by his faith." And, as a representative man, | paratively, have anything but the very haziHabakkuk has bequeathed to believers in est notions regarding nitro-glycerine, that Christ's Church, even in " the last plagues," we deem it almost necessary--at all events this standing prayer of " patience of hope," but of "a contrite spirit:" "O Lord, revive thy work in the midst of the years, in the midst of the years make known; in wrath remember mercy."

cooled by being surrounded with ice. When the chemical action ceases, it is found that a yellowish oily-looking fluid comes to the surface this is impure nitro-glycerine. To obtain it in the pure state, free from contaminating acid, the whole liquid mass is thoroughly mixed with fifteen or twenty times its bulk of cold water, and then permitted to settle. The nitro-glycerine collects in the lower part of the vessel and is drawn off by means of a siphon, or separated by the process of decantation. It is afterwards washed so completely that not the slightest trace of acid is found in the washings. The great importance of this precaution will be seen shortly.

gloved when working with vessels containing it. Notwithstanding what has frequently been said to the contrary, since the Newcastle explosion, and in some instances said authoritatively by scientific men, nitro-glycerine per se, and when prepared in a pure state, is a very stable compound at ordinary temperatures; if, however, it be impure, and contain any of the acid used in preparing it, there is a proneness to decomposition, and not only so, but decomposition even with explosive violence is almost certain to occur. When quite pure it will safely bear exposure to the temperature of boiling water, namely, 212° Fahr. It is not in the slightest degree volatile; it is practically if not even absolutely insoluble in water, but in ether, alcohol, and especially wood-spirit or methyl-alcohol, it is freely dissolved. The property which especially characterizes this substance is its explosiveness, or, to be more exact, its great explosive power, for it is not exploded with any unusual degree of facility. Of this property more shortly.

What we have now in imagination prepared is nitro-glycerine-a substance whose chemical nature is, in every sense of the term, both curious and interesting. Its scientific name has misled some of the ready writers of the newspaper press regarding its composition. Not possessing any profound knowledge of chemistry, it was almost natural that they should say -one or more Various persons have worked on nitroof them that it consists of nitrogen and glycerine since it was first discovered by glycerine, and that the statement when once Sobrero. Amongst others there may be made, and made with a show of learning, mentioned Railton, Dr. J. H. Gladstone, should readily get currency, as was the case De la Rue, Kapp, Dr. de Vrij, and beyond immediately after the Newcastle explosion. and above all others, Mr. Alfred Nobel, a Like ordinary cotton or cellulose, glycerine, Swedish gentleman of great scientific atthe material started with, consists of the tainments. It was while acting in the cathree elementary substances carbon, hy-pacity of a mining engineer that Mr. Nobel drogen, and oxygen; but when treated in became acquainted with this wonderful subthe manner already indicated, a nitro-com- stance, and he quickly saw that as a blastpound results which contains the same three ing agent it might become immensely useful. elements, the amount of hydrogen, however, He instituted numerous experiments in orhaving undergone a diminution, and a quan- der that he might become thoroughly ac2 tity of the nitric acid in a somewhat altered quainted with its properties, and in order, or reduced form having taken its place. likewise, that he might be able to prepare it Although prepared from glycerine, the nitro- in a state of absolute purity, and of perglycerine obtained does not, strictly speak- fectly uniform quality, so that it might be ing, contain that substance either; it is a secured against all that tendency to spontanew product entirely, consisting of nitric neous decomposition which had been obacid that has parted with some of its oxy-served by some of the earlier experimenters gen, and glycerine that has been robbed of with it, and which is still spoken of by very a portion of its hydrogen, as already men- recent writers. tioned. So much then for its name and its real composition; and now as to its properties.

What the Austrian General Von Lenk did for gun-cotton or nitro-cellulose, the Swedish mining engineer did for nitro-glycerine; Nitro-glycerine, when perfectly pure, is a he removed it from the laboratory and docolourless liquid, decidedly heavier than main of the scientific and theoretical chemglycerine (the specific gravities being, re- ist, and made it, in the hands of the practical spectively, about 1.600 and 1.200), per- man, one of the realities of modern manufectly inodorous, and possessed of a sweetish, factures-one that could be carried out on aromatic, and pungent taste. It is power- a large scale, and still with that amount of fully poisonous, and even a small quantity placed on the tongue produces violent headache, and headache may also result from the absorption of nitro-glycerine through the skin into the blood. On this account it is very desirable that the hands should be

rigidly scientific exactitude that is required in the circumstances of the case. Mr. Nobel patented his process in the principal countries of Europe, and in America, and shortly thereafter commenced to manufacture nitro-glycerine in the outskirts of the

free city of Hamburg, whence it is sent to almost all parts of the world where a blasting agent is required.

tact with the liquid for some time, till the latter gets heated, it will burn with flame, but without explosion; and if the bar be To proceed now with the further consid- removed, unconsumed nitro-glycerine may eration of the properties of this substance. still be found remaining, providing that the As an explosive agent, nitro-glycerine is whole of the wetted surface has not been almost unique amongst chemical compounds. actually covered by the hot iron bar. Now, Almost all explosive and detonating sub- gunpowder will explode with a simple spark, stances are nitro-compounds, consisting, as such as is produced by the sharp friction of they do, of two or more elementary ingre- a flint in contact with steel. Gun-cotton dients of which one is the element nitrogen. will actually explode at a temperature of Gunpowder- although it is not a definite 277° Fahr., a heat which is not very much chemical compound of its ingredients, salt- greater than that of boiling water. It will petre, sulphur, and charcoal, but rather a explode by contact with a wire that has been mechanical mixture of these ingredients exposed but for a very brief space of time very intimately and skilfully incorporated in a candle or gas flame. Of the ease with is a sufficiently good illustration. Nitrogen which gun-cotton may be exploded, the is present in the nitre or nitrate of potash, following circumstance may be taken as an in the form of nitric acid. Gun-cotton also illustration: - A scientific lecturer was recontains nitric acid, although in a somewhat cently performing to an interested audience modified or deoxidized state; and the same, the very beautiful and familiar experiment in a sense, is true of fulminating mercury, of burning a piece of watch-spring in a the substance used for charging percussion small glass jar of oxygen gas. The amount caps, and fulminating silver. The elements of burning steel was also very small; the chlorine, bromine, and iodine, form explo- amount of heat evolved could not, theresive compounds with nitrogen, known as the fore, be very great; but still it was great chloride, bromide, and iodide of nitrogen. enough to act by radiation in such a way The compound last mentioned is a solid that a quantity of gun-cotton was ignited body, and is probably the most sensitive ex- which was some inches away from the small plosive substance known, a touch with a point of combustion. A gentleman who feather being quite sufficient to cause its ex- has used tons of nitro-glycerine, and perplosion; but the nitro-compounds of chlo- formed all sorts of experiments with it, says, rine and bromine are oily-looking liquids, in a letter to the lecturer sympathizing with and in the possession of this peculiarity him on account of the scorching which his there is a close resemblance between them face met with,-"Nitro-glycerine would and nitro-glycerine. The explosive sub- not have played you such a trick." The stance under notice is probably the only present writer has had a good deal of expeliquid compound of organic origin that pos-rience with nitro-glycerine, and can bear sesses explosiveness, and in this sense it certainly is unique; still more so is it unique in being the only liquid explosive that has yet been rendered serviceable to man.

It is a very curious explosive withal, inasmuch as heat alone will not explode it, unless the heat be raised to about 360° Fahr. It will not explode by simple contact with fire. To demonstrate this fact, a quantity of the nitro-glycerine may be put in a saucer or other shallow vessel, and then a burning match or splint of wood may be plunged into and employed in stirring the explosive liquid, but no explosion will occur; the liquid will simply burn with a flame, which immediately goes out if the burning body be withdrawn. The nitroglycerine may be burned from an ordinary cotton wick, just like common lamp oil. If a quantity of it be spread over a flat stone or a smith's anvil, and then a red-hot iron bar be drawn along the surface of the nitroglycerine, the liquid will not catch fire; if, however, the bar be allowed to lie in con

testimony to the truth of the remark just quoted. He has also been informed of another instance of the readiness with which gun-cotton ignites. It was proved by an incident that must have been painfully severe to the operator, yet it had a humorous aspect also:- A photographer, who had prepared some gun-cotton to be used in making collodion, was drying it upon a tray in front of the fire, and while engaged in turning it over very cautiously it flashed off in his face, without giving him any warning, and instantaneously disappeared. In course of time the injury was attended with the removal of the entire skin of his face. The photographer's face was pock-marked before the accident, but after the injury was healed (although the writer does not vouch for the truth of the statement, still it deserves to be true), the pock-marks no longer existed to disfigure his face.

It is as a blasting agent that nitro-glyce rine has been specially used during the last three or four years: how it is used as such

falls now to be explained and illustrated. | or even water, is introduced above the From what has been already stated, it may nitro-glycerine as the tamping material. ⚫ be concluded that some other agent than Hard tamping or stemming is very objecheat must be employed to effect its explo- tionable; as just mentioned, water will sufsion: that agent is concussion. A very sim- fice; for, as the nitro-glycerine is fully one ple and perfectly harmless experiment may and a half times the weight of water, and be performed in illustration in starting. A insoluble in it, the latter will rise to the surquantity of the explosive liquid is spread face, even though the drill-hole contain over the surface of an anvil or a plane-faced water when the nitro-glycerine is poured weight-say a fourteen-pound weight; on into it. From this circumstance, it will be striking the moistened surface sharply with seen that nitro-glycerine may be used in wet a hammer, there will be a detonation or rocks or water-bearing strata with impuniexplosion; but, remarkable to relate, how-ty, while gun-cotton and gunpowder would ever, only that portion of the liquid will be useless. When the blasting liquid is in explode which is actually struck, and there the drill-hole, the fuse, tipped with a tightmay be as many detonations produced as ly-fitting percussion-cap, is introduced into there are strokes made on the weight or an- it, either before or after the tamping is vil where it is wet with nitro-glycerine. To done; but, whether before or after the explode the substance in mass, as in blast- tamping, it is in all cases absolutely necesing operations, the mechanical disturbance sary to see that the cap is actually in the must be effected in some other way. One blasting liquid. is to have at the end of the fuse a small bag When the explosion is effected there is of gunpowder actually dipping into the no residue, neither is there any smoke, and blasting liquid; another is to use a percus- the explosion is much quicker than that of sion-cap, of extra strength, at the end of gunpowder; hence the blasting operations the fuse. There must be great mechanical may be performed with greater than ordinary violence comparatively, and yet, from the rapidity. When rocks are much fissured results of numerous experiments with this this rapidity of the explosion is of great most curious and wonderful substance, that consequence, as the force does not get time mechanical violence must be exerted in a to spend itself through the fissures, but acts peculiar way. Glass bottles filled with it immediately in the vicinity of the place ochave been experimented on times without cupied by the blasting liquid. Perhaps the number. They have been dashed against most striking circumstance in connexion hard rocks, or from considerable heights, with nitro-glycerine, as a blasting agent, is with as great force as could be exerted by the fact of its being the most powerful exthe experimenters, and yet explosion of the plosive known; it possesses most enormous nitro-glycerine has not resulted. It is need- power, and of this a single explosion reless to say that the bottles have been broken moves all doubt where any doubt or unbeinto a thousand fragments. In one case lief exists. Dead weight, simply, is not a that has been recorded, a commission of good standard of comparison to set up in five scientific gentlemen superintended some point of economy; but even suppose that experiments of which the following is one: to be taken, one pound of nitro-glycerine ―Three glass bottles were filled with nitro- will do as much mechanical work as ten glycerine, and, in order to show the com- pounds of gunpowder, and some persons bined effort of heat and concussion, they have affirmed that it is even equal to thirwere heated in hot water to a temperature teen pounds of gunpowder. As regards the of 120° Fahr., and then thrown violently cost, it should be mentioned that, weight against a stone; the bottles were smashed, for weight, nitro-glycerine costs seven times but none of the blasting liquid exploded. as much as gunpowder; yet still its use is In another experiment, two tin canisters, attended with very great economy, of which such as the nitro-glycerine is sold in, were evidence will shortly be adduced. When filled with the liquid and packed in the the extraordinary force of this new blasting usual way in a wooden box; the cover be- material began to make itself known, about ing tightly screwed on, the box was thrown two and a half or three years ago, in various "down upon a rock at a depth of some nine mining districts in Sweden, Switzerland, Belgium, France, and a number of German or ten feet, but no explosion took place. When it is desired to employ this sub-states, great enthusiasm was almost invaristance as a blasting agent, drill or bore holes are made in the usual way, just as if gun-cotton or gunpowder were to be used. They are filled up to a sufficient height with the liquid, and then rock-powder or sand,

ably created by it in the minds of quarrymen, miners, mining engineers, railway contractors, &c., and more especially when it was found that its storage, carriage, and use were attended with as great safety as

was the case with gunpowder. Such state- this question of economy: "The final rements regarding nitro-glycerine as the fol-sult of three months' blasting with nitrolowing were deliberately put in writing by glycerine shows a saving, as compared to men of a plain, practical, and prosaic turn what it cost us to blast with gunpowder, of of mind, not men with heated imagina- 23 per cent. on the cost of the blasting (mations: terials included) ;" and that "the progress of the tunnel has been 87 per cent. quicker than when we made use of gunpowder, which has proved of great indirect benefit," Another railway contractor says: "Through the use of nitro-glycerine the blastings of the Great Northern Railway [of Sweden] have been contracted for at the reduced price of 75 per cent. of what we paid when gunpowder was used."

"The enormous explosive power of this marvellous substance has proved of great value to me. The statement made as to its power I consider noways exaggerated."

"Nitro-glycerine is a real conquest; and all the persons present at the experiments we allude to unanimously declared that it will constitute one of the most important agents for industrial

purposes."

"It opens a new era in the mining business." "The trials with the blasting oil showed an effect so marvellous that we have resolved to use nothing else for our blastings."

"This extraordinary power effects a valuable saving of time."

"I have made use of nitro-glycerine for blasting limestone with the highest success, and found it extremely profitable, as well as more easy to use and less dangerous than gunpow

der."

"An invention destined to play an important part in our mining operations and construction of railways is nitro-glycerine. It has effected a complete revolution."

66

"I have tried nitro-glycerine in the mines of Pehrsburg, and found that, if the precautions prescribed are observed, it is less dangerous to carry, to store, and to use than gunpowder."

Such testimony could be continued at very much greater length.

Testimony of this sort could also be given at great length, were it desirable to do so.

Most people who have read of explosions of nitro-glycerine have got some notion of the extraordinary power of that substance; and those who have used it practically, or have been present at experimental demonstrations of its great explosive effect, have notions of a very decided character. For the benefit of the former the results of two or

three practical illustrations of its power may be mentioned:

In a Swiss slate quarry one pound weight of nitro-glycerine, in a 64 feet bore-hole, and with water-tamping, completely scattered 2000 cubic feet of rock.

In the red sandstone quarries in the vicin ity of Eisleben, a town in Prussian Saxony, 3960 cubic feet of rock were removed by charge of two and a half pounds of nitroglycerine in one bore-hole 12 feet backwards.

Under the inspection of judges appointed by the Royal Cornwall Polytechnic Society, to report on this substance, a charge of four pounds completely scattered from forty to fifty tons of rock, while the surrounding rock was rent in all directions. In this experiment it was computed that had the hole been less in diameter, the same effect would have been produced with a much smaller charge.

The great explosive power of nitroglycerine renders it much more economical than would appear to be the case at first sight. This greater economy is owing chiefly to the fact that the drilling or boring of the holes required for receiving the blasting agent, and which always forms a very large part of the expense of blasting, whether in mines, quarries, tunnel-driving, or railwaycutting, is reduced to an exceedingly small amount when nitro-glycerine is used, that substance being so remarkably powerful when compared with the bulk of it required From a mass of notes which have been to produce a certain given effect. Stated kindly furnished to the present writer by generally, it may be said that the average the managing director of a large slate quarresult as to economy hitherto, has been a ry in Wales, regarding actual operations saving of from 50 to 60 per cent. in quar- performed under that gentleman's superinries, and from 30 to 40 per cent. in mines, tendence, the following case may be quoted: on the cost of blasting. The bore-holes - A vertical hole, one inch in diameter," required are so few in number that there is five feet deep, and eleven feet from the face not only a saving of the workmen's time, of the rock, was charged with one pound of but there is also a saving in the expense of nitro-glycerine, the tamping being slateboring tools and fuse for exploding the dust. The jotting made in the note-book, charges. A railway engineer who directed immediately after the charge was exploded, the construction of a tunnel on the Stock-was, "loosened all the rock in its immediholm Central Railway, says, in reference to ate vicinity, say eleven feet by fifteen feet,