Mr. Russell stated that greater effects are produced by gases generated from gun cotton than by gases from gunpowder, and it was only after long and careful examination that the committee were able to reconcile this fact with the low temperature at which the mechanical force is obtained. The great waste of force in gunpowder constitutes an important difference between it and gun cotton, in which there is no waste. The waste in gunpowder is 68 per cent of its own weight, and only 32 percent is useful. This 68 per cent is not only waste in itself, but it wastes the power of the remaining 32 per cent. It wastes it me-chanically by using up a large portion of the mechanical force of the useful gases. The waste of gunpowder issues from the gun with much higher velocity than the projectile, and if it be remembered that in 100 pounds of useful powder this is 68 pounds, it will appear that 32 pounds of useful gunpowder gas is wasted in impelling a 68 pound shot composed of the refused gunpowder itself.

There is yet another peculiar feature of gun cotton. It can be exploded in any quantity instantaneously. This was once considered its great fault, but it was only a fault when we were ignorant of the means to make that ve-locity anything we pleased. Baron Von Lenk has discovered the means of giving gun cotton any velocity of explosion that is required, by merely the mechanical arrangement under which it is used. Gun cotton, in his hands,' has any speed of explosion, from one foot per second to one foot in 1/1000 of a second, or to instantaneity. The instantaneous explosion of a large quantity of gun cotton is made use of when it is required to produce destructive effects on the surrounding material. The slow combustion is made use of when it is required to produce manageable power, as in the case of gunnery. It is plain, therefore, that if we can explode a large mass instantaneously, we get out of the gases so exploded the greatest possible power, because all the gas is generated before motion commences, and this is the con-dition of maximum effect. It is found that the condition necessary to produce instantaneous and complete explosion is the absolute perfection of closeness of the chamber containing the gun cotton. The reason of it is that, the first ignited gases must penetrate the whole mass of the cotton, and this they do, and create complete ignition throughout only under pressure. This pressure need not be great. For example, a barrel of gun cotton will produce very little effect and very slow combustion when out of the barrel, but instantaneous and powerful explosion when shut up within it. On the other hand, if we desire gun cotton to produce mechanical work, and not destruction of materials, we must provide for its slower combustion. It must bo distributed and opened out mechanically, so as to occupy a larger space, and in this state, it can be made to act even more slowly than gunpowder, and the exact limit for purposes of artillery Von Lenk has found by critical experiments. In general it is found that the proportion of 11 pounds of gun cotton, occupying one cubic foot of space, produce a greater force than gun-powder, of which from 50 to 60 pounds occupy the same space, and a force of the nature re-quired for ordinary artillery. But each gun and each kind of projectile requires a certain density of cartridge. Practically, gun cotton is most effective in guns when used as 1/4 to 1/3 weight of powder, and occupying a space of l 1/10 of the length of the powder cartridge. The mechanical structure of the cartridge is of importance as affecting its ignition. The car-tridge is formed of a mechanical arrangement of spin cords, and the distribution of these, the manner and place of ignition, the form and proportion of the cartridges, all affect the time of complete ignition. It is by the complete mastery he has gained over all these minute points that Von Lenk is enabled to give to the action of gun cotton on the projectile any law of forces he pleases.

Gun cotton is used for artillery in the form of a gun cotton thread or spun yarn. In this simple form it will conduct combustion slowly in the open air, at the rate of not more than one foot per second. This thread is woven into a texture or circular web. These webs are made of various diameters, and it is out of these webs that common rifle cartridges are made, merely by cutting them into the proper lengths, and inclosing them in stiff cylinders of pasteboard, which form the cartridges.

In these cylindrical webs it is also used to fill explosive shells, as it can be conveniently employed in this shape to pass in through the neck of the shell. Gun cotton thread is spun into ropes in the usual way up to two inches diameter, hollow in the centre. This is the form used for blasting and mining purposes; it combines great density with speedy explosion.

The gun cotton yarn is used directly to form cartridges for large guns by being wound round a bobbin, so as to form a spindle like that used in spinning mills. The bobbin is a hollow tube of paper or wood; the object of the wooden rod is to secure, in all cases, the necessary length of chamber in the gun required for the most effective explosion. The gun cotton circular web is inclosed in close tubes of India-rubber cloth to form a match line, in which form it is most convenient, and travels with speed and certainty. In large quantities, for the explosion of mines, it is used in the form of ropes, and in this form it is conveniently coiled in casks and stowed in boxes.

As regards conveyance and storage of gun cotton, it results from the foregoing facts, that one pound of gun cotton produces an effect exceeding three pounds of gunpowder in artillery. This is a material advantage, whether it be carried by men, horses, or in wagons. It may be placed in store, and preserved with great safety. The danger of explosion docs not arise until it is confined. It may become damp, and even perfectly wet, without injury, and may be dried by mere exposure to the air. This is of great value in ships of war, and, in case of danger from fire, the magazine may be submerged without injury. As regards its practical use in artillery, it is easy to gather from the foregoing general facts how gun cotton keeps the gun clean and requires less windage, and therefore performs much better in continuous firing. In gunpowder there is 68 per cent of refuse, or the matter of fouling. In gun cotton there is no residuum, and therefore no fouling. Experiments made by the Austrian committee proved that 100 rounds could be fired with gun cotton against 30 rounds of gunpowder. From the low temperature produced by gun cotton, the gun docs not heat. Experiments showed that 100 rounds were fired from a six-pounder in 34 minutes, and the gun was raised by gun cotton to only 120° F, whilst 100 rounds with gunpowder took 100 minutes, and raised the temperature to such a degree that the water was instantly evaporated. The firing with the gunpowder was, therefore, discontinued; but the rapid firing with the gun cotton was continued up to 180 rounds without any inconvenience. The absence of fouling allows all the mechanism of a gun to have much more exactness than where allowance is made for fouling. The absence of smoke promotes rapid firing and exact aim. There are no poisonous gases, and the men suffer less inconveniences from firing in casemates, under hatches, or in closed chambers. The fact of smaller recoil from a gun charged with gun cotton is established by direct experiment. Its value is 2/3 of the recoil from gunpowder, projectile effect being equal.