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along this line were promptly made. It ing in weight-implying, in turn, that was not, however, until July of 1900, a ship could, on a given weight, carry that the first grains of the new explosive just so many more potential blows for were turned out. Since then, the orig an enemy—such a change would mean inal plant has from time to time been greater ease of handling, greater range amplified, until now the establishment for the gun, and much less stress upon turns out many tons a month.
the weapon for a given result, together
with absence of the fouling common to The smokelessness of the modern pow
all smoky powders. The solution of the der is the consequence rather than the
puzzle lay in the adaptation of gun-cotdirect aim of certain ends for which the
ton as a basis for a new propellant—the chemist and the ordnance engineer were
substitution of a homogeneous substance
for the mechanical mixture of the past. working. Smoke, as every one knows, is evidence of incomplete combustion ; and, when the old black or brown pow
Gun-Cotton the Basis ders were used, but a trifle over one Gun-cotton, as most of us know, is the third of their bulk was consumed in the со on of commerce made explosive by generation of propelling gases: the two- soaking it in a mixture of nitric and sulthirds remaining were represented in phuric acids, and then, by subsequent mesmoke and inert or ineffective residue, chanical treatments, made into one of the which, together with the projectile, had safest and at the same time most powerto be driven out of the gun by the ef ful of explosives. fective or active one-third. In other The propellant used in our Navy's ordwords, could the chemist find a properly nance is what is technically known as a combustible propellant-one that would “gun-cotton powder;" but the term be regularly and completely consumed "powder" is decidedly a misnomer, the within the gun-one pound of such an units being perfectly-formed grains of ideal powder would in effect be nearly varying size instead of the shapeless parequal to three pounds of the old brown ticles characteristic of a "powder” propor black powders. Apart from this sav
erly so called.
Soluble gun-cotton is that containing During nitration, a certain percentage of less than 12.75 per cent of nitrogen. water is liberated, which, if not absorbed, This, when treated in a mixture of ether would weaken the nitric acid and graduand alcohol, becomes a jelly-like sub- ally lower the degree of nitration. The stance which, after the solvent has been mission of the sulphuric acid is to absorb withdrawn or dissipated, becomes a hard, the water and thus maintain the strength tough, translucent mass. Pressed into of the nitric acid at its proper standthe form of grains, this substance will ard. The strength of the acid mixture, burn regularly and without smoke. It its temperature, the duration of the soakcannot be detonated by shock, and re ing, the initial dryness of the cotton, and quires an ignition temperature of 185° C., even the condition of the minute mass of which, while lower than that of the old fibers as to their agglomeration, all bear powders, is misleading, for the substance directly upon the resultant product, both is really less inflammable than the latter, as to its nitration and as to its solubility. and actually requires a starting or igni
The nitration takes place in a centrifugal tion charge of black powder. The small wringer, which, after the proper period amount of smoke now seen at the time of quiescence, is put in motion and drains of discharge of our guns, is due almost the bulk of the acid from the mass. After entirely to the ignition charge of black this, the gun-cotton—for such it has bepowder.
come—is put in a large tank and washed
or "drowned" in fresh water, and after Processes of Manufacture—Nitration
that again washed in fresh water in an
other centrifugal wringer. So much for the reasons and the re Every effort is now made to remove sults. Now for the manufacture. Cot the least trace of residual acid, for it is ton-seed waste, lint cotton, and card this that most affects the stability or waste, after a proper cleansing in a keeping qualities of the subsequent socaustic bath, and a thorough drying, are called powder. To this end, the gun-cotthe materials used. This stuff is soaked
ton is put into large vats and boiled for for half an hour in a mixture of sul a couple of days, during which several phuric and nitric acids—one pound of changes of water are made. After this. cotton to fifty pounds of acid mixture. the material is put in pulping machines
just like those used in a paper mill, pounds of the damp cotton; and, under a where it is ground for fifteen or twenty pressure of 200 pounds per square inch, hours, the water again being continually the major part of the residual water is changed, and socium carbonate added forced out, the material being at the same from time to time to neutralize any free time formed into a compact cylindrical acid still remaining in the cotton. From mass. The piston is withdrawn; twentythe pulpers, the cotton or pulp is moved five pounds of alcohol is poured in, on top to big, circular vats called "poachers," of the cotton; the cylinder is closed; and and is then steamed and stirred for a air, under a pressure of 100 pounds, is period of forty-eight hours. Fresh water turned in, on top of the alcohol. The reis added frequently, and, after a proper sult is that the alcohol is forced through time, the mass is allowed to settle and the the mass, driving the water before it. top water drained off. By successive After most of the alcohol is out, which is washings, settlings, and drainings, all not until the cotton has been subjected to traces of alkali are removed, and the pulp a further pressure of nearly 3,000 pounds is then tested by heat for stability. to the square inch, the remaining 25 per
cent leaves the cotton in just the proper Mixing
condition for the admixture of ether, The pulp must now be thoroughly which is added to the amount of half the dried and all water removed before sub- weight of the mass, to provide the proper jecting it to the ether-alcohol. Large solvent. centrifugal wringers remove 75 per cent In order to insure a thorough mixing, of the water; after which the pulp, like a the cotton is next put in a “mixer”—the thick paste, is fed onto a wide blanket double of the mechanical kneader used in belt and led through rollers that turn out steam bakeries. There, after an hour, the "pyro," as it is called, in flakes which the solvent becomes thoroughly mixed feel not unlike slightly dampened crack with the cotton, and the mass looks and ers. In this flaky condition, the "pyro" feels like damp, coagulated corn meal. is carried to the dehydrating press. Into From the mixer, the material is put into the cylinder of this press is put fifty a press, and is formed into cakes weigh
ing about fifty pounds each. To the end of each wire being free-as there touch it is like crude rubber, and in ap are to be perforations in the grain. The pearance looks not unlike syrup-soaked colloid is now forced through this die, maple sugar. Technically, the substance backed by a pressure of from 4,000 to is now termed "colloid," and it actually 6,000 pounds, depending, of course, upon is smokeless powder; but there are still the size of the grain. The colloid comes a number of processes to be gone through out in a continuous rod like an interminabefore the material becomes the com ble, pale yellow snake, with a number of pletely finished product.
symmetrically disposed longitudinal perTo make sure, 1.owever, that the solu forations. As this rod passes to the end tion is complete, the rubbery mass is of the table or trough, it is run into a forced through a thick steel strainer "cutter" which clips off the grains in under a pressure of two and a-half tons. proper lengths. The object of the longiIt comes out in long cords of a pale straw tudinal perforations is to admit the flame
color, and, with the exception of a central to the interior of the grain, so that, as the hole, looks not unlike macaroni. This exterior decreases under the attack of the again, is packed back in the press, and gases, the interior surface of attack insqueezed once more into the form of a creases. The result is the maintenance large, rubbery cylinder—the color, how- of a uniform total area of combustion, ever, having become uniform through- and a consequent uniform development out.
of propulsive gases. The result of this,
in turn, is that the shot, during its run Making the Grains
from breech to muzzle, receives a gradThe mass is now ready to be made into ual increase of velocity as its inertia is grains. This time the press has only one overcome, and leaves the weapon with a opening, and that is of the size of the de much higher velocity than it is possible to sired grain. Into this opening is fitted secure on a given weight, with safety, by an ingeniously constructed die, into using black or brown powder—the rate which are set as many fine wires—one of burning of which is either spasmodic,
as in the case of the black, or only rela the grain have much to do with these diftively regular, as in that of the brown ficulties; so too—and intimately—have variety of the older propellants.
the number and character of the longi
tudinal perforations; and all of these are Drying
under constant examination and study at After the colloid has been made into
the Naval Powder Factory. grains, the next steps are devoted to drying it. The first of these processes is one of economy. At this stage the powder retains a large percentage of the solvent ether-alcohol, and to recover this is important. This is done by heating the powder, and reclaiming the volatile solvent by condensation. After this, the powder is put in drying houses, where the temperature is maintained uniformly throughout long periods. For the largesized grains, it takes about six months to dry out all but about 3.5 per cent of the solvent. During the process of drying, the grains change in color from a pale yellow to a deep golden brown, and by the time they are used in service the color is even darker.
Testing At various stages of the manufacture, the chemist steps in and most careful analyses are made. Even after the powder has passed all these tests, a sample lot is stored away in a surveillance magazine, where, day by day, it is watched, and, should it be found lacking in stability, the ships carrying it are at once so informed EXAMINING Powder IN PROCESS OF DRYING. and proper measures of safety taken. This, however, owing to the thorough
A National Enterprise and careful methods of governmental When the government factory was esmanufacture, has not been necessary for tablished, there was a howl from the pria long time.
vate manufacturers of powder; and, as That the powder is uniform in its the plant has increased, these private inworking, must be determined by firing terests have persistently opposed it, but tests, in which the developed pressures Congress has continued the necessary apare carefully checked; this is one of the propriations. duties devolving upon the United States The economic results of the establishNaval Proving Grounds, and the details ment of the plant have been many. The of the work must be reserved for treat price of manufacture by private concerns ment in a separate article.
is declared to have been unreasonably Smokeless powder, even with the im- high-making due allowance for all busiprovement it represents over the old pro ness interests—and the Government depellants, brings with its use its own prob- manded and secured a reasonable reduclems. One of these, as we have seen tion. The quality of the product is mainfrom the recent accident on the battle tained, and all of it chemically and balship Missouri, is based on the presence of listically tested, both that manufactured residual gases in the gun after discharge, at the government plant and that made and the danger of their ignition on the by private manufacturers. Moreover, imopening of the breech and the admixture provements have been discovered and iniof oxygen. The size and the shape of tiated, which private enterprise might