To understand this may not be easy. The waste of the solids of gunpowder accounts for one part of the saving, as in 100 pounds of gunpowder 68 pounds have to be projected in addition to the shot, and at much higher speed. The remainder Von Lenk attributed to the different law of combustion; but the fact is established.

The comparative advantages of gun cotton and gunpowder for producing high velocities are shown us in the following experiment with a Krupp's cast-steel gun - six-pounder. With ordinary charge, 30 ounces of powder produced 1338 feet per second; with charge of 13 1/2 ounces gun cotton produced 1563 feet. The comparative advantages in shortness of gun are shown in the following experiments -twelve-pounder: -

As to advantage in weight of gun, the fact of the recoil being less in the ratio of 2 to 3, enables a less weight of gun to be employed, as well as a shorter gun, without the disadvantage to practice, arising from lightness of gun. As regards durance of gun, bronze and cast iron guns have been fired 1000 rounds without in the least affecting the endurance of the gun. As regards its practical application to destructive explosions of shells, it appears that from a difference in the law of expansion, arising probably from the pressure of water in intensely heated steam, there is an extraordi-nary difference of result, namely, that the same shell is exploded by the same volume of gas into more than double the number of pieces. This is to be accounted for by the greater velocity of explosion when the gun cotton is confined very closely in very small spaces. It is also a peculiarity that the stronger the shell the smaller the fragments into which it is broken.

As regards mining uses, the fact that the action of gun cotton is violent and rapid in exact proportion to the resistance it encounters tells us the secret of its far higher efficiency in mining than gunpowder. The stronger the rock the less gun cotton, comparatively with gunpowder, is accessary for the effect; so much so, that while gun cotton is stronger than powder as 3 to 1 in artillery, it is stronger in the proportion of 6.274 to 1 in a strong and solid rock, weight for weight. It is the hollow rope form which is used for blasting. Its power of splitting up the material is regulated exactly as wished.

As regards military and submarine explosions, it is a well known fact that a bag of gunpowder nailed on the gates of a city will blow them open. In this case gun cotton will fail. A bag of gun cotton exploded in the same way is powerless. If one ounce of gunpowder is exploded on scales the balance is thrown down; with an equal force of gun cotton nothing happens. To blow up the gates of a city, a very few pounds of gun cotton, carried in the hands of a single man, will be sufficient, only he must know its nature. In a bag it is harmless; exploded in a box it will shatter the gates to atoms.

Against the palisades of a fortification, a small square box, containing 25 pounds, merely flung down close to it, will open a passage for troops. In actual experience on palisades, a foot diameter and eight feet high, piled in the ground, backed by a second row of eight inches diameter, a box of 25 pounds cut a clean opening 9 feet wide. To this, three times the weight of gunpowder produced no effect whatever, except to blacken the piles.

Against bridges, a strong bridge of oak, 24 feet span, was shattered to atoms by a small box of 25 pounds laid on its centre; the bridge was not broken, it was shivered.

As to its effects under water, in the case of 21 two tiers of piles in water, 13 feet deep, 10 inches apart, with stones between them, a barrel of 100 pounds of gun cotton, placed 3 feet from the face and 8 feet under water, made a clean sweep through a radius of 15 feet, and raised the water 200 feet. In Venice, a barrel of 400 pounds placed near a sloop, in 10 feet water, at 18 feet distance, threw it in atoms to a height of 400 feet.

All experiments made by the Austrian com-mittee are conducted on a grand scale, thirty-six batteries, six and twelve-pounders, having been constructed, and practised with gun cotton.

The reports of the Austrian commissioners are all based on trials with ordnance, from six-pounders to forty-eight pounders, smooth bore and rifled cannon. The trials with small firearms have been comparatively few, and are not reported on. The trials for blasting and mining purposes were also made on a large scale by the Imperial Engineers' Committee.

The writer of the article in the U. S. Service Journal, already referred to, says: -

"A change in the strength of the acids, in the condition of their mingling, in the duration of the chemical action, in the temperature, and in the removal of the free acid from the cotton, will each effect a marked change in the pro-duct Advantage is now taken of this fact, and gun cotton is prepared with reference to the special use for which it is intended just as gunpowder should be, and is to some extent.

"The gun cotton made at Hirtenberg, after the manner prescribed by General Lenk, differs, as might have been expected, very mate-rially from that made elsewhere. The process of manufacture is different, and the details are so arranged as to insure much greater uniformity in the results.

"The cotton is immersed in a mixture of one part strong nitric acid, and three parts concentrated sulphuric acid. It is permitted to remain in this bath for 48 hours; it is then washed in a stream of running water for four to eight weeks, so as to lose every trace of free acid; it is then carefully dried. Analysis shows that this gun cotton is of a uniform and fixed composition, and is almost wholly tri-iritro-cellulose, represented by the Austrian chemists by the formula: -

CI2H7(3N04)OIO

"It explodes at a temperature between 340° and 390° F., never below that, as was the case with gun cotton prepared after other formula). It does not deteriorate in quality when subjected to all the changes of temperature to which it is liable in service, nor when exposed to the various influences of dew, rain, and sun if afterwards dried.