutral salt, or fulminating silver (CjNjAgjOa) is formed by heating aqueous nitrate of silver with strong nitric acid and alcohol ; the same phenomena and products appearing as in the formation of fulminating mercury. Neutral nitrate of silver does not yield fulminating silver when boiled with alcohol, but the formation of that compound requires the presence of nitrous acid, inasmuch as cyanogen is thereby produced ; and, when nitrous-acid vapors are passed into an alcoholic solution of nitrate of silver, .fulminating silver quickly separates in large needles without ebullition of the liquid. QHeO + 2AgN03 + 2 HNO, = C,N,Ag,0, + 2HNO3 + 3H,0. Fulminating silver is also produced by boiling fulminating mer- cury with water, pulverized silver, and platinum-filings. Preparation. — Nitrate of silver- is heaied with alcohol and strong nitric acid till the liquid begins to boil ; and the crystals of fulminating silver, which form during the ebullition and when the liquid cools, are collected on a filter, washed with cold water, and dried either in the ordinary temperature, or, at most, at the heat of the water-bath. Dissolve one part of silver in a mixture of twenty-four parts of water and twenty-four parts of the strongest nitric acid ; add twenty-four parts of alcohol, and obtain 1.5 parts of fulminating silver. Its preparation requires great caution. Capacious vessels must be used so that the liquid may not boil over, as in that^ case the salt might dry on the outside, and then explode ; all flame must be removed to a distance, lest the vapors should take fire ; and the mixture must be stirred with wooden rods, not with glass rods or other hard bodies. Contact with hard bodies must especially be avoided after the preparation is dry. It has to be kept in paper vessels. It is soluble in thirty-six parts of boiling water. The Fulminate Mixture for the Filling of Caps. — The ad- mixture of the fulminate is ordinarily nitrate of potash alone, or a mixture of saltpetre and sulphur, and often meal-powdtr is added. FULMINATES OF SILVER. 1 33 The best proportions are : — loo parts fulminate of mercury. 50 parts nitrate of potash. 100 parts fulminate of mercury. 60 parts meal-powder. Also : — Fulminate of mercury . loo.o 109.0 loo.o Saltpetre 62.5 117.0 45.5 Sulphur 29.0 23.0 14.5 The mixing of these materials is done in a wet state. The sulphur and saltpetre are mixed to a pa.sty consistency on marble slabs, with wooden rollers, and the fulminate gradually added ; then follows the granulating, and then the drying. These three operations are carried on in separate buildings. The floors are laid with carpets, the tables are covered with woollen cloth, and all the vessels and tools must be kept very clean. The drying-house must be entered only with felt shoes, and must be heated by hot water or steam, and the temperature ought not to be raised above 100° F. The mixture must not be too dry for the granulating opera- tion ; while, owing to the great danger of the manipulation, only small quantities should be treated at a time. For the operation, hair sieves must be used, below which is placed a receptacle made of lead to receive the mixture pressed through the sieve ; and after each operation the sieve is drawn through dilute sulphuric acid. The grains are then put in lead-lined boxes, and are gently agitated in them. This manipulation causes the grains to acquire more consistency. The dry-houses have light frames with trays having canvas bottoms ; and on these is laid good paper, on which the damp grains are spread in thin layers. The frames have also India- rubber cushions for protection. The window-glass is painted white, to prevent the rays of the sun from entering. After the drying, the filling of the caps takes place, which is an operation requiring great skill, and special machines are employed for this operation. 1^4. THE MODERN HIGH EXPLOSIVES. PHOSPHIDE OF COi'PfiK. Copper and phosphorus unite readily at high temperatures. By carefully dropping phosphorus on melted copper in a cruci- ble, the metal may be made to take up as much as eleven per cent of phosphorus. Phosphorus increases the fusibility and hardness of copper, and, when present in large quantity, ren- ders it brittle at ordinary temperatures. Copper containing eleven per cent of phosphorus is extremely hard, and can scarcely be touched by a file. It has a variable steel-gray color, and is susceptible of a fine polish, but speedily tarnishes. Dicupric Phosphide (Cu^P) is a grayish-black crystalline sub- stance, obtained by passing hydrogen-gas over dicupric phos- phate (CUjHPO^) at a very strong red heat. A mixture of dicupric phosphide with chlorate of potassium and cuprous sulphide, or levigated coke, to increase its con- ducting-power, is used as a fuse for firing charges of gunpowder by magneto-electricity. SULPHIDES OF COPPER. Copper has a great affinity for sulphur, burning in its vapor, ,and uniting with it even at ordinary temperatures, when the two substances are triturated together in the finely divided state. There are two well-defined sulphides of copper, Cu^S and CujS, corresponding to the oxides ; and four more of less defined constitution, but supposed to contain respectively two, three, four, and five atoms of sulphur to two of copper. Protosulphide of Copper, or Cupric Sulphide (Cu^S, or CuS). — This compound is found native at Covellin, and is known as indigo copper, blue copper, or breithauptite : sometimes it appears in hexagonal plates with very perfect basal cleavage, more commonly massive or spheroidal, and crystalline on the surface. It is soft and flexible, in thin leaves, of specific gravity 3.8, opaque, of bluish-black color, and with faint resinous lustre. Cupric sulphide is precipitated from cupric salts by sulphi- dric acid or sulphide of ammonium, as a brown precipitate, which becomes brown-black when collected, and greenish-black PIC RATES. 13s on drying ; it oxidizes very quickly on exposure to the air, acquir- ing an acid re-action, and, if moist, is completely converted into cupric sulphate. It is likewise obtained by triturating cuprous sulphide with cold nitric acid, which abstracts half the copper. When cupric sulphide is treated with hot nitric acid, the cop- per is oxidized, part of the sulphur is converted into sulphuric acid, and the rest is separated, so that the resulting solution contains both nitrate and sulphate of copper. Hot concentrated hydrochloric acid slowly converts it into cupric chloride with evolution of sulphidric acid and separation of sulphur : this re-action takes place most easily with the recently precipitated sulphide. Cupric sulphide decomposes silver salts ; the copper dissolving, and sulphide of silver being precipitated. It is insoluble in aqueous sulphurous acid, potash, and the fixed alkaline sulphides ; slightly soluble in sulphide of ammonium. Hemisiilphide of Copper, Cuprous Sulphide, is prepared by triturating copper with sulphur. When sixty-four parts (two atoms) of finely divided copper, obtained by reducing the car- bonate with hydrogen, and sixteen parts (one-half atom) of milk of sulphur are dried together over oil of vitriol, and triturated together in a mortar so gently that no heat is produced by the friction, they combine as soon as a uniform mixture is attained, and form bluish cuprous sulphide ; the combination being at- tended with a development of heat which raises the mass to redness. If the proportion of the copper to the sulphur be even slightly altered, the experiment fails, even though the mortar be warmed. If the mortar be warmed to 20° to 25°, it is not necessary to dry the powders previously ; and, moreover, flowers of sulphur may be used instead of milk of sulphur, only that long trituration is necessary to induce combination. PICRATES (C5H4(N02)30H). The picrates are salts of picric acid, — C6H3(N 0^)30, or QH3N3O,. Picrate Powders. — The basis for the manufacture of picrate powders forms picric acid, which is produced through the action of nitric acid on carbolic acid (phenol). 136 THE MODERN HIGH EXPLOSIVES. Picric acid crystallizes in gold-yellow leaves, which dissolve but slightly in cold water, but freely in hot water and in alcohol. It melts at 230° F., and volatilizes at a higher temperature. Of the salts of picric acid, two are to be noted : — 1. The Picrate of Potash. — Which is soluble in hot water, and crystallizes out of it in gold-yellow needles. It is an ex- tremely dangerous explosive body. In heating it gradually to 310° CeL, it explodes violently, and also may be detonated by a violent blow. 2. The Picrate of Ammonia. — This explodes also violently when heated to 310° Cel., but is not so explosive as the picrate of potash, and does not seem to explode by a blow or concussion. Picric acid and those two salts are employed for the manu- facture of gun and blasting powder. France produces, yearly, from eighty to one hundred thousand kilograms of picric acid, which is partly employed for the manufacture of picrate powder, and partly for dye-stuff. In England, Germany, and France, during the last decade, the picrate of potash was employed for the filling of shells to be used in the destruction of iron-clad vessels. One kilogram of picrate of pofash gives, through its combus- tion, 585 litres of gases. (One kilogram of gunpowder gives about 200 litres of gases.) A mixture of 0.5 kilogram picrate of potash and 0.5 kilogram nitrate of potash produces 337 litres of gases; and a mixture of 0.5 kilogram picrate of potash and 0.5 kilogram chlorate of potash produces 352 litres of gases. The following mixtures, into which picrates enter for the manufacture of explosive compounds, may be found of value : — Borlinetto's Blasting-powder. — The same is composed of, — 10 parts picric acid, 10 " nitrate of soda, 8.5 " chromate of potash. This mixture is said not to explode through friction and blows. Designolles' Powder is manufactured on a large scale at Le Bouchet in France ; and it is to be remarked here, that France is about the only country in which the picrate-powders receive PIC RATES. 137 their proper consideration. In the factory at Le Bouchet, four kinds of picrate-powders are produced, — one for small arms, two for heavy guns, and one for blasting-purposes, which last is also employed in torpedoes. The picrate powder for small arms contains twenty per cent picrate of potash ; and that for heavy guns, eight to fifteen per cent. The one for blasting-purposes contains, besides nitrate of pot- ash, only picrate of potash ; but the powder for cannons contains also carbon. The manufacture of these powders at Le Bouchet is carried on as follows : The ingredients are moistened with six to four- teen per cent of water, and are pulverized in stamp-mills from three to six hours, and then compressed under hydraulic press- ure ; afterward they are grained, sifted, glazed, and dried. The picrate of potash, when deflagrated in a closed space, decomposes, probably, into nitrogen, carbonic oxide, hydrogen, carbonate of potash, and, according to other trials, into nitrogen, carbonic acid, hydrogen, carbonate of potash, carbon. The advantages of Designolles' powder are, that but little fume is produced, and that not of an injurious character; while its gases do not attack metal, owing to the absence of sulphur. Designolles' idea always was to produce a powder which differs from gunpowder, in that it should contain, instead of the nitrate, the picrate of potash, but in every other respect should possess its advantages, only in a higher degree. Broughres Picrate Powder is composed of fifty-four parts picrate of ammonium, and forty-six parts nitrate of potash. When heated to 310° Cel., it does not burn with half the ra- pidity of gunpowder, still it is said to be twice as strong. Its other advantages are, that the residue is only carbonate of pot- ash and a little smoke ; and it does not attack the metal of the guns. One kilogram of this powder gives four hundred and eighty litres of gases. In a chassepot, 2.6 grams are said to give the same effect as 5.5 of gunpowder. Abel, the English government chemist, — an authority of first rank on explosives, — has recommended the Broug^re powder for filling of shells ; but this idea has found but little favor in England. 138 THE MODERN HIGH EXPLOSIVES. CHLORATES. Chemical Test. — All the chlorates are soluble in water, and are decomposed on ignition; oxygen being given off, and a metallic chloride left. When heated with organic substances, they deflagrate with far greater violence than the nitrates. To detect this acid, add to a small quantity of the solid sub- stance under examination a few drops of concentrated sulphuric acid, without heat ; and the chlorate will be decomposed, sul- phate of potash and perchlorate of potash being formed, along with greenish-yellow colored gas (chlorous acid), which escapes. The application of heat must be avoided ; and the quantities operated upon should be very small, to prevent any loud and violent explosion from taking place. If the solution of a chlorate is colored light blue by adding some solution of indigo in sulphuric acid, and a little dilute sulphuric acid, then a solution of sulphide of soda added drop by drop into the blue fluid, the color of the indigo disappears immediately. The cause of this equally characteristic and deli- cate re-action is, that the sulphurous acid deprives the chloric acid of its oxygen, and the liberated chlorine decolorizes the indigo. Upon heating chlorates with hydrochloric acid, the constitu- ents of the two acids decompose, forming water, chlorine, and bichlorate of chlorous acid. The test-tube in which the experi- ment is made becomes filled, in this process, with a greenish- yellow gas, of a very disagreeable odor, resembling that of chlorine ; and the hydrochloric acid acquires a greenish-yellow color. If a mixture of a chlorate and cyanide of potassium is gently heated upon platinum foil, a very violent deflagration ensues, even with a minute quantity of chlorate ; but this experiment must be made with only very minute quantities of chlorate. In testing an explosive compound in which the presence of chlorates and nitrates is suspected, dissolve a certain quantity in hot water, and filter it. The solution contains the nitrates and chlorates. Now add to the solution in a test-tube a few drops of sulphuric acid and a small strip of zinc, and gently CHEMICAL TESTS FOR CHLORATES. 1 39 heat ; then add a few drops of nitrate of silver, and a curling white precipitate of chloride of silver indicates the presence of the chlorate. The marvellously powerful compound of chlorate of potash ■was first made known in 1785, by the celebrated chemist Ber- tholet, who proposed to substitute it for common gunpowder. When he first formed this salt, he named it oxygenized muriate of potash ; for, as chlorine is produced by the distillation o. black oxide of manganese and muriatic acid, he very naturally believed it to be a compound of muriatic acid and oxygen. To convey an accurate idea of its characteristics, it may be observed " that it appears to include the elements of thunder in its par- ticles ; and Nature seems to have concentrated all her powers of detonation, fulmination, and inflammation, in this terrible compound." To enumerate the experiments made with it, would only be tedious : sufifice it to say, that from the begin- ning they have always proven disastrous. Many individuals have lost their lives, or have been terribly maimed, in their at- tempts to manufacture gunpowder, or blast-powder, with this salt, or in the use of it when made. The lives of the two arti- sans that were first employed by Bertholet were sacrificed in the experiment ; for, as soon as they began to triturate the ingredients, they exploded, and, destroying the building, proved fatal to the luckless experimenters. This was already as far back as 1788; but, notwithstanding their melancholy fate, chemists have attempted, for a century since, to control this dangerous element. But, as far as the writer's knowledge ex- tends, none have succeeded ; and it is extremely doubtful, from the peculiarities of this salt, if anybody will ever overcome the obstacles due to its inherent chemical properties which nature manifestly seems to have made unconquerable. In mixing the^e compositions, great danger is attendant, and too much circumspection cannot be used. They explode instantly upon any violent stroke, very often by friction alone ; sometimes spontaneously, as when in a state of rest, and no known cause for their combustion can be ascertained. Many are deluded as to its safety by so-called experiments with freshly made powder. Manufacturers of the compound may attempt to show its safety by hammering and cutting it, and similar tests ; but let the I40 THE MODERN HIGH EXPLOSIVES. powder be exposed to the natural atmospheric action, attract some moisture during the damp, foggy night, then get dry, and the least friction or blow will cause an unexpected ex- plosion. These are truths which cannot be successfully con- troverted. If only three grains of some of its compositions are struck with a hammer upon an anvil, the report is as loud as that of a gun. A mixture of chlorate of potash and sulphur, or chlorate of potash and phosphorus, explodes violently by concussion. It will also ignite when quickly compressed with cinnabar or sugar in its admixture. The greatest objection against chlorate of potash is, however, that when manufactured into powder, with other ingredients, it will ignite by friction or concussion, thereby making its manufacture and use fraught with too great dangers. In ramming a cartridge well home in a bore-hole, the unsuspecting miner must either use blows or pressure, the latter being equally dangerous from the develop- ment of some friction ; and it is needless to say that chlorate of potash has already had its quota of victims in this country also. CHAPTER VII. ANALYSIS OF NITRO-GLYCERINE COMPOUNDS ACCORDING TO CAPT. PH. HESS OF THE AUSTRIAN ARMY. This method consists, — r. In the denitrification of nitro-glycerine by an alcoholic solution of potash ; and 2. In the determination of the formed saltpetre, either (a) According to Schulze's method ; (ii) According to Siewert's method. CjHjCONOJj + 3KOH = 3K(0N0.) + CjHsCOH),. The nitric acid is determined according to a method em- ployed by Pelouze, which consists in re-acting with a ferrous salt. 2 KNO3 + 6 FeCU +8 HCl = 2 KCl + 3 Fe.CU + 4 H,0 + 2 NO. The flask A (Fig. 11) serves for the reception of the salt- petre solution. It is closed with a cork having two openings, through which enter two bent glass tubes ABC and EFG; both of them have India-rubber connections with the tubes C D and G H. The last enters into the basin M, and the tube is protected at k with a piece of India-rubber also. The liquid containing the saltpetre solution is put into A, and H is filled half full with soda solution. The liquid is boiled in A till all the air is driven out. Then apply at G a pinchcock, so that the water-vapors can escape only through A B C D. After a few minutes, plunge D into a beaker glass containing a solution of iron chloride in muriatic acid, and close at once at C with the pinchcock, after having 141 142 THE MODERN HIGH EXPLOSIVES. Fig. II. — Analysis of Nitro-glycerine Com- pounds. taken away the lamp under A for a moment. Now put over h the inverted graduated glass tube N, filled with soda solu- tion. As soon as A is some- what cooled, open the pinch- cock at C, and the chloride-of- iron solution is drawn into the flask ; and before the beaker glass is empty add muriatic acid, so that, in the aspira- tion-tube, no chloride of iron should remain adhering. The greatest care should be taken, that no air enters the appara- tus ; and the pinchcock is closed at C, before all the muriatic acid is drawn out of the beaker glass. The flask A is next heated, and the pinchcock G is opened as soon as a gas pressure is noticed. The distillation is now carried on till there is no more augmentation of gas volume in N. The graduated tube is put now into a large cylinder con- taining cold water (15° to 18° C.) ; and, after a quarter of an hour, the volume of gas in the cylinder is read. After estab- lishing the temperature of the water, the barometric pressure, and the temperature of the quicksilver, all the data for the determination of the nitric acid and the nitro-glycerine are in the operator's possession. A series of trials were made, and the dynamite treated with ether, and the latter evaporated, when the kieselguhr and the extracted nitro-glycerine, after drying over sulphuric acid, were carefully weighed. Nitro-glycerine weighed about 1.6 grams, and was dissolved in absolute alcohol, and the solution transferred into a mixture of eighty cubic centimetres of absolute alcohol, and five to ten cubic centimetres of water, containing six grams of KHO. After letting it stand for two hours, it was diluted with water, and the solution acidulated with a little muriatic acid, and some acetate of soda or magnesia added, so as to replace any excess of muriatic acid by acetic acid, or, rather, to bind the same with ANALYSIS OF NITHO- GLYCERINE COMPOUNDS. I43 the magnesia or soda. After evaporating completely the alco- hol, the liquid was diluted to a certain volume, and a part of it submitted to the distillation with ferro-chloride and muriatic acid. The results agreed well in the different sampleg, but gave a remarkably small percentage of nitrogen. One species of dy- namite gave the following result : — Trial Series A. — i. Nitto-glycerine extracted with ether, and dried over H^SO^ = 10.70 per cent nitrogen. 2. Nitro-glycerine extracted with ether, and dried over HjSO^ = 10.47 per cent nitrogen. 3. Dynamite with 25 per cent kieselguhr, 7.79 per cent nitro- gen ; consequently, 75 per cent nitro-glycerine, 10.39 P^i" ^^"^^ nitrogen. 4. Dynamite with 23 per cent kieselguhr, 8.15 per cent nitro- gen ; consequently, 77 per cent nitro-giycerine with 10.59 P^"" cent nitrogen. 5. Dynamite with 24 per cent kieselguhr, 7.98 per cent nitro- gen ; consequently, 76 per cent nitro-glycerine with 10.50 per cent nitrogen. In another trial. Series B, several samples taken from one cartridge were extracted with ether, and the nitro-glycerine was mixed with alcoholic potash solution ; and this solution was (i) immediately, (2) after half an hour, (3) after two hours, diluted and neutralized. The results were : — Trial Series B. — i. («) 7.93 per cent nitrogen, 21.8 per cent kieselguhr; consequently, 78.2 per cent nitro-glycerine with 10.14 per cent nitrogen. {b) 7.96 per cent nitrogen, 21.8 percent kieselguhr; conse- quently, 78.2 per cent nitro-glycerine with 10.18 per cent nitrogen. 2. (a) 7.81 per cent nitrogen, 21.7 percent kieselguhr; con- sequently, 78.3 per cent nitro-glycerine with 9.97 per cent nitrogen. (b) 7.86 percent nitrogen, 21.7 per cent kieselguhr; conse- quently, 78.3 per cent nitro-glycerine with 10.09 per cent nitrogen. 144 THE MODERN HIGH EXPLOSIVES. 3. (d) 7.03 percent nitrogen, 22.2 percent kieselguhr; con- sequently, 77.8 per cent nitro-glycerine with 9.03 per cent nitrogen. {b) 6.97 percent nitrogen, 22.2 percent kieselguhr; conse- quently, 77.8 per cent nitro-glycerine with 8.96 per cent nitrosren. These trials prove beyond a doubt that certain re-actions take place during the denitrification, which bring about a loss of nitrogen ; and, the longer the alcoholic potash solution acts on the nitro-glycerine, the smaller is the yield of nitrogen which is determined. This loss arises from the formation of ammonium, as the trials of Messrs Ador and Sauer have proven. Siewert 's Method for the determination of saltpetre consists in the conversion of the nitrates into ammonium by the action of nascent hydrogen in alkaline so- lution. The following ap- paratus is employed : — One-half gram of per- fectly dried nitro-gela- tine is introduced into the glass retort A ; a mixture of one-third ab- solute alcohol and two- thirds ether is added in sufficient quantity to dissolve it : this always requires several hours. Into the recipient B introduce a decimal normal solution of a hundred cubic centi- metres, and, into the receiver C, fifty cubic centimetres, of sul- phuric or oxalic acid ; connect the receivers with A, and put them into the cooling-vessels Fand F'. In A, then, the com- plete solution of the gelatine will be effected; now about ten grams of aluminium must be added, and the funnel tube D adjusted, and through it a solution of sixteen to twenty grams of KHO in eighty per cent of alcohol introduced, and the cock E now closed. To moderate the somewhat violent re-action, the retort A is cooled off, and left for several hours, to be after- FiG. 12. — Siewert's Method for the Determination of Saltpetre. ANALYSIS OF NITRO-GLYCERlNE COMPOUNDS. 145 wards heated on a water-bath, and, by means of a gasometer, air passed through the apparatus, and the cock E opened for this purpose. The contents of the retort are evaporated nearly to dryness, and the gas-flame employed with great care, and, through the funnel-tube D, some water or potash solution added, and the distillation repeated ; but still it is impossible to drive off all the ammonium, for small quantities will remain behind in spite of this. The contents of the two recipients B and C were re-titrated "with a decimal solution of ammonium by using phenolphthaline as an indicator, and in that way the quantity of acid neutralized by the nascent ammonium is determined. The results obtained were from .33 to .79 per cent too low. I. .695 gram of nitro-gelatine produced sufficient ammonium to saturate 44.6 cubic centimetres of sulphuric acid ; of which one cubic centimetre contained .009227 gram H^SO^, correspond- ing to .01 1864 gram HNO3 or to .002643 gram N. Consequently the determined quantity nitrogen, .1178778 gram, = 16.96 per cent N, instead of 17.751 per cent as originally found. 2- -5776 gram nitro-gelatine saturated 71.4 cubic centimetres oxalic acid through the ammonium which it developed, of which one cubic centimetre contained .006285 gram H^C^O^ + 2 H^O, equal to .006289 gram HNO3 = .001401 gram N ; consequently, 71.4 cubic centimetres were equal to .1000314 gram N = 17.32 per cent N, instead of 17.751 per cent as originally determined. 3. .5600 gram nitro-gelatine required by the trituration for the saturation of the produced ammonium, 70.04 cubic centi- metres oxalic acid of the same strength as in 2, corresponding to .09813 gram N = 17.42 per cent N, instead of 17.751 per cent. Nitrometric Methods. — In the year 1877 Walter Crum ob- served that the acids of nitrogen in contact with quicksilver and sulphuric acid are entirely reduced : nitrogen oxide and mercuric sulphate are produced : — 2 HNO3 + 6Hg+ 3H,S04 = 3Hg,S0, + 2 NO + 4H,0; or, N.Oj + 2 Hg + H,S04 = Hg,S04 + 2 NO 4- H3O. 146 THE MODERN HIGH EXPLOSIVES. Crum employed this re-action for the determination of nitric acid in saltpetre and of nitrogen in gun-cotton. Lunge 's Nitrometer. — A very complete apparatus for the examination of nitro-sulphuric acid was constructed by Lunge in 1878, and the instrument was called by him a nitrometer. It is shown in the ad- joining figure ; and, in regard to its use, the following remarks may be made. The lower point of b is put a little higher than the cock c, and quicksilver is poured into b, which rises in a to a level with b. As soon as the quicksilver ap- pears in the funnel d, the cock c is closed, and it runs out through a side opening from the funnel ; at the same time, it is necessary to lower the tube h. With a pipette, introduce a certain volume of the nitric acid to be examined into the funnel d, and let it flow into a by opening the cock c, carefully avoiding any entrance of air. The funnel is cleaned twice with a little sulphuric acid : care being taken not to employ over four to five cubic centi- metres of sulphuric acid, for an excess must be avoided, other- wise the re-action may not succeed. The tube a is now taken out of the clamp e, and shaken up for several minutes, which causes a speedy decomposition : the tube a is again replaced, and left to the ordinary temperature of the room. Now b is moved up and down till the quicksilver Level in both tubes is even : the gas volume, the temperature, and the barometric reading are noted ; and from the latter is deducted the quick- silver column corresponding to the acid layer in a, or about one millimetre quicksilver for seven millimetres acid. Lunge's nitrometer can be very easily cleaned. The tube b is placed somewhat higher, the cock c is opened, and the nitrogen oxide is first driven out, and then the acid. The cock is closed when the quicksilver appears, and the contents of the funnel are allowed to escape through an axial aperture in the cock c ; after which the instrument is ready for another operation. Fig. 13. — Lunge's Nitrome- ter. ANALYSIS OF NITRO-GLYCERINE COMPOUNDS. 14; Fig. 14. — Lunge's Modified Nitrom- eter. As the nitrometer could contain only about fifty cubic centi metres of gas, it could not be adopted for the analysis of salt petre. Lunge modified it in 1881, according to Fig. 14. About .36 gram sodium nitrate or .44 gram potassium nitrate is introduced into the funnel d ; and, after the tube a is filled with quick- silver, about one cubic centimetre of water is added, and the cock c opened, so that the con- tents of d can flow into a. Some water is put in, and five cubic centi- metres of pure, concentrated sulphuric acid add- ed. The decomposition is accelerated through shaking ; then it is left for one hour, and b is so placed that the quicksilver surface is one-sev- enth lower than the acid surface in a. Some sulphuric acid is added in d, and the cock c carefully opened. As much of the acid will flow in as corresponds to the counter pressure in d. For the analysis of explosives. Lunge recommended his nitrometer in 1882, as the liquid nitro-glycerine can be so easily introduced into the apparatus. Not less than .3 and not more than .35 gram nitro-glycerine is introduced into the funnel d, and one to two cubic centimetres sulphuric acid added. The tube is shaken, and the decomposition is finished jn a few minutes. Nitro-gelatine dissolves very slowly in sulphuric acid, and consequently cannot be employed for this analysis. Walter Hempel's Nitrometer. — This is illustrated in the following figure. It consists of a glass cylinder c, five centimetres wide and nine centimetres long ; the upper end terminating in a capillary tube, the lower in a bottle-shaped neck. To measure the vol- umes, the burettes a and b are employed, which are connected with c by means of the capillary tube/. The cylinder c is held in place by/, and is closed above by « through an India-rubber tube with a pinchcock v ; but below, the neck is closed by an India-rubber cork with two holes. In one of the openings, the glass tube / is placed, which is connected through the India- 148 THE MODERN HIGH EXPLOSIVES. rubber tube m with the glass balloon e. The second open- ing serves for the glass tube q, which connects with the little glass vessel k. A little safety-guard n, made out of bent wire, prevents the weight of the quicksilver from forcing out the India-rubber cork during the operation. The balloon e is car- ried by the clamp g, and can be opened or closed by means of the cock o. At the beginning of an opera- tion, close the cock o, fill e com- pletely with quicksilver, and place .25 gram, by weight, of the nitro- compound in the funnel-tube k, and add five cubic centimetres of ' the concentrated sulphuric acid ; then the funnel tube k is fast- ened, by means of the India- rubber cork, into the cylinder c, which is quickly filled with quick- silver by opening the cocks v and o, and raising the balloon e con- When the quicksilver has reached the Fig. 15. — Walter Hempel's Nitrometer. taining the quicksilver, mark t, the cock v is closed. The time of the re-action depends on the nature of the nitro- compound. If it dissolves quickly in sulphuric acid, like nitro-glycerine or loose gun-cotton, the development of the nitro-oxide takes place in about half an hour ; but with mate- rials not readily soluble, like blasting-gelatine, the process lasts several hours, and it is best to have it stand over night. The completion of the re-action is recognized by means of the tube J, which is connected by an India-rubber tube r with e, and per- mits it to enter into the quicksilver level. The quicksilver ceases to rise in the tube s whenever the gas pressure in c remains in a normal condition. For the transmutation of the gas into the burette, connect b with the capillary tube /, and pour in quicksilver till b and / are completely filled ; then connect/ with the tube i, and open the cocks v and d. In raising e, all the gases are forced into ANALYSIS OF NITRO-GLYCERINE COMPOUNDS. 149 I ; and, when the sulphuric acid has reached the mark t, close V, and read off the volume of gas. The advantage of Hempel's method is, that it can be carried out with great exactness with all substances which develop in the nitrometer exclusively nitrogen oxide; but, if the substance should develop carbonic acid or other gases in any appreciable amount, the nitrometer cannot be employed. Methods of Hampe. — Free from all the defects of Hempel's method is Hampe's process. He decomposes with sulphuric acid and quicksilver, and re- converts the oxidation products of nitro- gen with oxygen and hydrogen super- oxide into nitric acid, and employs a titration of soda for its determination. For the execution of the analysis after this principle, the above apparatus may be employed. It consists of two parts. In 0, m, r, the development of the nitrogen oxide takes place ; and in «, its conversion into nitric acid takes place. 0, m, r, is an ordinary Geissler car- bonic-acid apparatus, in which only the cock a has been modified. The faucet is pierced exactly in the middle of the canal b, at right angle to it ; and the handle is pierced, so that an opening d is produced. This open- ing communicates with the inner space of a through the aperture c, but not with b. The absorption apparatus consists of a medicine-glass n, whose content is about five hundred cubic centimetres, which, with its opening reversed, is put into a beaker glass v. A bent glass tube / runs to the highest point of the medicine-glass, and com- municates through the India-rubber tube g, and through i, with the Geissler apparatus. The air-tight connection with the latter was effected by means of a good cork k. C^^ —<^^=~ 150 THE MODERN HIGH EXPLOSIVES. A gasometer, filled with oxygen, is now needed, and a con- tinuous-acting carbonic acid apparatus, together with the drying- apparatus for both. As nitrogen oxide, in the presence of water, is only converted partially into nitric acid, through the agency of oxygen alone, , but mostly turns into nitrous acid, hydrogen super-oxide is em- ployed to convert nitrous acid into nitric acid. Such hydrogen super-oxide must, however, be entirely free from metallic salts. The determination of the nitrogen is carried out now in the following manner : — One gram of the substance is introduced through the tube I into the lower vessel m, of the completely dried Geisler appa- ratus, and is weighed with the apparatus. After this is done, and the glass stopper is firmly set in /, the tube i is fastened, by means of the cork k, to the apparatus ; and the cock a is so set that the opening c communicates with m, and by means of an India-rubber tube the cock is connected with the drying-apparatus of the oxygen gasometer. A current of oxygen is passed through the apparatus, and the air is driven out ; then a certain quantity of hydrogen super-oxide is intro- duced into the beaker v with a burette, and the measured volume is noted down. Distilled water is poured into v, while another person sucks on the tube g, to which a tube with chloride of calcium is at- tached. The hydrogen super-oxide will now rise in the bottle n, the water follows ; and, as soon as the bottle is filled so that the liquid has reached the point of the tube/, stop sucking the tube, and close the pinchcock q, at the same moment compressing the tube g, so the liquid cannot escape from n. After g and i are connected, the pinchcock q is opened. Oxygen enters now in n ; and, as soon as the liquid has fallen to a mark at n, the pinchcock is closed. This mark shows when the glass contains two hundred and fifty cubic centimetres, and this quantity is sufficient for the oxidation of the nitrogen-oxide gases. By a small turn of the cock «, the communication of m. with the oxygen gasometer is interrupted, without putting in in com- munication with o. After putting in fifteen cubic centimetres pure concentrated sulphuric acid, the pinchcock q is opened, the glass stopper is taken off, and the cock a is turned care- ANALYSIS OF NITRO-GLYCERINE COMPOUNDS. 151 fully, SO that the sulphuric acid can flow easily through b, into the lower vessel ; and when that is done the flow is stopped by a turn in the cock a. As soon as the substance comes in contact with the sulphuric acid, it commences to dissolve in it: and the complete solution of one gram of nitro-glycerine requires half an hour, dynamite about an hour and a half, gun-cotton separated from nitro-gela- tine about three hours, and nitro-gelatine itself about twelve hours. The nitrous fumes can only pass over into n. When complete solution has taken place, the vessel is filled with quicksilver ; and nearly all of it is allowed, by turning the cock a, to flow into m. o '\% now closed with a glass stopper, as the apparatus has to be shaken up. As soon as the apparatus is shaken, white sulphate of mer- cury commences to form, but it takes some time before red vapors develop. After an hour to an hour and a half, a very active gas development takes place ; and in the bottle red fumes are noticed, which are quickly absorbed by the liquid. To accelerate the re-action, the vessel m is slightly heated, as soon as the first stage for the development of the nitrogen oxide is passed. When no more red vapors are noticeable, proceed to drive out of m the remainder of the nitrogen oxide. The carbonic-acid apparatus is put into communication through the tube s ; and the cock a is so turned that the car- bonic-acid-gas bubbles pass through in and r, and force the nitrosfen oxide into n, where its conversion into nitric acid takes place. As it is desirable to convert the very dilute nitrogen oxide into nitric acid, the whole apparatus is left over night at rest, keeping the pinchcock q closed. The bottle n is then taken out of the beaker, and emptied into it ; and it is boiled a quarter of an hour, to drive off the carbonic acid : the liquid is cooled, and eight drops phenolphtaline solution (one part phenolphta- line in thirty parts alcohol) added, and titrated with the soda solution till the rose color appears. Deduct from the soda solu- tion that portion which corresponds to the sulphuric-acid con- tents of the measured quantity of hydrogen super-oxide : the difference will give the produced nitric acid, or the nitrogen contents of the analyzed substance. 152 THE MODERN HIGH EXPLOSIVES. THE QUANTITATIVE ANALYSIS OF THE NITRO- COMPOUNDS. Determination of the Nitro-glycerine. — The best solvent for nitro-glycerine is ether, as the other nitro-compounds do not dissolve in it if it is absolutely pure, and does not contain any alcohol ; otherwise the bi-nitro-cellulose will dissolve. That process which consists in the extraction of the nitro- glycerine by digesting the nitro-gelatine in a flask, filtering, and washing on a weighed filter, does not give any exact quanti- tative results ; for the ether does not penetrate sufficiently into the body of the plastic gelatine, even when it is cut into very fine leaves. The analysis is much more completely and easily accom- plished by the use of Szombathy's apparatus, which he in- vented for the determination of fatty substances in milk. This ingenious apparatus is described in Fig. 17. A is the apparatus for the extraction of the nitro-glycerine ; B is the flask for the reception of the ether ; C is the cooling or condensing apparatus. Both are connected with A by means of airtight corks ; and are carefully washed in ether, so as to remove all soluble matters adhering to them. Szombathy introduces the sub- stance to be extracted into a paper cyl- inder, which fits into A, and reaches within one millimetre of the line a. This method cannot be employed where the weight of the residue has to be determined, as the paper cylinder cannot be perfectly dried and weighed. To avoid this inconvenience, the funnel-tube D is employed, having a platinum wire around its upper end, and, by means of a hook, is easily introduced and taken out of it, and having a small asbestos filter in the bottom. In weighing, it is hung in the small platinum tripod E, and, to exclude air, is covered with a small polished glass plate. This funnel-tube will easily hold ten to fifteen grams of gela- FlG. 17. — Szombathy's Apparatus. ANALYSIS OF NITRO-COMPOUNDS. 153 tine or dynamite. It must previously be dried over sulphuric acid, till its weight remains constant, and, when introduced into A, ought not to reach over the line a. Into B, twenty-five cubic centimetres of ether are introduced ; and the flask, by means of a cork, is connected with A. Ether is now poured into A, till the siphon c overflows ; and the cool- ing-apparatus C is connected with A, and B is heated over a water-bath F. The temperature must not reach, in F, over 70° C. The ether in B evaporates : the vapors rise through b into the cooler, and condense, and the ether-drops fall into the funnel-tube and on the substance, which they penetrate, and soon fill A ; but, as soon as the level a is reached, the siphon c overflows, and the contents of A are emptied to the last drop into B. This operation takes five minutes, so that in one hour the contents of the funnel-tube are washed out about twelve times with boiling-hot ether. In this last, appears the great efficacy of this apparatus. About five hours are sufficient to free all the nitro-glycerine from the nitro-gelatine, and three hours for gelatine dynamite. When this is done, the ether is once more driven into A ; and B is changed shortly before the siphon commences to act, so as to regain the largest part of the ether. The funnel-tube and flask are heated now in a drying-appara- tus to 60° C, till the smell of ether disappears. Both are put under the bell of an air-pump over sulphuric acid, and they are weighed. The increase in weight of B, and consequently the quantity of nitro-glycerine extracted, must equal the decrease in weight of the funnel-tube D. This is not always perfectly exact, since the weight of nitro-glycerine is always somewhat less than the difference between the weighed and the extracted substance. Probably there is a small loss in weight through evaporation during the distillation. The loss of ether is also very small. Capt. Hess proposes to extract explosives containing nitro- gelatine with a mixture of two parts ether and one alcohol, and to separate the nitro-glycerine from the bi-nitro-cellulose, which is also in solution, by means of chloroform, which precipitates the bi-nitro-cellulose. But some authorities do not approve of this system. 154 THE MODERN HIGff EXPLOSIVES. It may be remarked, that the foregoing operation requires the greatest care, as there is danger from explosion due to super- heating the very volatile ether. Determination of Gun-cotton. — Nitro-gelatine, after the ex- traction of the nitro-glycerine, leaves gun-cotton as a residue. Gelatine dynamite gives a residue which contains, beside gun- cotton, saltpetre, soda, and wood-fibre. If this mixture is treated with alcoholic ether to dissolve the nitro-cellulose, a cloudy filtrate will always result. The residue is therefore treated with water, which dissolves the saltpetre and soda : the remaining cellulose and gun-cotton are dried at 60° C. till their weight remains constant, and then the latter is extracted by alcoholic ether. For this purpose, the flocculent mass is taken out of the funnel-tube, and put into a beaker with about twenty-five cubic centimetres absolute alcohol and fifty cubic centimetres ether, and left for several hours, and then filtered. The filtrate is collected in a small flask, out of which the ether is distilled in the water-bath ; and the alcohol is evaporated at 90° to 100° Cel. The increase in weight of the flask coincides with the diminution in weight of the residue, and gives the quantity of the extracted gun-cotton. Trials were made to determine the contents of the gun-cotton by a direct nitrogen determination in the nitrometer, but they did not succeed. An examination of the resting cellulose for tri-nitro-cellulose, which is insoluble in alcoholic ether accord- ing to Capt. Hess's method, — by boiling with sulphide of sodium, and determining the loss in weight, gave, as a result, the complete absence of this substance in the sample. Determination of the Saltpetre and Soda. — As already indi- cated, the saltpetre and soda are leached out with water, after the separation of the nitro-glycerine. The residue from the funnel-tube is transferred into a beaker, and heated with water at 60° C, till the mass is completely saturated ; then it is fil- tered into a platinum cup. The residue is dried in the funnel- tube at 60° till its weight is permanent. The difference in weight of the funnel-tube, before and after leaching, will give the extracted quantity of saltpetre and soda: This ought to coincide with the result of the direct determina- tion, which is obtained by evaporation of the filtrate and com- plete desiccation of the residue at 120° C. ANALYSIS OF NITRO-COMPOUNDS. 155 If the nitrate of potash has to be separated from the nitrate of soda, in one portion of the liquid the nitrogen is determined, and in another portion the potash, contents are estimated with platinum chloride. The amount of potassium and sodium nitrate present can now be estimated ; and from the difference of their sums, as compared with the original weight, the quan- tity of soda is found. Determination of the Celhdose and Ash. — The wood fibres remain behind after the extraction with ether, water, and ether alcohol. The admixture of inorganic matter is determined by incineration. PART II CHAPTER I. DIRECTIONS FOR USING THE HIGH EXPLOSIVES. In what Condition to use the Nitro-glycerine Compounds. — It is advisable in all cases not to use the dynamites in a frozen state, but in a soft condition, and especially to employ wooden ramrods for charging bore-holes. If the use of frozen dynamite cannot be avoided, it should be handled with the same care as the soft dynamite. Some instructions even go so far as to say that it is dangerous to cut frozen dynamite with a sharp knife : and they caution users against digging holes with a sharp instrument in a frozen cartridge, for the purpose of putting the cap in, as the opinion exists that the frozen crystals of nitro-glycerine are very sensi- tive to scratching ; but, so far as known, not any reason has been given for this supposition. When dynamite is frozen, a single force-cap will not explode it ; and special primers are made in European factories, for the explosion of frozen dynamite. But dynamite can be made to explode by extra-strong caps, even when frozen. Weak caps, however, should not be employed in winter. Where large quantities of dynamite have to be kept soft in cold weather, it is advisable to have large chests with double bottoms and sides, and keep these spaces filled with manure. Such small magazines will easily hold from twenty-five to fifty pounds of dynamite, and more, and are convenient for use on railroad-work or on highways. A word of caution is necessary, as oftentimes, when dynamite may feel soft, still the nitro- glycerine in it may be frozen ; and this is specially the case with the lower grades. Thawing-out of Dynamite. — To thaw out dynamite, two ves- sels are employed, of different sizes. The larger one contains '59 l6o THE MODERN HIGH EXPLOSIVES. warm water, and the smaller one the caftridges to be thawed out : then, by putting the smaller into the larger vessel, the thawing-out will take place gradually. To thaw out frozen dynamites, and keep them soft, only employ lukewarm water, in which the hand can be put with- out pain. Boiling water ought never to be employed, as a sudden thawing of the liquid may separate the nitro-glycerine from the absorbent, and in that way, and by a possible decom- position of the nitro-glycerine in consequence of the high temperature, give rise to serious accidents. As the apparatus generally in use for the thawing out of frozen dynamite allow only the treatment of small quantities, it is necessary, in locali- ties where the consumption is large, to have moderately heated rooms for that purpose. But let it be noted, that the thawing out must never take place in the vicinity of ovens, hearths, or open fires. Thawing-out Apparatus is generally made of two tin cans, one set into the otheV, so as to leave a space or jacket between the two, while the whole apparatus can be fitted into a basket. The inner space of the small can A (see Fig. i8) serves to hold about five pounds of dynamite, while the space B is a re- ceptacle for hot water (but not boiling hot) ; C is the cover of the vessel ; G, a tube for filling and emptying the receptacle ; E is the basket ; Fig. i8. — Thaw- ^"'^ ^^ space between the basket and cans can ing-out Apparatus, be filled with Straw, blankets, or rags, so as to keep the water hot as long as possible. Preparation of the Charge. — As already mentioned, the deto- nation of the nitro-glycerine compounds is effected by a cap, and the firing of the fulminate of mercury in the cap is effected by a fuse or electric spark. Therefore the labor required to effect the explosion of the cap should be the first consideration. A fuse with its end cut square is best employed, inserted into the cap till the end of it touches the fulminate filling. But avoid any twisting or scratching of the fulminate in the cap. Take a pair of nippers, and press the upper part of the cap against the fuse, so that it cannot slip out ; and take care not to press the fulmi- nate, but above it, as on the line a a in Fig. 20. In blasting DIRECTIONS FOR USING THE HIGH EXPLOSIVES. l6l in dry ground, use single-tape fuse, but in damp ground a double tape should be employed, while under water gutta-percha fuses are necessary. Any interstices between the cap and fuse are filled with wax or tallow. If the charge is in water over six inches in depth, it should be fired by electricity. The explosion of the nitro-glycerine compounds is safely and surely effected, only when the powder is in immediate and direct contact with the cap. Fig. 19. — Adjusting the Cap. Fig. 20. It is not well to push the cap too deep into the powder, as in that event the fuse might set the dynamite on fire before the cap explodes, and in that case the dynamite would simply burn up ; but, naturally, with an ■electric fuse it -is immaterial how deep the cap is embedded in the powder. Figs. 21 and 22 illustrate how an ordinary blast- ing-cap is inserted in the powder. First, a hole must be pressed in the powder, and the cap with fuse attached to it is inserted in this hole. a is the cap, b b the fuse, and c c the dyna- mite cartridge. Take the paper, and tie it with Fig. 21. — Method of Inserting Blasting-Cap in Powder. Fig. 22. a string fast to the fuse, so it cannot slip out. If the powder-charge has to remain for any length of time l62 THE MODERN HIGH EXPLOSIVES. under water, it is advisable to make a water-tight primer by- using tin cylinders. For submarine blasting, the whole charge of dynamite is put into a tin cylinder with the elec- tric-fuse attachment, as shown in Fig. 23. Caps. — The caps, or exploders, are made of copper, and contain fulmi- nate of mercury. They are classified according to the quantity of fulminate they contain, such as sin- gle, triple, quadruple force \^_^ caps. Fig. 24. — Blasting Caps. Single-force caps (Fig. 24, A) are used for the explosion of Nos. i and 2 dynamite ; the other caps, B, for Nos. 3 and 4 powder, and for the detonation of gelatine.' The following extract from Mr. Drinker's, " Explosives " ^ best illustrates the method of tamping: — "With pure nitro-glycerine, no tamping is needed but water; therefore nitro- glycerine, having greater specific gravity than water and no affinity for it, is an especially suit- able agent for sub-aqueous blasting, where it can simply be poured down into the holes through a tube and funnel.' Fig. 25 shows a charge of nitro-glycerine with water-tamping and tape-fuse and exploder. Where the rock is split or seamy, nitro-glycerine must be incased in some sub- stance, — say tin cases ; and this, it is said, lessens its explosive force by preventing close contact. Where the rock is firm, it can be poured directly into the hole. In this respect, dynamite fig. 25. Fig. 23. ' It is advisable to always use, even with higher-grade powders, the triple-force caps. 2 Drinker's Explosive Compounds, p. 112. John Wiley & Sons, New-York City. 3 There was shown in the British section, Paris Exposition of 1878, a patented water- cartridge tamping, by MacNab, claimed to yield superior results in coal, etc., with black- powder. (See also MacNab's Patent for wedging charge.) DIRECTIONS FOR USING THE HIGH EXPLOSIVES. 163 has a great advantage over nitro-glycerine, in that it can be charged in roof-holes and in seamy rock ; there being no danger of running out, leakage, etc. In charging No. i dynamite, it was formerly thought that no tamping would be required ; but the general experience of blasters has led to the practice of tamping the holes solidly to the lip with clay. The fact that tamping is not so essential with the high explosives as with the lower ones should not be taken as proof of any radical differ- ence in the theory of tamping being required in both cases. The law of tamping is the same, for in both the disruption is effected by the sudden liberation of expansive gas : only, in the one case, the liberation of gas is instantaneous, and in the other gradual. In either case, strong confinement promotes the effect, A wooden rammer should be used with dynamite. " That vacancies about a charge do have a practical effect in reducing the force of explosion of nitro-glycerine or of its com- pounds, is shown by the following record. The experiments were made at the works of the Atlantic Giant-Powder Company, with the mortar described pp. 72, 75. The charge used with each shot was one-quarter ounce of No. 2 dynamite ; and the object of the experiments was to see whether a small space left between the ball and the bottom of the bore would have any appreciable effect in lessening the distance the ball was thrown. Number. Shot raised. Thrown. Loss. No. I 00 inch. 630 feet. 00 feet. " 2 -h " 579 " 51 " "3 2 i.i 550 " 80 « "4 ^ " 490 " 140 " " s TT? " 440 " 190 " "6 -«■ *' 400 " 230 " " 7 ■ 4 " 350 « 280 " " This effectually shows that the hollow-space theory of old has no application to the high explosives. The same conclusion has been reached in Gen. Abbot's recent researches. " Should the supply of exploders run out, dynamite may be exploded with a small charge of gunpowder placed above it, in which a fuse is inserted as in ordinary blasting with black- 164 THE MODERN HIGH EXPLOSIVES. Fig. 26. powder. In this case, the tamping should be firmly rammed, so that the black-powder may explode under as great pressure as possible. Either dynamite or nitro-glycerine fired with a gun- powder fuse is very uncertain in action. Some- times it is exploded, and sometimes not ; and, even when exploded, its force is much less than when the fulminate is used. Deportment under Water. — As water has a greater affinity for the guhr than nitro-glycerine, which is held there only by capillary attraction, it is necessary, when dynamite is used under water, and has to remain there for any length of time, to make the cartridges as water-tight as possible. This is not necessary with nitro-gelatine, which, in contact with water, will retain its properties, and, even after being saturated, the water can be pressed out : when dried in the sun, it will assume its explosive properties. Dynamites Nos. 2 and 3 spoil easier in water, or in a moist atmosphere, than the No. i, on account of the nitrate and wood pulp they contain. But, in mines, they are not generally exposed for a sufficient length of time to become injured by moisture. Gelatine is very impervious against water ; and, even when containing a certain percentage of water, it can be exploded. In blasting under water, prepare a perfectly water- proof cartridge P, either from paper or tin, sufficient to hold the entire charge. This cartridge is let down through the water W (Fig. 27) ; and above it is the priming-cartridge Z, also carefully protected against the influence of water. The employment of damp gun-cotton requires extra strong caps or primers, even stronger than frozen dynamite. General Rules. — It is not advisable to allow car- tridges with caps attached to them to be scattered around ; nor should dynamite ever be packed in the same box as the fuse and caps ; nor should dynamite cartridges be transported with caps %. lip Fig. 27. DIRECTIONS FOR USING THE HIGH EXPLOSIVES. 165 Sticking in them, nor in the same freight-car with caps ; nor should it be stored in the same magazine with them. When a charge of dynamite misses, and does not talce fire, the attempt should never be made to scrape out the charge (this is a very dangerous operation), but if the exact depth of the tamping is known, it can be carefully removed within about two inches of the powder ; and by inserting a strong primer or cartridge on top of the tamping left in the hole, and exploding it, the car- tridge in the bottom, which missed before, will now generally explode, for the intervening two inches of tamping permits the propagation of the initial explosion, but this is not always certain. Application of the Nitro-glycerine Compounds. Blasting in Rock. — For the choice of the different kinds of dynamites according to the kind of material to be disrupted, the following rules can be applied. Dynamite No. i is applied in rocks of great tenacity and toughness, or in tunnels with a small square section ; also in quartz, porphyry, hard basalt, quartzose slate, and the hard kinds of hornblende. It can also be used in wet ground and under water. Dynamite No. 2 is used in rocks similar to above, but of less tenacity, and in tunnels with larger square face, and in all hard rocks, like limestone, granolite, gneiss. Dynamite No. 3 in all rocks not having a great tenacity : for experience has proven that dynamite No. 3 can do good work even in tunnels, if the rock does not offer too great resistance ; and in frozen earth, clay loam, in shaly and broken ground, it will do well. It should be used in quarries for stone and brown coal ; and where rock is to be split and not broken, as in case of blocks intended for building purposes, holes are drilled in a line about twenty inches apart and of sufficient depth ; then these are filled with water, and pieces of dynamite No. 3 about two inches in length are placed in the mouth of each hole ; and then these are fired by electricity, always giving a good result. Where large quantities of earth or rock have to be broken down, and in large mines, the ordinary black-powder is em- ployed ; and the Judson Powder, manufactured by the Giant- Powder companies, is an excellent substitute for it. CHAPTER II. ELECTRICITY AS APPLIED TO BLASTING-OPERATIONS. SIMULTANEOUS IGNITIONS. To produce the maximum effect in removing obstructions, and in work of a similar character, both in civil and military operations, it is often desirable to cause the simultaneous ex- plosion of many mines, or sometimes the simultaneous igni- tion of many fuses distributed throughout the charge in one large mine. In the present state of science, this will always be effected by electricity ; and the form usually preferred will be the voltaic or magneto-electric current, acting upon numer- ous low-tension fuses. ADVANTAGES OF ELECTRIC FIRING. The firing of blasts with ordinary fuses has two dis- advantages : — 1. Shots miss entirely, and then the blaster has to wait a long time before he dares to approach the place ; as imper- fect fuses will sometimes burn very slowly before they finally explode. Such shots which hang fire ought never to be ap- proached until quite a lapse of time, and not then till the blaster is entirely satisfied the fuse has failed. The neglect of this precaution is a very fruitful source of accidents. 2. The effects of consecutive shots are always less than when they are properly combined, and fired simultaneously. The electric firing permits of this, and allows, also, the bore-holes to be placed double the distance from one another ; while ordi- nary fuses only permit an interval of one or one and a half i66 THE DIFFERENT SYSTEMS OF ELECTRIC FIRING. 167 times the distance of the line of the least resistance. They also offer greater safety to the miner. Experience has proven that double the effect is obtained by the simultaneous discharge of a set of holes than where they are fired consecutively. In ordinary cases there is generally a saving of twenty-five per cent in the work of drilling, and in the quantity of dynamite used. MATERIAL FOR ELECTRIC BLASTING. 1. The electric machine. 2. The conducting-wires. 3. The exploders. THE DIFFERENT SYSTEMS OF ELECTRIC FIRING.- " One method of firing is by interposing an exceedingly fine platinum wire (iron or alloyed metal will also answer) in the path of a current of electricity from a powerful voltaic battery ; the resistance offered by the diminished conducting-power of the fine wire to the passage of the electric current heating the wire to redness, and thereby exploding the charge. Another system of electrical blasting depends upon a sudden discharge of static electricity between the terminals of two wires, em- bedded in a suitable priming-composition, which is thereby fired. For this, various appliances have been used ; as, — " I. A frictional electric machine, or Leyden-jar. " 2. An electro-magnetic machine, as Wheatstone's, Bre- guet's, Saxton's, Clarke's. " 3. An electro-dynamic machine, such as Siemens', Ladd's, Farmer's, Gramme's. "4. A voltaic-battery induction-coil. " Static electricity is doubtless the most convenient and most expeditious mode of firing : it is questionable whether it is the most certain for firing twenty or thirty holes at a time. Mow- bray claims, however, that such batteries will fire as many as fifty charges simultaneously, with safety. A fuse for static elec- ' Drinker's Explosives, p. 110. John Wiley & Sons. 1 68 THE MODERN HIGB EXPLOSIVES. tricity depends for its value on the arrangement of the ends of the wires, so that they shall neither touch each other, nor be too far apart ; and on the priming-pow- der between the wires, its sensitive- ness, etc. ; and finally, of course (ag in all electric fuses), on the proportion of Fig. 28.-r^^caiFuse. fulminate used. Electrical firing can, of course, be used indifferently, in ex- ploding charges of either black-powder or of the higher explo- sives. Fig. 28 shows the electrical fuse sold by the Laflin & Rand Company, and which, it is claimed, will cause the deto- nation of common blasting-powder." FRICTIONAL APPARATUS. In principle these instruments are all identical. They con- sist, essentially, of a generator of frictional electricity ; a condenser to receive, store, and multiply the charge ; and a key to send it through the circuit and fuse at will. Bornhardt 's Frictional Machine. — This machine is largely employed in France for electrical blasting. Two sizes are made, of which the larger may be described as follows : — The machine is contained in a wooden case, twenty-one inches long by eleven inches wide, and sixteen inches high ; the whole weighing forty-two pounds. One end has a hinged cover, which, when opened, exposes a shallow compartment containing the terminals, the firing-key, and the testing-scale. The latter consists of sixteen copper-headed tacks, driven on a straight line seven inches long, leaving fifteen small intervals aggregat- ing about 1.4 inches in length. Chains are provided for con- necting the end tacks with the terminals. The number of turns required to generate a spark that will traverse the tack-heads is the gauge of the condition of the instrument. From twelve to sixteen turns are stated by the inventor to be the usual number, but even twenty-five are admissible. The top of the box is secured by ten screw-bolts ; and, when removed, it exhibits an iron case filling the entire cavity, and closed by a flat ebonite cover, which is held closely in contact by six steel springs compressing an elastic cushion. FRICTIONAL APPARATUS. 169 The generator consists of two circular ebonite discs, F (Fig's. 29 a, b, c, d), three inches apart, each eleven and a half inches in diameter, and rigidly attached to the common axis. Revolution is given by the crank d on the outside of the box, one turn of the crank being multiplied by gearing to give three and a quarter turns of the discs. The rubbers each con- FiG. 29a — Bornhardt*s Frictional Machine. sist of a strip of cat-skin, R, four by two and a half inches in size, wrapped over the edge of the disc, and pressed against it by two steel springs with large washers. These springs are in contact with the metal of the inner box, and thus place both of the rubbers in metallic connection with the outer coating of the condenser and with the lower external terminal. The collectors, I, for each disc, consist of two tin-foil rings, armed with the usual points, and held near the edges by a wooden frame. This frame rises from two pint bot- tles, to the corks of which it is attached. These bottles L are coated with tin-foil ; and together they constitute the condenser of the machine, having a capacity of .0010 microfarads. The inner coating is connect- ed with the collectors by spiral springs, and a tin-foil circuit Fig. zijb. I70 THE MODERN HIGH EXPLOSIVES. carried inside the wooden frame to secure insulation. The outer coating is placed in electrical contact with the iron case by metallic clasps, which hold the bottles in position. Fig. 29c. The discharging-key K is a brass rod with an outer ebonite head. When pressed, it moves an ebonite rod eight inches long, so as to close the circuit between the inner coating of the jars oJ -k ^ !" (J \ V e \ /■ e tf- -'e d I 9 Fig. 290!. and the upper external terminal. This is effected by an in- sulated brass ball G carried on the end of the rod, and con- nected with the terminal by a spiral brass spring. FRICTIONAL APPARATUS. 17I To prevent escape, this terminal is protected by two circular ebonite plates, B B, six inches in diameter, — one inside and one outside the metallic case. They are connected by an ebon- ite tube, through which the metallic circuit-closer is carried. If we press on the knob K, the lever G turns over, and the ball G comes in contact with the Leyden flask ; and if a circuit is established through the insertion of the wires into C and D, by pressing on the knob K, the Leyderi bottle is discharged. If, at different points of the circuit, blast charges are inserted, naturally the spark travelling through them will cause their explosion. To absorb moisture, two wooden boxes, each twelve by three and a half by one and a half inches, packed with charcoal, and covered by paper, are inserted near the rubbers. To use the machine, the testing-scale is connected with the terminals by its chains, and the number of turns required to cause the spark to jump along the tack-heads is found by trial. The chains are then replaced by the leading wires, and a simi- lar charge is sent through the external circuit. The India-rubber plate near the eye C must be perfectly dry, as the least moisture present between the two eyes (electrodes) C and D prevents the discharge from taking place by means of the wires, and the current would pass directly from C to D without any resulting explosion. The knob is pressed to cause the discharge, immediately after ceasing to turn the crank, or may be done while turning the same. The India-rubber-coated wires are only pliable at an ordinary temperature ; for when cold they become hard and brittle, but heating will render them pliable again. Hence the India-rubber wire should be treated with great care, and protected from ex- cessive heat by covering it with a damp cloth. If it be exposed to the sun for some time, it should be moistened occasionally with a sprinkler. Care should be taken never to drag India-rubber wire over rough or rocky ground, as there is danger of scraping off the coating. The Leyden flask L is discharged at the same moment the knob is pressed, and the firing of the inserted exploders takes place instantly. The greatest number of exploders that can 172 THE MODERN HIGH EXPLOSIVES. be fired by means of the foregoing apparatus is twelve ; and it is necessary to give the crank thirty to forty revolutions, and not to exceed twenty-four hundred feet of conducting-wires. The crank should always be turned in one direction, so as not to break the hair of the fur. The electric apparatus should be tested in respect to its efficiency before the conducting-wires are attached. For that purpose, the movable brass bar (spark-drawer) G is moved forward by degrees : first it is pushed to a distance of two-fifths of an inch from the brass plate B. The crank is turned, the thumb of the left hand is kept on the knob K, and turning the crank with moderate rapidity (two turns per sec- ond), at the eleventh turn the knob K is rapidly pressed down for about one second. If, in pressing down the knob, a spark jumps over, then the spark-drawer is moved four-fifths of an inch from the brass plate, and this operation is repeated by turning the crank twenty-one times ; and, if successful, the spark-drawer is moved one and one-fifth inches from the brass plate, and the crank turned thirty-one times. This is the limit to which the spark-drawer should be moved. If, in the first trial at two-fifths of an inch distance and eleven revolutions, no spark appears, then the spark-drawer is pushed against the brass plate ; and, on pressing down the knob K, the apparatus is discharged. Move again the spark-drawer at two-fifths of an inch distance, and turn the crank thirteen times : if unsuccessful, discharge the apparatus again, and re- peat the operation with fifteen turns of the crank, or till the spark appears. If a spark is obtained at twenty revolutions, then the spark- drawer is moved four-fifths of an inch, and the crank is made to turn forty revolutions, and at one and one-fifth inches distant sixty revolutions, but not beyond that number. An apparatus which at sixty turns and two-fifths of an inch does not emit a spark should be rejected, and turned over to the repair-shop. The turning for two-fifths of an inch (eleven turns) is sufficient for a few shots, for a short conducting-wire, and for dry ground; but for numerous shots, long conducting-wires, and damp ground, the number of turns may be increased to forty-five. MAGNETO-ELECTRIC APPARATUS. 173 It is advisable, in preparing for the shot, to push the spark- drawer G against the metal plate B first, by pressing the knob K ; and, after this precaution is taken, connect the conducting- wires at C, and also the return-wire in its place. The ball of the spark-drawer G is also put into proper position at the desired distance from the brass plate. Be careful, in putting in wires, they do not cross one another, or even touch one another. During the use and storage of the apparatus, it must not be exposed to the rays of the sun, and, if there is no shady place available, cover it with a damp blanket. It is best to store the apparatus in a place which has the same temperature as the place where it is to be used. MAGNETO-ELECTRIC APPARATUS. The electricity generated by magneto-electric machines has a lower potential than that given by frictional and voltaic induction apparatus. The Breguet Machine. — This instrument (Fig. 30) consists of a horseshoe-magnet, the poles of which, prolonged with soft iron, constitute the cores of two induction coils of very fine insulated wire. A soft iron armature in contact with the ends of these cores is attached by a brass plate to a lever extending outside the case. The lever is so pivoted on a horizontal axis, that a smart blow will separate the armature suddenly from the poles, and thus cause a current, induced by the change in the locus of magnetic polarity, to circulate through the coils. This current is greatly intensified by ""'"" an extra spark caused by the following ingen- "^' ''"'n^chine ^^^^ ious device : The coils are united in series, and the circuit is extended to two terminal posts outside the case. Another circuit, forming a shunt between the coils and the ter- minal posts, consists in part of a spring attached to the lever, and moving with it. Aft^^r moving a certain distance, this ^ ^ 174 THE MODERN HIGH EXPLOSIVES. spring breaks the shunt circuit, thus producing a strong extra spark by the interruption of the current at its maximum. It is chiefly this spark which passes through the exterior circuit, and fires the fuses. The instrument is incased in a neat box i8 x 7 x 6 inches high, the whole weighing twenty-one pounds. A sliding key blocks the lever when not in use, and thus guards against acci- dents from careless handling. G. MOWBRAY'S EXPLODER. This machine, shown in Fig. 31, is contained in a wooden barrel-shaped case, and is known as the "powder-keg " exploder, the form and di- mensions of the case being those of a powder-keg. The cable-wires having been attached to the ter- minals at one end of the keg, the handle at the other end is turned forward to excite the electricity, and the con- denser is discharged by making a quarter-turn backward. Fig. 31. — Mowbray's Exploder. DYNAMO-ELECTRIC APPARATUS. This class differs from the magneto-electric apparatus just described, only in the use of the electro-magnets instead of permanent magnets to maintain the magnetic field of force requisite to the development of the electrical currents. In other words, with dynamo machines physical power is employed to generate both the magnetism and the electricity. The chief advantages of these machines are, that they are not liable to deteriorate from the gradual loss of the permanent magnetism, and that, with equal weight, they can be made far more powerful. On the other hand, they require more physical force. Their action is certain, because the core of an electro-magnet always retains a slight residual charge of magnetism. The DYNAMO-ELECTRIC EXPLODER. 1 75 feeble waves of electricity, developed by the movement of the armature in this feeble field of force, are, if alternating, first caused to move in the same direction by the use of a commu- tator, and then are passed through the wires enveloping the cores. The intensity of the magnetic field is thus increased, and by mutual action and re-action it soon becomes exceedingly powerful. DYNAMO-ELECTRIC EXPLODER. The dynamo-electric exploder of Messrs. Siemens is shown in Fig. 32. The apparatus consists of an ordinary Siemens armature, which, by turning the handle, is made to revolve between the poles of an electro-magnet. The coils of the electro-magnet are in circuit with the wire of the armature ; the residual mag- netism of the electro-magnet cores excites, at first, weak currents ; these pass into the coils, thereby increasing the mag- netism of the cores, and inducing still stronger currents in the armature wire to the limit of magnetic saturation of the ^'°- 32- -Dynamo-Electric . , , ^ Exploder. iron cores of the electro-magnets. By the automatic action of the machine this powerful current is, at every second turn of the handle, sent into the cables lead- ing to the fuses. To iire with this machine, the handle is turned gently, till a click is heard from the inside, indicating that the handle is in the right position to start from. The cable-wires are then attached to the terminals, and the handle is turned quickly but steadily. At the completion of the second revolution, the current passes out through the cable and the fuses. The blasting-machine which has the greatest sale at the present time is a magneto-electric instrument of small size, weighing only about sixteen pounds, occupying considerably less than one-half a cubic foot of space, and sold at twenty- five dollars. It is constructed on the Wheatstone and Siemens principle, 176 THE MODERN HIGH EXPLOSIVES. having a magnet of the horseshoe character, of iron, wound about with coils of insulated copper wire. Between the poles of the magnet there is fitted to revolve an armature of cylin- drical construction, carrying in its body other insulated wire, coiled longitudinally as to the cylinder. The rapid revolution of the armature, by suitable means, generates and sustains in the machine an accumulative current of voltaic electricity of great power, which, at the moment of its maximum intensity, is practically switched off to the outside circuit, in which are the fuses ; and in the interior of each fuse the ignition is accomplished instantly. In magnetic-iron mines, the " frictional machine " fails through diversion or dissipa- tion of the electricity ; but the "=g, " magneto " works there per- ^= fectly well, and in submarine j^ or very wet work is also supe- ^^ rior, as imperfect insulation is ^^ not always an obstacle to its successful working. One of these small (No. 3) "magneto" instruments has fired fifteen fuses ; the current of electricity having been conveyed through one-quarter of a mile of bare iron telegraph-wire in the water at the bottom of a canal, the fuses also being immersed. The capacity of this machine is for about twelve or fifteen holes, though under entirely favorable circumstances many more can be fired. As to durability, the construction is such that one should last as long as a clock. No uncertainty exists. They have never failed to give satisfaction. In the deep mining of the Territories, especially in Colorado, many of them have been used in very wet shafts, and have been found invaluable. The patent self-discharging arrangement, a remarkable inven- FiG. 33. — Blasting-Machine. MAGNETO MACHINE. 177 tion, has made them far superior for practical use to any instru- ment ever made.' Fig. 34. — Magneto Machine. Fig. 35. — Magneto Machine. MAGNETO MACHINE No. 3. The above cuts show the interior arrangement of the machine. A, the principal magnet. B, the armature revolving between the poles of the principal magnet. C, the loose pinion, its teeth engaging with the rack-bar, and by clutching also enga- ging with the spindle of the armature on the downward stroke (only) of the rack-bar. D, the spring, which, when struck by the foot of the descending rack-bar, breaks the contact between two small platinum bearings ; and this causes the whole current of electricity to pass through the outside circuit, — the leading wire and fuses. E, the two platinum bearings, — one on the upper face of the spring, the other on the under side of the yoke over the spring. F, the commutator. These machines are sold by the Rand Powder Company. 178 THE MODERN HIGH EXPLOSIVES. So far the causes for any defect in the working of this machine have been but three, as follows : — The first — which is believed to have existed in but few of the machines of the earliest construction — was the breaking of the small pinion C, owing to defective temper of the steel used. If such an accident should occur, a new pinion can be easily adjusted. The second cause is one which may occur to some machines, and will be a gathering of dust, or the introduction of some foreign substance, between the platinum plates E. These points of contact should be clean ; and, if they be not so, the rack-bar will push down with varying resistance, — the best evidence of this fault. Removing the screws, and opening the case in the rear, it will be a simple task to cleanse them. The "commutator" is a thin ring of copper like a section of a tube, or would be so were it not divided by a saw-cut on each side into two equal parts, which are fastened upon a hard rubber hub. The commutator has pressing upon it (on the outer sur- face of the ring) two copper springs. These should press firmly upon it, and its surface should be bright and clean. In the course of time, particularly if the machine should not have been used, this surface may become tarnished ; then it will be necessary to make it bright. Rubbing with dry emery-paper will serve the purpose. Also, small particles of the copper, the result of the wear of the ring or the springs, may fall into the crevices between the two parts of the ring. If these crevices become filled with dust of copper, the result will be to weaken the effectiveness of the machine, as it is necessary that the two parts of the ring should be insulated ; and this is the reason of the hard-rubber hub. In order to cleanse this ring or commutator, the rack must be taken out of the case, which can be done by removing the small pin near the lower end of the same. Then the interior works of the machine, with the shelf on which they rest, can be moved partly out of the case, far enough for the purpose. Having done this, remove the springs which press upon the commutator, and then remove the yoke which holds in place the spindle upon which the commutator runs, when the latter can be readily cleaned and replaced. MAGNETO MACHINE. 7 79 In very few of the machines has there been any necessity found for this cleaning process. The spindle-bearings, front and rear, will need oiling occa- sionally. Machines made hereafter will have openings in the case for conveniently doing this. All being ready, and not until the men are at a safe distance, connect the leading-wires, one to each of the projecting screws on the front side of the machine, through each of which a hole is bored for the purpose, and bring the nuts down firmly upon the wires. Now, to fire, taking hold of the handle for the purpose, lift the rack (or square rod toothed upon one side) to its full length, and press it down, for the first inch of its stroke, with moderate speed, but finishing the stroke with all force, bringing the rack to the bottom of the box with a solid thud, and the blast will be made. Platinum Fuses. — These are the fuses which are to be used with the "magneto" machines. The cut shows in section a platinum fuse nearly of actual size. A, the shell, of copper, having a raised rim thrown out from the inside, which holds the sulphur cement more firmly in place. B, the chamber containing the charge of explosive, composed mainly of fulmi- nate of mercury, very powerful. C, the fuse-wires, of copper, entering the shell, having a covering which is a partial insulator sufficient for all ordinary purposes. D, the bare ends of the copper fuse-wires, projecting above the sulphur cement and into the charge. E, the small platinum wire, or bridge, sol- dered to and connecting the two ends of the fuse-wire : this is heated to redness or combustion by the passage of the elec- tric current. F, the sulphur cement holding the fuse-wires firmly in place. These fuses are kept in stock with wires of four, six, and eight feet in length. Any required of greater length of wire must be made to order. The above are all cotton-covered wires. Those of gutta- FiG. 36. l8o THE MODERN HIGH EXPLOSIVES. percha covering, if required, must be made to order ; but this nicety of insulation by gutta-percha covering is not needed for general work, and only where blasting is to be done in deep vrater, — probably not then, unless several fuses are to be fired simultaneously through a great length of submerged wire. Other Dynamo-electric Apparatus. — The Farmer machine, the Smith machine, the Lafiin & Rand machine, the Ladd machine, the Hochhausen machine, the Wilde machine. Note. — For further information on the subject of electric machines, including the voltaic batteries, the reader is referred to Lieut.^Col. H. L. Abbot's work on '' A System of Submarine Mines.'' The Wires. — The wires are employed to conduct the elec- tricity from the apparatus to the spot where it is to be applied, — namely, to the blast; and, in consequence, they should be good conductors of electricity. In each electric conduit, there is the air or conducting wire, which emanates from the eyelet c (Fig 19 a) of the apparatus, and conducts the electricity to its place of action (and, for this, metal wires have to be used, thoroughly insulated) ; and the earth or return conduit, which leads from the knob K of the apparatus to the earth or to a return-wire running from the electric fuse to the eyelet D. If from one to six shots in wet or damp ground are to be fired, or even in good conducting-material, the return-wire is run into this conductor. In that case, put the eye D, or the knob K of the electric apparatus, as well as the last wire protruding from the last shot, in metallic connection with the ground. This is done by taking a piece q£ Jj.qj^^ ^jj^ connection is made with clean wire. For instance, in blasting piles (Fig. 38), use only the conducting-wire, and put the eye E of the apparatus (Fig. 29) in connection with the ground, while the return-wire from the electric '°' •''■ fuse is left in the water. In making the connection of fuses, see that no crossing of the wires occurs, as in Fig. 37, for in that case the discharge MAGNB.TO MACHINE. i8r Fig. 38. of the current would not enter the cap at all ; but, on reaching the crossing-point k, take the shorter road Lakb'E.. The connecting-wires, if they are not insulated, ought never 1^ to touch the earth. In blasting single piles in water, we only insulate the con- ducting-wire, whereas the re- turn-current is left to travel through water and earth. In this case, the eye E of the ap- paratus and the return-wire from the fuse are put in commu- nication with the ground. This is done by putting a piece of iron so deep into the ground that it reaches moisture, and this iron is connected by a clean piece of wire with the above two parts. In short conducting-spaces, where the current does not travel a long distance, it is sufficient to let the return-fuse wire remain in water or in the earth (Fig. 38). In quarries and mountain slopes, where electric firing is used, it is best to keep the elec- tric apparatus stationary ; and the firing is done from that point. The leading and return wires are fastened to stationary poles ; and from them branch wires ramify, which can be connected or detached ad libitum. In Fig- 39> f^he stations W^ and W^ show how the current passes from A to 5. Where important blasts are to be made, and it is desirable not to risk any failure, always employ well-insulated conduct- ing and return wires. For elec- tric blasting, it is usual to em- ploy clean iron or brass wire, or copper wire covered with India-rubber. The iron and brass wires should be well an- nealed. In using, they should be stretched on poles over insulators. These insulators are gen- erally made of glass, porcelain, or vulcanized rubber. When Fig. 39. 1 82 THE MODERN HfGH EXPLOSIVES. Stretched over these insulators without coming in contact with any other object, the insulation is perfect. If gutta-percha- covered wire is used, then no insulators are required : but still their use is recommended. As long as the gutta-percha cov- ering is not injured, and does not expose the copper wire, it can be laid on the ground or in water. The submarine wires differ from the others somewhat : they are surrounded by coarse linen well tarred. In using for the conducting-wires metals other than those named, their power for conduction is very sensibly diminished. Table SHOWING THE Electric Conductibility of Different Metals. Mercury . .... 1.8 Platinum . . . . 8.0 Lead 9.0 Iron 12.3 Tin 14-0 Zinc .... ... 24.0 Annealed gold 65.0 Annealed copper 92.0 Annealed silver loo.o In France, the resistance of metals is calculated from a unity represented by a hundred metres of iron wire four millimetres in diameter, similar to that used for telegraphing. The resistance of wires is in direct proportion to their length, and in indirect proportion to their conductibility and the square of their diameter. Therefore, if we know the resistance of a wire and its conducting power, we can determine its equivalent or reduced length. The equivalent or reduced length is that which presents a resistance to the passage of the electric current equal to unity, or a hundred metres of telegraph-wire. Galling r the resistance of the telegraph-wire, c its conducti- bility, / its (ength, and d its diameter, we will have, — for another wire, / r = —r, formula a ; >-' = -7-^, formula B ; r a ^ MAGNETO MACHINE. 1 83 According to the preceding table, c = 12.3, c' = 92. If we suppose for the iron wire four millimetres diameter, and for the copper wire two millimetres diameter, then ^ = 4^ = 16, d'- = 2^ = 4, /= I. In replacing c, (f, d^, d'^, and / by their respective values, in the formulas a and y3, I I 12.3 X 16 196.8 I' _ _^ " 368" 92 X 4 If we compare the two results, /' I i68 = ^8' ^'^"'■"^"'■^ ^'= ^-^l- Consequently, 1.87 metres of copper wire of two millimetres diameter will offer the same resistance as one metre of telegraph- wire ; or, in other words, a hundred metres of telegraph-wires represent a hundred and eighty-seven of this cop- per wire as to their resistance. In tunnels and underground works, the apparatus should be kept station- ary, and insulated cables used for con- ducting and return wires. On the charging-points, wooden boards are fixed, in which- the different wires terminate; and wire spirals are used as connecting-links, as in Fig. 40. The Application of Electric Firing. — In the application of electric firing, while the machine, wires, and fuses must be in proper connection, it is usual to commence with the "prepara- tion of the shot." (a) Preparing the Shot or Blast. — The miner in charge of the bore-holes has to see that the wires connected with the // TT Fig. 40. 1 84 THE MODERN HIGH EXPLOSIVES. electric fuses are long enough, so that their ends project quite a distance when inserted into the bore-hole. These projecting ends should be perfectly clean and bur- nished. In putting in the first tamping, do it carefully, avoiding- hard ramming. To offer a proper conducting medium, the con- nections of the wires ought to be very carefully arranged. If two non-insulated wires are to be connected together, rub off any dirt or oxide, wind them together, and bend back the points (see Fig. 41), and, with a pair of pincers, press the =oococ@&osooooos= Fig. 41. twisted wires together. If wires are insulated by India-rubber,, cut it away from that portion of the wire which is to be twisted together (Fig. 42), and then a piece of India-rubber tubings iQoaoooo o ooeoo- FlG. 42. which had been .previously put on one of the wires (Fig. 42, on- left-hand side), is now pulled over the connection (Fig. 43), and Fig. 43, tied fast with fine wire, or the connection is covered over with some paste, or India-rubber strips (Fig. 44), and the India- rubber tube pulled over it. Fig. 44. The connection of the bore-hole wires with the main wires, and among themselves requires great care ; and a man thor- oughly instructed ought to manipulate this part of the work, especially if the wires are laid under water, for there the closest connection and covering are required. MAGNETO MACHINE. I8S Connection of the Shots among themselves and with the Main Wires. — After the blaster has inserted his fuses in each bore-hole, leaving the ends of the fuse-wires projecting, the man having charge of the blasting connects one wire of the first shot with the conducting wire, not directly, but by means of a piece of independent wire called a coupling, through which the connection is made. The second wire of the first shot is coupled on to a wire of a second shot ; the second wire of the second shot is coupled to one wire of the third hole, and so on till all the connections are made ; when, at last, the remaining end of the last shot is coupled to the return wire. Figs. 45 and 46 show the arrangement. Fig. 45. The condueting-wire is the (negative — ) wire leading to the ear C, and the return wire (positive +) leads to the ear D of the apparatus A (Fig. 45). The couplings «, a, a, a, connect Fig. 46. the fuses b, b, b, b, b, and ought not to touch the ground, unless they are insulated wires (Fig. 45). 1 86 THE MODERN HIGH EXPLOSIVES. The battery has to be set up quite a distance from the bore- holes ; and the shots are first connected among themselves, and then the couplings are inserted for the main connecting-wires (Figs. 45 and 46). After the connections are made, then the ends of the wires are attached to the eyes of the knobs of the apparatus ; the crank is put on the apparatus, which is charged by thirty to forty turns, and the knob K is pressed for the discharge. After firing, the wires are disconnected again, the crank taken off from the apparatus, and the blast-holes are inspected, no matter whether they have all exploded or not. ELECTRIC FUSES. High and Low Tension Fuses. — An electric fuse consists of a charge of an explosive compound, suitably placed in the cir- cuit of an electric current ; which compound is of a character to be acted upon by the current in a manner and in a degree suificient to produce explosion. The mode in which the cur- rent is made to act depends upon the nature of the source of the electricity. That which is generated by a machine is of high tension, but small in quantity ; while that which is gen- erated by a battery is, on the contrary, of low tension, but is large in quantity. Electricity of high tension is capable of leaping across a narrow break in the circuit ; and advantage is taken of this property, to place in the break an explosive compound sufficiently sensitive to be decomposed by the pas- sage of the current. The electricity generated in a battery, though incapable of leaping across a break in the circuit, is in sufficient quantity to develop a high degree of heat. Advan- tage is taken of this property, to fire an explosive compound by reducing the sectional area of the wire composing a portion of the circuit at a certain point, and surrounding this wire with the compound. It is obvious that any explosive compound may be fired in this way; but, for the purpose of increasing the efficiency of the battery, preference is given to those compounds which ignite at a low temperature. Hence it will be observed that there are two kinds of electric fuses ; namely, those which may be fired by a machine, and which are called "tension" ELECTRIC FUSES 1 87 fuses ; and those which require a battery, and which are known as quantity fuses. Advantages of High and Low Tension. — An advantage in vising high-tension fuses is the small effect of line resistance upon the current ; a consequence of which is, that mines may be fired at long distances from the machine, and by means of an iron wire of very small section. A disadvantage of high tension is the necessity of perfect insulation for the wires. When electricity of low tension is employed, the insulation of the wires need not be so perfect, and leakages arising from injury to the coating of the wire are not of such great impor- tance ; while, in many cases, bare wires may be used. Other advantages of low-tension fuses are the ability to test the fuse at any moment, by means of a weak current and an almost absolute certainty of action. For this reason, these are usually preferred for torpedoes and important submarine work. On the other hand, the copper wires used must be of comparatively large section ; and the influence of line resistance is so consid- erable that only a small number of shots can be fired simulta- neously when the distance is great. Low-tension Fuses. — The name "low-tension" is applied to that class of electrical fuses which are exploded by the heating of a very fine wire bridge, uniting the insulated conductors in the priming-chamber to a degree sufficient to ignite the prim- ing in which it is embedded. Such fuses differ in the kind of wire, its diameter, and length required, and in the chemical composition of the priming. General Classification. — Electrical fuses may be divided into three classes: viz., low-tension, for use with strong electrical currents of low potential ; high-tension, for use with condensed sparks capable of jumping a sensible air-space; and medium- tension, specially designed for magneto-electric machines, which generate electricity characterized by a potential higher than the former and less than the latter. This nomenclature is adopted because sanctioned by common use, although the word ^'tension" is objectionable as no longer employed by many writers on electricity. Although the three great classes are thus well marked, it by no means follows that a given variety of fuse can only be 1 88 THE MODERN HIGH EXPLOSIVES. ignited by a particular kind of electrical generator. While this is true for some varieties, others may be fired by electricity under any of its characteristic forms. For example, the Abel magnet fuse, although belonging to the medium-tension class, is not unsuited to frictional machines ; and it may also be used with voltaic currents of high electro-motive force. As a rule, however, each of the three classes of generators should be provided with a fuse specially adapted to it. Every electrical fuse suitable for use with explosive com- pounds should have, — 1st, Two insulated conductors for conveying the current; 2d, A plug to receive and firmly hold an end of each near Fig.B Fig.A Fig.O X -I to, but not touching, the other ; 3d, a small priming suitably arranged for ignition at this point ; and, 4th, a metallic cap, containing a detonating-charge, usually of fulminating mercury. The only essential difference between the three classes lies in the manner of causing ignition. The low-tension variety usually acts by the heating of a very fine wire, uniting the insulated conductors, and embedded in a suitable priming. The second and third classes are fired by the passage of the electricity through a small break in the metallic circuit at this point, the spark igniting a sensitive priming. They differ from each other in the chemical composition and the electrical resist- ance of this priming. ELECTRIC FUSES. 1 89 Conditions common to All Fuses. — Reserving the third of the above conditions for future consideration, the conclusions reached as to the best method of fulfilling the other three may be stated at once. I. The insulated conductors should be flexible, tough, and of low electrical resistance. Lake-Superior copper wires of good quality, in size about No. 20, have been adopted. The insula- tion must be proof against the deterioration of age, — a con- dition which excludes gutta-percha and India-rubber : it is well fulfilled by a closely woven wrapping of cotton thread coated with paraffine, or with beeswax, rosin, and tar boiled together. The free ends are bared for about 1.5 inches. II. The plug must be a non-conductor of electricity, not liable to deteriorate with time and exposure to damp air, nor to corrode the copper wires. Beech-wood, kiln-dried, and coated thickly on the outside with Japan wax, well fulfils these condi- tions. The shape must be such as to render any contact between the wires impossible, and to clamp them so firmly that no acci- dental strain on the free ends can disturb their internal adjust- ment. The form adopted is the following. The plug consists of three parts : — 1st, A cylinder, .25 inch in diameter and .7 inch long, grooved longitudinally on its opposite sides to receive the wires. En- tirely round the middle is a cut .05 inch deep and .15 inch wide. The wires, with their wrapping of cotton, are each pressed into one-half of the longitudinal grooves, until they reach the cut. They are then both bent sharply to the left, nearly at right angles, and are led through this cut, until they have passed half round the cylinder, when they are again bent at right angles, and pressed into the other half of the longitudinal grooves. Thus each wire leaves the plug in the opposite groove from which it entered, and at no point can they come in contact with each other. The inside ends of the wire are then bared, scraped, cut to the proper length (about . i inch), and prepared according to the class to which the fuse belongs. 2d, Of a hollow cylindrical cap, with a stout shoulder at one end, leaving a smaller hole for the passage of the free ends of the insulated wires. This cap is made to closely fit the solid I go THE MODERN HIGH EXPLOSIVES. cylinder; and the latter, smeared with glue, is forced into it, until the end abuts firmly against the shoulder, leaving a small chamber round the bridge to receive the priming. 3d, Of a paper disc, held in position by a drop of collodion, to close the latter. These several parts, are turned by ma- chinery to fit each other accurately, at a trifling cost ; and the whole plug is solid, strong, and a perfect protection to the bridge and priming. III. The detonating-cap is made by punching a disc of stout sheet copper into a cylindrical form, fitting the plug closely. The bottom is solid, and contains twenty grains of fulminating mercury, full weight, held in place by a paper disc secured by a drop of collodion. This charge, which, added to the priming, amounts to about twenty-four grains, is found, by experiment, to be amply sufficient to detonate dynamite in the shape of loose powder, whether soft or frozen. The cap is one inch long and .4 inch in diameter, and entirely incases the chamber of the plug. It is rigidly attached to the latter, by applying a pressure at two opposite points near the top, sufficient to indent them into the wood. The fuse thus formed is 1.4 inches long and .4 inch in diameter. As soon as completed, it is dipped into melted Japan wax, which supplies a uniform waterproof coating to the whole. Medium and High Tension Fuses. — The fundamental dis- tinction between medium and high tension fuses is based upon the conductivity of their priming. Theory of Ignition. — The theory usually accepted for the ignition of high tension and medium tension fuses is, that the heat generated by the passage of the spark through the priming raises the temperature sufficiently to produce explosion. Some classes of these fuses are so excessively sensitive to electrical disturbances, that, for them at least, it is not easy to accept this theory. A person placed in the same circuit experiences no sensible shock from charges greatly exceeding the minimum required to explode them. An ebonite comb passed a few times through the hair of a child holding one of the terminal wires, the other being insulated in the air, generates a current quite sufficient to fire the priming. ELECTRIC FUSES. I9I Many varieties of tension fuses are so sensitive to electrical disturbances as to be criminally dangerous for practical use. The Abel Magnet Fuse, Low Tension. — This fuse was devised by Professor Abel, in 1858, specially for use with magneto-elec- tric apparatus. He had in view the explosion of several fuses simultaneously, and modified his priming accordingly : so that, after ignition, no conducting residue should remain between the terminals in the priming-chamber. His fuse, when newly made, has a high reputation for uniformity and certainty of action ; but, if kept long on hand, it is liable to become uncertain when used with electricity of high potential. The priming consists of : — Sub-phosphide of copper lo parts. Sub-sulphide of copper 45 " Chlorate of potassa 15 " 70 The ingredient first named is the igniting agent ; the potas- sium chlorate supplies the oxygen ; and the sub-sulphide of copper gives the requisite degree of conductivity. The above formula is varied according to circumstances, and I give here another much employed in the Abel fuse : — Proto-sulphide of copper 64 Proto-phosphide of copper 22 Chlorate of potassa 14 100 These materials are separately ground, and intimately mixed by adding alcohol. The drying is effected in the open air. This compound takes fire by friction and blows. The Abel Submarine Fuse, Medium Tension. — The Abel magnet fuse, both as originally devised, and as recently modi- fied by varying the proportions of the component parts, is liable to the objection that it will accidentally explode if subjected to the continued action, even of a weak testing battery. To meet this defect, which is a very serious one in submarine mining. Professor Abel has devised a new composition, consisting of an intimate mixture of powdered graphite and fulminating mer- 192 THE MODERN HTGH EXPLOSIVES. cury. This mixture is compressed into the cavity containing the wire terminals, until the desired resistance is obtained, which may easily be ascertained by keeping a feeble current passing through the priming, with a galvanometer in circuit. The poles of this fuse, like those of the older one, consist of two fine copper wires, arranged parallel, and embedded at a distance of .05 inch apart in an insulating column, which, in the new fuse, consists of a mixture of Portland cement with sufficient sulphur to allow of its being melted, and cast in a mould, producing a very rigid support, upon which the priming composition can be consolidated over the slightly projecting terminals of the copper wires or poles by the application of considerable pressure, the electrical resistance of the fuse being regulated by the degree of compression of the composition. This cast column or insulating support of cement was adopted in place of the gutta-percha used in the old fuse, because the want of rigidity in the latter material did not permit of the at- tainment of uniform and permanent compression of the priming composition. Ebner's Fulminating Compound, Medium Tension, is com- posed of — Sulphide of antimony 44 parts. Chlorate of potash 44 " Plumbago 12 " 100 parts. This fuse was devised by Gen. von Ebner, of the Austrian engineers, for use with frictional electricity. The plumbago is also sometimes applied in the form of a mark drawn between the wire terminals, and sometimes it is entirely omitted. The Dowse Fuse, Medium Tension. — T. B. Dowse of Lock- port, 111., patented the application of fulminate of copper as a priming for electrical fuses, under the name of " copper amal- gam." His formula is : — Finely divided copper 3 parts. Fulminate of mercury i part. ELECTRIC FUSES. 1 93 Add about thirty per cent of water; raise temperature to about 212° F., intimately mix. When about half the water has evaporated, charge as follows : place 0.4 of a grain of the com- pound between small polished leaden discs, and submit to a pressure of about six hundred pounds ; bottle for two days to prevent too rapid evaporation ; attach wires, and place the primed discs in the exploding-charge of the fuse. Dowse prepared his copper by intimately mixing lampblack with protoxide of copper, in such proportions as to form car- bonic-acid gas with the oxygen, and heating to redness in a vessel from which the air was excluded. He states, " The manufacture of copper amalgam requires the utmost caution. I advise no person to attempt it, unless he has been accus- tomed to handle fulminates." This caution is not unneces- sary ; and it might be well to add, that with this priming the free ends of the fuse-wires should always be kept twisted into good metallic contact until ready for use, to guard against accidental explosion due to insensible disturbances of electrical equilibrium. The following extracts from the valuable paper by Mr. Abel, on " Electricity applied to Explosive Purposes," read before the Institution of Civil Engineers of Great Britain, are thought to be of great interest by the author, who regrets space does not permit a fuller quotation : — " The possibility of applying the electric spark to the igni- tion of gunpowder suggested itself independently to Franklin, in America, in 1751,' and to Priestley in 1767; but it was not until some years after the discovery of the electric pile by Volta that serious attempts were made to apply electricity as the ignit- ing agent of powder-charges used in mining and military opera- tions. The first practical application of the voltaic battery in this direction was made about forty-five years ago, by French ' In his Letters on Electricity, dated 29th June, 1751, Franklin says, " I have not heard that anybody in Europe has yet succeeded in firing gunpowder by means of electricity. We do it in this way : A small cartridge is filled with dry powder, which is rammed in tightly enough to crush a few grains ; two pointed brass wires are then fixed in it, one at each end, so that their points are not farther apart than half an inch at the centre of the cartridge, is'hich is then placed in the circuit of the electric machine ; when the communication is com- pleted, the flame, leaping from the points of one wire to that of the other, through the powder in the cartridge, fires it instantaneously." 194 THE MODERN HIGH EXPLOSIVES. military engineers ; and a few years afterwards Sir Charles Pasley, whose name is so well known in the engineering world, was the first to bring the use of electricity in the firing of gun- powder to a practical issue in England. The art of firing pow- der-charges under water was in a very backward state when Col. Pasley first made it the subject of practical investigation in 1812; and, finding that the slow-burning fuse subsequently invented by Bickford could only be used at comparatively small depths with any prospect of success, he devised a fairly efficient arrangement of powder hose, which could be led to- considerable depths," and which he employed with some success- in operating upon the wrecks of the ' Royal George ' and ' Edgar,' which were submerged in deep water off Spithead. It was while engaged in this work that Pasley, profiting by the counsels and instructions of Daniell and Wheatstone, carried out, between 1835 and 1840, the first blasting and mining operations by electrical agency which were accomplished on a practical scale in t.his country. "In the winter of 1842-43 experiments were instituted at Dover, with the Daniell battery, upon a considerable scale, preliminary to the explosion of the great mines by which the destruction of the Round Down Cliff was accomplished, on the 26th of January, 1843, when more than forty thousand cubic yards of rock were dislodged by the explosion of three chambers containing eighteen thousand five hundred pounds, of powder. "The general method of operating, pursued at that time by our military engineers, was adhered to with little modification for many years. In the centre of the charge of gunpowder was placed a so-called burster, or fuse, — a small box or case of wood, with two short copper wires passing to the interior, and firmly fixed, the enclosed extremities being connected by a short bridge of thin wire, composed of metal of inferior con- ducting power ; iron in the first instance, and afterwards plati- num, which was surrounded by very fine-grain powder. The protruding extremities of the copper wires thus arranged were connected with the terminals of the circuit-wires by means of binding wire, the connections being covered with insulatin" wrappings. The heating to redness of the fine-wire connection, ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. I95 or bridge (or its fusion, in the case of iron being used), conse- quent upon the resistance which it opposed to the current, ignited the fine-grain powder by which it was surrounded, and the charge was thereby exploded. Simple self-acting arrange- ments were used for causing the battery-wires to be short-cir- cuited for a sufificient time after the arrangement of a mine was completed, to allow the operators to reach a place of safety, the current passing through the entire circuit, and thereby firing the fuse, at a fixed period. " As a whole, the manner in which the operations of forty years ago were carried out evinced a sound knowledge of the principles of electrical science, and considerable practical skill and ingenuity in their application by the Royal-Engineer offi- cers who devoted themselves to this work. "The copper-zinc battery continued for some time in use as the exploding agent for military service, but some improve- ments were gradually introduced into the methods of operating by Royal Engineer officers. Col. Ward, more especially, did very useful work in this direction, and published in the ' Aide Memoires' of the Royal Engineers for 1854, the results of a very careful investigation of the merits of different batteries, and of the conditions to be fulfilled in operating through differ- ent lengths of wire-circuit, with details on the construction of the fuses and arrangement of charges for simultaneous explo- sions, and other important points. One result of his labors was the adoption for military service of a form of Grove bat- tery specially adapted to work of this kind, which, with the rough form of platinum-wire fuse described, continued in use until, in i860, instruments developing currents of high tension gradually displaced voltaic batteries as exploding agents. "In 1853 a Spanish officer, Col. Verdu, associated himself with M. Ruhmkorff in experiments on the application of electro- magnetic induction coils to the explosion of gunpowder. The success of these experiments led Verdu to pursue them further in Spain, where he soon succeeded in firing six mines simulta- neously by one element of Bunsen's battery, at a distance of upwards of three hundred yards, through the agency of the Ruhmkorff coil. The mode of operation and the difficulties which Verdu had to overcome will be presently described. 196 THE MODERN HIGH EXPLOSIVES. While his success led the military engineers in Spain, France, and Russia to pursue the development of the application of electro-magnetic induction-instruments to exploding purposes, a committee of Austrian military engineers (of which Baron von Ebner was from the first a most distinguished member) was laboring to apply frictional electricity to military uses as an exploding agent ; they having come to the conclusion that the electro-magnetic induction apparatus was too complicated and too easily susceptible of derangement for military uses. " But little success had up to that time attended attempts to apply frictional electricity to this purpose. In 1831 Moses Shaw of New York succeeded in exploding several mines simultaneously by means of frictional electricity, with the em- ployment of fuses containing an admixture of fulminate of silver with gunpowder ; but he was foiled in his attempts to apply this agent to practical purposes by the fact that he could not con- duct operations with any chance of success except in very dry weather. Somewhat more promising results attended several attempts in Germany by Warrentrap and Gotzmann, between 1842 and 1845; and, in the latter year, Mr. Charles Winter succeeded in firing a powder-charge, by means of a sensitive fuse and a Leyden-jar, through the telegraph-line between Vienna and Hetzendorf, a distance of 5,390 yards. But the prospect of practical success was still not encouraging, when the Austrian committee of engineer officers took the matter in hand, and eventually produced a portable glass frictional electric machine, which, when in good working order, furnished results surpassing those hitherto obtained with volta-induction apparatus. Some very extensive operations were conducted with this machine : thus fifty land-charges and afterwards thir- ty-six submarine charges were simultaneously exploded. Even, however, with all the precautions adopted, the machine was still too seriously affected by damp to be thoroughly serviceable for military purposes ; while the induction-action of the firing-charge was sometimes so energetic that explosions were occasionally determined in mines not intended to be fired, and not connected with the electrical machine. But the persevering labors of Von Ebner eventually resulted in the production of an electric ma- chine which was free from most of the objections hitherto attached to this form of apparatus. ELECTRICITY AP1>UED TO EXPLOSIVE PURPOSES. I97 "In 1855 Sir C. Wheatstone directed the attentior of Field- Marshal Sir John F. Burgoyne to the importance of instituting an experimental inquiry into the relative advantages of differ- ent sources of high-tension electricity as agents for exploding^^ gunpowder. The Ordnance Select Committee, of whom Sit C. Wheatstone and Mr. Abel were then members, were conse quently instructed to pursue this inquiry ; and a series of inves tigations was carried out in the first instance by a working branch of the committee, and subsequently by Mr. Abel at Woolwich and Chatham., the results of which were eventually embodied in a report presented by the above-mentioned gentle- men to the Secretary of State for War in i860. " Meanwhile the subject of the application of electricity to the firing of mines, etc., continued to receive attention in Aus- tria and other countries, and considerable impetus was given to work in this direction by the efforts of the two opposing powers in America, between 1862 and 1865, to apply electricity as the exploding-agent of submarine mines ; the prominent part played by these in the Civil War having had the effect of directing the attention of England and other nations to the prominent rSle likely to be played in future wars by methods of subma- rine attack and defence, and to the importance of applying the resources of electrical science to their development. "It has been stated that Col. Verdu succeeded, in 1853, in exploding several mines simultaneously by means of a Ruhm- korff induction-coil. The ignition of the gunpowder was ef- fected in these experiments by introducing one or more small but complete interruptions into the circuit, across which the electric spark of high tension would leap upon the current being passed. This spark will inflame gunpowder, but not very readily, although its production is attended with development of heat considerably in excess of that necessary ; the reason being that powder requires for its ignition either the close proximity of a considerable heated surface, or the continuous application of heat for a brief period, while the disruptive dis- charge from an induction-coil consists of a series of instanta- neous discharges following each other in very rapid succession. Hence a charge of gunpowder is not always instantaneously fired when a series of sparks is passed : indeed, unless the pow- 1 98 THE MODERN HIGH EXPLOSIVES. der be closely confined round the wire terminals between which the spark passes, it is sometimes dispersed by the mechanical action of the discharge without being exploded ; and, when a succession of sparks is passed simultaneously through a num- ber of charges, it frequently occurs that only a few are exploded, in which some of the grains happened to be in positions or under conditions more favorable to the action of the source of heat than in other instances where the powder escaped ignition. It need scarcely be stated that the same difficulty is experienced in attempts to apply the discharge from a frictional electric machine or Leyden-jar to the explosion of powder. Moses Shaw was the first to overcome it by exposing to the action of the spark a mixture of powder with a much more readily explodable material ; Verdu succeeded similarly, in increasing the certainty of simultaneous ignition of several charges by the spark from an induction-coil machine, by surrounding the wire terminals with a substance much more readily inflamed than powder, — the fulminate of mercury. Another source of difficulty in effecting the simultaneous ignition of a considerable number of charges by the spark from an induction-coil is the enfeebling effect upon the spark-discharge exerted by a number of suc- cessive small interruptions in the circuit. This was to some extent overcome by employing a fuse constructed by Messrs. Statham and Brunton, in which the space between the wire terminals was bridged over by a film of finely divided substance, — the sub-sulphide of copper, the conducting power of which is suflSciently great to aid the passage of the electric discharge across the interruption, while it is at the same time readily combustible, and therefore directly promotes the ignition of the powder. "The invention of the Statham and Brunton fuse may be regarded as the starting-point in the production of so called high-tension fuses, as contra-distinguished from the thin wire or low-tension fuse ; and the circumstances which led to its con- struction therefore present special interest. In August, 185 1, a length of copper wire which had been covered at the Gutta- percha Company's works with gutta-percha containing about ten per cent of sulphur was being passed through water from one reel to another, for the purpose of discovering what ap- ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. I99 peared to be a fault in insulation, when suddenly a bright spark was observed in the water. On examining the wire at that particular spot, it was found to be broken, and the gutta-percha burnt. Several pieces of similarly covered wire were then pur- posely broken, in each case with similar results. A length of the gutta-percha was then removed from the wire ; and, on ap- plying the two poles of one hundred cells of the battery in use at various distances, to the inner surface which had been in contact with the copper, and had become coated with a film of sulphide of copper, — which in comparison to copper is of very high resistance, — heat was generated, in proportion, of course, to the distance of the poles. Gunpowder was placed upon the gutta-percha, and on applying the battery-poles it was immedi- ately ignited. Consequently, by removing a small portion of the gutta-pereha from the upper surface of the wire, then sever- ing the latter at that point, and slightly separating the two extremities, a suitable fuse for igniting explosive substances at long distances, and simultaneously at several points, was produced. When the cable was laid from Dover to Calais, in September, 185 1, cannon were fired by the aid of these fuses at Dover by a person at Calais, and vice versd. Also, when the ■first Mediterranean cable was laid from Spezzia to Corsica, a distance of ninety miles, similar experiments were successfully made. " Col. Ward, in his important paper already mentioned, on the application of the voltaic battery to the explosion of powder, carefully examined into the properties of this fuse, and com- pared its behavior with that of the wire fuse. He pointed out, that, while the amount of heat required to ignite the sulphur- and-copper compound formed on the surface of the gutta-percha was very much less than that needed for firing a platinum-wire fuse, the conducting power of the substance was very low ; but that whatever number of cells (roughly speaking) it is found necessary to arrange in series to produce ignition of the fuse at a distance of one foot by conduction of the current across the interrupted metallic circuit bridged over by the sulphide, will produce the same effect through a copper-wipe circuit of one mile, and that an addition of about one-fourth the number of cells of the battery will permit one-half of the copper circuit 200 THE MODERN HIGH EXPLOSIVES. to be replaced by ordinary moist earth, the resistance of the fuse being so great that a large addition to the metal-circuit, or the introduction of a great distance of earth-circyit, effects no material diminution in the actual quantity of electricity circu- lating. The battery used by Ward in his instructive experi- ments with these fuses was a zinc-and-copper sand-battery, four inches by four inches, of which one hundred plates were needed to fire the fuse with certainty, while three hundred plates of the same battery were not found to develop any sensible heat in the platinum-wire fuse ; and he pointed out the important bearing of the internal resistance of this battery upon the attain- ment of these results. He also showed, that, while the diameter and material of the metallic conductor are matters of material consequence in using the platinum-wire fuse, it is of no con^ sideration to know the resistance of the conductor in the case of the Statham-Brunton fuse. On the other hand, he insisted upon absolute insulation of the conductor as essential to the successful employment of this fuse. " While Ward was engaged upon experiments with this fuse in 1854, it was demonstrated to him by the late Mr. Southby, a well-known pyrotechnist, who devoted himself much to ex- perimental electricity, that the current induced in a secondary coil, wound round a helix of the primary conductor through which the current from three or four cells of a Grove's battery was passed, sufficed to ignite the Statham-Brunton fuse. Ward found that with such a helix, and four cells of Grove's battery,, four inches by four inches, he could fire the fuses at a distance of thirteen hundred yards from the operator (the longest dis- tance he was able to try), and with the employment of a return earth-circuit. These results were therefore obtained in Eng- land concurrently with, if not before, those which Col. Verdu obtained with the excellently constructed coil of Ruhmkorff. "The employment of the Statham fuse for effecting simulta- neous explosions was not pursued to any great extent by Ward ; but, so far as his experiments went, with the use of the sand- battery, he found that the difficulties were much greater than those to be encountered with the platinum-wire fuse. Even with the use of the Ruhmkorff induction-coil, and with a prim- ing of mercuric fulminate added to the Statham fuse, Verdu ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 20I found that the number of charges which he could fire simul- taneously was very limited. He was, however, able to obtain a fair result by the following simple arrangement : Separate small groups of mines were all connected with earth, and an insulated conducting-wire connected each group with one of a series of small insulated plates. By bringing these in very rapid succession into circuit with the coil-machine, the several groups were so rapidly exploded as to produce results somewhat similar to those attainable by the really simultaneous discharge of a considerable number. Not long after this contrivance was adopted by Verdu, Savare applied the so-called branch-circuit- arrangement, whereby a much more rapidly successive discharge of a number of mines was accomplished through the agency of the coil. The metallic circuit which passed to the mines was divided into a number of branches : so that, upon completion of the circuit, the currents, following each other in very rapid suc- cession, would distribute themselves through all the branches with a degree of uniformity regulated by the resistance met with in each branch. Thus, when one or more fuses were inter- posed in each branch of the circuit, those which happened to offer the greatest facilities for the passage of the current would be first fired, whereupon the escape of electricity in that direc- tion would be interrupted, and the explosion of fuses in another branch would follow. With the employment of currents suc- ceeding each other with the enormous rapidity with which they pass off from the induction-coil machines, the discharge of a number of mines is thus accomplished in such very rapid suc- cession as almost to have the effect of a simultaneous discharge. It will be seen that this arrangement is the same in principle as that used by Royal-Engineer ofificers in England and Ireland in 1843, when first the voltaic battery was applied to the ignition of powder. "The Ruhmkorff coil was used, to some extent, by the Rus- sians in mining operations during the Crimean War ; and some very extensive operations were carried out with its aid at Cher- bourg in 1854 by Dussaud and Rabattu, according to a system arranged by Du Moncel. In the first of these, six mines, containing many thousand kilograms of powder, were simulta- neously exploded, displacing more than fifty thousand cubic 202 THE MODERN HIGH EXPLOSIVES. metres of rock. A series of experiments was instituted by the lecturer, in 1856, with two excellent induction-coils, produced by RuhmkorfE ; in the course of which, various descriptions of priming materials were tried in the fuses, for the purpose of increasing the power of the machine to fire numbers of charges simultaneously. At that time the fulminate of mercury was found to be the best inflaming agent, but not more than twelve charges were fired simultaneously by means of the most power- ful coil available and a battery of twelve cells (without employ- ing Verdu's or the fork-method of explosion). One defect in this class of instruments was found to be the want of uniform action of one and the same apparatus at different periods ; an- other was the liability to derangement of the machine, especially of the condenser. Far more successful results were afterwards obtained with the same coils, and the fuse constructed at a later period of the Woolwich investigations. Fifteen charges were fired simultaneously with a battery of six cells ; and fifty charges, arranged in branch-circuits in groups of ten, were exploded with the effect of a simultaneous discharge. These results were ob- tained with machines produced by Ruhmkorff in 1855. There is no question, therefore, that induction-coil machines are avail- able for special operations of considerable magnitude ; but, in point of simplicity, certainty, and constancy of action, they are far surpassed by other forms of electric instruments now in general use for explosive purposes. " At the suggestion of Sir Charles Wheatstone, experiments were commenced at Woolwich, in 1856, on the application of currents induced by permanent magnets to the explosion of gunpowder. The first were instituted with a very large and powerful magneto-electric machine, constructed by Mr. Henley, of which the armature, carrying two powerful coils, was suddenly detached from the magnet by means of a lever. A few experi- ments sufficed to show that the induced current obtained, even with this powerful instrument, was not adequate to ignite one single charge of gunpowder with certainty. Somewhat better, but still uncertain, results were obtained with Statham's and one or two other forms of fuses existing at that time.' A care- ' A fuse which gave better results with this magneto-electric machine than any then existing was prepared by the late Mr. Henley. Its nature was not, however, disclosed by him. ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 203 ful investigation was then undertaken by the lecturer (with the invahiable assistance of Mr. E. O. Brown) into the conditions to be fulfilled in the production of a fuse which should be cer- tain of action with the magneto-electric machine. The results of extensive experiments indicated that a combination of com- paratively high conducting-power with great susceptibility to ignition appeared to include essential elements of success in a material to be used as the exploding-agent in such a fuse. The uniform arrangement of the poles, or wire terminals, in the fuse, the space between which was to be bridged over by the igniting composition, also proved a matter of great importance. A mode of constructing fuses, which insured great uniformity in this respect, was ultimately perfected, and has proved quite success- ful. This consists in the enclosure of two fine copper wires, side by side, in gutta-percha, by which material they are also uniformly separated from each other, so that great similarity as to distance between the poles, or exposed sections of the wires, is attained by simply cutting pieces of the double-covered wire off a long length of the same. "A fairly efficient fuse was obtained, with the aid of the poles thus arranged, by employing as the igniting-agent gunpowder impregnated with a small proportion of calcium chloride, which caused it, on brief exposure to air, to imbibe moisture sufficient to render the gunpowder highly conducting. It is obvious, how- ever, that there must be a liability to want of uniformity in the proportion of water absorbed by the powder, and a consequent variation in the conducting-power of the latter. Eventually a material was prepared (consisting of the sub-phosphide of cop- per, sub-sulphide of copper, and potassium chlorate) which com- bined the essentials of perfect certainty of action with very great sensitiveness to ignition. Henley's large magnet fired three of these fuses in simple circuit with certainty, while a small horseshoe-magnet with revolving armature exploded twentyyfive in divided circuit in exceedingly rapid succession. A combination of six small compound magnets was afterwards employed, with which an exceedingly rapid succession of cur- rents was obtained ; and this apparatus exploded twenty-five fuses, in divided circuit, with a rapidity, which, on the ear, had the effect of an instantaneous explosion. Even the small 204 THE MODERN HIGH EXPLOSIVES. magneto-electric instruments used for medical purposes wilt explode these fuses without fail. " It may be mentioned, in illustration of the difficulties to be grappled with in such an inquiry as led to the production of this, fuse, that the first phosphide-of-copper mixture employed in the priming of these high-tension fuses contained finely divided coke as the conducting-medium (in place of the sulphide of copper afterwards used) ; and that, so far as uniformity and permanence were concerned, this mixture left little to be desired. But, in the course of searching experiments with such fuses, a slight residue, consisting chiefly of the coke employed, was found occasionally to remain between the closely contiguous poles of the fuse, after its ignition, and to form a connecting link or bridge between them, which interfered with the firing of other fuses in the arrangement, by completing the circuit through that one, and thus preventing the rapidly successive currents from a magneto-electric machine from performing work upon others in branch-circuits. The substitution of the readily com- bustible and dispersable sub-sulphide of copper, for the coke, conquered what appeared likely to prove a formidable difficulty. " The application of magneto-electric machines having been successfully accomplished, a series of experiments was carried on by the lecturer, with the valuable aid of Gen. H. Y. D. Scott, R.E., at Chatham, during the years 1857-58, on the explosion of charges, both land and submarine ; and the great advantages of these instruments, as regards simplicity and per- manent efficiency, over the voltaic arrangements then in use, were fully demonstrated. Very compact but powerful exploding- instruments were constructed by Wheatstone, and these have received many important applications. Thus the proof of cannon at Woolwich and the firing of guns, from a safe distance, in the numerous experiments at Shoeburyness, is effected by means of Wheatstone's exploder, which is, moreover, an important adjunct in all electro-ballistic experiments, when the operator desires himself to fire a gun at a particular moment. Magneto- electric machines have also been found very useful in connec- tion with blasting-operations on land, and in mines, except in instances when the absolutely simultaneous explosion of a large number is required. ELECTRICITY APPLIED TO EXPLOSIVE PUTPOSES. 20S " When the success of Wheatstone's exploders had been fully established, several other forms of magneto-electric machines were devised, especially on the Continent and in America. Powerful instruments, similar to Wheatstone's, were manufac- tured by Siemens and Halske of Berlin ; Markus of Vienna ■constructed very efficient instruments in which one separation and return of the armature to the magnet are made to explode the charges. The disadvantage of these instruments is, that a ■succession of currents cannot be obtained from them, as in the case of machines with revolving armatures : hence the number of mines which can be exploded by them in divided circuit is limited. Mr. Beardslee, an American electrician, also devised a modification of Wheatstone's exploder, in which the magnets are made to revolve between the armature coils, and which fur- nishes currents of greater quantity, but lower tension, than Wheatstone's. A fuse was constructed by Beardslee, for em- ployment with this instrument, similar in principle of construc- tion to Abel's. The materials which bridge over the space between the terminals, or poles, of the fuse, are black lead, with the addition of a minute quantity of a substance, apparently collodion, which adds to the size of the scintillations produced, when the current passes, and thus increases the certainty of ignition of the powder, which is in close contact with the poles. These fuses are efficient with magneto-electric instruments, which, like that of Beardslee, furnish currents of comparatively low tension ; but they are much less delicate than the Wool- wich fuses, and the number which can be simultaneously ex- ploded is, therefore, more limited. Wheatstone also constructed more powerful modifications of his original magnetic exploder, which might at will be made to furnish currents of greater quantity and lower tension, or to produce the high-tension currents. Lastly, Ladd, Browning, and Breguet produced in- struments of comparatively low price, but quite powerful enough for ordinary blasting and quarrying operations. The only ob- stacle — but a most important one — to the general use of these machines, for the explosion of mines on land and under water, is, that very slight defects in the insulation of the conducting- wire, which leads from the instrument to the mines, are fatal to their exploding-power. In consequence of the high tension 206 THE MODERN HIGH EXPLOSIVES. of the current developed by them, and the 'small quantity put into circulation by even the most powerful, the complete diver- sion of the current from its destined course to earth is promoted by the smallest points of escape presented to it, — a result which is, moreover, facilitated by the very high resistance of the fuses in circuit. With care this source of failure can be guarded against in operations on land : but such is not the case with regard to submarine arrangements ; while, moreover, very minute defects in the coatings of the wires, when submerged, which would hardly influence the results at all on land, com- pletely nullify the exploding-power of the machines. Hence magneto-electric instruments are the least reliable of all electric exploding-apparatus for submarine purposes. "A few experiments were instituted at Woolwich in 1857, on the employment of frictional electricity as an exploding- agent, and especially with a small hydro-electric machine con- structed for the purpose by Sir William Armstrong. The power of this machine to explode a number of charges simul- taneously, when it was in good working-order, far surpassed any other instrument experimented with at that time ; one hun- dred fuses, arranged in simple circuit, were frequently exploded by its means ; but the great uncertainty of its action, and the difficulty of employing it in the field, did not afford encourage- ment for continuing experiments with it. " The great difficulties encountered in the Austrian experi- ments, in attempts to employ glass frictional electric machines for military purposes, led Baron von Ebner to direct his atten- tion to the production of an instrument, in the construction of which glass was altogether avoided, and which might therefore be e.vpected to be less subject to atmospheric influences. His labors in this direction were eventually crowned with success : for he found in the hard vulcanized India-rubber (known as ebonite or vulcanite) a di-electric material excellently adapted to the construction of the frictional apparatus ; while, by em- ploying a sheet of soft vulcanized India-rubber, coated with tin-foil, and compactly rolled up, he obtained, without the use of glass, a powerful condenser, or Leyden-jar arrangement. The improved machines were constructed -in a very compact form (with cases excluding all the working-parts from direct ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 20-J exposure to air) by Messrs. Siemens of Berlin and Lenoir of Vienna, who exhibited specimens in England in 1862, at which time the electric machine had already received important appli- cations, and been regularly adopted for military use in Austria. Von Ebner had also, from the commencement of his experi- ments, labored assiduously at the production of an efficient fuse to be used with electricity of tension ; and the Austrian service is indebted to him for a simple and thoroughly service- able fuse, which, as regards the arrangement of its poles, and the character of the igniting composition, may be said to com- bine the principles of the Statham and the Abel fuses. Though much less sensitive than the Abel fuse, a very considerable number may be exploded in single circuit by the ebonite electric machine. The power of this apparatus, in its most portable form, is nearly equal to that of the hydro-electric apparatus just now referred to, when the latter was in perfect working order ; and a far greater number of mines may therefore be simulta- neously exploded by its means than by very large batteries, or by the most powerful portable magneto-electric machines hith- erto constructed. One hundred Abel fuses have frequently been simultaneously exploded with one of the portable machines ; and still greater results can be obtained with a larger instru- ment, havin'g a battery of condensers, which was specially constructed by the late Mr. Becker, at the suggestion of Capt. Maury, and designed for use in connection with land and sub- marine mines. In very damp weather, when the most perfect glass electric machines would have been useless unless housed in a warm apartment, from which the external air was excluded as much as possible, these ebonite machines have been used from time to time throughout the day with very satisfactory results. " Another important advantage which they possess over magneto-electric machines consists in the fact that very con- siderable defects in the insulation of even submerged conduct- ing-wires do not so greatly reduce the power of the current they furnish as to interfere with the accomplishment, by its agency, of the most extensive operations under water likely to occur in practice. Unfortunately, however, the very circumstance which constitutes their chief advantage — viz., the powerful character 2o8 THE MODERN HIGH EXPLOSIVES. of the current of high tension with which they charge an insu- lated wire — is also a source of serious defects, to be presently noticed, which very greatly limits the usefulness of these machines for naval and military purposes. "Other more recent Continental and. American forms of fric- tional machines, constructed of vulcanite or ebonite, in some of which fur is used as the exciting agent and different forms of condensers are employed, are in favor in different countries, or mining districts ; and one of the most compact and efficient exploding instruments, excellently illustrating the simplicity to which machines of this class can be reduced by ingenuity and a thorough knowledge of the conditions to be fulfilled by a really practical apparatus, is the frictional electric exploder, manufactured of various dimensions by Laflin and Rands of New York, in the form of an ebonite cylindrical box (or disc), on which the only protruding objects are the connecting-screws for wires, and the handle for working the machine. When the handle has been turned sufficiently to charge the enclosed con- denser, a reversal in motion of the same discharges the latter, and fires the mine. This machine has been found specially valuable in boat-work, under conditions when it would have been very difficult to use any other form of frictional machine, and when other electric exploding-apparatus, depending for their operation upon mechanical arrangements more or less accessible, would have sustained injury from the effects of contact with water, or an atmosphere laden with moisture or salt-water spray.' "Although ebonite frictional electric machines held their own for some considerable time, as the most powerful and generally effective exploding-apparatus, for extensive operations they had to make way for a class of machine which, as com- bining general efficiency with simplicity, power, permanence, and independence of any influence emanating from atmospheric or local conditions, now occupy decidedly the highest posi- tion as practically useful agents for developing explosions. It is scarcely necessary to say that the machines referred to ^ One defect of ebonite, in its application to the construction of frictional machines, is, that the surface becomes roughened and worn after a time by the amalgam used in the cushions, so that the discs require re-polishing occasionally. ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 209 are those known as dynamo-electric, the first conception and elaboration of which we owe to Werner and William Siemens, Wheatstone, and others. " The action of the most simple form of these instruments may be described as follows : The residual magnetism existing in an electro-magnet suffices to develop an induced current in a rapidly revolving coil-armature. This current, re-acting upon the electro-magnet, determines the development of powerful magnetism in the latter by the inductive action of its insulated coils ; the currents developed by the electro-magnet are, con- sequently, in their turn greatly increased in power, and re-act again upon the armature ; and thus a great accumulation of ■electric force is very rapidly accomplished. When that accu- mulation has reached the maximum attainable, without detri- ment to the insulation of the wire coils, a simple interrupting arrangement causes the current to be diverted from the machine to conducting-wires, by whose medium it is utilized. The de- tails of the machines vary according to the different plans adopted by the several constructors ; but the above explanation applies more particularly to the earlier machines of Siemens and Halske, who were the first to produce a small instrument of this class thoroughly applicable to mining purposes, and almost equal in power to the ebonite frictional-electric machine. Fifty Abel fuses, arranged in simple circuit, have been repeat- edly exploded, without any failures, by one of these machines ; it therefore provides with certainty the power necessary for the most extensive land or submarine mining operations, and is, at the same time, quite free from all disturbing atmospheric influ- ences. Its mechanism is simple, and less easily susceptible of derangement than that of most magneto-electric apparatus ; and, as it is independent of every thing but the application of manual power for the development of its action, it is far supe- rior to the most perfect of these, independently of the fact that it surpasses them all greatly in power. "Various improvements have been introduced into these dynamo-electric exploders by Siemens Brothers, some at the instigation of the Royal Engineers' committee, at whose rec- ommendation this instrument was adopted some years ago as the military-service exploding-machine. Other modifications ,2iO THK MODERN HIGH EXPLOSIVES. bf the dynamo-electric machine have recently been applied it> forms suitable for use as a portable mine-exploder. A smalt description of Burgin's machine, and a very simple American ratchet machine, are among the most efficient of the dynamo- exploders now constructed. "The Siemens high-tension dynamo-electric machine now used in the Royal Engineer service, and which is not too heavy to be carried some distance by one man, is capable of firing between one hundred and twenty and one hundred and fifty Abel fuses in continuous circuit, and over two hundred in two parallel circuits. "Although the phosphide-of-copper fuse was specially de- signed for use with generators' of high-tension electricity, sus- ceptible of advantageous employment as substitutes for voltaic batteries, its great sensitiveness to ignition rendered it equally available with voltaic piles, or batteries of high internal resist- ance; and this circumstance has exercised an important influ- ence upon the rapid development of methods of applying electricity to important uses connected with naval offensive and defensive warfare. " It has been pointed out, that magneto-electric instruments cannot be relied upon for submarine operations, on account of the very perfect insulation of the conducting-wires, joints, etc., required to insure success with them. On the other hand, fric- tional-electric and dynamo-electric machines supply ample power for the simultaneous ignition of numerous submarine mines, even through cables in the insulation of which some defects exist. Hence, when any extensive submarine operation has to be accomplished, these machines may be used with advantage ; but, for reasons to be presently pointed out, the frictional machine cannot be used as the exploding-agent in connection with a system of submarine mines, of which it may be desired to explode any one particular mine, while leaving others in its vicinity intact. Dynamo-electric machines share this disadvan- tage with the frictional machines, when applied in conjunction Arith high-tension fuses. In addition to the special attention required by both these classes of machines, in localities where they might be applied to submarine operations, there is one general objection to the use, in connection with naval and mill- ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 211 tary operations, of any source of electricity, the development of which is entirely dependent upon manual operations to be performed at the instant an electric discharge is required ; namely, that, however perfect all arrangements may be, their action at the last moment is still dependent upon individual vigilance and presence of mind. It need scarcely be stated, that this objection would vanish in the case of dynamo-electric machines, if power were provided for working them continuously as long as any possibility existed of their being required. " The only sources of electricity which at present thoroughly fulfil the conditions essential in the exploding-agent to be used with an efficient system of submarine mines are constant vol- taic batteries. By means of the high-tension fuse, it became possible to use batteries which were previously inapplicable to the explosion of mines ; because, even when employed in con- siderable numbers, the quantity of electricity furnished by them is not sufficient to effect the ignition of platinum-wire fuses. Thus a number of elements of a Daniell's battery, or a sand- battery, quite incapable of heating a platinum wire to redness, fire an Abel fuse with perfect certainty. The heat developed in the latter, by the passage of a current from such a battery, amply suffices to raise to its igniting-point the readily explosive priming-mixture, which serves as the conductor in the fuse. Moreover, the resistance presented by the fuse is so consider- able, in comparison with that offered by the longest cables likely to be used in actual practice, that a current from a bat- tery which possesses tension sufficient to overcome the resist- ance of the fuse will explode the latter with as much certainty, through cables of great length, as when it is close to the battery. A number of cells of a Bunsen battery, of sufficient power to ignite an Abel fuse, and also a fuse of platinum wire several inches long, when close to the battery, will no longer render even a very short piece of thin platinum wire moderately hot, if four or five hundred yards of ordinary conducting-wire be placed in the circuit ; while, on the other hand, its power to ignite an Abel fuse will not have become at all affected. It is evident from this illustration, that the necessity for greatly add- ing to battery-power, when mines are to be exploded through considerable lengths of wires, which existed with the use of 212 THE MODERN HIGH EXPLOSIVES. the wire fuses, is obviated by employing a high-tension fuse ; and thus one great objection to voltaic batteries, as exploding agents in mining-operations, was set aside. Again, the sand- batteries, or Daniell batteries, used for telegraphic purposes, which, when once charged, continue, with very little attention, in good working action for several months, could be substituted for the batteries (e. g.. Grove's or Bunsen's), which it was for- merly necessary to employ in order to attain sufficient quantity of current, and which only continue in good action for a few hours. Sand-batteries have been repeatedly employed at Wool- wich for the explosion of fuses, after having been in action four or five months, with the occasional addition of a little water to compensate for evaporation. " It will be thus seen, that constant voltaic batteries possess the essential qualifications of efficient exploding-agents for use with any system of mines which it is desired to maintain for lengthened periods in a condition ready for explosion at any moment. They are simple of construction, comparatively inex- pensive, require but little skill or labor for their arrangement or repair, and very little attention to keep them in constant good working-order for long periods ; and their action may be made quite independent of any operation to be performed at the last moment. " When first arrangements were devised for the application of electricity in our naval service to the firing of guns, and the explosion of so-called outrigger charges or mines, as originally used in boat attack in the American War, the voltaic pile rec- ommended itself for its simplicity, the readiness with which it could be put together and kept in order by sailors, and the con- siderable power presented and maintained by it, with very fair constancy, for a number of hours. Different forms of pile were devised at Woolwich for boat and ship use, the latter being of sufficient power to fire heavy broadsides by branch-circuits, and to continue in a serviceable condition for twenty-four hours, when they could be replaced by fresh batteries, which had, in the mean time, been cleaned and built up by sailors. The pile for use in boats was of very portable form, and was enclosed in a suitably fitted box to protect it from the weather. "The Daniell and sand batteries first used, in conjunction ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 213 with the phosphide fuse, in the earlier experiments for explod- ing submarine mines for purposes of defence, were speedily replaced by a modification of the battery known as Walker's, consisting of one zinc and two carbon plates immersed in dilute sulphuric acid. This battery was, after some time, converted into a modified form of the Leclanchd battery, the packed carbon plate being surrounded by a U-shaped zinc plate. " The importance of being able to ascertain, by direct elec- trical tests, that the circuits leading to a mine, as well as the fuses introduced into that circuit for exploding the mine, are in proper order, became manifest when these applications of elec- tricity were quite in their infancy. " The testing of the high-tension fuse, in which the bridge, or igniting and conducting composition, is composed of a mix- ture of the copper phosphide and sulphide with potassium chlo- rate, is easy of accomplishment (by means of feeble currents of high tension), in proportion as the sulphide of copper pre- dominates over the phosphide. Even the most sensitive fuses, i.e., those containing the highest proportion of phosphide, may be thus tested without fear of exploding them ; but when the necessity for a repeated application of tests, or even for the passing of an electric signal through the fuse, arises, as in the case of a permanent system of submarine mines, the case is different : for this particular fuse is susceptible of consider- able alterations in conductivity on being frequently, or for long periods, submitted to even very feeble test-currents ; and its accidental ignition, by passing through it such comparatively powerful test or signal currents as might have to be employed, becomes then so far possible as to create an uncertainty which is most undesirable. " For this reason, and also because the priming in these fuses is liable to some chemical change detrimental to its sensitiveness, unless thoroughly protected from access of moist- ure, another form of high-tension fuse, specially adapted for submarine mining-service, was devised at Woolwich. This, though much less sensitive than the original Abel fuse, was quite sufficiently so for service requirements, while it presented great superiority over the latter in stability and uniformity of electric resistance ; and, though it was not altogether unaffected 214 THE MODERN HIGH EXPLOSIVES. by the long-continued transmission of test-currents through it, their action was not found to become detrimental to the effi- ciency of the fuse. This tension fuse was prepared by com- pressing a very intimate mixture of graphite and mercury fulminate into a- cavity, in which the terminals of the fuse very slightly projected ; a feeble electric current was passed con- tinuously through the fuse during the operation of pressing, a galvanometer and resistance coil being in circuit, and the compression was continued until the desired resistance, or degree of conductivity, of the fuse was reached. To some comparatively small and variable extent, this conductivity fell gradually after the fuses had been manufactured ; but, on the whole, a remarkable degree of uniformity was attained in their production. " In the employment of these fuses, which are always used in pairs in a mine, they are carefully selected and classed by testing before actual introduction into the mines. " Although high-tension fuses presented decided advantages in point of convenience and efficiency over the platinum-wire fuse, as used in the earlier days of electrical firing, the require- ments which arose, in elaborating thoroughly efficient permanent systems of defence by submarine mines, and the demand for a form of battery for use in ships, which would remain practically constant for long periods, and thus dispense with the necessity for frequent attention to the firing arrangements, caused a very careful consideration of the relative advantages of the high and low tension systems of firing to result in favor of the employ- ment of wire fuses for these services. The limits placed upon the amount of test or signal current which could be passed even through the least sensitive high-tension fuse, and the tendency of the latter to alter in conductivity when submitted to the action of those currents for long periods, were considera- tions decidedly in favor of the conclusion arrived at. In addi- tion to these, there was an element of uncertainty, or possible danger, in the employment of high-tension fuses, which, though in part eliminated by the employment of voltaic batteries in place of generators of high-tension electricity, might still occa- sionally constitute a source of danger; namely, the possible liability of high-tension fuses to be accidentally exploded by ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 21 5 ■currents induced in cables, with which they were connected, during the occurrence of thunder-storms, or of less violent atmospheric disturbances. "It has been amply demonstrated by experiment, and by results obtained in military operations, that if insulated wires, immersed in water, buried in the earth, or even extended on the ground, are in suiBcient proximity to one another, each cable being in circuit with a high-tension fuse and the earth, the explosion of any of the fuses by a charge from a Leyd en- jar, or from a dynamo-electric machine of considerable power, may be attended with the simultaneous ignition of the fuses attached to adjacent cables, which are not connected with the source of electricity, but which become charged by the induc- tive action of the transmitted current to a sufficient extent to produce this result. Such being the case, it appears very pos- sible that insulated cables, extending to land or submarine mines in which high-tension fuses are enclosed, may become charged inductively, during violent atmospheric electrical dis- turbances, to such an extent as to lead to the accidental explo- sion of such mines ; many well-authenticated cases being on record. " In consequence of the difficulties experienced in the special application of the high-tension fuses to submarine purposes, arising out of the circumstances just alluded to, the production of comparatively sensitive low-tension fuses, of much greater uniformity of resistance than those employed in former years, was made the subject of an elaborate experimental investiga- tion by the lecturer, in the course of which several points of interest and of value in the subsequent application of the results were arrived at. It was found that very considerable differences in the amount of forging, to which the metal in the form of sponge had been subjected, did not affect to any important extent either its specific gravity or its conductivity, and that the fused metal had only a very slightly higher degree of conductivity than the same sample forged from the sponge. It was, therefore, clearly established, that the conductivity of such very fine wires as it was proposed to use in the construc- tion of fuses was but slightly affected by physical peculiarities of the metal of which they were composed, and that the con- 2l6 THE MODERN HIGH EXPLOSIVES. siderable differences in conductivity, observed in different sam- ples of platinum, were ascribable to variations in the degree of purity of the metal. As it appeared likely, therefore, that more uniform results would be attained by the employment of some alloy of definite and uniform composition as the bridge for low-tension fuses, than by the use of commercial platinum, varying considerably in composition, experiments were made with fine wires of German silver (which had been used by a well-known American electrician, Mr. Farmer, in the construc- tion of comparatively sensitive wire fuses), and of the alloy of sixty-six of silver with thirty-three of platinum, employed by Matthiessen, for the reproduction of B. A. standards of elec- trical resistance. It was found that both these alloys were greatly superior to ordinary platinum in regard to the .sist- ance opposed to the passage of a current, and the heat conse- quently developed in given lengths of wire of a particular diameter, and that German silver was, in its turn, superior in this respect to the platinum-silver alloy, although the difference was only trifling in the small lengths of fine wire used in a fuse (0.25 inch). On the other hand, the comparatively ready fusibility of a platinum-silver wire contributed, with other phys- ical peculiarities of the two alloys, to reduce fine German- silver wire to about a level with it. Moreover, German silver was found not to resist the tendency to corrosive action exhib- ited by gunpowder, and other more sensitive explosive agents^ which have to be placed in close contact with the wire bridge in the construction of a fuse, so that the latter may be at once fired, when the required heat has been developed, by the resist- ance which the wire bridge offers to the current : platinum silver, on the other hand, was found to remain unaltered under corresponding conditions of exposure. " The superiority of platinum silver, and even German silver, as a material for the bridges of fuses, appeared, therefore, to be established from a practical point of view ; but eventually very fine wires of an alloy containing ten jDer cent of iridium were selected as decidedly the best materials for the production of wire fuses of comparatively and very uniform high resistance^ this alloy being found decidedly superior in the latter respect^ as well as in point of strength (and, therefore, oi manageable- ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 217 ness in the state of very fine wire, o.ooi inch in diameter), to the platinum-silver wire. The fuses now used in military and submarine service are, therefore, made with bridges of iridio-platinum wire, containing ten per cent of the first-named metal ; the wire bridge in the fuses for submarine mining ser- vices, which are fired by means of Leclanch^ batteries, being somewhat thicker, and therefore of higher conductivity, than those used for land service, which are exploded by low-tension dynamo-electric machines, manufactured by Siemens Brothers. "The electrical gun-tubes used in the navy are fired by means of a Leclanch^ battery, specially devised for the pur- pose, and the circuits to the different guns are arranged in branch. When broadside firing is required, it is important that the wire bridge of any one of the gun-tubes which is first fired should be instantaneously fused on the passage of the current, so as to cut this branch out of circuit. In this respect it was believed that the platinum-silver alloy, being much more fusible than iridio-platinum, presented an advantage, and hence the naval electrical fuses are made with bridges of that alloy : there is, however, no reason to believe that the finest wire of iridio- platinum is not quite as efficient for this particular service. " It is very possible, now that dynamo-electric machines are applied to illuminating purposes in our large ships of war, and that the electric light is used for signalling and tactical pur- poses at the submarine-mining stations of our naval ports, that the explosion of mines and the firing of guns by dynamo- electric agency may also be provided for in time to come ; as there would be no difficulty in providing the power for working these continuously, whenever they were likely to be called into use." In regard to the applications of electricity to the explosion of gunpowder, Mr. Abel says, — " One of the earliest of these was the firing of guns upon proof at Woolwich by the voltaic battery ; which was very efficiently carried out, as far back as 1854, by Sergeant McKin- lay, the proof-master, who employed a Grove battery, and con- structed a very neat gun-tube, which was fired by a platinum- wire bridge, surrounded by gunpowder in a small cup fixed on 2l8 THE MODERN HIGH EXPLOSIVES. the top of the tube, the wire bridge being soldered to two small copper tubes, or eyes, which passed through the cup, and served to receive the terminals of the battery, — an arrangement which was applied in various forms of electric tubes and fuses after- wards devised. The current was successively directed into the individual circuits connected with the guns, to be proved at one time by means of a simple shunt-apparatus. Before the employment of this arrangement, the proof of guns was more than once attended by casualty, consequent upon the uncertain nature of the appliances which had to be adopted in firing the guns by means of a species of time-fuse. When the high- tension phosphide electric fuse had been devised, gun-tubes were made to which it was applied ; and after the proof opera- tions had been carried out for some time by their means, with the use of Henley's large magneto-electric machine, an exploder was arranged by Wheatstone, which was provided with a large number of shunts, so that as many as twenty-four guns might be brought into connection with the instrument in rapid suc- cession, and fired by the depression of separate keys connected with each. " The regulation of the time of firing the gun, by electrical agency from a distance, appears first to have been accomplished in Edinburgh, where, since 1861, the time-gun has been fired by a mechanical arrangement, actuated by a clock, the time of which is controlled electrically by the mean-time clock at the Royal Observatory on Calton Hill. " Shortly after the establishment of the Edinburgh time-gun, others were introduced at Newcastle, Sunderland, Shields, Glas- gow, and Greenock. The firing of the gun was arranged for in various ways. In some instances it- was effected, either direct from the observatory at Edinburgh, or from shorter dis- tances, by means of Wheatstone's magneto-electric exploders. " Unquestionably, however, the low-tension gun-tubes, having a bridge of very fine platinum-silver wire, surrounded by readily ignitable priming composition, are much more suited to our naval requirements than the comparatively very sensitive high-tension fuse. "The arrangements in Her Majesty's ships for firing broad- sides electrically, and also for the electrical firing of guns in ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 2ig turret-ships, have been very carefully and successfully elaborated in every detail, including the provision of a so-called drill or dummy electrical gun-tube (which is used for practice, and re- fitted by well-instructed sailors), the careful testing and balan- cing of the gun-tubes, examination of the gun-circuits, etc. ; and the guns may be fired, either simultaneously from the conning- tower on deck, or independently. For gun-firing, ships are supplied with a set of six very large Leclanche cells, arranged in series, a stout zinc plate being on either side of the packed carbon element, which is built of four gas-carbon plates attached to one common bridge. The ebonite trough, containing the plates, etc., measures sixteen inches in length, and is nine inches deep by two and three-fourths inches wide. The object of these large cells is to obtain a considerable quantity of elec- tricity with as few elements as possible, thus reducing the loss of power which occurs when a large number of separate cells are connected up. The power of this battery-force is main- tained for a long period, in excess of the work it has to perform. A very portable arrangement of the Menotti form of Daniell battery, fitted with a galvanometer, is provided for testing bat- teries, etc., both for ship and boat service. The firing-keys, and all other arrangements connected with electrical gun-firing, are specially designed to insure safety and efficiency at the right moment. " The battery supplied for the firing of outrigger torpedoes, and for other operations to be performed from open boats, con- sists of a portable arrangement of three smaller cells of the Leclanche battery (the carbon element fitting into a U-shaped zinc plate) enclosed in a box, which is fitted externally with connecting-screws, and a firing-key, with safety arrangement to guard against its acting accidentally, and a strap to pass over the operator's shoulders, so that he has the instrument quite at his command in front of him. The electric detonators used with this battery correspond, so far as the bridge is con- cerned, with the naval electric gun-tubes. "The subject of the application of electricity to the explo- sion of submarine mines, for purposes of defence and attack, received some attention from the Russians during the Crimean War under the direction of Jacobi. Thus a torpedo, arranged 220 THE MODERN HIGH EXPLOSIVES. to be exploded electrically when coming into collision with a vessel, was discovered at Yeni-Kale, during the Kertsch expe- dition in 1855. Torpedo defence, in its most simple form, was first applied by the Austrian Government in 1859, when a sys- tem of submarine mines, to be fired through the agency of elec- tricity by operators on shore, was arranged by Von Ebner for the defence of Venice, which, however, never came into practi- cal operation. Early in i860 Henley's large magneto-electric machine, with a supply of Abel fuses, and stout India-rubber bags with fittings to resist water-pressure, were despatched to China, for use in the Peiho River ; but no application appears to have been made of them. The subject of the utilization of electricity for purposes of defence did, however, not receive systematic investigation in England or other countries until some years afterwards, when the great importance of subma- rine mines as engines of war was demonstrated by the number of ships destroyed and injured during the war in Arnerica. Twenty-five vessels belonging to the Federal navy were de- stroyed, and nine others injured, by the explosion of mines and torpedoes ; while the Confederates lost three vessels by acci- dentally coming into collision with their own mines, and one which was attacked by means of a torpedo, and destroyed by the Federals. In only two of these cases of destruction, how- ever, were the explosions accomplished by electrical agency : in all the others, the mines were exploded by mechanical means. " It was towards the close of the labors of the so-called Float- ing Obstructions' Committee (in 1867) that the School of Sub- marine Mining at Chatham, and the Naval Torpedo-School at Portsmouth, were developed, the foundation of the latter having been laid at the Chemical Department, Woolwich. Some Con- tinental governments also devoted attention to the subject of the application of electricity to submarine mines at about this time, and more especially the Austrian Government, for whom Baron von Ebner, who had already applied submarine mines to the defence of the harbor-entrance of Malamocco in 1859, devised an ingenious and elaborate system of electric-torpedo defence, for employment in conjunction with his high-tension fuses, which was applied to the defence of Venice, Pola, and ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 221 Lissa during the war of 1866, though its efficiency was not put to any actual test, except by way of experiment. " The application of electricity to the explosion of torpedoes was, as stated, very limited during the American war; but arrangements for the extensive employment of that agent as the exploding-power were far advanced in the hands of both the Federals and Confederates at the close of that war ; men of very high qualifications — such as Capt. Maury, Mr. N. J. Holmes, and Capt. McEvoy — having worked arduously and successfully at the subject. " The most important advantages secured by the application of electricity as an exploding-agent of submarine mines are as follows : They may be placed in position with absolute safety to the operators, and rendered active or passive at any moment from the shore ; the waters which they are employed to defend are therefore never closed to friendly vessels until immediately before the approach of an enemy ; they can be fixed at any depth beneath the surface (while mechanical torpedoes must be situated directly or nearly in the path of a passing ship), — a circumstance which very considerably simplifies the arrange- ments for their application in tidal waters ; lastly, electric mines may, when no longer required, be removed with as much safety as attended their application. "There are two distinct systems of applying electricity to the explosion of submarine mines. The most simple is that in which the explosion is made dependent upon the completion of the electric circuit by operators stationed at one or more posts of observation on shore. The particular mode of arrange- ment, and the operation to be adopted, depend, in great meas- ure, on the nature of the locality to be defended. If this be a river or channel, the plan of arranging and exploding mines is comparatively simple, but will serve sufficiently to illustrate the general nature of this system of applying torpedoes. The mines are arranged across the river or channel in rows or lines, converging towards a station on shore, to which the conducting cables are led which are to connect each mine with the explod- ing-instrument. The operator at this station has it in his power, therefore, to explode any one of the mines at will, by comple- tion of the circuit through the particular cable and the earth. 222 THE MODERN HIGH EXPLOSIVES. Some other position on shore is selected as a second station, which commands points of view intersecting the lines of mines. The operators at the two stations are placed in telegraphic com- munication with each other ; and, when a ship is observed by the operator at the second station to approach in the direction of any one of the mines, he will signal -to the man who looks along this line, and the latter will complete circuit as soon as the vessel appears over the particular mine specified. Should the vessel alter her course in approaching the mine, the operator at the observing station will inform the man at the firing station, who will alter his arrangements accordingly. Or the man at the observing station, when he perceives a vessel to approach in a line with any of the mines, places the cable of that mine in electric connection with the operator at the other station ; and the latter will complete the circuit through the earth as soon as he sees that the vessel is over the first line of mines. Other more or less elaborate modifications of these modes of observ- ing and exploding have been proposed : they all depend for efficiency on the experience, harmonious action, and constant vigilance of the operators at the exploding and observing sta- tions. They are, moreover, entirely useless at night, and in any but clear weather. Mines arranged solely for firing by observation are therefore not to be compared in general effi- ciency to self-acting mines, which are either exploded by their collision with a ship, whereby electric circuit is completed within them, or by the vessel strilcing a circuit-closing arrange- ment moored near the surface of the water, whereupon either the mine, moored at some depth beneath, is instantly exploded, or a signal is furnished at the station on shore, which indicates to an operator the particular mine to be exploded. The object to be attained in these circuit-closing apparatus, which are so moored as to be within range of a passing ship, is to oppose in the path of a vessel a contrivance which will not be affected by the motion of the water, but which will complete electric cir- cuit between the conducting-cable and the fuse, or will bring a relay into operation which throws the fuse into circuit with the firing-battery if the circuit-closer be struck in some particu- lar part, or thrown into a particular position by the advancing ship. Many ingenious contrivances have been devised for this ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 223 purpose, and experimented with ; but only a few have furnished satisfactory results, the conditions essential to success being numerous, and their combined fulfilment not easy of attainment. Simplicity of mechanism, and a combination of sufficient but not excessive delicacy of action, with permanence during long immersion, are among the most important objects to be aimed at in the construction of these circuit -closing or signalling machines, or self-acting mines. " One of the earliest circuit-closers with which any measure of success was obtained was devised by the lecturer in 1864, and extensively experimented with by successive committees at Chatham : though efficient of its class, it was decidedly infe- rior to circuit-closers of which the entire mechanism is enclosed, and therefore protected from injury. Of this class, the first really efficient one was that devised by Mr. Matheson (late quartermaster-sergeant, R.E.), which was adopted into the ser- vice some years ago, and was gradually modified and improved until the present English service circuit-closer was produced. " In an official report upon investigations to develop a sys- tem of submarine mines for defending the harbors of the United States, printed in 1881, Gen. Abbot includes an account of a most valuable series of experimental and theoretical inves- tigations of the physical phenomena and force developed by submarine explosions with all the most prominent explosive mixtures and compounds, and of the properties and relative merits of the various high, medium, and low tension fuses, and of every class of electrical igniting-apparatus. This work is rich in original and important observations and deductions, and well illustrates the very comprehensive nature of the science of submarine mining. " Illustrations of actual results capable of being produced in warfare, by the application of electricity to submarine opera- tions, have hitherto been very few ; but of the moral effects of submarine mines we have already had abundant proof. " The application of electricity to the explosion of military mines, and to the demolition of works and buildings, from a safe distance, has, it need hardly be stated, been of great im- portance in recent wars in expediting and facilitating the work of the military engineer. 224 ^^^ MODERN HIGH EXPLOSIVES. "The application of electricity to the explosion of mines for land-defences during active war is by no means an easy opera- tion ; inasmuch as not only the preparation of the mines, but also the concealment of electric cables and all appliances from the enemy, entails great difficulties, unless circumstances have permitted, or have appeared to render it prudent to make, the necessary arrangements in ample time to prevent a knowledge of them reaching the enemy. " Electrical blasting, especially when used in combination with rock-boring machines, has revolutionized the operations of tunnelling and driving of galleries; and although in ordi- nary mining and quarrying operations the additional cost in- volved in the employment of fuses and conductors, and the original price of the exploding-machine, are not unfrequently of serious consideration, there are, even in those directions, many occasions when the power of firing a number of shots simultaneously is of very great importance. There is little doubt, moreover, that accidents in mining and quarrying would be considerably reduced in number if electrical blasting were more frequently employed, especially in dangerous mines, in- stead of the comparatively uncertain system of firing by slow- burning fuse. Many men meet their doom through going up to a shot-hole, in the false belief that the fuse has burned out or become extinguished. With electric firing the simplest pre- cautions suffice to insure absolute safety. "A substitute for electrical firing, which possesses consider- able merit, and which has been applied with success to the practically simultaneous firing of several charges, claims a passing notice here. It is a simple modification of the Bick- ford fuse, which, instead of burning slowly, flashes rapidly into flame throughout its length, and hence has received the name of instantaneous fuse, the earliest form having been brought from America under the name of lightning fuse. The fuse, as manufactured by Messrs. Bickford, Smith, & Co., burns at the rate of about a hundred feet per second : it has the general external characteristics and flexibility of the ordinary mining- fuse, but is distinguished from the latter by a colored external coating. Numerous lengths of this fuse can be coupled up together in a simple manner, so as to form branches leading ELECTRICITY APPLIED TO EXPLOSIVE PURPOSES. 22? to different mines, or shot-holes, which may be ignited together, so as to fire the holes almost simultaneously. In the navy this fuse is used as a means of firing small gun-cotton charges, which may be thrown by hand into boats, when these engage ■each other, the fuse being fired from the attacking boat by means of a small pistol, into the barrel of which the extremity is inserted. In hurried attacks of this nature, it .would be difficult to deal with wires and electrical exploders. "The conveniences presented by electric-firing arrangements, imder special circumstances, are interestingly illustrated by a novel proceeding at the launch of a large screw-steamer at Kinghorn, in Scotland, about a year ago. This launch was accomplished by placing small charges of dynamite in the wedge-blocks along the sides of the keel, and exploding them in pairs, one on each side of the vessel ; hydraulic power being applied at the moment that the last wedges were shot away. " In the deepening of harbors and rivers, and the removal of natural or artificial submerged obstructions, the advantages of electric firing are so obvious that it is only necessary to refer to them : but this account of the application of electricity as an exploding-agent cannot be better concluded than by a brief recital of the most extensive operation of the above kind which has hitherto been carried out ; namely, the destruction of the reef of Hallett's Point (Hell Gate) in East River, New York, in September, 1876, as described hereafter." PART III CHAPTER I. PRINCIPLES OF BLASTING. The following extract from Mr. Drinker's excellent work ' best illustrates THE PRINCIPLES OF BLASTING. " Now, what is blasting .' It may be defined to be the rend- ing, or tearing apart, of any solid body, by the pressure or shock exerted upon it from the sudden development of gas of high tension, evolved on the ignition of some explosive compound placed contiguous to it. As the drilling of the holes may be said to be the dearest part of blasting, it follows that great care should be taken in setting each hole in such a position, and in drilling it of such width and depth, as to insure the greatest effect at the least cost. When we recall the many circum- stances that may influence the effect of a shot, it is evident that the proper setting of a hole is a matter rather of judgment based on experience than one to be decided by empirical rules ; for, even were a set of rules deduced from experiments in one material, they would only apply, under similar circumstances, in the same material. The effect of a shot may be influenced, among other considerations, by, — " (a) The shape in which the rock is presented, the size and number of the open faces, the shape of the piece it is desired to take out (if that is an object), and, of course, primarily, the size of the cross-section of the face, if it is heading-work. " (d) The texture of the rock, — whether it is hard or easy, ' Drinker on Tunnelling. Published by John Wiley & Sons, Astor Place, New Vork City. 229 230 THE MODERN HIGH EXPLOSIVES. firm or loose, whether it is brittle or tough. Thus experience gained in blasting close-grained, hard granite, trap, gneiss, etc., would not apply to limestone, sandstone, slate, etc. " if) The structure of the rock, as to whether it is laminated, stratified, or fissured ; upon its cleavage, etc., and upon whether it is massive or broken, etc. " {d) The elasticity of the rock. " (e) The explosive used. " (/) Whether the hole is to act alone, or simultaneously with or following others. In the case of simultaneous firing, the question arises, of how the waves of oscillation will best act in concert. " k^ The character of the fuse and tamping. " And now, supposing a shot is to be placed in any position whatever, we have seen that its action will be in the line of least resistance with the lower explosives ; and its greatest effect will also be in the direction of that line with the higher ones (as to the difference between the two terms, see p. 97). Let us consider the line of least resistance in black-powder. We must assume, that, on ignition, the gases developed act, prima- rily, radially ; that therefore the tension of the gas extends from the point of ignition (which must be assumed to be in the centre of the charge) in all directions ; and that, according to the location of the charge and of the number and relation of the open faces, an undulation in the rock is produced, which, when the limit of elasticity is passed, will cause the splitting and tearing apart of the rock ; and, as the force developed will naturally find its vent by the shortest road, the distance between the charge and the nearest external point is called the line of least resistance. " (In a perfectly homogeneous material, a regular funnel or crater would be formed; but this, of course, is only approxi- mately attained. In actual practice, an irregular separation of the rock is effected.) " We accordingly have the following general rules : — " I. The hole should not be located in the line of least resist- ance, otherwise the tamping would simply be blown out. (Be it remembered, this discussion is as to black-powder, not nitro- glycerine.) PRINCIPLES OF BLASTING. 231 " 2. Experience has established the average ratio between the depth of hole and the length of the line of least resistance to be as four to three, or the length of the line of least resist- ance will be three-quarters of the depth of the hole ; and expe- rience has further shown, that the charge of black-powder should be, on the average, about one-third (}) of the depth of the hole, the varying limits being .29 to .45. " If, in a massive rock not fissured, presenting a vertical face, we bore a hole a b (Fig. 47), we may, in general, expect a break Fig. 47. Fig. 48. In the general direction a b c, which can be measured by the line b c drawn perpendicular to a b. It is, moreover, proved by general experience, that the sphere of rupture determined by i c will seldom be larger than the depth a b oi the hole ; and it would probably be equal Xo a b only in very easy material, when a b\% set at an angle of less than forty-five degrees with the facj a c. If we bore the hole ^/"(Fig. 48) on an angle of forty- 232 THE MODERN HIGH EXPLOSIVES. five degrees, we will have for the length/,^ of the line of least resistance the expression, fh = efcos 45° = ef.707 ; by which the greatest possible value (f) is reached. "While in Fig. 47, on account of the assumed firmness,, structure, coherence, etc., of the rock, the line of least resist- FiG. 49. Fig. 50. ance formed an angle less than forty-five degrees with the face, there may be other cases (Fig. 49) where the hole should be set at a greater angle, — say even sixty degrees. In this instance, if the face z in be all firm rock, it is not probable that the vol- ume i k m would be detached ; but, in general, the wedge i k g n would be ejected. But, say op represents a fissure or holing, or perhaps an open face produced by a former shot, we may then, irrespective of the line of least resistance k I, assume, that, under favorable circumstances, the section i k o p would PRINCIPLES OF BLASTING. 23i be thrown, provided k o he not larger than the depth / k of the hole. From these considerations, we may deduce that, — "3. Holes ought, in general, to be bored at or under an angle of forty-five degrees : a larger angle, increasing to as much as ninety degrees, is advisable when open faces (as r s in Fig. 49) occur, and a smaller angle (Fig. 47) is ad- visable when the tex- ture and structure of the rock necessitate as- suming the line of least resistance as less than three - quarters of the depth of the hole. Fur- ther, as the mass thrown breaks in the general direction of the line of least resistance, and as, in fact, this line lies in the mass ejected, or, in the extreme case of an angle of ninety degrees, bounds the ejected mass, we must carefully ob- serve, — "4. The external shape of the rock, in order to reach a maxi- mum effect. " (a) \i af (Fig. so) represents a hole paral- lel to the open face e b, the line of least re- sistance e d will indicate the general throw of the shot. It will not be necessary to bore the hole a f to the total depth e b, for it may be assumed in most cases that a curve will be formed in the general direction / b. Similarly, we may pre- sume, under favorable circumstances, that the blast will also break in the direction f g. The shot « /would have been set nJ'ku Fig. 51. 234 THE MODERN HIGH EXPLOSIVES. very favorably if there ran from g a crack about parallel to the hole, and from b another perpendicular to it. "((5) If, as in Fig. 51, we assume an existing lower cut in the cavity at d, we might then take b d zs, the line of least resistance, and to obtain a maximum would extend it to three- quarters of the depth of the hole, — i.e., set the hole still more obliquely than shown in the figure ; for, in this case, the deeper the hole, and the more the rock to be blasted bulges, the greater will be the result of the shot. " (c) The shot a b (Fig. 52) may be considered as an unfavorable case, provided the hole cannot be set above a ; for now the shot can only break approximately in the lines a b f as, if the line of least resistance were sought in a line drawn perpendicular to the hole, it would be nearly vertical : fur- ther, the shot cannot act as far as d (supposing the rock to be solid), for the distance c d is longer than the hole a b. A hole set more obliquely at a, and bored to a greater depth, would be also unfa- vorable ; for the mass of the por- tion _/" the stump, and by raising the stump out of the ground with a cartridge placed in it, or, still better, below it ; this posi- tion depending on the condition of the ground (Figs. 105 and 106). The simultaneous explosion of these charges, accompanied by a dull report, causes the tearing of the stump and its sepa- ration from the main roots, and also the breaking of the adjoin- ing smaller ones. FiG. 103. GRUBBING OR BLASTING OF STUMPS. 317 Only small fragments of wood are thrown to any distance. If electric ignition is not possible, the arrangement of the bore-holes in the strongest roots is dis- pensed with : all of those which are ex- posed must be chopped off, and the charges are placed under the stump and exploded (Figs. 104 Fig. 104. and 105). The bor- ing of stumps downward from the radial cut, or sideways, clean into the root-knob, has proven somewhat impracticable. The charges for shots in the roots are from two to four ounces, and the charge under the stump, if about thirty inches in diameter, sixteen ounces of dynamite No. i. For larger stumps, this charge has to be increased in proportion. For tamping these bore-holes, earth may be used. Stumps already taken out are torn into pieces through bore- shots which are arranged analogous to those of tree-blasting, but the charges are much smaller. The following rules can be laid down : — 1. The side-roots ought to be chopped off. 2. The bore-hole ought to penetrate into the main root, and even Fig. 105. go through it. 3. The bore-hole ought to have three times the length of the powder-charge. 4. The tamping ought to fill the bore -hole to the top. Where heavy stumps, of say five feet diameter, are to be operated on, bore down from the top three perpendicular holes, which are parallel to one another and about one foot apart. There is not only a saving of time and labor by grubbing stumps with high explosives, but an additional advantage is 3l8 THE MODERN HIGH EXPLOSIVES. gained by shaking up the ground, and rendering it fit for agri- cultural purposes. The young trees are not injured by this operation ; but, on the contrary, the saplings seem to grow more vigorously in the shaken soil. The following rules are generally applied in this operation : — When the stump is above ground, and the wood is sound, the hole is made in the middle of it, and directed toward the strongest root. The hole should always go through the healthi- est and most resisting part of the stump. In case the stump is rotten, the hole should be bored through the strongest root. Examples. — Oak Stumps. — Seventeen oak stumps from six to nine inches above the ground, and from twenty-four to forty inches in diameter, were blown out with three pounds of No. I dynamite. The depth of the bore-holes varied from twelve to eighteen inches, and the time required to make each hole with an auger was from four to five minutes. The result was five hundred cubic feet of cord-wood, and it required ninety-nine hours of labor to accomplish this result. It took about fourteen minutes to bore, load, and fire each stump. Seventeen similar stumps, grubbed out with an axe and wedge, took a hundred and forty-two hours' labor. The -comparison of labor and economy stands as follows : — 1. Grubbing with dynamite : — , Labor for boring and blasting, 4 hours at 20 cents per hour . %o 80 Labor for chopping the pieces, and piling up, 99 hours at 20 cents 19 80 3 pounds No. I dynamite at 50 cents per pound i 50 17 caps at r cent apiece 17 25 feet of fuse at i cent per foot 25 Total JS22 52 2. Grubbing with axe and wedge : — 142 hours at 20 cents per hour $28 40 A saving of $5.88, which, with cheaper labor, can be in- creased. Poplar Stumps (from a French report). — The result of work executed on poplar stumps, which were completely embedded in the ground, and were mostly rotten in the centre, is here given. This occurred in preparing the ground for the founda- tions of a large building. All the holes made in one stump GRUBBING OR BLASTIXG OF STUMPS. 319 were connected by wires, and fired by electricity. Most stumps had three holes in the body, and one in the main root. (a) One enormous stump, composed of three trunks of the following dimensions, interlaced together: diameters, two metres twenty centimetres, two metres fifty centimetres, and two metres eighty centimetres, — required the boring of ten holes, and the time occupied in boring was seventy minutes. The charge was 1,365 grams of dynamite. The effect was good ; but one of the stumps remained in- tact, requiring three more holes and 332 grams of explosives to disrupt it. The whole was shattered, and could easily be removed. (b) Stump one metre eleven centimetres in diameter, and four metres seventy-four centimetres long, required seven holes charged with 1,000 grams of dynamite. The effect was good, but not sufficient. Six new holes were bored, and a charge of 680 grams used. A good result ensued, and what little re- mained of the stump was easily removed with an axe. {c) Diameter one metre ten centimetres, length two metres twenty -one centimetres. Three holes, charged with 580 grams, were fired. The effect was satisfactory, with the exception of one strong piece, which remained. Another hole, charged with 120 grams, removed this block. Blasting of Stumps in Austria.^ — (a) At Hohmanns Klippen, a trial was made on 368 stumps, of which 221 were old oak stumps, and the rest were beech-tree stumps ; and they gave 413 cubic metres of wood, at an expense of 934 francs, as per details : — ft. c. Labor required for 413 cubic metres wood at i franc 95 centimes per cubic metre 806 30 28-ji^j kilos of dynamite at 4 francs per kilogram 1 1 2 50 425 caps at 2 centimes 8 50 Fuse 6 75 Total 934 05 The price per cubic metre of wood thus came to two francs twenty-five centimes. (p) Spielberg. (183 stumps.) There were 34 old oak, two ^ From a report made by Mr. Trautzl. 320 THE MODERN HIGH EXPLOSIVES. red-beech, and 147 white-beech stumps. The product was 279 cubic metres of wood at two francs twenty-three centimes the cubic metre, of which one franc ninety-five centimes was for labor, and twenty-eight centimes for material. (c) Kahlenberg. (690 stumps.) There were 310 old oak, 61 red-beech, and 319 white-beech stumps. Product 1,213 cubic metres of wood, costing two francs seventeen centimes per cubic metre, of which one franc' ninety-five centimes was for labor, and twenty-two centimes for material (The remark is to be made here, that wages, in those coun- tries, are very low as compared with the United States ; and laborers receive from two francs to two and a half, or barely fifty cents per day.) There is generally, in those countries, an economy of fifty per cent in time and twenty per cent in money in removing stumps by high explosives. {d) Nine stumps having diameters from sixty centimetres to one metre were blasted with dynamite, and nine stumps of same dimensions were taken out by hand-labor. In both cases, six cubic metres of wood were obtained. In the first case, ten and a half hours were required, and twenty hours in the second, — a saving of fifty per cent in time in favor of the explosives. The expenses were respectively seven francs fifty centimes and seven francs eighty centimes. {e) The blasting-out of sixteen oak stumps, whose diameter varied from seventy centimetres to one metre twenty-five centi- metres, with bore-holes from twenty-five centimetres to forty centimetres, required fifty-nine hours' labor and one and a half kilograms dynamite, sixteen caps, and six and a half metres fuse. They produced fourteen cubic metres of wood. The total expenditure was twenty-nine francs fifteen centimes, or two francs ten centimes per cubic metre of wood. The same labor with the axe required a hundred and forty-one hours' work at forty centimes, or fifty-five francs ten centimes, — an econo- my in favor of the explosive, of fifty per cent in money and fifty- eight per cent in time. The results of a great number of trials have led to the follow- ing conclusions : — A hundred stumps, varying from fifty centimetres to one BLASTING OF PILES AND BEAMS. 321 metre in diameter, require twenty hours' work, and from five to ten kilograms (average eight kilograms) of explosives, be- sides a hundred caps, and a hundred metres of fuse. Mr. M. V. Hamm, of the Department of Agriculture in Austria, gives the following views on the subject : — "There is no doubt that the employment of high explosives in grubbing out stumps is of great economic value, as the soil is thereby prepared for different agricultural purposes. But what lends it most value is the mortal blow which the employ- ment of explosives strikes at the noxious insects ; as in blasting out the stumps and roots the ant-hills are destroyed, whose inhabitants carry devastation in all directions. There is hardly a for- ester who is ignorant of the evils of these little insects, and who will not appreciate this advantage in its proper light. In a very short time the clearings can be rid of all stumps and roots, and, in most cases, the wood gained covers the expenses ; and, no doubt, it will be everywhere adopted in place of the hard and laborious task of clearing stumps with axe and wedge." BLASTING OF PILES AND BEAMS. Blasting of Piles. — If the piles reach above the water, and are to be torn out below the bed of the stream, then a hole is bored in the axis of the pile to the required depth, and charged with one pound of dynamite No. i. But, if piles are to be broken off on a level with the bed of the stream, then the charge is tied to a wooden hoop, and pushed down to the bed of the stream. If this cannot be done, for any reason, the charge is tied to a pole, which is pushed into the river-bottom alongside of the pile, and tied to the pile. Such free charges ought to weigh two pounds ; and, under ■water, it is advisable to use electric firing. (Figs. 107 and 113.) Fig. 106. 107. 322 THE MODERN HIGH EXPLOSIVES. If the piles are close to one another, employ one charge for two piles. (Fig. io8.) Wood and iron structures are broken by charges which lie free on top ; and, as a rule, the ap- JiV>. J . plication of such a blast will always. ®--@ #.^W-'® be effective. If big blocks of iron or steel are , i@, to be broken, holes are drilled in ^* %, them, and shots are fired in these FiG."io8. holes. The removal of piles, temporary- bridges, timber foundations, sheet-piling, milldams, etc., is done more easily and quickly by means of blasting than in any other manner. The operations are of different nature, accordingly as the piles to be blasted are on dry land, in water, or below the river- bottom. Blasting of Piles on Dry Ground. — Piles that are not situ- ated in water can be blasted in two different ways : — {a) Through bore-holes. (b) Through externally applied charges. I. Through bore-holes it is possible to blast piles of twelve- to fourteen inches in diameter, after boring them with an American wood-auger at the required height, or a height de- pendent upon their wood superstructure, in a radial direction, to a depth of two-thirds of their diameter, and loading this bore-hole to one-third of its depth with dynamite No. i, and, after tamping with earth, exploding the charge. By this blasting, which is always accompanied by a loud deto- nation, the piles are completely broken off at the height of the bore-hole, and the remaining stumps splintered to a depth of one and a half to two feet. With externally applied charges, the blasting of piles is done by exploding a charge of two and a half pounds of the above- mentioned explosive in a compact form, the charge being fas- tened with ropes or a string to the pile at the corresponding height, or at its foot. The piles will be completely broken off at the height of the lower edge of the charge, and splintered from half a foot to a BLASTING OF PILES UNDER WATER. 323 foot below the plane of breaking. If the charge was placed near the ground, a small funnel would be blown in it. The explosion manifests itself by a violent detonation, and the pile is blown for a distance of fifteen to twenty paces in the direc- tion opposite the location of the charge. If a row of piles driven in close order (fourteen-inch round timber) should be blasted, the cylindrical charge applied out- side at the base of the piles should be one and a half pounds of dynamite No. i per running foot. The charge is arranged in such length as will correspond with the openings to be made in the row, and is in the shape of tin canisters, rubber bags, or linen covers. The firing is done from one end of the charge. ' By externally applied charges, a good effect is only possible when the charge is brought into the closest contact with the object to be removed. Blasting of Piles under Water. — In case it is desired to break piles situated in water, and where they have to be blown off close to the river-bottom, it is generally done by the application of ex- ternal charges, which are fastened on a horizontal hoop, and sunk by means of long poles. (Fig. 109.) For twelve to fourteen inch piles, a charge of one pound of dynamite No. i is sufficient. This should be put into tin can- isters provided with an exploder, and made waterproof. The firing of the charge is done, as already mentioned, by means of electricity. Through the explosion, the pile is broken off com- pletely at the seat of the. charge, and a waterspout of about fifteen feet is formed. The detonation is insignificant. If a row of piles (for instance, sheet-piling) should be blown out, then the corresponding cylindrical charge must not be fas- tened on a hoop, but on a lath, and sunk alongside of the piles to the proper depth at which they should be blown off, by means of two poles. Fig. log. 324 THE MODERN HIGH EXPLOSIVES. One pound of dynamite No. i per running foot is calculated as a charge, and is applied in waterproof tin canisters. The length of the charge is equal to the length of the open- ing to be blown out in the row of piles. The tin canisters are made about two feet long. Blasting of Piles below the River-bottom. — Here the blasting is done with bore-holes, which are bored longitudinally in the centre of the pile, and to a depth corresponding to the length of the piece to be blown off. (Fig. i lo.) Ship-augers of different length, which are handled by two men, are used for boring. One pound of high explosive is sufficient as a charge, and it is put in a tin canister provided with an electric cap. The tin can- ister is fastened to a thin wooden slip, by means of which it is shoved into the hole. Water is used for tamping. The explosion takes place with a weak detonation, and a waterspout six feet high is thrown up. The pile is completely de- molished at the height and seat of the charge. One-pound charges make it possible to tear up piles driven nine feet below the river-bottom. Submarine Wood-Blasting. — Fig. 1 1 1 shows the method em- ployed for submarine blasting in wood. This stump lay in mid-stream, and was pretty well embedded in the mud, the depth of water being about six feet. The stump was about seven feet long and three feet in diam- eter. In this case a tin cartridge, con- taining about eight pounds of dynamite, was tied to a pole, and put in the posi- tion indicated in the figure. The firing was performed by electricity ; but, should the water be cold, it is advisable to have specially pre- pared primers which are uiade for submarine purposes. Fig. 1 10. Fig. 111. SUBMARINE WOOD BLASTING. 325 Fig. 112. In the case of Fig. 112, we have a log twenty-four feet long, and five feet in diameter, embedded in the bottom of a stream in six or seven feet of water. This log received two charges, of twelve pounds each, which were tied to poles driven into the river-bed ; and the firing was done, as the figure shows, by electricity. The explosion of such a charge is sure to break it into several pieces. Formula for Blasting of Wooden Beams. — Square beams, supported at one or both ends, are blasted by simply placing the charge free on the top. The amount of the charge is determined by the formula : — L = ch^\JJ, in which L is the charge in pounds, h the height, b the width in inches, and c the char- ging co-efficient. For the last, different values must be used, according as the wood is hard or soft. In conformity with experiments heretofore made, the char- ging co-efficient for No. i dynamite can be assumed to be as follows : — (a) For soft wood, c = 0.0045 > (J>) For hard wood, c = 0.0090 ; Consequently, for the determination of the charges for blast- ing of square wooden beams, the following equations are to be used : — For {a), L = o.oo/^^h^\lb ; For {b), L = o.ooi^oh^^l). Fig. 113. Here it is to be remarked, that in beams where the width is less than the height, the charge must be calculated always as though for a square section of a beam in which the width is equal to the height. 326 THE MODERN HIGH EXPLOSIVES. The charge is put in a cylindrical tin canister, the length of which is equal to the width applied in the calculation, and is laid on the top of the beam sO that it covers the whole width ■of it. On beams where the width is less than the height, the cartridge is laid obliquely. For blasting round beams, the charges are calculated as for beams of square cross-section in which the sides are repre- sented by the diameter. The length of the charge adopted is equal to the diameter of the round beam which is to be blasted. For the purpose of blasting, the cartridge is placed on the top of the beam, parallel to the longitudinal axis of the same. In consequence of the explosion of the free charge, the beam will be completely broken through : and it will be observed that, in the plane of breaking nearest to the charge, the beam is completely crushed ; in the middle of the section, the beam is broken evenly ; and in the lower portion of the section, it is splintered and rent. BLASTING OF ICE. The high explosives are employed in cold countries to break up the ice in the rivers and water-courses. This operation should be performed in places where the blocks of ice can be carried away by the current. , To obtain this result, a series of cartridges is placed on the ice, one after the other, and covered with earth and sand. Quantities of dynamite, placed in spots separated from each other, would only form funnels, without breaking up a large quantity. The ice is first broken near the shore, and then the cartridges are placed under the ice in the water, and the explo- sions under these conditions produce more powerful effects. Vessels which are blocked up in ice are disengaged in this manner ; and a similar operation was conducted during the siege of Paris. To break up large blocks of ice, they should be drilled similarly to rock, and charged in the bore-holes. It is not practicable to break up the ice in standing water like canals and lakes, as it will not float away. CHAPTER VII. SUBMARINE MINES. SUB-AQUEOUS BLASTING. In blasting under water, the explosive must be protected from moisture, which is not an easy matter to accomplish under the most favorable circumstances ; but when the depth of water is considerable, it becomes very difficult to attain that object. The pressure of a considerable " head " will force the water through substances, which, not under pressure, are suffi- ciently impervious. India-rubber bags are most commonly employed, instead of tin canisters. India-rubber tubing is em- ployed also for holding charges of nitro-glycerine, and is known as "blasting-tubes." In using dynamite it also becomes necessary to enclose it with some impervious substance, to prevent the exudation of nitro-glycerine. When the charge is contained in a bore-hole in rock, exuda- tion can hardly occur; and therefore, in such cases, water- proofing is unnecessary. When detached or projecting masses of rock have to be broken up, it is sufficient to place the charges upon them ; and the quantity of explosive is increased, since there is economy of time and labor, as compared with boring holes. BORING UNDER WATER. The percussive drill is effectively used under water, and is driven by compressed air. The tripod stand, having its legs weighted to give it stability, is generally the most suitable support. These drills need the attention of a diver. Some- 327 328 THE MODERN HIGH EXPLOSIVES. times the boring is carried on by hand from the deck of a vessel, or from a raft provided for the purpose. The following description will give a general idea of the operations involved in sub-aqueous boring : — The working-vessel having been moored over the rock by lines attached to buoys, placed about fifty yards from each quarter of the vessel, the diver descends, and selects the most suitable position for the blast ; he then signals, by a certain number of pulls upon his signal-line, to have the drill and stand lowered to him. This being quickly done by means of a steam derrick, he guides the drill-stand to its place, and finally fixes it in position by means of its adjustable legs; he then signals for air, to commence drilling. As soon as the hole is drilled to the required depth, the drill is stopped ; the diver then fastens the derrick-chain, which is- lowered to him for the purpose, to the drill-stand, and signals, to hoist away, whereupon the machine is quickly hoisted on deck. After having examined the hole, and cleared away any debris remaining at the bottom, the diver comes to the surface, and, taking in his hand the charge contained in a water-tight car- tridge, and provided with its electric fuse, to which a sufficient length of insulated wire is attached, returns with it, and inserts it into the drill-hole, carefully pressing it to the bottom with a rod. The tamping, if used, is then inserted above the cartridge,, and the diver comes up. The working-vessel having been quickly hauled by the moor- ing-lines to a safe distance by means of capstans worked, when- ever practicable, by the steam-engine, the wires are attached ta the machine ; and at the signal " All ready ! " the charge is fired. The working-vessel is then hauled back to its position ; and,, as soon as the mud stirred up by the blast has settled suffi- ciently to enable the diver to see, he descends to examine the- result. If the blast has been effective, he signals for the stone chains to be lowered to him ; which, being done, he proceeds to sling the large pieces of broken rock, one after another, as they are hoisted up, and deposited on deck. All the pieces large enough, to sling having been thus removed, he signals for the tub and SUB-AQUEOUS BLASTING. 329 shovel to be lowered to him, and then proceeds to shovel into the tub the small fragments, which are hoisted and piled on deck, until the surface of the rock is sufficiently cleared to place the drill for a new blast. BLASTING SUBMARINE ROCKS. Formerly rocks under water were removed by blasting them by means of bore-holes. By this method the bore-holes must be drilled, loaded, and fired from a scaffolding erected above the object that is to be blown up. The execution of these three operations requires, — 1. The making of the bore-hole; 2. The charging of the same ; 3. The firing of the charges. These operations present many difficulties, which increase with the depth of the water and the rapidity of the current. Making the bore-holes requires the construction of a scaffold- ing of such device that the boring can be done in quiet water, and at any stage of the tide. For the purpose of blasting in rivers, anchored rafts are used. To overcome the motion of the waves, and the current, they are provided with a submarine contrivance (spuds, grousers), which reaches to the bottom of the river. This contrivance answers where the bole-holes are made by hand-labor'; but not where boring-machines are used, as they require a steady s'caffolding to make a central and even boring possible. Besides the construction of the raft or of the solid scaffolding, the labor of boring is also a very difficult one, especially in cases where the water carries a quantity of sand, and filling up the bore-holes is to be feared. In such cases, by hand-boring, pipes have to be inserted in the bore-hole, which reach above the water-level, and in which the drills play freely up and down. If the object to be blasted lies twelve feet or more below the water-surface, and if the current-velocity is very considerable (as, for instance, six feet per second), then making bore-holes is hardly possible, since the water exerts a great pressure upon the drill-shafting. 330 THE MODERN HIGH EXPLOSIVES. By blasting in the sea, making bore-holes is connected with less difficulty than drilling in rivers, since the sea-currents are not very strong ; and peculiarly constructed bore-machines in the hands of a diver, or the use of a portable apparatus for making the holes by hand-labor, are rendered possible even at a great depth. The bore-holes are made vertical, and are driven down about from six to nine inches deeper than the line to which the rock is to be blown off. The distance between the holes should be one and a half times their depth in the rock. The quantity of the charges for the bore-holes must be deter- mined by trial-shots, but such charges should be made compar- atively small. In all cases, only No. i dynamite is to be used ; and this is placed in tin canisters or tarred-paper covers, which are, after the insertion of the exploders, made waterproof and fastened on to wooden strips or poles. Charging the bore-holes for blasting in rivers is most readily done by means of iron pipes set over the hole ; and these shots do not require any tamping. The following sketches illustrate some sub-aqueous blasting carried out on the Yellowstone River in Montana, under the direction of Capt. Edward Maguire of the United States En- gineer Corps. There were four large bowlders, which impeded the naviga- tion considerably ; and it is a source of regret, that the quan- tity of dj'namite used in breaking bowlders Nos. i and 2 is lacking. The drilling was done by an Ingersoll-drill, set up on a flat scow. Figs. 114, 115, 116, 117, show the shapes and di- mensions of the bowlders, depth of water, position, and depth of bore-holes. The following extract is compiled from a report to the United States Government, by Major-Gen. J. G. Foster. Published in Report of Chief Engineer U.S.A., 1869, pp. 421-433. DRILLING APPARATUS USED IN THE REMOVAL OF TOWER AND CORWIN ROCKS, BOSTON HARBOR, MASS. The working-vessel having been moored over the rock by means of mooring-lines attached to buoys, placed about a hun- dred and fifty feet from each quarter of the vessel, the diver, TOWER AND CORWfN ROCKS, BOSTON HARBOR, MASS. 331 arrayed in his submarine armor, descends, and selects the exact position for the blast, and then signals, by a certain number of pulls upon his signal-line, to have the drill and stand watermd^s lowered to him. This be- ing quickly done by means of a steam-derrick, he guides the drill-stand to its place, and finally fixes it in position by means of its adjustable legs. He then signals to haul up and make taut the drill-lines attached to the motive-power on deck; and, this being done, he signals to commence drilling. The crank-plate of the engine being thrown into gear, the engine being in motion, the end of the drill-line attached to the crank-pin is raised, which raises the ballasted block, the Fig. it;. drill-chain, and the clutch, which latter grips and raises the drill, turning as it rises, until the forked end of the clutch 332 THE MODERN HIGH EXPLOSIVES. atet-S' Strikes against the trip-pin, wiien, tiie drill-chain still hoisting, the grip of the clutch is disengaged, and the drill falls straight, cutting the rock by the force due to gravity. The crank-pin contin- uing its revolution, the drill-line and chain are lowered, permitting the clutch to descend to its first position, ready to grip and raise the drill again. The revolutions con- tinuing, the drill is raised and let fall, making a cut at each revolution of the crank-plate ; and in this manner the drilling pro- ceeds. Usually the drill makes from sixty to eighty blows per minute. As soon as the diver sees the drill in perfect operation, he either busies himself with any other ^ - . -^ Water T work that he may have to perform upon the bottom, or he comes to the surface of the water, and, supporting himself upon the ladder attached to the side of the vessel for his use, waits for some necessity of his diving again (Fig. 1 19). Sometimes the drill works uninter- ruptedly till the hole is drilled to the depth required. At other times its working requires the constant attendance of the diver, either in replacing drill-heads, broken by contact with hard crystals; or in regulating the "turn" or "hoist" of the drill; or in clearing the holes of cuttings, or " spooning out," as it is termed; or rectifying the direction of the drill by adjusting the legs or guys. { / 2'll. jf \ -«;|r. I 1 2>l W. j Water S'&" Fig. 117. TOWER AND CORWIN ROCKS, BOSTON HARBOR, MASS. 333 To afford an indication above water, of the motion of the drill below, and thus to obviate the necessity of the diver going down for this purpose, an iron rod is fitted into a square socket on the upper end of the drill-shaft, and to the upper end of this rod a wooden pole, extending above water, is attached. This pole being held by an attendant standing upon a movable sta- ging, g, rigged out from the side of the vessel, indicates clearly to him the motion of the drill, and also enables him with his hand to prevent the drill falling repeatedly into the same cut, or " bouncing back " as it is termed. In rough weather, the staging and index-pole cannot be used. Profil* on Line LS SaritoatatStaU . co?-^"^,^oc^ Mte.MtanMsh milerristeSVlabivtmanL SraU adrift. •i 4 s !S * ti i, Fig. 118. At such times the motion of the drill-line is the only indication above water, of the working of the drill. The tendency of the drill to "bounce back" is prevented by a ratchet and pawl, placed on the upper guide-plate, and operated by a vertical groove in the drill-shaft, and a pin on the ratchet. It was found that the drill could be worked in a rapid current as well as in slack water. This will enable the operation of drilling and blasting to be conducted in an extremely rapid tidal current, by a proper division of time and labor, so that the principal work of the divers in inserting charges for blasting, slinging stone, etc., may be done near the periods of slack- water ; while the drilling may be advantageously continued during the period of rapid flow. 334 THE MODERN HIGH EXPLOSIVES. R^.l ''.^H — ■ \\ \ \\ \ ■ w \ \\ v \\ A k ' \\ / l\ \S/,i li\ ^ ,„ •* ^ \ iia " Fig. 119. Upon Corwin Rock the current had a velocity of four miles an hour, which did not interfere in the least with the work of the divers at any stage of the tide. TOWER AND CORWIN ROCKS, BOSTON HARBOR, MASS. 335 In a rapid current, the stoppage of the drill for the purpose of " spooning out " the hole becomes unnecessary ; as the mo- tion of the drill works up the powdered cuttings to the mouth of the hole, whence they are sucked out and carried off by the Fig. 120. current in a dark stream, like the smoke from the stack of a locomotive. In a sluggish current, or during slack water, the hose of the air-pump was sometimes introduced, and air forced into the hole, creating a current of water extending to the bottom, which 336 THE MODERN HIGH EXPLOSIVES. by this means was cleared of cuttings more thoroughly than by the most careful "spooning out." To attach this arrangement permanently to the drill, it is proposed to have a small hole along the axis of the drill-shaft, with outlets on each face of the cutter, and a hose attached by a swivel to the upper end of the shaft, through which air or water is to be forced to the bottom of the hole, by which means the drill may be kept constantly clear. Charging the Hole, Firing, Powder used, etc. — As soon as the hole is drilled to the required depth, the drill is stopped, the drill- line is detached from the crank-pin, and unrove from the bal- lasted block ; the diver then descends, fastens the derrick-chain (which is lowered for the purpose) to the drill-stand, and then signals to hoist away, upon which the whole machine is quickly hoisted on deck. After an examination of the hole, and clearing away any cut- tings remaining in the bottom, the diver comes to the surface, and, taking in his hand the charge, — contained in a water-tight cartridge, usually of India-rubber, carefully prepared with its fulminating exploders inside, its mouth hermetically closed, and insulated wires extending to, but not yet connected with, the electric battery on deck, — descends, and inserts it into the drill-hole, carefully pressing it to the bottom with a rod. The tamping, if any is used, is then inserted above the cartridge, and the diver comes up. The working-vessel is then quickly hauled by the mooring- lines to a safe distance, the capstans, worked by the steam- engine, being used for the purpose ; the wires are then attached to the battery ; a few turns are given to its crank, to generate electricity; the operator asks, "All ready.'" and being answered, "All ready," by the diver, pulls the connection-knob; when a. shock, followed instantly by a second shock, and the upheaval of the water, announces the explosion of the charge. The working-vessel is then hauled back to her position by steam, as before ; and as soon as the water becomes sufficiently cleared of the dark, muddy matter with which it is filled by the blast to enable the diver to see in it, he descends, and examines the result. If the blast has been effective, and thrown out a crater from TOWER AND COR WIN ROCKS, BOSTON HARBOR, MASS. 337 the rock, he signals for the stone-chains to be lowered to him ; which being done, he proceeds to sling the large pieces of broken rock one after the other, as they are hoisted up by steam, and deposited on deck. All the pieces large enough to sling being thus removed, he signals for the tub and shovel ; and, upon their being lowered to him, proceeds to shovel into the tub the small fragments, and to have them hoisted up and piled on deck, until the sur- face of the rock is sufificiently cleafed to place the drill for a new hole and another blast. This operation is repeated, and the work thus progresses steadily. After some experience, such facility was attained in drilling and blasting as to enable the work to be continued in a rough sea, and during all stages of the tide. To accomplish this, the slot in the clutch is made of such an oblique form as to permit the clutch to run up the drill-shaft, after tripping, a sufficient distance to accommodate its motion to the upward heave of the vessel in a swell of the sea. The peculiar adjustable connection between the drill and the motive-power is also so arranged as to afford the means for compensating for the rise and fall of the tide, by simply letting out or taking in the line attached to the cleat on the rail of the vessel. In addition, this arrangement also enables the vessel, when threatened by a collision, or a sudden storm, by casting-off this line, to detach itself entirely from the drill, and haul out of danger. The powder used first was common blasting-powder. This proving too weak to rend the rock, Dupont's best sporting-" powder was tried, in charges of from six to twenty pounds, with better, but no satisfactory, results. Trials were made with the Patent Safety Blasting-powder Composition : — Chlorate of potash 50 parts. Kutch or gambia 50 " 100 parts. 338 THE MODERN HIGH EXPLOSIVES. This gave results nearly twice as great as the sporting-powdery and its composition was modified as follows : — Chlorate of potash 80 parts. Gambia 20 " 100 parts. The powder was put into India-rubber cartridges of a cylin- drical form. They possess the indispensable requisite of being perfectly water-tight, and of leaving after the blast no debris to fill the bottom of the hole. They also, being elastic, easily yield to any irregularities of the hole, so as to be readily pushed to the bottom. The mouth was easily made water-tight by being tightly wrapped around the electric wire with twine, and then covered with a water-tight compound. Recent Improvements in Submarine Drilling. — Submarine- rock excavation is always a costly and laborious work, and par- ticularly so when submerged reefs are covered with strata of sand, gravel, or silt. Mr. William L. Saunders, an engineer who has had consid- erable experience in this class of work, designed and patented an apparatus embracing some novel and valuable features. The object of his invention is to relieve the drill from friction occasioned by the pressure of the sand or mud through which it may be necessary to pass in order to operate upon the rock ; to remove the debris and cuttings from the point of the drill as rapidly as they accumulate ; to permit the drill to be removed at any time, at the same time preserving the hole, both through the bed of sand or mud and" in the rock itself, free from obstruc- tive accumulations ; and to facilitate the insertion of blasting- cartridges. The invention consists in surrounding a steel drill, of the construction commonly employed for submarine work, with a tube or hollow cylinder, constructed in two or more sections, telescoping into each other. The lower section is provided with a conically tapering extension, which, in turn, is united with a straight tube having an internal diameter slightly exceed- ing that of the hole formed by the drill. Within this tube, and parallel with the shank or steel of the drill, extends a small IMPROVEMENTS FN SUBMARINE DRILLING. 339 pipe, terminating above the bit of the drill, and arranged to convey a continuous stream of water to it. At a suitable dis- tance above its lower extremity, the conically tapering section is provided with a lateral opening, through which the debris accumulating within the lower extension is discharged. The means for effecting this discharge consist of a suitable steam or water pipe extending downward along the enclosing cylinder or tube to the conical section thereof, into which it enters, ter- minating in a nozzle^ concentric with the discharge-opening, and constituting a device known as an "ejector." By forcing a jet of steam or stream of water downward through this pipe and out of the discharge-opening, the water received through the pipe terminating at the bit of the drill, and the accumulations forced by it into the conical section, will be carried out through, the discharge-opening. When a hole is to be drilled in rock covered by alluvial layers, the casing is lowered, and water is forced through the small pipe. The casing sinks by its own weight, until it reaches bed- rock. The drill-rod is then introduced ; and drilling proceeds in the ordinary way, except that Mr. Saunders has so modified the plan, that the drill-rod can be extended without drawing it from the hole. The constant scouring of the hole considerably aids progress ; and we shall farther on quote some figures from actual practice, and show what has been achieved in this man- ner. Another advantage obtained by the use of the casing in charging the holes, as explained above, is dispensing with the services of a diver. Mr. Saunders has, in addition to this, simplified the plant by providing a drill-stage, the principal features of which are shown in the accompanying Fig. 121, which also shows two of his ejectors. By a small wrench, the stage, after being floated into place, is hoisted above the water, so that it is not affected by changes of tide. A six-inch pipe rolling along the top of the gallows-frame affords facilities for handling the drills, which are of the Ingersoll pattern, and which are provided with a special bed-plate. In referring to Fig. 121, A represents the drill, which may be operated by machinery in the customary manner. Surrounding the drill A is an enclosing case B, which consists of two or more 340 THE MODERN HIGH EXPLOSTVES. cylinders, b and b', — one of which is constructed to slide into the other, like the sections of a telescope, — and of a conically tapering terminal section b ^ secured to the lower extremity of b', and provided with a lower extension b^, consisting of a straight metallic pipe or tube. The sections b and b' serve to support the remaining por- tions of the apparatus, and, together with the extension b^, to protect it, as well as to control the direction of the drill. The section 3 ' is prefera- bly of cast iron, and serves to unite the cylindrical por- tion of the enclosing case with the tubular extension b 3. The tube b ^ follows the point of the drill through the comparatively soft earth or other material which may cover the rock to be operated upon, as shown at F ; the width of the bit a being preferably nearly equal to the interior diameter of the tube. The tube b^ thus forms an interior wall for the drill-hole, and prevents the surrounding earth F from pressing against the steel a' after the bit has penetrated it. Upon reaching the surface of the rock G, further descent of the tube ^^ is prevented, for the reason that the hole formed therein by the bit of the drill will not be of sufficient size to receive the tube. The latter will, in consequence, rest upon the upper surface of the rock, and, while in that position, serves to steady the motion of the drill, causing its successive strokes to fall upon the same point until it has entered the rock. In this manner, a clear passage IMPROVEMENTS IN SUBMARINE DRILLING. 34 1 is always maintained, from the surface of the water to the bottom of the hole, whereby the drills may be removed and replaced with great facility, and through which the blasting- cartridge may afterward be inserted. For the purpose of clearing the pulverized rock and clippings from the hole as rapidly as they are formed by the drill, and thereby preventing the formation of a collar about the steel above the bit, a tube C is used for conveying a stream of water to the bottom of the hole, thereby occasioning a continuous agitation and outflow of water and debris. To the upper extremity of the tube C, a hose c is attached, constructed of rubber or other suitable material for convenience of handling. The hose c extends through a pipe c, secured to the interior of the section b, which section serves to retain the hose away from the steel of the drill, and to prevent it from being bruised. Suitable means are provided for allowing the pipe C to descend into the hole at the same rate as the drill, and for maintaining its lower extremity a short distance above the bit of the drill. To facilitate the discharge of the water and powdered rock, or other accumulations, from the tube b^,2>. discharge opening D is provided for, which consists of a short branch tube d secured to the side of the conical section b ', with the interior of which it communicates. A jet pipe E extends downward from the upper extremity of the enclosing case B, preferably outside and parallel with it, to the tapering section ^% into the interior of which it extends, terminating in a nozzle e, concen- tric with the discharge opening D. The discharge-tube D and the nozzle e preferably extend in an upward direction from the section b", and they together form an ejector for discharging the muddy water from the tube b^; suitable means being pro- vided for forcing a stream of water or jet of steam through the pipe E. During the operation of the drill, streams of water or steam are constantly forced through the two tubes C and E, which keep the hole free from debris , and in this manner a hole may be drilled to a great depth in a submerged rock without neces- sitating the frequent removal of the drill and pumping out the hole, as has heretofore been customary. Whenever it is desired to remove the drill, it is simply with- 342 THE MODERN HJGJl EXPLOSIVES. drawn from the enclosing case B, which is allowed to remain in position in order to facilitate the insertion of the charge of explosive material for blasting. This is preferably effected by introducing a suitable cartridge provided with a fuse, and hav- ing electric conductors attached thereto, within the tube B, and thus lowering it into the hole drilled in the rock. A graduated plunger is then employed for ascertaining whether the cartridge has descended to the bottom of the hole ; and this may be readily determined by comparing the distance to which the Fig. 122. drill has been sunk with that registered by the plunger when resting upon the cartridge. The tamping of sand, or other suitable material, is also introduced through the tube B, after which the latter is withdrawn or removed, the upper extremi- ties of the electric conductors having been previously attached to floats for more readily securing them after the tube B has been drawn from over them. In excavating the opening to the rock through the overlying bed of sand, mud, or gravel, it is in some instances unnecessary to employ the drill for loosening, as the stream of water forced through the jet tube will be sufficient for the purpose. The debris will be discharged through the lateral opening in the same manner, and the tube will gradually descend to the rock. SUB-AQUEOUS BLASTING. 343 The boiler and pump are placed on a separate scow. As TOOst of the holes are drilled at an angle, it is generally onl)' necessary to raise the ejector a short distance above the surface of the rock to let it swing entirely out of the range of the shot. A very interesting report of the operations on Black-Tom Reef, New-York Harbor, from the beginning of work. May 2, 1882, to Aug. 21, 1882, is here given. In 283 net working- days, 17,658 lineal feet of hole were drilled, 16,567 feet being effective drilling. Out of 1,736 holes c^^^ft■^«'»5^^ AB. and 1,629 charged, 1,542 were blasted. The average depth of the holes was 10.17 feet, and the distance between them four feet. The area drilled over was 32,100 square feet ; and 5,136 cubic yards of rock were re- moved with three drills, using 20, 46 1 i pounds of dy- Fig. 123. namite, 200.19 tons of coal, 394.48 pounds of steel, 77.25 pounds of connect- ing-wire, and 7 rolls of rubber tape for covering connections. The total cost of plant was about 1^15,500. The largest diameter of bit was 3.75 inches, and the smallest 2.5 inches. Holes have been drilled, charged, and blasted with the Saunders ejector, through six feet of gravel overlying the rock. Destriiction of a very hard Granite Bank, forming a Dam across the River Moselle at £pinal in Fra7ice. — This bank was ■eleven and a half metres long, one metre ninety centimetres high, and two metres ninety centimetres wide. A row of holes was bored horizontally, as shown in Fig. 123, the canal being emptied for this purpose. 344 '^^^ MODERN HIGH EXPLOSIVES. These holes were bored at a depth of 1.60 metres to 2 metres from the top of the bank; and every hole was charged with seven hundred grams No. i dynamite, consuming together seven kilograms. Before the holes were fired, the canal was filled again with water; and the holes were tamped in this manner with water. The effect was excellent. There was no trace of the dam left ; and the debris amounted to sixty-three cubic metres, which was all broken in such a manner as to be easily handled for removal. REMOVAL OF THE HELL-GATE ROCKS. The great obstruction impeding the ship-travel between the Atlantic Ocean and New-York City, viA Long Island Sound, is located at a promontory of Long Island called Hallett's Point. It extends out into the East River, approaching Ward's Island, which occupies three-fifths of the width of the river at that point ; and some dangerous rocks are found in the imme- diate vicinity. The narrow channel thus formed has been a danger and a difficulty to navigators ever since this part of the country was first explored ; and the rush of water taking place through the pass gave it the name of Whorl-gate, afterward Hurl-gate, whence the name by which it is now known was easily derived. The first mention of preparations for commencing the work of removing the obstructions is found in the Report by Lieuts. Davis and Porter, of the United-States navy, made in the year 1848. This document gives a very accurate description of the course of tidal currents, the dangers to navigation caused by the rocks, obstructions, etc. ; and it recommends that Pot Rock, the Frying Pan, and Way's Reef be blasted and scattered. The two former are single rocks of a pointed shape : the latter is long, and has the character of a ledge. The report also rec- ommends that the middle channel be improved by blasting, so as to make a clear channel of sufficient depth for common ves- sels and steamboats ; and it also speaks of the increased facili- ties for naval defence which this improvement would afford. The difficulty of blockading the port of New York, with twa outlets instead of one, would be, at least, doubled. Lieut. Porter did not exactly agree with Lieut. Dayis as to the best REMOVAL OF THE If ELL-GATE ROCKS. 345 plan for improving the channel. They both recommended the removal of the small rocks — Frying Pan and Pot Rock — from the middle of the channel ; and Porter included a part of the reef at Hallett's Point, the shell of which was blown in atoms, its interior having been removed and deposited far away on dry land. The art of blasting under water was almost unknown at the inception of this work ; and engineers agree, that even the little improvement recommended by them could not have been effected without the inventions and discoveries which have since been made. The process adopted at that time for submarine blasting was to take down cans of powder, place them against the side or top of the rock, and explode them by means of a gal- vanic battery. This did well enough for rough and jagged rocks and bowlders ; but so soon as the surface had been levelled off, it was of little or no use to attempt to continue the operation. In 1832, Congress having made an appropriation of twenty thousand dollars for the removal of the rocks at Hell Gate, Major Fraser, of the engineers, began operations according to the Maillefert process above described. The sum of eighteen thousand dollars was expended on Pot Rock, and the depth of water was increased from 18.3 to 20.6 feet. This was all that had been accomplished up to 1868, when the duty of an examination of Hell Gate was committed to Gen. Newton of the United-States engineers, who made a report in January, 1867. For operating on the rocks in the middle of the channel, a steam-drilling scow was constructed. It had a well-hole in it thirty-two feet in diameter, through which twenty-one drills were worked ; while the scow lay on the surface of the water directly over the rock to be operated upon. This formidable machine was first used in the spring of 1869, on Diamond Reef. A large number of holes were drilled into this rock, varying from seven to thirteen feet in depth, four and a half inches in diameter at the top, and three and a half inches at the bottom ; and the rock was broken up by charges of nitro-glycerine of from thirty to thirty-five pounds. Coenties Reef was operated upon in 1871. Ninety-three holes were drilled, and charged with nitro-glycerine ; and seventeen surface-blasts were made. In 1873 three hundred and seven holes more were drilled, and thirty-nine surface-blasts were made. The amount of nitro- 346 THE MODERN HIGH EXPLOSIVES. glycerine consumed was 17,127 pounds, and the reef was thor- oughly broken up. The debris had been partly removed, when, in 1875, Congress, owing to a mere clerical blunder, failed to' include Diamond Reef in the appropriation ; and work at that place had to be suspended. In 1872 the drilling-scow was towed to Frying-pan Rock. Seventeen holes were drilled, and eleven surface-blasts made. Operations for removing the reef at Hallett's Point were begun in August, 1869. A coffer-dam was built of timber, securely fastened to the rocks by bolts passing through the framework. The coffer-dam was pumped out about the mid- dle of October ; and operations on the interior for sinking the shaft were begun early in November, and continued till the middle of June, 1870, when work was suspended on account of the funds appropriated for this part of the work being ex- hausted. At that time four hundred and eighty-four cubic yards of rock had been taken out, at a cost. of $5.75 per yard. In the latter part of July operations were resumed ; and, dur- ing that fiscal year, the shaft was sunk to the required depth of thirty-three feet below mean low water, and the heads of the ten tunnels opened to distances varying from fifty-one to one hundred and twenty-six feet. Two of the cross-galleries had also been opened. The amount of rock excavated from this place that year was 8,306 cubic yards, and the drilling was all done by hand. During the next year the use of steam-drills partially succeeded hand-drilling, and the work was pushed more rapidly. The number of feet of tunnel driven during the year was 1,653, and of transverse galleries 653.75. The quantity of rock removed was 8,293 cubic yards. A ground-jolan of the work herewith gives an excellent idea of the excavation as completed. An exceedingly well-executed model of the works was exhibited at the Centennial Exhibition at Philadelphia. It is made ex- actly to scale, and well represents the nature and extent of the vast operations that have now been successfully completed. The rock-bed of the river is, in the model, raised from the pillars that support it, so that a close inspection of the interior may be made. There are one hundred and seventy-two of these pillars, pierced with about four thousand drill-holes ; and the shell, or roof, or bed of the river, varies from six to sixteen feet REMOVAL OF THE HELL-GATE ROCKS. 347 in thickness. No less than thirty thousand cubic yards of broken stone was left under water, all of which was removed by dredging. A detailed survey of the upper surface of the reef was made in 1 87 1, by Mr. William Preass, assisted by Mr. F. Sylvester. They took more than sixteen thousand soundings, each separ- ately located, by means of instruments, from the shore. Great )ains were taken to delineate exactly the surface of the rocks. The appropriation of 1871 was two hundred and twenty-five thousand dollars, — just one-half the amount asked for by Gen. Newton, who regretted that the beginning of operations on the Gridiron was thus prevented, as he considered this rock more dangerous to the navigation of large vessels than Hallett's- Point Reef. For the next year he asked six hundred thousand dollars, but got less than half that sum. About the middle of November, 1873, work was suspended for want of funds; but at the end of the fiscal year, June 30, 1874, it was found, that, for the four months and a half during which operations had been carried on, 896 linear feet of tunnels had been opened, and 4,648 cubic yards of rock removed. The total length of tunnels and galleries then amounted to 6,780.67 feet. The excavation now being nearly finished, the manner of finally blowing up the whole mine began to exercise the minds of the engineers. Gen. Newton finally suggested his own plan for blowing up the reef at Hallett's Point, which was to perforate each pier with drill-holes entirely or partly through its mass, a sufificient number of these being provided to complete the destruction of the pier when fully charged. The charges in the different holes of the same pier were to be connected together ; and a fuse, composed of a quick explosive, would connect the system of charges in each pier with those of the neighboring piers. By this mode, the communication of heat or the elec- tric spark to a few centres of explosion would suffice to propa- gate it through the whole system, because the explosion of the connecting fuse would advance more rapidly than the demolition of the rock. Gen. Newton's plan was adopted, with few slight changes, principally suggested by himself. Instead of depend- ing on explosives to convey fire from pier to pier throughout the mine, an electric spark was sent directly to every centre, insur- 348 THE MODERN HIGH EXPLOSIVES. ing the simultaneous explosion of the whole mine. It was decided that the minimum amount of explosives could be deter- mined by placing one charge in each square pier and two in each oblong pier ; but this mode would make the lines of least resistance the maximum, and thus increase the shock, which would be propagated through the reef to the dwellings upon the land. It was therefore determined to decrease the lines of least resistance, which would multiply the number of blasts, and increase the quantity of explosives, but would, at the same time, reduce to a minimum the vibrating influence through the reef. It was, therefore, calculated that the exterior effect, except an agitation of water, would be small. The proximity of the reef to habitations at Astoria, Ward's Island, and Blackwell's Island, made it necessary to devise a system of explosion, which, effecting the work of demolition^ would, at the same time, do no damage to life and property. The atmosphere and the rock being the mediums through which the shock would be transmitted, it was essential that the waves propagated through these should be made as small as possible. It was evident, in the first place, that, if to each charge its full capacity of useful work in the breaking-up of the rock were 'assigned, regard being likewise had to the superincumbent weight of water, no external effect of moment would be per- ceived in the atmosphere. In the second place, it was evident that the magnitude of the rock-wave would depend greatly upon the amount contained in individual charges ; that is, if eighty pounds were required for the individual charge, the vibration of the rock would be much greater than if these charges did not exceed twenty pounds. It was known that eighty-pound charges of nitro- glycerine, fired in numbers of twelve to twenty, did not cause a destructive wave. Again : the reef, after excavation, being connected with the rest of the rock formation only through the piers and the outer edge of the roof, it was inferred that the shock propagated in the rock should be estimated as due mainly to the charges necessary to disrupt the piers and roof from their connection with the bed-rock ; and, also, that the additional number of REMOVAL OF THE ff ELL-GATE ROCKS. 349 charges required to break up the roof and piers would not enter largely into the amount of shock transmitted under ground. These were the fundamental ideas upon which the system of mines was established. As the tunnels in radial lines concen- trated upon the land, an accumulative explosive effect in that direction was prevented by so proportioning the charges that the roof should be broken through by the first impulse in many places, and thus give vent upward. To prevent a concentric explosion, by which the debris might be heaped up in large masses near the centre of the area, the charges in the outer zone of the semi-elliptical reef were in- creased beyond those of the other portions; and by this means the masses of debris fell generally back in the places to which they originally belonged. Some portions were thrown beyond the limits of the reef toward the channel, and constituted what may be termed a dispersive explosion. Hallett's-point Reef is in the shape of an irregular semi- ellipse; the major axis, which lies next to the shore, being seven hundred and seventy feet in length, and the minor axis project- ing straight into the channel about three hundred feet. The cubic contents above the depth of twenty-six feet at mean low water amount to fifty-one thousand yards. Besides the risk of striking the reef, it produces eddies on both sides of it accord- ing to the direction of the tidal currents, and is much in the way of vessels coming down in the ebb in the effort to hug the shore, and thus avoid being drawn upon Middle Reef. The explosives used in tunnelling at Hallett's Point have been nitro- glycerine and its compounds, and gunpowder ; the' latter being used only when the rock was weak and seamy. Nitro-glycerine was always used for driving the headings of the tunnels. To drive a heading, the drill-holes are made at an angle with the fuse, so that the charge lifts out the rock by its explosion. A cavity being made in the middle of the heading, holes are drilled around it, and the surrounding rock blown into it. Only one blast is exploded at a time, as great care has to be taken not to shake the structure overhead by too heavy vibrations. There is consequently no volley firing, and the galvanic battery is not used for discharging the blasts. The average twelve 350 THE MODERN HIGH EXPLOSIVES. months' work, with six Burleigh drills, was the excavation of two hundred and thirty-five liiieal feet of heading per month. Up to June, 1872, the work had been prosecuted by hand-drill- ing, with the exception of 20,160 lineal feet of drilling by the Burleigh drill, and 7,000 feet by the diamond drill. That by the Burleigh drills was done by contract, at so much a foot ; and the diamond drill, purchased for the purpose of exploring the rock ahead, was put in competition with it. The cost of drilling, after a long trial with the Burleigh, is found to be between thirty-six and thirty-seven cents per foot, including repairs, etc. The cost of hammer-drilling was found to be about ninety-five cents per foot. The number of feet of holes drilled by each machine per shift of eight hours was thirty feet. The diamond drill, owing to the encounter of frequent veins of pure quartz in the rock, often gives out, and has to be re- paired. Owing to the restricted area of the tunnels and gal- leries, the work of excavation was almost exclusively that denominated heading, without the advantage of enlargement. The rock, after being blasted, was lifted by hand into a box resting on a truck-car, which was run down to a point upon a rail-track, and thence drawn by a mule to the shaft, where the box was hoisted by a derrick, and its contents emptied into dump-cars, to be rolled away, and deposited in the pile. Calling the cost of blasting and removing one cubic yard one dollar, the following gives the proportion of each item of expendi- ture : — Blasting I.4600 Transporting rock to shaft 1700 Hoisting 0328 Dumping 0203 Pumping 1037 Incidental 2132 $1.0000 The work of excavation having been finished, the drills were set to work perforating the roof and piers with holes to receive the final charges which are to explode the mine. The mode of calculating and arranging the charges was to REMOVAL OF THE HELL-GATE ROCKS. 35 1 consider the roof-holes as the receptacles of explosives enough to form common mines. The line of least resistance was assumed as the distance from mid-length of the charge to the surface of the rock. Since the charges were perfectly tamped by the confined water within the excavation, this rule of measuring the line of least resistance was assumed to be practically correct. With less perfect tamping, the lines of least resistance for such mines designed to break through the roof would have required esti- mates quite different. The average amount of explosives required to break up and dislodge one cubic yard in enlargement had already been found to be .97 pound ; and from this resulted C = charge in pounds = 0.03 8Z' j L being line of least resistance in feet. All roof-holes, excepting those over piers, were treated by this formula. The piers, being very irregular in shape and size, would have exacted much care and time to have located the holes and proportioned the charges to the exact mathematical requirements in each case. One pound and a half of explo- sives were assigned, as a rule, to each cubic yard of the piers ; it being considered of the first importance to demolish com- pletely these supports of the roof. The roof-holes above piers were charged from the formula : — C = nL'; being successively .038, .05, and .06, increasing from the shaft outward. The bodies of piers within the outer zone were charged with two pounds per cubic yard. Within the inner zone, where the depth was comparatively little, it was considered proper to reduce the charges to the smallest limit capable of affording a good result, both to avoid disturbance of the atmosphere and to prevent a concentrated action, due to the direction of the tunnel upon the land. The increased proportion given to the charges within the outer zone favored this intention, by giving quick vent to the gases in that direction. 352 THE MODERN HIGH EXPLOSIVES. The cubic contents of the roof and piers were 63,135 yardSi and the amount of explosives as follows : — Rend-rock 9, 127 J lbs. Vulcan powder 11,852^! lbs. Dynamite 28,935^ lbs. Total 49,9ij^\lbs. Being at the rate of 0.79 pound to each cubic yard. The explosives were packed at the respective places of manu- facture, in tin cartridge-cases, the last being furnished by the Government. The number of holes charged was 4,427, and the number of tins used was 13,596; eighty-seven percent being twenty-two inches, and the remainder eleven inches, in length. The holes being tapering, the cases varied in diameter from one and three-eighths to two and a half inches ; the intermedi- ate sizes differing by one-eighth of an inch. One end of the tin case was fitted with a screw cap, with rubber washers to exclude water ; the other end being arranged with four short lengths of brass wire, soldered on the perim'eter of the bottom, and spread out. When the cartridge was pushed home, the wires, by their elasticity, pressing against the side of the hole, prevented a falling-out. On the nth September the charging of holes was com- menced, and finished at nine p.m. on the 20th, — consuming nine days. Had the cartridges been delivered in good condi- tion, this operation would have consumed only about four days. These holes were made from two to three inches in diameter, and from six to ten feet apart, and their average depth about nine feet. The size of the holes, and their direction and dis- tances apart, were made to vary according to the character of the rock to be broken. The drilling of these holes up into the roof of the mine soon increased the leakage of water into the works from three hundred gallons per minute to five hundred, it being impossible to avoid tapping a seam occasionally. Many of the holes that were found to be leaking were plugged up temporarily, and the leakage thus reduced. The outside gallery and the No. 4 heading were deepened so as to concen- trate all the leakage, and cause it to flow to the shaft-end of REMOVAL OF THE HELL-GATE ROCKS. 353 that heading, where pumps were placed. The following shows the amount of the appropriations made by Congress each year for Hell-gate and East-river improvement, and the whole amount expended up to the date of the last report of Gen. Newton to the chief engineer : — 1868 $85,000 1873 $225,000 1869 180,000 1874 250,000 1870 250,000 1875 250,000 1 871 225,000 1872 225,000 $1,690,000 After this report was made, Congress appropriated ^250,000. 'Total amount of appropriations $1,940,000 00 Total amount expended to Aug. I, 1876 1,686,811 45 Estimated cost of completing entire work of improving Hell Gate and the East River 5,139,120 00 Care had been taken to test the various kinds of explosives. Up to the middle of 1874, nitro-glycerine had been principally used for blasting purposes. Several hundred pounds of mica- powder were then tried, some giant-powder, several thousand pounds of rend-rock, and, later, considerable vulcan-powder was used. All of these are nitro-glycerine compounds. Neither of them was found to be as powerful as the glycerine itself ; but it was repeatedly demonstrated, that, with ten ounces of rend- rock or vulcan-powder, they could break as much rock as they formerly did with eight ounces of nitro-glycerine, while the cost per pound was less than one-half that of glycerine. The Mode of Firing {Final Explosion). — After the holes had been charged with tin canisters, the next operation was to in- sert the priming-charges, which were contained in brass tubes. Brass was preferred to tin on account of greater durability in salt water and better protection against leakage, — conditions insuring the detonations at least against moisture, should the •exposure be of long duration. The amount of these charges — three-fourths of a pound to each primer — has been included in the grand total already given. The primers contained also, as detonators, fuses holding each twenty grains of fulminate of mercury. The terminals of 3S4 THE MODERN HIGH EXPLOSIVES. two connecting-wires were inserted in each fuse, and bridged with .ooi-inch silver platinum wires a quarter incu in length. The fuses, in groups of twenty, were connected in continuous series with connecting-wires. A lead and a return wire were attached to each group. Twenty primers, with fuses and wires properly arranged in a box, with lead and return wires on reels, were carried to each party engaged in this work. The time consumed in placing 3,680' primers, unreel- ing the lead and return wires, and ■- — leading these out of the shaft, was two- days and a fraction. The connecting-wires, in length varying in the different groups from twenty to thirty-five feet, were copper wires of No. 1 8 American gauge (.04303 inch), insulated by a coat of gutta-percha ; the size after coating being No. 9 American gauge (.11443 inch). The total amount used was 118,525 feet. The lead and return wires were copper wires of No. 12 American gauge (.080808 inch), insulated with two coats of gutta-percha; size of coating. No. 4 American gauge (.2043 inch). The tcftal amount used was 147,703 feet, in lengths from 250 to 625 feet. The batteries used consisted respectively of forty, forty-three, and forty-four cells of zinc and carbon, or nine hundred and sixty cells in all, divided into twenty-three distinct batteries, each battery to fire a hundred and sixty fuses, arranged in divided circuit, m eight groups of twenty each. The fluid was made in the proportion of six pounds of bichromate of potassa, one gallon concentrated pure English sulphuric acid, and three gallons of water. Fig. 124. REMOVAL OF THE HELL-GATE ROCKS. 355 The separate batteries were so arranged in two frames, that all the cells could be immersed by the same operation. The system then consisted of 3,680 mines and twenty-three bat- teries ; each battery assigned to a hundred and sixty mines, which were divided into eight groups of twenty each. The mines of each group were connected in continuous series, and a lead and return wire to the battery closed the circuit. To insure the simultaneous discharge of the whole system, a " circuit-closer " was introduced. The method, which will be explained, for one division of a hundred and sixty charges, will suffice for the others. One lead-wire from each group of the division — i.e., eight in all — was connected with one pole of the battery. The other pole was then connected with a brass pin, penetrating through a vvooden horizontal disc, which, being let go by the run, would cause the brass pin to enter a cup filled with mercury, planted in a second wooden horizontal disc fixed in position. If the eight return-wires of the same group were then connected with the brass cup containing mercury, it is evident, that, when the brass pin entered the mercury-cup, the circuit would be closed, and explosion would result. Obviously, if, instead of one pin and one mercury-cup, twenty-three pins and twenty-three cups were attached respectively to the two discs, and the same con- nections as just described made for each and every division of a hundred and sixty mines, a simultaneous explosion would result at the moment when the upper disc should fall upon the lower. The upper disc was held over the lower one, and apart from it, by a cord passing and looped over the tin case of a torpedo, securely attached to a frame. This torpedo, or cartridge of dynamite, was provided with a detonator, from which two wires passed to a small battery situated twenty-one hundred feet distant. The torpedo was fired by closing this circuit with a Morse's key : the cord being severed, allowed the upper disc to descend upon the lower, and thus close the circuit of the, great batteries. The siphon was started at 12.07 a.m. on the 23d of Septem- ber, and at 7.30 p.m. the excavations were filled to the level of the tide. 356 THE MODERN HIGH EXPLOSIVES. The mines were fired at three seconds past 2.50 p.m., on Sept. 24, 1876. The explosion was distinguished by the absence of hurtful shock in the atmosphere, in the water, or under ground. The elevation of spray, vapor, and gases, projected upward, reached to the height of a hundred and twenty-three feet, measured at the centre and highest point. The quantity of -irFf^ IMPaOTEHEST lAST EIVERANDHELr. GATE KEnrxoHKL Fig. 125. water actually raised was trifling, as evidenced by the almost total absence of a propagated wave. The explosive effort in the air was not perceptible ; the glass in buildings close to the dam, and of one in particular along the shore-line of the shaft itself, not having in a single instance been broken. The underground shock was trifling, but perceptibly felt in the cities of New York and Brooklyn. Along the line of the reef, a little plastering was dislodged from a ceiling in a house REMOVAL OF THE HELL-GATE ROCKS. 357 a hundred and fifty yards, and in two houses six thousand yards, from the work. The new facts obtained by this experience are: — 1st, That an unlimited amount of explosives, distributed in blast-holes in moderate charges, proportioned to the work to be done, thoroughly confined in the rock, and tamped with water, may be fired without damage to surrounding objects. 2d, That an unlimited number of mines may be simultane- ously fired by passing electric currents through the platinum- wire bridges of detonators. The total cubic contents demolished by the explosion were 63,135 cubic yards solid. On the different suppositions for the broken dibris of once and a half, and of twice, the original volume, there would result respectively 94,702.5 and 126,370 cubic yards. The contractor was set at work removing the broken rock with a steam-grapple. The cost to the government is $2.40 per ton of 2,240 pounds. The quantity of broken stone to be grappled in order to obtain a depth of twenty-eight feet was 45,488 cubic yards. CHAPTER VIII. THE APPLICATION OF THE HIGH EXPLOSIVES FOR MILITARY PURPOSES. APPLICATION FOR MILITARY PURPOSES. I. Destruction of Palisades. — From what has been said before as to the effects of dynamite on timbers and trees, it naturally follows that a sufficient number of cartridges placed alongside ■of a palisade will destroy it. Canvas sacks containing about five pounds are best for this purpose. Mr. P. Champion of the French Artillery Corps furnishes us the following valuable information, which he gathered during a series of practical trials in the siege of Paris by the Prus- sians : — Experiment. — The palisade which was constructed in view of our experiment had a length of one metre, and was of the ordinary model. At the base, a cartridge containing five pounds of fifty per cent dynamite was placed. The explosion destroyed all the stakes, and the fragments were projected in all directions. Complete ruptures of palisades of the ordinary model were produced by employing cartridges charged with four pounds of 'dynamite, and suspended at their ends from the palisades. The same effect was also produced by zinc tubes containing five and a half pounds of dynamite per running metre, placed at the foot of the palisades. In the first explosion, out of fourteen stakes, nine were cut at the height of the cartridge; five were injured more or less without being thrown down. In the second explosion, five stakes which were in front of the cartridge were cut away. 358 APPLICATION FOR MILITARY PURPOSES. 359 The fact was also established, in the second explosion, that no splinters were thrown in the direction of the operator. Doors, Wooden Enclosures, Plastering. — Small cartridges, weighing three to four ounces, are hung up on nails along the walls, about four inches apart. By exploding one of them, the other cartridges will explode simultaneously along the whole line. The weight of the cartridges varies with the thickness of the obstacles. Tamphig, in both cases, would diminish the quantity of explosive used, without modifying the result. Sacks of earth, or any other debris, can be employed for tamping. Trials on Walls. — The third series of experiments was made on a wall ten feet high and one and a half feet wide, constructed of rough stone masonry, joined by good mortar, and forming regular layers in the lower part. The wall, covered with a coping of flagstones, was very solid, and made of the very best kind of material, and could be considered as a very substantial structure. A can containing three kilograms eight hundred grams of fifty-per-cent dynamite was placed vertically at the foot of the wall, and the cap was introduced through the cork-stopper, and fire was given. A gap eighty centimetres wide and eighty-five centimetres high was opened at the foot of the wall. The same aspect of the opening was noticeable on both facings of the wall. The rocks fliew in both directions of the opening ; but, on the side opposite to where the explosive was placed, the rocks were projected as far as fifteen metres. Beside the breach, the wall was so shaken, that, with a small hammer, it was enlarged to an opening of one metre fifteen centimetres height and one metre seventy centimetres width. A second trial was made under the same conditions, but cov- ering the can of explosive by four sacks filled with sand. The effect was notably increased ; and the breach made was one metre seventy centimetres wide by two metres forty centime- tres high, and the base of it was covered with rocks to a height of seventy centimetres. The wall was shaken to the top, and two metres fifty centimetres in width. The sacks of sand were projected to a distance of twenty-five metres back of the explo- sive, and some bowlders were sent flying to a distance of sixty metres in front of it. Therefore the tamping augments very 36o THE MODERN HIGH EXPLOSIVES. Fig. 126. largely the effects of dynamite; but the weight of the sacki renders them inconvenient to carry, especially when in the presence of an enemy, and when the work has to be rapidly executed. The following figure illustrates the effect of the last trial (Fig. 126). In the third trial, the object in view was to determine the most advantageous method .-i^nsass^sssg? for placing the dynamite- can against the wall, with- out being obliged to cover it with sand. It was placed against the wall, on a slab about seventy centimetres high, and was fired without any other preparation. The breach about fifty cen- timetres above the ground presented an opening of eighty centimetres in width and one metre in height on the face against which the explosive was placed, and of one metre by one metre fifty centimetres on the opposite side. See the following Fig. 127. The wall was also shaken two metres high and two metres wide, and the breach could be enlarged by hand. There is, according to this trial, a great advantage in rais- ing the charge of dynamite about one-third of the height of the wall, instead of placing it on the ground. A fourth experiment was made to substantiate an experiment previously made by M. Champion. He had established the fact, that, when a charge of dynamite is placed against one of the walls in the interior of a room, only one breach in this wall is made, whereas the three others are thrown down : on the contrary, if the charge is placed in the middle of the room, the four walls would tumble down. The question naturally arose, if it would not be advantageous, to place the charges at some distance from the wall which we desire to destroy. Fig. 127. APPLICATION FOR MILITARY PURPOSES. 361 Four kilograms of dynamite, in two canvas sacks, were placed on a little earth-knoll about fifteen centimetres high and fifty centimetres distant from the wall, and surrounded by some sacks full of earth, but open against the face of the wall. The explosion produced only a small breach, fifty centimetres by fifty centimetres ; but the wall was shaken up to its full height and three metres in width. The slabs on the coping of the wall were displaced. With very little exertion, and with- out tools, all the shaken part could be taken down. (See ,^. „ , ^ Fig. 128. Fig. 128.) . Probably enclosure walls, which are generally of poor masonry, can be best destroyed in this manner. The quantity of the dynamite charge should be in proportion to the solidity of the wall. The less solidity a wall possesses, the more difficult it will be to throw it down, or to make a breach into it ; as a bad wall gives way easily to the breaking effect of the explosion, and propagates the shock but little. The charge is therefore placed at a greater distance, and has a chance to act on a greater sur- face ; and, owing to the bad construction of the wall, it will throw it down. A fifth experiment was made. In a box twenty-four centi- metres by fourteen centimetres, four cartridges of dynamite were placed, each cartridge weighing seventy-five grams ; and they were placed at one metre thirty centimetres above the ground. The explosion opened a breach sixty centimetres by thirty centimetres opposite the charge, and seventy centimetres by ninety centimetres on the other side of the wall. The shock also fissured the wall, so as to enlarge the opening to one metre by eighty centimetres, one metre above ground. In fact, all the experiments were conclusive in favor of the employment of dynamite in preference to gunpowder, when it is desired to produce quick effects. Its weight is very small as compared to that of powder required to produce the same effect, and the charge need not be tamped to give satisfactory results. Consequently, without 362 THE MODERN HIGH EXPLOSIVES. fatigue, a sapper can carry to great distances all that is required to make a breach in a wall for giving passage to a whole regi- ment if necessary. Experiment made at Drancy in 1870. — Wall forty centimetres at the base, built of hard stones, having a height of two metres fifty centimetres. The dynamite employed amounted to 3 kilos and 500 grams. Two sacks filled with earth were placed on it. The explosion threw down the wall for a length of three metres ; and the formation of this long breach can be explained, because the wall terminated on one side at a short distance from the application of the blast, which notably diminished its resistance. Experiment made at tke School of Application of Fontaine- bleau. — Six kilograms of fifty-per-cent dynamite were placed at a distance of ten centimetres from the foot of the wall, which is sixty-four centimetres thick, constructed of rough stone, and at distances of three metres, strengthened by cut -stone masonry. The charge exploded ; and the effect was such, that, with a pick, an opening in the shattered walls of sixty-eight centime- tres in width could be made, and with slight effort this breach could have been considerably enlarged. M. Champion declared, after the results of these experiments, that six kilograms of fifty- per-cent dynamite were sufficient to open convenient breaches in any of the walls around Paris. Trials made at the Military School of St. Cyr. — The wall was newly constructed of rough stones ; length, three metres ; height, two metres ; thickness, thirty centimetres. Six kilo- grams of fifty-per-cent dynamite were placed in three tin boxes, each containing two kilograms, at the lower part of the wall, equidistant one from the other. The explosion threw down the wall its whole length, and tore out part of its foundation. A great amount of debris was thrown toward the operator. Destniction of a Wall at Avron, December, iSjO. — The wall we experimented upon was also of rough stone, thirty-five centimetres thick, and intercepted the aim of our cannons, and served as an intrenchment to our enemy. The sappers com- menced to destroy a portion of the wall by ordinary means. During this time we placed along the portion which we had reserved for our trial tin boxes containing each two kilograms APPLICATION FOR MILITARY PURPOSES. 363 five hundred grams of fifty-per-cent dynamite, and which were ten metres apart. When the approach of the enemy compelled us to retreat, we fired the dynamite boxes, whose explosion produced very large breaches. Better results, are generally obtained by starting the work of destruction with dynamite, which shakes the walls, and demol- ishing afterward with pick and hammer those portions which remain standing. But in similar cases we had to work with great rapidity, not to compromise the life of our men, who were constantly harassed by the enemy. Destruction of Walls at Biizenval. — The enemy was in- trenched behind the enclosure of the park. A first explosion produced a breach. The operation presented great difficulties. Our men who had to carry the explosives were few in number. Nevertheless, some soldiers and men of the engineering-corps volunteered, under the directions of Mr. Pellet, and approached the indicated spots, and, by means of canvas sacks containing two kilograms of dynamite, made openings which permitted some soldiers to pass through. The walls were thin, and it was only necessary to fire the charges without tamping to open these breaches. M. Barbe, and most of the French engineers, coincide with the Austrian experiments, which prescribe that the dynamite should be placed in immediate contact with the obstacle to be thrown down ; and that it should be arranged in long cartridges at the foot of the wall if it is desired to throw down its whole length, but that the cartridges should be placed in a heap when the breach is to be only a limited one. M. Champion, according to his experiments made during the siege of Paris in January, 1871, claims the contrary; and Commander Houbigant coincides with him. They say that better results are obtained by placing the explosive at a short distance, say ten centimetres, from the wall, and not in contact with it, so as to put a column of air in vibration, and to divide the effect of the charge on a greater surface. Lieut. B seeks to explain this last method by some the- oretical considerations. Starting from the principle that all explosive bodies, whatever be the rapidity of their deflagration, produce, in a homogeneous mass like the atmosphere, a vibra- 364 MODERN HIGH EXPLOSIVES. tion which propagates itself spherically, and whose intensity is inversely proportionate to the spheric surface, and varies in consequence in an inverse ratio to the square of its radius, — that is to say, the distance from the centre of explosion, — Mr. B draws the following conclusions : — I. That the charge of dynamite must be placed opposite to the centre of resistance of /I'C /a m,//Mi//M/Mi/M/i/iMXb^/iM/M/Mi/M the wall. 2. That the charge must not touch the wall, as it may happen that its effect will be reduced, and result in a small hole not large enough for the breach which it was intended to produce ; and there would be in compen- sation only a projection of dibris to a great distance, which is rather dangerous. Seeking for the best place to put the charge of dynamite so as to obtain a breach which would have the width 2 L, and con- sidering that the resistance of the wall would be the greater the nearer the charge is placed to the ground, he established the fact, that the charge should be placed on the ground oppo- site to the middle of the breach to be opened, and that it should have the form of a half-ellipse, having its centre at the point O, the projection of the charge, and its vertical radius being larger than the horizontal radius, the surface resistance being greater at A than at B. DESTRUCTION OF HOUSES. 1. In a small dwelling at Drancy, about twelve feet wide, four kilograms of dynamite were placed inside the building, against the wall. Doors and windows were left open. The house was thrown down without projection of building material, and only the wall against which the dynamite was placed re- mained standing, although the walls were cracked and fissured. 2. Stone cabin at Bobigny. Thickness of wall, thirty centi- metres. Four kilograms fifty-per-cent dynamite, the same as in APPLICATION FOR MILITARY PURPOSES. 365 the preceding example, was placed in a corner which seemed to offer the most resistance, — opposite the door. The cabin was completely destroyed, and the rocks went flying in all directions. It is preferable, in destroying buildings, to place the charge in the middle of the room, as an even pressure is exerted on the surface of the exploding chamber; and experience has confirmed this theory. APPENDIX. QUESTIONS RELATING TO THE PRESERVATION OF NITRO-GLYCERINE COMPOUNDS. 1. The explosive materials can ^i^ preserved without any spon- taneous decomposition, under ordinary atmospheric conditions, in different climates, in a moderate temperature, under mod- erate hygrometrical conditions, and when not exposed to an unusually strong light. 2. A very strong light has to be feared for nitro-compounds, quite often causing their chemical alteration. 3. Great variations of temperature have also an important influence, especially when they cause the congealment of the nitro-glycerine, or in the other extreme, when they augment its fluidity and its tendency to exude. The repeated freezing and thawing-out of the dynamites will bring about the separation of the nitro-glycerine from its absorbent, so that violent and rapid changes of temperature ought to be avoided. Under the influence of a tropical climate, certain compounds are liable to slowly evaporate, and thus modify the primitive composition of the mixture. This occurs if ordinary dynamite is heated for some time on a water-bath. The nitro-glycerine evaporates slowly, and the material loses its strength in conse- quence. 4. The preservation ought to be satisfactory, even under varying hygrometric conditions of the ambient atmosphere. It is this condition which has debarred the use of deliques- cent bodies, like nitrate of soda, in the manufacture of gun- powder. This salt ought not to be employed in the manufac- ture of dynamite ; as the accidental formation of a concentrated solution of nitrate of soda would cause the separation of the 367 368 APPENDIX. nitro-glycerine, and convert the dynamite into a dangerous, non- homogeneous mass. 5. The salts which impregnate the sea-air cause the deterio- ration of explosives during voyages, as the sea-air enters the closest receptacles, in consequence of the variations of temper- ature and pressure. PROOFS OF STABILITY. 1. Stability in the Air. — The material must maintain itself in the air, without evaporation, liquation, or alteration, and should not attract humidity from the atmosphere. 2. Neutrality. — It must be neutral, and preserve this neu- trality ; especially, there should not be any disengagement of acid fumes, even when heated for a few seconds in a water-bath to 60° Cel. 3. Exudation. — There ought to be no exudation of nitro- glycerine by pressure, or spontaneously; and when heated to 55° or 60° C, no sweating-out of drops of oil should be noticed, even after slightly pressing it. When submitted to repeated changes of temperature, from below zero to the ordinary temperature, no exudation should take place. The exudation must not take place under the influence of moist atmosphere : for instance, when leaving the material for fifteen days in a box with wet rags. The material ought to be submitted to some rapid movement for several days, which would imitate the jolting action of a wagon or railroad-car, to see if drops of nitro-glycerine will separate. 4. Immersion. — The explosive is put under water, without an envelope, during fifteen or twenty minutes. It ought not to dissolve, nor should liquid drops separate. This test is special- ly for materials prepared for sub-aqueous blasting. 5. Heat. — The material has to be examined as to its inflam- mation when in contact with a burning body, and how it burns in that condition. It should be noticed if a gradual heating produces an evap- oration of some of its component parts. 6. Shock. — An explosive ought not to explode by a blow or from friction of wood on wood, or wood on metal. There are APPENDIX. 369 explosives which do not detonate by a blow of bronze on bronze, but explode between iron and iron. 7. Electricity. — The electric sparks set it on fire, but it should take a rapid succession of these sparks : and, under cer- tain conditions, they even cause the explosion of nitro-glycer- ine ; for instance, under the influence of a series of strong sparks, nitro-glycerine alters, darkens, and then explodes. The degree of sensibility of dynamites to percussion is one of the fundamental particularities, especially in their military applications. It is of the utmost importance to supply the soldier with a material which does not explode during trans- portation or by the shock of a bullet. The ordinary kieselguhr dynamite has not this quality, and consequently does not fulfil the conditions ; and compressed gun-cotton has been preferred, but even this substance is not entirely safe. The necessary conditions seem to be fulfilled by the nitro- gelatine compounds, but we meet here with another drawback : this material requires for its detonation special caps and a strong dose of fulminate. Special primers of compressed gun- cotton with large fulminating charges are required ; which com- plicates the question. When dynamite is enclosed in a strong vessel which is her- metically closed, it explodes when heated. When dynamite shows the least sign of deterioration and acid re-action, it is liable to spontaneous explosions, especially when strongly confined ; Whereas, neutral and well-prepared dynamite can be pre- served during ten years in a magazine without any weakening of its explosive effects. Water, when in contact with dynamite, displaces the nitro- glycerine, which separates : this action is slow, but inevitable, and renders soaked dynamite dangerous. Dynamite will explode, even if fired into at a distance of fifty yards and more; a circumstance which is very much against it for military purposes. The detonation of dynamite advances, in tubes entirely filled with this substance, at the rate of five thousand metres per second. 370 APPEA'D/.\. DYNAMITE WITH NITRATE OF AMMONIUM BASE. This substance is of much interest on account of its great power, which arises from the combination of nitro-glycerine and nitrate of ammonium, associated with some other comple- mentary combustible materials. Different inventors have proposed different admixtures, which accomplished a double object, — the utilization of the excess of oxygen furnished by the nitro-glycerine and by the nitrate of ammonium, and the completion of the absorbing qualities of the substance. This dynamite has one great drawback, — the hygroscopic qualities of the nitrate of ammonium separate the nitro-glycer- ine and the water at once. NITRO-GELATINE. It has been estimated, that the initial blow which is required, to cause the explosion of 'nitro-gelatine is six times as heavy a& the one required to cause the explosion of ordinary dynamite, other things being equal. This difference must be attributed to the cohesiveness of the material ; that is to say, to the larger particles, in the body of which the blow, transformed into heat„ determines the initial explosion. On account of these circum- stances, nitro-gelatine is not so sensitive to explosions from, external influences. All these conditions are very much in its favor as an agent for military purposes ; but still, all the great hopes which were entertained in regard to it remain still uncertain : the difificulty of a regular production, and the necessity of special primers, which do not always cause its explosion, have been an opposi- tion to the general introduction of this substance. Some of the advantages of nitro-gelatine are, — It does not absorb water, and only becomes white on the surface when under its influence, in consequence of the dis- solution of some nitro-glycerine contained in the superficial layers ; but the action does not go any farther. The collodion, separated by the action of the water on the first layers of the material, being insoluble in the solvent, envelops the remainder with a protecting film ; and nitro-gelatine can remain for forty- APPENDIX. 371 eight hours under water without alteration, while its explosive force remains unchanged after this test. Freezing does not alter its strength, but it loses its insensi- bility to blows. Its density is 1.6, — equal to liquid nitro-glycerine, — on account of its structure being without pores. Nitro-gelatine burns when set on fire, without exploding; that is, when operated upon in small quantities, and avoiding a previous heating. It has been kept heated for eight days, at a temperature of 70° Cel., without decomposing. When kept for two months between 40° to 45° Cel., nitro- gelatine lost half of its camphor and some nitro-glycerine, with- out any other alteration. When slowly heated it will explode at 204° Cel., unless it contains ten per cent camphor, when it will not explode. GUN-COTTON. If compressed gun-cotton, which has been previously heated to 100° Cel., is set on fire.'it will explode; and this is a mate- rial more liable to explode by ignition than dynamite. Gun-cotton, maintained at a temperature of 80° to 100° Cel., will slowly decompose, and finally take fire. When exposed to the rays of the sun, it will slowly decom- pose. It must be neutral to litmus paper, and ought not to evolve any acid fumes, even after a long storage. In the navy, gun-cotton is submitted to the heat -test. It is heated in a water-bath to 65° Cel, till fumes are evolved, which redden litmus paper ; and it ought to resist this test for eleven minutes. The heat-test can be applied on the raw nitrated cotton, or on the washed cotton, dried at a low temperature, and exposed for some time to the open air. A slow decomposition can be quickened more and more on account of the heat developed, and may end in a spontaneous explosion. Still, gun-cotton has been kept in store for ten years, without any alteration, and ships have carried it on long voyages in tropical countries. 372 APPENDIX. Gun-cotton is very sensitive to explosions from external in- fluence. Experiments made in England have proved that an attacking torpedo, placed at quite a distance, can cause the ex- plosion of a whole line of torpedoes charged with gun-cotton. The rapidity of propagation of the explosion of gun-cotton, in metal tubes, has been found to be five thousand to six thdu- sand metres per second in tin tubes, and four thousand metres in lead pipes. In the open air, the gun-cotton in flakes will burn eight times as fast as gunpowder. THE QUALITIES OF EXPLOSIVE BODIES.' The Sensibility of the Explosive Materials. — i. Some explo- sives are very sensitive to the least elevation of temperature ; others, to a quick pressure ; others, again, to a rapid blow ; and others, to the least friction. For instance, oxalate of silver explodes at about 130° Cel. (298" F.) ; the sulphide of nitrogen, at 207° Cel. (450° F.) ; the fulminate of mercury, at 190° Cel. (or 406° F.) ; and yet the ful- minate is more sensitive to blows and to friction than the other two. There are special properties, depending on the individual structure of each substance, which is especially for the solids, that favor the decomposition under certain circumstances. 2. The sensitiveness for the same substance is much greater, the higher the temperature is raised. A very striking example is presented by a material known as celluloid, which does not explode at the ordinary temperature, but acquires that property when heated to a point where it softens, — that is, about 160 to 180° Cel. (or 388° F.), — which is the point at which this substance Commences to decompose ; and so it is with the other bodies when heated to the point where a spontaneous decomposition commences. 3. When two different explosive bodies are compared, which decompose at the same temperature and with the same rapidity, their sensitiveness to blows and to friction at a lower tempera- ture depends on the quantity of material which, in the first instance, the blow or the friction acts upon; that is to sav, it I By M. Berthelot. APPENDIX. Z7l depends on the coherence of the substance, which regulates the transformation of the blow into heat at the point where it is struck, and, in consequence, the temperature which is devel- oped around that point. 4. The sensibility depends on the degree of temperature at which the decomposition commences. This temperature being lower for the chlorate of potash than for the nitrate, the first one is the more sensitive. 5. The sensibility depends also on the heat developed by the decomposition ; that is to say, the sensibility is greater if the re-action develops more heat. 6. The same quantity of heat will produce different effects on the same weight of material, according to the specific heat of this material. For instance, chlorate of potash, whose spe- cific heat is .209, substituted for an equal weight of nitrate of potash, whose specific heat is .239, in the decomposition of an explosive mixture will furnish a powder much more sensitive than the nitrate. This condition coincides with the lower tem- perature of decomposition and the absence of cohesion, which makes the chlorates very dangerous. Modes of Combustion. — The great variety of explosive phe- nomena depends on the rapidity with which the re-action propa- gates itself, and the pressures which result therefrom. Let us suppose an explosion caused by the fall of a weight from a certain height. The effect is supposed to result from the heat which is developed by the compression caused by suddenly arresting the falling body. But a simple calculation shows that the shock of a few pounds, falling from a height of one or two feet, could not raise the temperature of a mass of explosive to even a fraction of a degree, if the resulting caloric is uniformly distributed in the entire mass, and could not raise it to a temperature of 190° to 200° Cel, or the ex ploding temperature of nitro-glycerine, for instance. This effect is, nevertheless, obtained by the transformation of a blow into heat; as the pressure resulting from a. quick blow on the surface of nitro-glycerine is too quick to divide itself uniformly in the whole mass, and, in consequence, the transformation of force into heat takes place in that portion of the mass which is directly struck by the weight. 374 APPENDIX. If the pressure of the shock is violent enough, the layers struck can be heated to 200° : they will decompose, and produce a large volume of gases. The production of these gases is so violent, that their quick expansion produces another blow, more violent than the first, on the surrounding mass. This second blow is changed into heat, and causes the complete explosion of the mass. The. reciprocal succession of blows produces pressure, which changes into heat ; and this heat brings the surrounding explo- sive mass to a degree of explosion which is capable of produ- cing another blow, which transmits the heat throughout the entire mass of the explosive body, and is the real cause of the explosion. It is the mechanical energy of the weight which is trans- formed into heat, that originates the effect ; and the transforma- tion of the mechanical energy into heat takes place especially among the first layers reached by the shock. The propagation of the deflagration takes place this way, in consequence of actions comparable to those which produce a sonorous wave ; that is to say, by producing a real explosion, which advances with a rapidity incomparably greater than that of a simple burning provoked by the contact of a body in igni- tion, and operating under conditions where the gases expand freely in proportion to their production. The explosion of a solid mass or of a liquid may develop itself according to an infinite number of different laws, each- one of which is determined, all other things being equal, by the original impulse. The more violent the initial shock, the greater will be the resulting violence of the decomposition, and the greater will be the pressures which are exerted during the entire course of this decomposition. One and the same explosive substance may produce very different effects, according to the method of ignition. The changes brought about in the explosive power of some materials by the addition of camphor and resinous substances are the result of a modification brought about in the cohesive- ness of the mass, which has acquired a certain elasticity and solidity of parts, in consequence of which the initial shock of the detonator propagates itself at the beginning through a much APPENDIX. 375 greater mass. Besides, a portion of the effect is expended in the work of rending and separation : but there still remains the smaller portion, which is capable of producing heat in the parts ■directly struck; this heating, however, being dispersed through a larger mass. Therefore a sudden elevation of temperature at one spot, capable of producing successive chemical and mechanical action, can only be produced with difficulty, and re- quires the employment of a much greater weight of fulminate in the detonator. Explosions by Influence {Sympathetic Explosions). — We will now consider what are called explosions by influence, whose existence was formerly suspected from certain known facts relative to the simultaneous explosion of several buildings sep- arated by considerable space from each other, as in catastrophes occurring in powder-mills. Attention has been specially directed to this class of phenomena by the study of nitro-glycerine and gun-cotton. We will begin by giving the most important characteristic facts. 1. A dynamite cartridge, made to detonate by means of a fulminate cap, causes the adjoining cartridges to detonate, not only by contact and by direct shock, but even when at a dis- tance. In this way, an indefinite number of cartridges, arranged in a regular course, may be made to detonate. 2. The distances to which the explosion may be propagated are relatively great. Thus, for instance, with cartridges con- tained in rigid metallic envelopes, and placed on a resisting soil, the detonation produced by one hundred grams of seventy- fi ve-per-cent dynamite communicates itself .3 metre of distance, according to the experiments of Capt. Colville. D being equal to the distance in metres, and C the weight of the charge in kilograms, the experiments of this officer show that, — When the cartridges were laid on a rail, D was found to be equal to 7 C. On soft or ploughed-up earth, the distances, on the contrary, are less. 376 APPENDIX. When a cartridge is suspended in air, there is no detonation' by influence ; perhaps because the cartridge, not being fixed^ can recoil freely, which diminishes the violence of the shock. Nevertheless there are experiments w?hich show that the air suffices for the transmission of the detonation by influence, although with greater difificulty, and requiring a greater mass of the explosive. With a dynamite less rich in nitro-glycerine, contained in similar cartridges, and placed along the ground, the experi- ments of Capt. Pamard have given as the smallest distances, — D = .90 C. If metallic envelopes having less resistance are used, the dis- tance at which the explosion is propagated is likewise diminished. Dynamite simply spread along the ground ceases to propagate the explosion. The experiments in Austria have given similar results. They have shown that the explosion is communicated either in the free air with intervals of four centimetres, or else through pine boards eighteen millimetres thick. In a lead tube with a diameter of .15 metre, and a metre in length, a cartridge, placed at one extremity has caused the detonation of a car- tridge at the other end. The explosion is still better transmitted through tubes made of wrought iron. 3. An explosion which is propagated in this manner will go- on weakening itself from cartridge to cartridge, and even change its character. Thus, according to the experiments, made by Capt. Muntz, at Versailles, in 1872, a first charge of dynamite, exploded directly, excavated a funnel-shaped hole in the ground, with a radius of .30 metre. The second charge, detonated by influence, produced an opening of only .22 metre. The effect of the detonation was then reduced. This reduction should manifest itself towards the limit of the distance, at which the influence ceases. The propagation by influence depends on the pressure ac- quired by the gas, and on the nature of the support. It is not even necessary that it should be rigid. 4. Finally, in operating vmder water at a depth of 1.30 metres, a charge of five kilograms of dynamite brought on an explosion of a charge of four kilograms, situated at a distance of three APPENDIX. 377 metres. The water then transmits the explosive shock, at least to a certain distance, as does a solid body. This transmission is so violent, that the fish are killed in ponds within a sphere of a certain radius by the explosion of a dynamite cartridge, — a process which is frequently employed to fish a body of water, but which is objectionable as one which would depopulate the stream. 5. Similar experiments have been made by Abel with com- pressed gun-cotton. According to his observations, the explo- sion of the first block determines that of a series of similar blocks. The propagation under water has likewise been studied. The explosion of a torpedo charged with fulminating-cotton cadsed the detonation of adjoining torpedoes placed within a certain radius of activity. The sudden pressures transmitted by the water, when measured by means of the compression of lead at different distances, — such as 2.50 metres, 3.50 metres, 4.50 metres, 5.50 metres, — go on decreasing, as would be ex- pected. Besides, experiment has shown, that the relative posi- tion of the charge and of the crusher is of no consequence ; which is in harmony with the principle of the equal transmission of hydraulic pressure in ail directions. 6. Explosions of fulminating substances, which are rapidly propagated by a great number of caps, belong to this same order of explosions by influence. 7. It follows, then, from these facts, and especially from the experiments made under water, that the explosions by influ- ence are not due to inflammation, properly so called, but to the transmission of a shock arising from the enormous and sudden pressures produced by the nitro-glycerine or the gun-cotton. Let us enlarge upon this explanation : it is the same funda- mentally as that which we have already shown as accounting for the influence of the shock which determines the direct detonation of explosive substances. 8. In an extremely rapid re-action, the pressures may ap- proach to the limit which corresponds to the matter detonating in its own volume ; and the commotion due to the sudden devel- opment of almost theoretical pressures can be propagated, both through the ground and supports as intermediary, or through the air itself, projected en masse, as has been shown by the 378 APPENDIX. explosion of certain powder-factories and of gun-cotton maga- zines, and even by some of the experiments with dynamite and compressed gun-cotton. The intensity of the shock, propagated either by a column of air or by a liquid or solid mass, varies with the nature of inflammation : it is of greater violence, according as the length of the chemical re-action is shorter, and develops more gas ; that is to say, a higher initial pressure and more heat for the same weight of explosive material. 9. This transmission of a shock is conveyed better by solids than by liquids, and better by liquids than by gases. With gases, it becomes more rapid, the more they are compressed. Through solids, it is better propagated according to their degree of hardness ; iron transmitting it better than earth, and hard ground better than ploughed soil. All breaks of continuity in the transmitting material tend to weaken it, especially if a substance is interposed. Thus it is that the use of a tube made from a goose-quill, as a receiver, stops the effect of mercury fulminate ; while a tube or a capsule of copper transmits this effect in all its intensity. The explosions by influence are the better propagated in a series of cartridges, according as the envelope of the first detonating cartridge is the more resisting, which allows the gases to attain a greater pressure before the covering is destroyed. The existence of a space, filled only with air, between the fulminate and the dynamite, on the other hand, diminishes the violence of the shock transmitted, and, in consequence, that of the explosion ; generally the effects of breaking-powder are lessened when there is no contact. 10. To form a full conception of the transmission of sudden pressures which produce shock by the supporting medium, it is desirable to recall this general principle, in virtue of which, in a homogeneous mass, pressures are transmitted equally in all directions, and are the same in a small element of surface what- ever its position. Detonations produced under water with gun-cotton show that this principle is equally applicable to the sudden pressures which produce the explosive phenomena. But it ceases to be true when one passes from one medium to another. APPENDIX. 379 11. If the inert chemical matter which transmits the explo- sive movement is fixed in a given situation on the surface of the ground ; or, better, on the surface of the rail on which the first cartridge was placed ; or, better still, held by the pressure of a mass of deep water, in the midst of which the first deto- nation is produced, — the propagation of the movement in this matter will hardly be able to take place, except under the form of a wave of a purely physical order, and consequently of an essentially different character from the first wave of a chemical and physical order simultaneously developed in the explosive body itself. This new wave propagates the concussion away from the explosive centre, all around it, and with an intensity which decreases inversely as the square of the distance. Even in the neighborhood of the centre, the displacements of the molecules may break the cohesion of the mass, and disperse it, or crush it by enlarging the chamber of explosion, if the operation is con- ducted in a cavity. But at a very short distance (the magnitude of which depends on the elasticity of the surrounding medium) these movements, confused at the beginning, arrange them- selves in such order as to produce a wave, properly so called, characterized by compressions and sudden deformations of the material ; the amplitude of these oscillations depending upon the magnitude of the initial impulse. They move with a very great rapidity, and preserve their regularity up to the point where the medium is broken. Then these compressions and sudden deformations change their nature, and are transformed into a movement of impulse ; that is to say, they reproduce the shock. If, then, they act on a new cartridge, they may determine its explosion : the shock will be otherwise weakened by the dis- tance, and in consequence the character of the explosion may be modified. The effects diminish in this manner up to a cer- tain point, from which the explosion ceases to propagate itself. When this occurs on a second cartridge, the same series of effects will be produced from the second to the third cartridge, but they depend on the character of the explosion of the second cartridge. And thus it goes on. 12. Such is the theory that appears to me to explain explo- 380 APPENDIX. sions by influence, and the phenomena which accompany them. It depends, definitely, on the production of two orders of waves : one series represents the explosive waves, properly so called, developed in the midst of the matter which detonates, and consists of a continually reproduced transformation of the chemical actions which transmit the shock to the support and to the contiguous bodies ; the other is a purely mechanical and physical series, which transmits equally the sudden pressures all round the centre of the concussion to the adjoining bodies, and by a singular circumstance to a new mass of explosive material. 13. A theory differing from this was originally proposed by Abel. It is the theory of synchronous vibrations, to which we shall now direct our attention. According to this English savant, the originating cause of the detonation of an explosive lies in the synchronism between the vibrations produced by the body which provokes the detonation, and those which the first body would produce in detonating ; precisely as a violin- string resounds at a distance in unison with another vibrating chord. > Professor Abel has cited the following facts in support of this theory. To begin with, the detonators appear to differ with each variety of explosive. For instance, nitrogen iodide, so susceptible to shock or friction, cannot cause the detonation of compressed gun-cotton. Nitrogen chloride, so easily ex- ploded, will not produce the same detonation, except when ten times the weight of the necessary fulminate is used. In the same way, nitro-glycerine will not produce a detonation of gun- cotton in sheets on which is placed the case containing the nitro-glycerine. In this way nitro-glycerine, up to 23.3 grams, can be detonated without effect. On the other hand, the in- verse influence is proved ; 7.75 grams of compressed gun-cotton having caused the detonation at a distance of twenty-five milli- metres of nitro-glycerine, wrapped up in an envelope of thin sheet-iron. A cap filled with a mixture of potassium ferro- cyanide and potassium chlorate likewise (according to Brown) will not detonate gun-cotton. Finally, a cap consisting of a mixture of mercury fulminate and potassium chlorate should be used of much heavier weight than if it be filled with the APPENDIX. 381 pure fulminate (according to Trauzl). Nevertheless, the heat given off by the same weight is greater by one-fifth than that with the first mixture. 14. Messrs. Champion and Pellet have brought to the sup- port of this ingenious hypothesis the following experiments : They attached to the strings of a double-bass particles of nitrogen iodide, a substance which detonates on the slightest friction. Then they made the strings of a similar instrument vibrate at a short distance off : a detonation was produced, but only for sounds higher than a certain note, which corresponds to sixty vibrations per second. They also took two conjugate parabolic mirrors placed 2.5 metres apart; and they arranged along the line of foci, at different points, several drops of nitro-glycerine or of nitrogen iodide : then they detonated at one of the foci a large drop of nitro-glycerine. They observed that the explosive substances placed in the conjugated foci detonated in unison, to the exclusion of the same substances placed at other points. A layer of lampblack placed on the surface of the mirrors was designed to prevent the reflection and the concentration of the heat-rays. 15. As yet none of the experiments appear to me to be con- clusive, and several of them seem even to be formally opposed to the theory. We shall begin by observing that the charac- teristic feature of a given musical note, capable of determining each variety of explosion, has never been established : it is only below a certain note, that the effects cease to be produced, while they take place by preference, whatever the explosive bodies may be, by the action of the most acute notes. Besides, these effects cease to produce themselves at distances which are incomparably less than the resources of the chords in unison ; which goes to prove that the detonations are functions of the intensity of the mechanical action, rather than of the character of the determining vibration. Similarly the detona- tion ceases to be produced when the weight of the detonator is too slight, and, in consequence, when the mechanical energy of the shock is weakened. Nevertheless, the specific vibratory note, which determines the explosions, should always remain the same. For instance, cartridges filled with seventy-five per 3S2 APPENDIX. cent of dynamite cease to detonate when the capsule contains a weight of fulminate less than .2 grams ; the detonation only- being assured in all cases by the regulation weight of one gram. This confirms the existence of a direct relation between the character of the detonation and the intensity of the shock pro- duced by one and the same detonator. If it is true that gun-cotton will cause the nitro-glycerine to detonate in consequence of the synchronism of the vibration communicated, then we do not understand why the reciprocal action does not take place, while the absence of reciprocity can be easily explained by the difference of the structure of the two substances which play so important a part in the transfor- mation of the mechanical energy into work. 16. This same diversity of structure, and the modifications which it introduces into the transmission of the phenomena of shock, and the transformation of mechanical energy into ther- mal energy, may be called upon to explain the facts observed by Abel. The difference between the energy of pure fulminate and of the fulminate mixed with potassium chlorate is no less easily explained, the shock produced by the first body being sharper on account of the absence of all dissociation of the product (which is no other than carbon monoxide) : this absence should be contrasted with the dissociation of carbon dioxide formed in the second case. Perhaps, also, the formation of potassium chloride disseminated through the gas produced, with the con- currence of potassium chlorate, weakens the shock, just the same as silicon does in the case of dynamite. 17. All the effects observed with nitrogen iodide may be explained by the vibration of the supports, and by the effects of rubbing which results therefrom ; this substance being par- ticularly sensitive to friction. 18. The experiment with the conjugate mirrors may also be easily explained by the concentration in the focus of the move- ments of the air, and, therefore, of the mechanical effects which result. 19. Besides, M. Lambert has proved, by experiments made for the commission on explosive substances, that in the explo- sion of dynamite cartridges in tubes of cast-iron of large APPENDIX. 383 diameter, regarded from the standpoint of detonations by influence, there does not appear to be any difference be- tween the ventral segments and the nodes characteristic of the tube. 20. Desiring to clear up this entire question by removing it from the influence of the supports and of the diversity of cohe- sion and physical structure of solid explosive substances, I undertook a series of special experiments on the chemical stability of matter in sonorous vibration, and especially on that of gaseous bodies such as ozone, hydrogen arsenide ; or liquids, such as hydrogen peroxide and persulphuric acid ; all of these bodies being selected from among those which decompose, or change spontaneously, at ordinary temperatures, with the dis- engagement of heat, precisely as explosive substances do. They lead to the conclusion, that substances which are trans- formable with the disengagement of heat are stable under the influence of sound-waves, while they are decomposed under the influence of ethereal vibrations. This diversity in the mode of action of the two classes of vibrations is not surpris- ing, when we consider that the most acute sonorous vibrations are incomparably slower than the luminous or thermal vibra- tions. 21. Hence it appears certain that the propagation of explo- sions by influence is not made in virtue of an undulatory move- ment, which is a complex motion of a chemical and physical order in the midst of the explosive substance which is decom- posed, while it is purely physical in the midst of intermediary substances which suffer no decomposition. But that which distinguishes this sort of movement of the vibrations, properly so called, is, first of all, the magnitude of the mechanical energy which it transmits; it is also the unique character of the explo- sive wave which is propagated in contra-distinction with the multiplicity of successive sonorous waves. Finally, it is essen- tial to observe, that the explosive material does not detonate because it transmits the movement, but, on the contrary, be- cause it arrests it, and because it transforms on the spot the mechanical energy into thermal energy, capable of suddeniy raising the temperature of the substance up to the degree which will produce its decomposition. 384 APPENDIX. THE ORIGIN OF THE NITRATES. The Natural Nitrification. — i. The formation of nitre in nature has always been regarded as a very obscure phenome- non, in spite of the numerous researches on the subject. It is a well-known fact, that the alkalies and alkaline carbon- ates, when exposed to the air for any length of time, give re- actions of nitric acid. Stahl noticed this two hundred years ago. Under all circumstances, and under all conditions, and under the action of the natural forces, there is a continual production of small quantities of nitrates in nature. There are also certain plants which produce nitre, at the expense of the nitrogen combinations contained in the soil or in the manure, as borage, parietary, beet, tobacco ; but still the conditions of the natural nitrification are unknown. 2. I will not speak here of the nitrate deposits of Peru, formed under the influence of geologic conditions of which we are ignorant, but will limit myself here to the nitrification which is produced every day under our eyes. 3. We will consider the nitric acid, formed in the atmos- phere in small quantities under the influence of storms with a little nitrate of ammonium, which is carried by the rain-waters into the soil, where it unites with the bases. This formation is of great interest ; but a profound study of this subject has shown that this origin is not sufficient to account for the pro- duction of the nitrates in nature, and for their concentration in a soil impregnated with animal matter. 4. In effect, the natural nitrification results principally from the slow oxidation of azotized organic compounds, or even ammonium, effected by the oxygen of the air, with the assist- ance of water and an alkaline or earthy carbonate. A brilliant light prevents it. Argillaceous and porous materials seem to favor it, but it does not seem that free nitrogen enters into this mode of for- mation of saltpetre. S- Different questions present themselves here. It is pos- sible that this slow oxidation is brought about by the presence of clay and porous bodies, as demonstrated by Kuhlman, who changed ammonium into nitrous vapors and nitric acid in con- tact with platinum sponge and oxygen at three hundred degrees. APPENDIX. 385 The humic elements, the sulphuretted compounds, ferruginous and other oxidizable bodies which decompose in earth, at the same time as the nitre forms, — are they intermediary in some special re-action ? Do they provoke the oxidation of ammonium, and become oxidized in return, as copper does in the presence of air ? Phosphorus produces a similar re-action ; and, consequently, this influence has been attributed to the humus. Does an oxidizing body intervene, as in the re-action where the peroxide of manganese, heated to redness, changes the ammonium into nitrous vapors ? Does ozone play any rdle in this re-action, as Schonbein sup- posed, according to whom certain vegetable matters emit ozone, — a gas which is capable of burning ammonium in the cold, with the formation of nitrite ? Do the microderms and microbes bring about this oxidation after the manner of a fermentation ? These are the principal hypotheses which have been brought forward, since the eighteenth century, to explain the spontane- ous formation of nitre in nature. To-day these questions, so long controverted, have made a decided advance in consequence of the experiments of Schlo- sing and Muntz. 6. These scholars have ascertained that the nitrification of the ammonium and of the azotized organic compounds takes place under the influence of organized corpuscles, punctiform, rounded and slightly elongated ; occasionally two and two are fastened together, of very small dimensions, and analogous to the germic corpuscles of the bact^res. These corpuscles are to be found in all arable soil, and in the sewer-waters, which they tend to purify. They determine the fixation of the oxygen on the ammonium and on the azotized materials, producing thereby the nitrates ; sometimes nitrites when the temperature is below twenty de- grees, or the ventilation insufficient. The nitrites result also from the reduction of the original nitrates by the intervention of the butyric fermentation and analogous secondary fermenta- tion. Their influence is felt between certain limited temperatures. 386 APPENDIX. Under 5° C. it is insensible, but at 12° becomes appreciable. The higher the temperature, the more their effect, up to 37°, — the temperature at which the nitrification is ten times more rapid than at 14°. Beyond that temperature it slackens, and at 45° is less active than at 15°, and at 55° stops entirely. In proportion as the temperature rises, and especially when it reaches 100°, the vitality of the corpuscles diminishes. They die at 100°. A patch of ground, or a body of water, in course of nitrification, loses that property, if exposed to that degree of heat, and does not recover it after cooling. They die also under the influence of chloroform vapors and antiseptics. Humidity is indispensable for them ; and it is only necessary to desiccate a fertile patch of ground, that it should become entirely sterile. The corpuscles cannot resist a prolonged privation of oxygen, at least when we operate in water. They act equally in the obscurity, or under the influence of a moderate light ; but a strong light is hurtful to them. Their action requires the concurrence of a slight alkalinity,, be it in the shape of carbonate of lime, or a slight percentage of alkaline carbonates. Beyond that slight quantity, the alka- linity is injurious, which explains the unfavorable influence exerted by manuring on the process of nitrification. The development of the nitric fermentation in water requires the simultaneous presence of an organic material and of an azotized compound. The nitric fermentation multiplies itself by sowing the nutritive liquid, or earth, by means of a small parcel of arable soil, or by a few cubic centimetres of sewage- water. The multiplication is slow, and seems to operate by budding. The presence or absence of porous bodies seems to play no role in the nitrification, contrary to old opinions. The mouldiness and the ordinary microderms are entirely distinct from this fermentation, and even contrary to its action. In effect, they destroy the nitrates, and change them into nitrated organic compounds, during the development of their mycelium : they act in the same manner on ammonium or on amraoniacal salts. Later, during the fructification, a portion of the nitrogen is eliminated in a gaseous form, occasionally with an intermediate reproduction of ammonium. APPENDIX. 387 The result of all these observations makes it evident that there exist particularly organized, organic animalcules, analo- gous to the acetic ferment, which determine the fixation of the oxygen on the ammonium and on the azotized organic compounds, and, consequently, the metamorphosis of these substances into nitrates. They resolve the problem of the nitrification, operated in nature at the expense of the azotized and ammoniacal compounds, — a problem entirely distinct from the fixation of free nitrogen, derived from the atmosphere. They are, nevertheless,, connected ; as the natural nitrification acts on azotized compounds which already are formed. The nitrification produces itself principally on the gaseous compounds, resulting from putrefaction, mixed with an excess of atmospheric air. (These compounds are ammonium, carbon- ate of ammonium, hydrosulphate, cyanhydrate of ammonium,, and, perhaps, hydrocyanic acid.) The nitrification requires humidity. It takes place easier in presence of alkaline and earth salts than in their absence. As an instance : — A basket containing clean chalk, when suspended over a mass of blood in putrefaction, will contain, after a few months, two and a half per cent of nitrate. A dish containing clean mortar, placed in the atmosphere of a stable, .will contain ni- trates in three weeks. These conditions are in accordance with the biological condi- tions which direct the development of the nitric ferment, as above explained. Ammonium and oxygen are, therefore, the generators of the nitrates. The disengagement of the ammonium gases produces itself only in an alkaline medium, and is furnished by the slow metamorphosis of the azotized organic principles. In an acid liquor, it is very clear that such a disengagement could not take place. It cannot take place in a liquor capable of furnishing, by double decomposition, the fixed and neutral ammoniacal salts, as the sulphates. Again : the ammonium production is facilitated, when the liquor can produce, by double decomposition, a volatile ammo- niacal salt, as the carbonate. 388 APPENDIX. The presence of a fixed alkali or alkaline carbonate is not only necessary to liberate the pre-existing ammonium in the ammoniacal salts, but determines the generation of ammonium, at the expense of the azotized organic principles, by virtue of a kind of predisposing affinity, which is due to the intervention of a certain energy which results from the saturation of the bases by the acids during the oxidation. Air, or, rather, oxygen, is indispensable, as it is a phenome- non of oxidation which is wanted ; and such a phenomenon could not take place in a reducing medium, as, for instance, matter in putrefaction. An alkali or alkaline salt is very effectual in promoting the oxidation of the organic principles by means of the oxygen from the atmosphere : in an acid medium, this re-action does not take place. The slow oxidation of the ammonium produces nitrous acid, which is converted into nitric acid, which combines with free ammonium to form nitrate of ammonium, — a fixed salt at the ordinary temperature. An alkaline carbonate transforms the nitrate of ammonium into a fixed alkaline nitrate and into car- bonate of ammonium, which is dissociated again to produce free ammonium, which is subject again to a posterior oxida- tion. It is an established fact, that nitrate of ammonium, when dissolved, and in presence of carbonate of potash or soda, is transformed instantaneously into nitrate of potash, or soda, and carbonate of ammonium ; the strong acid preferring the strong base, leaving to the weak acid the weak base. Carbonate of lime produces the same re-action. INDEX. INDEX. PAOB Advantage of electricity in blasting i66 Analysis of nitro-glycerine compounds 141 " for cellulose and ash 155 " for gun-cotton Ij4 " Hampe's method 145 " Lunge's method 145 " quantitative 149 " saltpetre and soda 154 " Siewert's method 144 " Walter Hempel's 147 Application of high explosives in agriculture 314 " " " " for military purposes 358 " " bore-holes, in rock 247 Bank blasting 279 Beaujard process 26 Big blasts 271 Blasting earth 277 " ice 326 " iron plates 311 " piles and beams 321 " " " " under water 323 " in shafts 263 " in St. Gothard Tunnel 261 " stumps 316 " submarine wood 324 " sub-aqueous 3^7 " submarine rocks 329 " trees 3'. 5 " principles of 229-239 Boring under water 3^7 Borlinetto's powder 13^ Bornhardt's machine '68 Breaking up sunken vessels 3°9 Brain's blasting powder 94 Brougire's picrate powder '37 391 392 INDEX. PAGR Canal, Suez 293 " Panama 295 " Corinth 299 Cannon-barrels, disruption of 312- Caps, their introduction 54 Cartridge-machines 9' Cellulose 31 Chambering o£ deep bore-holes 246 " with hydrochloric acid 273 Charging of a bore-hole 1. 263 Chlorates 138 Collodion 122 " its preparation . . . , r—r .- 122 " its properties 122 Colonia powder 94 Connecting the shots .' .' 185, Decomposition of fats 20 Denitrification of the resting acids 9& Deportment under water 164 Demolishing walls and structures 307 DesignoUes' powder 136 Destruction of a dam 343 " " palisades 358 " " doors, enclosures 35gh " " houses 364 Determination of powder-charges and tables 248 " " " " in tunnels 255. in shafts 263 " " " " on rocky slopes 243 Dextrine 33 Dualine 59 Dynamite or giant powder 55 " actual experience 65 " authority 66- " composition and properties 5j " containing chemically active absorbents 57 " confinement and compression 62 No. I 56. " " its experimental test 64 " " its manufacture 57 " " in metallic cases 63 " " its properties 58 " " its temperature 61 " " its thawing and enclosing 64 " " its transportation 66. No. 2 67 " " discussions on ... • 67 Dynamo-electric exploder . 174 INDEX. 393 PAGE Effects of shots charged with dynamite 268 Electric conductibility of metals 182 Electricity in blasting 165 Explosives 36 Explosive bodies, qualities 372 Explosions by influence 375 Force and effect of explosive bodies 240 Forcite 85 " qualities of 91 Frictional electric apparatus "... 168 Fulminates 126 Fulminate of mercury 130 " " " its preparation 130 " " " its properties 131 " " silver 132 " " " its preparation 132 Glycerine 11 " its chemical relations 14 " its examination 29 " filtering "... 24 " its history 11 " its properties 12 " its production 15 " its production from lyes 21 " its purification 25 " pure, its production 23 " test for 13 " waters, their composition 20 Gun-cotton . 107 371 " compressed 113 " its fumes 117 " its history 107 " its manufacture 109 " compressed, its manufacture 113 " " in mining operations 117 " " its preparation 120 " " its properties 115 Havelay Tunnel 263 Hell-Gate rocks 344 High explosives, directions for using them 157 Hydraulic mines, bank blasts 278 Large mines 37' Lignose 95 Lime Point, Cal., blasting at 282 Lithofracteur 93 rLyttelton harbor, blasting 275 394 INDEX. PAGE Magneto-electric apparatus '73 Material for electrical firing 167 Mining problems 254 Mole at Oakland, Cal 264 Mowbray's exploder 174 Nitric acid S " " examination 5 " " quantitative determination S Nitro-cellulose 107 Nitro-gelatine 96 " action of water (01 " decomposition loi " experiments 103 " storing loz " sympathetic explosion 105 Nitro-glycerine 37 " the chemistry of its production 39 " gases of 30 historical notes on 38 manufacture of . . .' 85 Mowbray's process 40 " Nobel's process 45 " incompatibles 48 " properties of 46 " proofs of stability 368 " compounds, their preservation , 367 " in tunnelling 44 " various notes on 53 Nitrates, their origin 384 Nitrate, potassic 3 Nitrate, sodium 3 Obstruction to navigation 307 Oleate of lead 15 Oil-well torpedoes 311 Phosphide of copper 134 Picrates 135 Picrate of ammonium 136 " " potash 135 Platinum fuses I79 Preparing blasts 183 Preparation of the charge i6o Pyroxyline 107 Quarry of Ruisseau 273 " " Morgeret 273 Rodman crusher 25a INDEX. 395 PAGE Saccharine group ,i Saponification of fats ig Submarine drilling, improvement 338 Sulphide of copper 13^ Sulphur - Sulphuric acid g " " examination of 10 " " determination of n System of electric firing 167 Thawing-out apparatus igo Tonite ,24 Tower and Corwin rocks, removal 331 Wheatstone & Siemens' exploder 175 Wires ,go SHORT-TITLE CATALOGUE OF THE PUBLICATIONS OF JOHN WILEY & SONS, New York. 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