The sieves are formed of parchment skins, which have round holes punched in them, and within the sieves the piece of lignum vitæ is made to revolve till it has forced all the powder through the apertures, and grains of several sizes are consequently formed. From these grains the dust caused by the rubbing is separated, and then the hard corners and edges of the particles left are taken off, by being run for some time in a reel, which is made to describe a circular motion by the aid of machinery. This process is called glazing, as it puts a slight gloss upon the powder, which is afterwards sent to a stove to be dried, care being taken to regulate the heat by a thermometer, that the sulphur may not be dissipated or driven off by the process. Only about forty or fifty pounds of this composition is worked at a time, as explosions occasionally occur from the upright stones coming in contact with the bed on which the powder is placed and on which they revolve.

The cause of the explosion of gunpowder is this: a spark falling on one particle heats it to the degree of ignition, then nitre is decomposed, and its oxygen being set free, immediately combines with the charcoal and sulphur, which are also made hot, and the combination produces heat enough to inflame the whole mass with such rapidity, as to cause it to force away any object before it with great power.

While on the subject of gunpowder, we may mention the apparently remarkable invention of a gentleman named Warner, a captain in the navy, who has lately offered to sell to the government the secret of his discovery for the benefit of the country, but demanded a large price as his reward. The value he placed upon his invention induced one of those noble-spirited and patriotic individuals who have risen through the exercise of their own faculties to station, influence, and wealth, of which the annals of the country contain so many examples, Mr. Joseph Soames, a shipowner, to present a vessel of his own, of about four hundred tons burden, to test the truth of Capt. Warner's assertions. That gentleman had declared that, without any communication with the vessel at all, he could in an instant blow the largest ship to atoms.

The experiment was made off the coast of Brighton; and, as the time approached, the shore was crowded with eager spectators, among whom were the government commissioners, and a large number of officers eminent in the military service of the country. Shortly before the time fixed, the John of Gaunt hove in sight, towed by a small steamer, while Capt. Warner, in another boat, was waiting to fulfil or disappoint the anxious multitudes on the cliff, who were observing his proceedings. The tow-rope was cast loose; and, at a signal from the shore, the inventor completed his design. The distance between Capt. Warner and the John of Gaunt might be from half to three-quarters of a mile; but within two or three minutes after the signal had been given, the fated vessel was seen to rise upon the surface of the sea, her decks were forced out, and, in the succeeding instant, her masts and rigging were dishevelled, and she sank a ruin beneath the waters-a complete evidence how one puny hand, directed by reason and armed by science, can, in an instant, destroy the proudest vessel that may have braved unscathed the wildest storm.

Capt. Warner has also stated that, by his discovery, he is able to destroy ships even at five miles' distance, and with a variety of objects intervening; and a trial, at the expense of government, was made on the Marquis of Anglesea's estate in Wales. But it would seem that the invention is not yet complete, as the experiment in that instance failed.

Another equally efficacious, and indeed more powerful instrument of destruction than gunpowder, has of late been made known to the world by M. Schonbein, a professor of chemistry at Berlin. He found that by immersing the common flax cotton in equal quantities of nitric acid and sulphuric acid, and then washing and drying it, that an explosive power was obtained quite equal to that of gunpowder. It is stated in a report of the Parisian Academy of Sciences, that "if we are to believe the statements that have been made by persons of high respectability, the explosive cotton of M. Schonbein is a perfect substitute for gunpowder, possessing, weight for weight, much more strength than that article, and, at the same time, being free from the many serious objections which attend the manufacture of gunpowder. On the other hand, it does not appear that any of the specimens of other discoverers have given fully satisfactory results, that is to say, they are by no means of so destructive a property as the cotton of M. Schonbein. Many charges of illiberality have been brought against that gentleman for not making his process known, and endeavouring to make a good speculation of it for his own interest, under the protection of patents. We do not join in this outcry. If M. Schonbein, who is reported, we know not how truly, to have disposed of his patent right in England for £40,000, could make a million sterling of his different patents, we should not think him too highly rewarded, if it be true that his cotton is so much more powerful than that of his competitors, as his friends represent it to be. The man who invents the most rapid and the most effectual means of destruction, as regards war, is the greatest friend to the interests of humanity. Before gunpowder was invented war was a very favourite pastime of the rulers of nations, for it served to gratify their bad passions without presenting the chances of utter ruin to them. By risking a portion of the money derived from the labour of their subjects, and sacrificing a few hundred lives, they were able to play at the game of ambition; and, having always the hope of success before them, they had a constant excitement to violence and outrage. Nor did the pastime cease with the invention of gunpowder. The scale on which it was carried on was greater; but in a few years, when military tactics had been improved, and fire-arms had been made on surer principles, the game became too hot for the gamesters, and they were glad to retreat at length from the struggle of vain glory. The bow and arrow work of the ancients was nothing more than child's play to the fields of Austerlitz and Waterloo; and, when once a suspension of hostilities had taken place, governments began to reflect that the game was too costly. Thirty years of peace have served to give birth to better ideas; but there is every now and then an indication of a desire to involve nations in warfare. We are quite sure, however, that if any man could invent a means of destruction, by which two nations going to war with each other would see large armies destroyed, and immense treasure wasted, on both sides, in a single campaign, they would both hesitate at entering upon another. We repeat, therefore, that in this sense the greatest destroyer is the greatest philanthropist; and supposing what is said of M. Schonbein's invention to be true, we think that all governments will, in the event of differences, try all possible means of concession and conciliation before coming to a trial of strength in which the strong as well as the comparatively weak must be such great losers."

No better result could have been desired, and as the world grows wiser the truth of these assertions will be not only readily recognised, but acted on. The governments of England and France have both declined to use the "gun-cotton," as it is called, instead of gunpowder, because it is alleged that it explodes with such a small degree of heat, that after a few discharges a musket would be so hot as to go off the moment the charge was put within the barrel.

The invention is not, however, quite so new in principle as was generally supposed, for at the same meeting of the academy to which we have alluded, M. Pelousi, one of the members, said, "Although M. Schonbein has not published the nature or mode of preparation of his cotton, it is evident that the properties which he assigns to it can only apply to xyloidine. M. Dumas, as well as myself, made this remark in the origin of the first communications of M. Schonbein. Reasoning on the hypothesis that the poudre coton is nothing else than xyloidine, I may be permitted to say a few words with respect to its history, and some of its properties. Xyloidine was discovered in 1833 by M. Braconnet, of Nancy. He prepared it by dissolving starch and some other organic substances in nitric acid, and precipitating these solutions in water. In a note inserted in the Comptes rendûs de l' Academie des Sciences, in 1833, I showed that the xyloidine resulted from the union of the elements of the nitric acid with those of starch, and explained, by this composition, the excessive combustibility of the substance produced. I ascertained and this I think is a very important result in the history of the applications of xyloidine-that, instead of preparing it by dissolving the cellulose, it might be obtained with infinitely greater facility and economy by simply impregnating with concentrated nitric acid, paper, cotton, and