Chapter 4

If what I have here claimed for the above smokeless powder be true, it would appear that it may be taken as really an ideal smokeless powder. Why, then, has it not already been universally adopted? Surely such a powder is just what every government is seeking. In reply to this, let me say that, in order for the above compound to be an effective and successful smokeless powder, with the manifestation of the many desirable qualities which I have recited, a great many other conditions are necessary, some of which I will mention. To arrive at the knowledge that this compound would constitute the best smokeless powder has required a great deal of experimenting. It was first thought that gun-cotton colloid, without any nitro-glycerine, that is, gun-cotton dissolved and dried, would burn more slowly, keep better, and give better ballistics than it would if combined with nitro-glycerine. It was also thought that gun-cotton of a high degree of nitration when made into colloidal form would even then burn too quickly to be suitable for use in firearms. Consequently, the first experiments were with low grade gun-cotton, what is called collodion cotton, such as is employed in the manufacture of celluloid. But, as this would not explode without the addition of some oxygen-bearing element, various oxygen-bearing salts were combined with it, such as nitrate of potassium, nitrate of ammonia, nitrate of baryta, etc. Also a great many of the first smokeless powders were made of low grade gun-cotton combined with nitro-glycerine in varying proportions. These powders would often give very good results when first made; but low grade gun-cotton or di-nitro-cellulose, as it is called, is a very unstable compound, and these powders, after giving very promising results, were found to be constantly undergoing change, sooner or later resulting in complete decomposition.

When nitro-glycerine was first combined with gun-cotton in small quantities, camphor was often added, to lessen the rapidity of combustion which the nitro-glycerine was supposed to impart and also to render the compound more plastic, and to tend to prevent the decomposition of the low grade gun-cotton. But camphor being volatile, would, by its evaporation, cause the powder to constantly change in character. Castor oil has been found to be a better diluent, as this will not evaporate.

As all of the smokeless powders made of a low grade gun-cotton were found to deteriorate and spoil, experiments were made with gun-cotton of the highest degree of nitration, both alone and in combination with nitro-glycerine. These experiments were first conducted in England by private parties and by the British government, when it was found that high grade gun-cotton would give excellent results if made into a colloidal solid and used alone, or in combination with certain other constituents. With a view to saving the large quantity of solvents necessary to reduce the gun-cotton, and to get a more prompt and certain ignition with a larger grain, experiments were cautiously made by the admixture of varying proportions of nitro-glycerine to the gun-cotton when dissolved, or rather along with other solvents in the process of dissolving it.

It was soon found that nitro-glycerine added in quantities, even equal in weight to the gun-cotton itself, did not materially increase the rapidity of the explosion of the compound. And it was also found that high grade gun-cotton, when combined with nitro-glycerine, gave very much better results than low grade gun-cotton.

I have spoken here of high and low grade gun-cotton, when in fact the word gun-cotton should be applied only to the highest nitro-compound of cellulose. The word gun cotton has always been rather loosely used. Pyroxyline would be a better word, as this applies to all grades. When cotton fiber is soaked in a large excess of a mixture of the strongest nitric and sulphuric acids, gun-cotton proper, or that of the highest grade, is produced. When weaker acids are used, lower grades of nitro-cellulose are formed.

The first mentioned or highest grade gun-cotton, when thoroughly freed from its acids, has always proved to be a perfectly stable compound. The lower grades have always been found to be unstable and subject to spontaneous decomposition. Nitro-glycerine has also been erroneously thought to be a very unstable compound. But experiments have proved that, when made pure, it is perfectly stable.

Having now explained how the knowledge came to be arrived at that the aforementioned compound of highest grade nitro-glycerine and highest grade gun-cotton would constitute the best basis for a smokeless powder, I will now mention a few of the other conditions necessary to success with its use, without assuming that smokeless powder has yet passed its experimental stage, and is beyond further improvement. Nevertheless, such is the compound which has come to stay as the basis of all smokeless powders; and any smokeless powder, if a successful one, may be counted upon as being made of this compound of gun-cotton and nitro-glycerine, or of a colloid of gun-cotton, either alone or combined with diluents, oxygen-bearing salts, or inert matter. The fact that smokeless powder may still be said to be in somewhat of an experimental stage is not to admit that it is not a success. Firearms, cartridge cases, and projectiles are also still in an experimental stage, for they are constantly being improved; yet their use has been a great success for a good many years.

The question of success of a smokeless powder does not rest alone with the powder itself. The gun, the cartridge case, primer, and bullet have been as much the subjects of experiments in adapting them to the use of smokeless powder as has the smokeless powder in being adapted to them. To impart a velocity of 2,000 feet per second to a rifle ball, with corresponding long range and accuracy of flight, has been a question as much of improvement in rifles and projectiles as in the powder. To give a velocity of 2,000 feet per second to a bullet, requires a pressure of at least 15 English tons in the chamber of a gun. This would be a dangerous pressure in an old-fashioned shoulder arm; while a bullet made only of lead would strip on striking the rifling and pass right through the barrel of the gun without taking any rotary motion whatever. It might at first seem that the powder is the only thing to be considered; but high ballistics can only be obtained when everything else is adapted to its use.

The projectile, the cartridge case, the fulminating cap, and the gun have had to be all built up together, and a very large amount of experimenting has been necessary to determine what would constitute the best projectile, best cartridge case, best fulminating cap, and what should be the character of the rifling and the quality and temper of the steel of the gun barrel.

It has been necessary first to conduct experiments to test the smokeless powders for velocities and pressures, and then with the powders test various kinds of projectiles and guns. In order to obtain the high ballistics which have been secured, it has been found necessary to cover the bullet with something harder than lead and to rifle the gun in a special manner.

The French, who were the first to definitely adopt smokeless powder, were the first also to make a rifle, projectile, cartridge case and primer suited to its use.

To obtain long range with a small long bullet such as is now used, it should rotate at a very high speed. It is well known to artillerists that a projectile of four or more calibers in length has to be rotated at a much higher speed than one of half that length, in order to keep the projectile stiff in the air, and to prevent it from ending over in its flight. To communicate this very high rotary movement to the bullet in the instant of time during which it is passing through the barrel, the rifling of the gun has to exert an enormous torsion on the bullet. Lead, no matter how hardened, is not sufficiently strong, as it will not only strip and pass straight through the gun without taking any rotary movement whatever, but under such very high pressures it behaves like wax, and is thrown from the gun in a distorted mass.

The French cover their bullets with German silver, a substance made of nickel, zinc and copper; and in order to put as little strain upon the rifling and projectile as possible, the rifling of the gun is made with an increasing twist, and has no sharp edges. The French rifle is made very strong at the breech and is of tempered steel throughout. In this way the French have made smokeless powder a success--a smokeless powder made substantially of a character such as I have herein described. With smokeless powder, the French rifle imparts a muzzle velocity of 2,000 feet per second to the bullet, with a range of about 2,400 meters.

If smokeless powder be divided into sufficiently small grains to be ignited by an ordinary fulminating cap, it would burn too quickly, thereby causing the pressure to mount too high, and without giving the desired velocity. Consequently very large and strong fulminating caps have to be employed. Smokeless powder is not ignited in the same manner as black powder. Something besides ignition is necessary. Black powder simply requires to be set on fire; while a smokeless powder, on the contrary, not only requires that it be set on fire, but that a certain degree of pressure be set up inside of the cartridge case. For instance, if a primer of a certain size should be found to operate perfectly well, giving prompt ignition in the cartridge case of a rifle of small caliber, it would be found that the same primer would not ignite a charge of the same powder if loaded into a gun of one inch caliber. In the latter case a few grains only lying near the primer would be ignited, and these would soon become extinguished by sudden release of pressure bringing about a cooling effect due to expansion of the gases. In small cartridges a large fulminating cap is all that is required, but in large cartridges it is necessary to resort to additional means of ignition.

In France, where experiments were conducted with a 37 millimeter Maxim gun, it was found to be impracticable to use a fulminating cap sufficiently large to ignite the powder and cause it to burn. Therefore, a small ignition charge of black powder was employed, it being put in a capsule or bag and placed next the primer. On firing at the rate of 300 rounds per minute, the black powder, though small in quantity, produced a cloud of smoke through which it was quite impossible to see. The inventor of the gun then prepared for the French some wafers of pyroxyline canvas, which were placed next to the primer, securing thereby prompt ignition without the production of any smoke.

Smokeless powder, made as I have described, cannot be detonated by a fulminating cap of any size or by any means whatever. A large charge of fulminate of mercury placed inside the cartridge case next the primer will not detonate the powder, it serving only to ignite it and cause it to explode. But even this would not cause the powder to explode except it be confined behind a projectile, that sufficient pressure may be run up to make it burn in its own gases.

Some curious experiments with smokeless powder may be tried with a shot gun. If the fulminating cap be large, the powder fine, the wads numerous and hard and the charge of shot heavy, all being well rammed down, and the paper case well spun over the last pasteboard wad, a charge of smokeless powder about equal in weight to one-half of what would be employed of black powder would give about the same results as black powder. But if the charge of shot be omitted, the primer will only ignite the powder, and there will be set up sufficient pressure merely to throw the wads about half way up the barrel of the gun, when the powder will go out. Now if this same charge of powder be collected and reloaded into a new cartridge case and well confined behind wads and a charge of shot, as above explained, it will all burn, giving the same results as black powder.

Attempts have been made to use this powder in pistols and revolvers, but here it has proved a failure, as the pressure is not great enough to cause the powder to be consumed, unless it be in the form of very fine grains or dust, in which case the pressure mounts too high. However, this might be overcome to a degree by making the powder porous. The chemical conditions of the powder might be the same, but the physical conditions must be different. A powder suitable for shot guns and pistols would not be suitable for rifles.

One not familiar with the characteristics of smokeless powder would be almost certain to fail in his first attempt to fire it. Many persons have been convinced by their first experiments that this powder would not burn at all in a gun, any more than so much sand.

Smokeless powder is consumed with a rapidity which accords with the conditions of its confinement. Therefore, the bullets which have been experimented with by different governments have been the cause of much of the varying pressures attributed to the smokeless powders.

The Austrians use the Mannlicher steel jacketed bullet. The steel casing or jacket is first tinned on the inside and then the lead is cast in, thus melting the tin and adhering firmly to the jacket. This projectile sets up enormous friction in the barrel of the gun when used with smokeless powder; as the smokeless powder leaves the gun barrel perfectly clean and the two steel surfaces being in absolute contact cause tremendous friction; and as the coefficient of friction varies with every shot, the pressure in the gun constantly varies greatly.

The German silver covered bullet used by the French has the disadvantage that when firing rapidly the chamber of the barrel becomes nickel plated and great friction is caused, mounting up the pressures and causing the muzzle velocities to fall off.

The Austrians, in order to prevent their steel cased bullets from rusting and to lessen the friction in the barrel of the gun, cover them with a heavy lubricant, which gives the cartridges an unsightly appearance and causes them to gather dust and sand. The French employ a lubricant at the base of the projectile, with a small copper disk between the same and the powder.

Col. A.R. Buffington, commander of the National Armory at Springfield, Mass., has made a steel covered projectile which he prevents from rusting by blackening by a niter process. Several grooves are pressed in the base of the bullet which carry a lubricant, and when the bullet is inserted in the cartridge case the grooves are covered by it. Furthermore, these grooves prevent the lead filling from bursting through the steel casing, leaving the latter in the barrel, as often occurs with the Austrian and French projectiles when using smokeless powder.

A new projectile has lately come out, the invention of Captain Edward Palliser, of the British army. This bullet consists of a jacket made of very soft Swedish wrought iron, coated with zinc and filled with lead, the lead being pressed into this jacket. The bullet is corrugated at its base, after the manner of the one made by Colonel Buffington. This projectile has been experimented with very extensively by the British government, and at the works of the Maxim-Nordenfelt Guns and Ammunition Company, in England. The zinc coating of the bullet is too soft to stick to the barrel of the gun, and also in a measure acts as a lubricant. This projectile has given better results than any other that has been experimented with. The great velocities and the most uniform pressures by the use of smokeless powder have been attained with this Palliser bullet.

NOISELESSNESS.

A great many stories have been told about the noiselessness of smokeless powder. But there is no such thing as a noiseless gunpowder. The report of a gun charged with smokeless powder is very sharp, and is as loud as when black powder is used, yet the volume of sound is much less, so that the report cannot be heard at so great a distance.

The report of a gun using smokeless powder is a sound of much higher pitch than when black powder is used, and consequently cannot be heard at so great a distance as the lower notes given by black powder.

As smokeless powder exerts a much greater pressure than common black powder when burned in a gun, one would naturally think that the recoil of the barrel would be greater, owing to the greater pressure exerted by the smokeless powder on the base of the cartridge case and the breech mechanism. However, such is not the fact; for the barrel actually recoils very much less when smokeless powder is used. This is due to the suddenness with which the pressure is exerted by smokeless powder, it acting more like a very sharp blow on the metal, whereby more of the energy is converted into heat instead of being spent in overcoming the inertia of the barrel to give recoil. Similarly when smokeless powder is fired in a gun, the displacement of the air is so sudden that the sound waves do not possess the same amplitude of recoil or vibration as is given by black powder.

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THE CONSTRUCTION AND MAINTENANCE OF UNDERGROUND CIRCUITS.

BY S.B. FOWLER.

The numerous disastrous storms of the last winter have brought out very vividly the advantages of having all wires placed underground, and many inquiries have been addressed to the companies operating underground circuits as to their success. It is not probable that all of the answers to these inquiries have been of the most favorable character. To many central station managers an underground system means frequent break-downs and interruptions of service, with, perhaps, slow and expensive repairs, which bring in their turn numerous complaints, loss of customers, and reduced profits. In many installations burn-outs both underground and in the station are frequent, with the natural result that the operating of circuits underground is not there considered an unqualified success. The writer has in mind two very different experiences with underground cables. Several miles of cable were bought by a certain company, carefully laid, and up to to-day not a single burn-out or interruption of service can be attributed to failure of cables; at about the same time another company bought about an equal amount of the same kind of cable, and in a comparatively short time the current had to be shut off the lines and the whole installation repaired and parts of it replaced. Both of these experiences have been repeated many times and will be again, although it is simply a distinction between a good cable properly laid and a good cable ruined by careless and incompetent workmanship.

Every failure can be traced to poor work in the original installation or to the use of a cheap cable, both causes being due, generally, to that false economy which looks for too quick returns. A poorly insulated line wire and a poorly insulated cable are two very different things. However, it is a fact that by the use of a good cable it is not difficult to construct an underground system for light, power, telegraph or telephone uses that will be superior to overhead lines in its service and in cost of maintenance. The ideal underground system must have as a starting point a system of subways admitting of the easy drawing in and out of cables and affording means of making subsidiary connections readily and with the minimum of expense and interruption of service. This is practically accomplished by a subway consisting of lines of pipe terminating at convenient intervals, say at street intersections, in manholes, for convenience in jointing and in running out house connections. These pipes, or ducts, as they are called, should be for two kinds of service; the lower or deeper laid lines for the main or trunk circuits, and a second series of ducts laid nearer the surface, running into service boxes placed near together for lines to "house to house" connections. In some cities where it is allowed to run overhead lines, the plan of running but one service connection in a block is followed, all customers in the block being supplied from a line run over the housetops or strung on the rear walls.

This makes unnecessary all subsidiary ducts except a short one from the manhole to the nearest building in the block, and effects a considerable saving in pipe, service boxes, cables and labor. The manholes should have their walls built up of brick, the floors should be of concrete, and there should be an inside lid which can be fastened down and the manhole thus made water-tight.

For ducts wood, iron or cement lined pipe may be used. To preserve the wood it is generally treated with creosote, which, in contact with the lead cover of the cable, sets up a chemical action, resulting in the destruction of the lead. Wood offers but little protection for the cable, as it is too easily damaged and broken through in the frequent street openings made by companies operating lines of pipe in the streets, and as one of the main purposes of a subway is that of a protection to cables, wooden ducts have little to recommend them except their cheapness.

Iron pipes are either laid in trenches filled in with earth or are laid in cement. Iron pipe will of course rust out in time, and if absolute permanence in construction is desired, should be laid in cement, for after the pipe rusts out, the duct of cement is still left. However, if we are going to the expense of laying in cement, it would be much preferable to use cement lined pipe, which is not only cheaper than iron pipe, but makes the most perfect cable conduit, as it affords a perfectly smooth surface to draw the cable over and give a good duct edge.

It is not necessary, however, in small installations of cable, especially where additional connections will not be of frequent occurrence, to go to the expense of subways, for cable may be safely laid in the ground in trenches filled in with earth, or can be inclosed in a plain wooden box or a wooden box filled with pitch.

There are, of course, many localities where, if the cable is laid in contact with the earth, a chemical action would take place which might result in the destruction of the cable.

Underground cables are of the following classes: 1. Rubber insulated cables, insulated with rubber or other homogeneous material. 2. Fibrous cables, so called from the conductors being covered with some fibrous material, as cotton or paper, which is saturated with the insulating material, paraffine, resin oil, or some special compound. Under this latter head is also included the dry core paper cables.