George M. Mowbray

“ Erhardt of London, Colonel Shaffner, and others familiar with tunnelling, that while our rock is not in general harder to drill than many others, it is most persistently tough. That is, the number of charges we fire, if they could be in granite or lime or in any brittle stone, would bring out two or three times more of debris than now. It is therefore necessary that we should have the quickest explosive to get the best result. As preparations of mercury are not to be thought of on account of their danger, we take Nitro-Glycerin as being next in power, while it is comparatively safe. ”

“ When, therefore, holes can be made with a crow-bar, and not drilled, do not use Nitro-Glycerin, but if you have rock, be it as hard as emery, or as the magnetic iron ore of the Lake Superior or Ottawa Iron mines, the harder the better for the economy of drilling, which is very great, so few holes being required, the introduction of Nitro-Glycerin, with a good steam or air drill, causes the progress of the work to advance to that degree that it is only limited by the ability to remove the debris of blasted material. ”

“ Several remarkable results of an exceptional character have, however, been obtained, which indicate that the development of explosive force under the circumstances referred to, is not always simply ascribable to the sudden operation of mechanical force. Thus silver fulminate, which explodes much more suddenly, and with much more powerful local force than mercuric fulminate, nevertheless, when applied under the same conditions, does not induce the explosion of gun-cotton so readily as mercuric fulminate. ”

“ Better to face the difficulty, construct efficient electric apparatus, convey the electricity along wires of perfect insulation to a safe priming, and by complete and violent explosion of the Nitro-Glycerin, or powder, make such effective blasting as not to throw away the labor of drilling, candles, power, and blasting materials. I believe this the true economy. These details may seem wearisome, but the casualties of blasting can best be diminished by avoiding missed holes, a result only attainable by using materials absolutely reliable ”

“ If charges in adjoining holes can be fired as though but one charge, then they help each other and much more rock will be torn away. The whole top may be thrown down or the bottom brought up by proper arrangement of holes, and by means of a ring of converging holes the center may be dragged out. The passage of the electric spark through one system of wires occupies practically no appreciable time, while through several systems it may. If the charges in adjoining holes are fired with the interval of an instant, it may just as well be a week so far as the tearing of the rock is concerned. ”

“ Nitro-Glycerin or Glonoin, which bears some resemblance to chloride of nitrogen in the suddenness of its explosion, requires the fulfillment of special conditions for the full development of its explosive force. Its explosion by the simple action of heat can be accomplished only when the source of heat is applied for a considerable time in such a way that chemical decomposition is established in some portion of the mass, and is favored by the continued application of heat to that part ”

“ To construct an apparatus that will, under every condition of atmosphere, whether damp, dense or rarefied, evolve, at the will of the operator, abundance of electricity; such electricity to possess the property of developing intense heat, so as not to need a very sensitive priming, and to possess sufficient tension to overleap numerous solutions of continuity, say fifty, at a flash. ”

“ I have been told, and the newspapers teem with assertions, that these patented explosive compounds, with high sounding names, will bear “tamping” as hard as gunpowder, are safer, more powerful and cheaper than Nitro-Glycerin. We are a people, Barnum says, who like to be humbugged; I am afraid we are not the only people who like to be humbugged—it is a weakness of humanity—but this I do believe; the man who is addicted to humbug, had better give Nitro-Glycerin a wide berth, that is, if he hopes to end his days on a feather bed. ”

“ The advantages claimed (only by the inventor) for dualin, are, that it is cheaper, safer, and more powerful than Nitro-Glycerin, and some experiments made in Prussia, are adduced in proof. I have to observe, on this point, that the Nitro-Glycerin made by the Nobel process, probably used in Prussia, is very inferior to the Tri-Nitro-Glycerin made by my process, both in stability and in explosive force, and it is much more readily exploded, fifteen grains of fulminate of mercury being necessary to ensure explosion of this latter, without chance of failure. ”

“ But if once a blast is shewn, and they have to hoist out the rock, their obstinacy succumbs, and in three months, men, who knew it was poison, and so dangerous it was wicked to ask them to drill holes to receive it, have positively refused to descend a shaft if powder was attempted to be used merely in a comparative experiment, alleging, that the powder was unhealthy and not fit to be used at the bottom of a shaft, where the air was confined. ”

“ In drilling holes for blasting with Nitro-Glycerin, a depth of not less than five feet should be reached; six feet are better, but ten and twelve feet are the right depth for a heading, whilst fifteen feet for bench work, and eight feet apart, or, for quarry work ten feet apart, and ten feet from the face, provided the rock is hard enough (in clay, owing to the sudden shock Nitro-Glycerin is ineffective) ; exploded in holes of such a depth it will throw out everything before it—and make progress. ”

“ By the action of the mercury upon the liberated nitric acid, deutoxide of nitrogen soon begins to be evolved, and, usually in about two hours, without the application of heat, the whole of the nitric acid is converted into that gas. Sometimes agitation is necessary, and it is easily performed by giving a jerking horizontal motion to the upper part of the jar. The surface of the sulphuric acid is then marked, and three-fourths of an inch of solution of sulphate of iron recently boiled, let up into the jar. ”

“ For the past hundred years, the greatest chemists the world has ever known, have given the results of their researches free, and untrammelled by any patents, though they might, indeed, have justly taken toll of the world at large for their discoveries. I need only instance Berzelius, who threw open to the world the numerous discoveries of his long and valuable life, and Pelouze, the celebrated French chemist, who devoted fifteen years of his life to the [Pg 52] investigation of the constituents of fatty matters and their decomposition into stearic, margaric, oleic acids and glycerin. ”

“ Several fatal accidents have occurred to miners, from premature explosions of the charge whilst loading the holes, and these fatalities having been traced to the “over-sensitive priming” used, it [Pg 40] behooves the mining engineer to look well to the exploders offered him, and in every case he will find where cotton immersed in a varnish is sufficient insulation to protect the wire from losing its electricity, the priming used for charging such exploders is too dangerous for miners’ use, and involves a grave responsibility. ”

“ Curious thought, that a man carrying a couple of harmless looking pails with only a little colorless fluid in them, should have enough explosive matter about him to annihilate a regiment.
In the magazine the Nitro-Glycerin is poured into “crocks,” as they are called, earthenware jars holding 60 lbs. These crocks are then placed in a wooden tank 21⁄2 feet deep, which holds 20 of them, and immersed to within six inches from the top of the jars in water warmed by a small pipe from the boiler, to raise the temperature to 70°, at which temperature it is kept all the time, as nearly as possible. ”

“ Mowbray’s experience in a number of instances with that manufactured by himself, I should judge [Pg 23] his Nitro-Glycerin to be as safe as powder in the hands of experienced persons. It is of a light yellowish color, with pungent aromatic taste, rather sweet than otherwise, and is so poisonous, that in handling, should one allow it to remain on his hands, it would produce intense head ache. It does not explode from the application of flame to its surface, yet will burn, but explodes only from severe concussion, as by the explosion of detonating mixtures and fulminates. ”

“ When the question as to whether this form of blasting, viz.: in oil wells, is patentable has been decided, it will be time to renew the careful application of Nitro-Glycerin in oil wells, but at present, the careless handling, the pursuit of wealth regardless of the lives of the employed, and the unscrupulous assertion prevalent among those interested in the patent referred to, is depriving the oil producers of a valuable agent. ”

“ After a correspondence with [Pg 22] different manufacturers of machine drills, we found no one of them ready for business at once, and before we were able to make terms, our primitive style of drilling advanced almost to completion. We sent to Mr. Mowbray who was then in Titusville, Pennsylvania, to try his Nitro-Glycerin, and made an experiment in a square of a little over ten yards, where the rock to be removed was over seven feet deep. The holes were drilled a greater distance apart, but to the same depth as used for powder (15 feet from surface of water) . ”

“ He has four sons employed, of whom one takes charge of the works at Maysville, Kentucky, another, is foreman of the Nitro-Glycerin factory.
Three men are employed in the acid house, working in three shifts of eight hours each, but they do not actually work more than seven hours; every movement is like clock work, every man has his place and special duty, which he is expected to perform at the proper time. In the morning, at 7 or 71⁄2 a. m., two men dump the carboys of acid into the soapstone tank and mix them, while a third is filling the glass jars with glycerin. ”

“ The action of tin, iron, and lead, slowly decomposing the Nitro-Glycerin, 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-Glycerin does not seem to be affected; with sulphuretted hydrogen, as with sulphuret of sodium, potassium and ammonium, the action is prompt, and if these reagents be added in sufficient quantity, the Nitro-Glycerin is wholly decomposed, sulphur being precipitated. ”

“ Attached to the factory is a building about 90 feet long, for covering the copper wire (used in exploding) with gutta-percha, so as to render the insulation perfect. The first process is to purify the crude gutta-percha which is imported in blocks about a foot long. This is placed against a rasping machine with toothed knives about four inches apart, which crush and tear the gutta-percha to pieces, delivering it into a trough of water. The impurities sink, while the gutta-percha floats. ”

“ Thirty per cent. more blasting power is evolved, when the Nitro-Glycerin reaches the bare rock of the drill hole, than when, by insertion in cartridge, the metal of the cartridge and a layer of air or water are interposed between the blasting gases and the rock. ”

“ At the East heading, partly owing to the rock being softer than either at the West End or in the Central Shaft, partly to the miners being accustomed to powder, partly to the heavy battery of drills enabling twelve drilling machines to work at once, and thus make progress satisfactory to the contractors, who, wisely, let well enough alone, the holes when drilled to a depth of from two feet six inches to three feet, are each charged with from one to two and one-half pounds of blasting powder, then tamped ”

“ Proceeding back to the factory, two ice-houses will be noticed, capable of containing 400 tons of ice, required for crystallizing Nitro-Glycerin in summer. There is a small engine-house with a boiler of fifteen horse power, and engine of about ten horse power; this latter, to pump water into the washing tank, run the two “blowers,” and give power in the gutta-percha factory. The air is not pumped directly into the pipe which distributes it to the pitchers, as the pressure would not be always uniform ”

“ Walter Crum [5] describes a method of analysing bodies containing nitric acid, applicable to the nitro-compounds; when nitrate of potash is used, it is previously purified by crystallization, and fused at little more than its melting heat. Nitro-Glycerin, gun-cotton, etc., must be deprived of moisture.
A glass jar eight inches long and an inch and a quarter in diameter, is filled with and inverted over mercury; a single lump of time fused nitrate, weighing about six grains, is let up through the mercury into the inverted jar, and afterwards fifty grains of water. ”