The

next executed. The sole-leather, in hides, is first steeped in a tank of water to soften it, then it is thoroughly dipped, and afterwards cut by a machine into measured lengths of a certain breadth, according to the size of sole wanted. After having become sufficiently dry, these cut strips of leather are run between rollers, and also submitted to severe pressure under plates in a press, so as to effect as complete a compression of the fibres as is attained according to the old mode by beating with a hammer upon a lapstone. From these compressed strips, soles of the different sizes are punched out at a single blow by a machine, the cutter of which is of the size and form required, and it turns round so as to cut a right and left sole alternately. Heel pieces are also cut out by hollow punches at a single blow. The edges of the soles and heels are next smoothed and polished in a small rotating machine, and another machine then makes the channels in the soles for the rows of stitching. After this the under soles and uppers are fitted upon lasts and made ready for sewing. This operation is executed by Mackay's peculiar machine, adapted for this specific purpose. waxed thread is wound upon a vertical spool, and is conducted through a guide situated on the top of an elbow secured on a swivel joint capable of turning under the needle, and conducting the thread into the crease around the sole. The needle operates vertically above the sole, and the waxed thread is fed into the interior of the boot or shoe by the guide, the needle descending through the sole, drawing through the thread and forming the stitches, which are pressed down close into the crease by a tracer-foot, upon which great pressure is exerted. In this manner the sole and upper are united firmly and neatly together in a few seconds without employing a welt. Hand sewing cannot be compared with such machine-work for accuracy and rapidity. Another machine is employed for putting on double soles with copper pegs. A thin strip of copper is fed in at one side, and the holes are punched in the sole, the pegs cut and put into the holes, and then driven down at one continuous operation, with a speed corresponding to that of sewing the soles. The crossing of the half sole at the instep is pegged, and also fastened with a screw at each side by hand; the heels are also pegged down. The edges of the heels are neatly trimmed by a small rotating machine, and the soles are also rubbed down by a machine; so that nearly all the operations connected with the manufacture of boots and shoes in this establishment are performed by machines designed especially for the purpose. The legs of the boots are stretched and the wrinkles removed by new boot-trees secured to benches, and are expanded in an instant from the interior by pressing on a treadle with the foot. These boot-trees are altogether superior to the clumsy old wedge kind. The materials used in the manufacture of these articles appear to be of a superior quality, the machines not being adapted for operating on inferior patch leather.

The accurate operations of these machines, and the rapidity of their action, place them in a highly advantageous position for manufacturing boots and shoes. The price of hand labor had become so high and workmen so scarce that such machines became a necessity, and the change effected by their use is equal to four times the quantity of work executed by hand labor; that is, one hundred men will turn out with these machines as much work as four hundred men without them.

The

saving of labor to the country is therefore immense. About five hundred pairs can be turned out daily in this establishment. Perhaps no labor connected with boot-making is so severe as that bestowed upon burnishing the heel with a warm iron. This work is still executed by hand, but a machine is now being set up to accomplish this finishing operation, and it will soon be at work. For centuries, no improvement seems to have been made upon the old system of boot and shoe making; when, all at once, as it were, within the space of two short years, the whole art

has been revolutionized.

CULINARY IMPROVEMENTS.

New Mode of Preserving Provisions. —A patent has been applied for by A. H. Remond, of London, for preserving provisions by passing a current of electricity through the cans or cases containing what are called "preserved provisions," after they are sealed up. The electric fluid is made to pass through the case on a fine iron wire; the wire is caused to become red-hot by the intensity of the current, and thus the oxygen in the can is said to be consumed, because it will unite with the hot iron wire and form an oxide.

Roasting Coffee. In order to prevent the loss of aroma, W. Symington, of London, roasts coffee in a close vessel, which has a funnel that conveys the volatile oil, which contains the aroma, into a receptacle containing cold ground coffee, and where the aroma is absorbed. All the roasted coffee, after it is ground and becomes cold, is exposed for a short period in the absorbing chamber. Scientific American.

ARTIFICIAL IVORY.

Patents have been taken by Dr. R. Havemann, of New Brunswick, N. J., for an imitation of ivory, produced by the action of chlorine on India rubber or allied gums. By his process, solid lumps of India rubber or gutta percha are dissolved in one of the well-known solvents used for the purpose; and this solution is brought in contact with chlorine by passing streams of gaseous chlorine into the same. When the combination of the gum with the chlorine is perfected, the solvent is removed by evaporation at a low temperature. After removing the liquid by filtering or evaporation, the composition of gum and chlorine is well washed with alcohol and then pressed and dried, when it forms a white, hard mass, similar to ivory in appearance and elasticity. We have seen billard balls made of it, but we think they lacked the weight necessary to render them equal to ivory; for many purposes, however, it is an excellent substitute for ivory. · Scientific American.

SIEMANS'S REGENERATIVE GAS FURNACE.

A brief description of the construction and use of this furnace was given in the Annual of Scientific Discovery for 1863, p. 32. Since its first introduction, we understand that the principle of heating involved has been extensively applied in England, France, Germany, and other countries, to glass-houses, for heating gas retorts and muffles for metallurgical purposes, for melting steel, and for puddling and welding iron. At the meeting of the British Association for 1863, Mr. Siemans was present and exhibited the plan for a furnace for welding and working

iron, and the gas generator connected with it. The heated chamber is of the usual form, but instead of a fireplace there are four passages (two at each end of the chamber) leading downwards into four regenerators or chambers filled with loosely piled firebricks. The lower extremities of these four regenerator chambers communicate with two cast-iron reversing valves. The gas arriving from the producer through a pipe is directed by the valve into one regenerator or other, according to the position of the valve. The gas then ascends through the one regenerator, where it takes up the heat previously deposited in the brickwork, and issues into the furnace at a point where it meets with a current of heated air arising from the second regenerator to effect its combustion. The products of combustion pass away through the opposite regenerator and the reversing valves into the chimney flue. The last-named regenerators receive at this time the waste heat of the furnace, becoming heated at their upper extremity to the temperature nearly of the furnace itself, but remaining comparatively cool towards the bottom. Every hour or half-hour the direction of the currents is reversed by a change of the valve lever, the heat before deposited in the one pair of regenerators is now communicated to the air and gas coming in, while the waste heat replenishes the second pair of regenerators. The gas producer consists of two inclined planes upon which the fuel descends, being gradually deprived in heating of its gaseous constituents, and finally burnt to carbonic oxide by the air entering through the grate at the bottom of the inclines. Water admitted at the bottom also assists in the decomposition of the ignited coke at the bottom, converting the same into carbonic oxide and hydrogen gas. The saving of fuel which has been effected by this arrangement amounts to from forty to fifty per cent. In the application to re-heating and puddling furnaces, a saving of iron has been effected, owing to the mildness of the gas flame, of from three to four per cent. of the entire quantity put in; the iron also welds more perfectly than it does in the ordinary furnaces. Smoke is entirely obviated. By another arrangement the regenerative principle has been applied also to coke ovens, the result being that the separation of the coke from its gaseous constituents is effected without losing the latter. In placing the coke ovens, constructed on this plan, near the works where the iron is puddled and re-heated, the latter operation may be entirely effected by the gas generated in producing the coke necessary for the blast furnace in producing the pig iron. The gas resulting from the regenerative coke oven may be used to heat the blast and boilers connected with the blast furnace. These latter improvements are now in course of being carried into effect on a large scale. The gas produced from the lastnamed producers is of a very illuminating character, and may, it is reported, be used for that purpose in preference to the hydrocarbon now manufactured for that purpose by a much more expensive process.

American manufacturers desirous of acquainting themselves in detail with the principles of Siemans's furnace will find a descriptive paper by the inventor in the Proceedings of the Society of Mechanical Engineers, London.

IMPROVEMENTS IN THE SCIENCE OF WAR.

In accordance with the plan pursued during the last two years, we give under the above head a summary of such inventions, discoveries, and applications relative to the science of war, brought before the public during the past year, as have seemed to the editor as most worthy of

notice.

IMPROVEMENTS IN GUN-COTTON.

At the British Association meetings of 1862, a joint committee of chemists and physicists was appointed to inquire into and report on the so-called "Austrian Gun-Cotton." At the last meeting of the Association, a chemical report was submitted by Dr. Gladstone, and a report on the mechanical portion of the question by Mr. J. Scott Russell. We present first an abstract of Dr. Gladstone's report.

sive.

Chemical Report.· Since the discovery of gun-cotton by Schönbein, its application to war purposes has been frequently thought of; and many experiments, with a view of using it, have been made, especially by the French. Such serious difficulties have, however, presented themselves, that the idea gradually came to be abandoned everywhere but in Austria. Here experimentation was kept up, and it having been reported on good authority that the experimenters had succeeded in overcoming many of the difficulties encountered elsewhere, the committee of the Association applied to the Austrian government for information, which was furnished them. The following is a summary of the more important facts elicited. In the first place, the gun-cotton prepared by Baron Von Lenk, the inventor of the Austrian system, differs from the gun-cotton generally made in its complete_conversion into a uniform chemical compound. It is well known to chemists that if cotton is treated with mixtures of strong nitric and sulphuric acids, compounds may be obtained varying considerably in composition, though they all contain elements of the nitric acid, and are all exploThe most complete combination (or product of substitution) is that described as C H21 (9 NO1) O∞, which is identical with that termed by the Austrian chemists trinitrocellulose, C12 H; (3 NO4) O10This is of no use whatever for the making of collodion; but it is Von Lenk's gun-cotton, and he secures its production by several precautions, of which the most important are the cleansing and perfect dessiccation of the cotton as a preliminary to its immersion in the acids, — the employment of the strongest acids attainable in commerce, the steeping of the cotton in a fresh strong mixture of the acids after its first immersion and consequentim perfect conversion into gun-cotton,the continuance of this steeping for forty-eight hours. Equally necessary is the thorough purification of the gun-cotton so produced from every trace of free acid. This is secured exclusively by its being washed in a stream of water for several weeks. These prolonged processes are absolutely necessary. It seems mainly from the want of these precautions that the French were not successful. From the evidence before the committee it appears that this nitro compound, when thoroughly free from acid, is not liable to some of the objections which have been urged against that compound usually experimented upon as

gun-cotton. It seems to have a marked advantage in stability over all other forms of gun-cotton that have been proposed. It has been kept unaltered for fifteen years; it does not become ignited till raised to a temperature of 136° C. (277° Fahr.); it is but slightly hygroscopic, and when exploded in a confined space, is almost entirely free from ash. There is one part of the process not yet alluded to, and the value of which is more open to doubt, the treatment of the gun-cotton with a solution of silicate of potash commonly called water-glass. Some Austrian chemists think lightly of it; but Von Lenk considers that the amount of silica set free on the cotton by the carbonic acid of the atmosphere is really of service in retarding the combustion. He adds, that some of the gun-cotton made at the Imperial factory has not been silicated at all, and some imperfectly; but when the process has been thoroughly performed, he finds that the gun-cotton has increased permanently about 3 per cent. in weight. Much apprehension has been felt about the effect of the gases produced by the explosion of gun-cotton upon those exposed to its action. It has been stated that both nitrous fumes and prussic acid are among these gases, and that the one would corrode the gun and the other poison the artilleryman. Now, though it is true that from some kinds of gun-cotton, or by some methods of decomposition, one or both of these gases may be produced, the results of the explosion of the Austrian gun-cotton without access of air are found to contain neither of them, but to consist of nitrogen, carbonic acid, carbonic oxide, water, and a little hydrogen and light carburetted hydrogen. These are comparatively innocuous, and this weight of evidence is, that the gun is less injured by repeated charges of gun-cotton than of gunpowder, and that the men in casemates suffer less from its fumes. It seems a disadvantage of this material, as compared with gunpowder, that it explodes at a temperature of 277° Fahr.; but against the greater liability to accidents from this cause may be set the almost impossibility of explosion during the process of manufacture, since the gun-cotton is always immersed in liquid, except in the final drying.1 Again, if it should be considered advisable at any time, it may be stored in water, and only dried in small quantities as required for use. The fact that gun-cotton is not injured by damp like gunpowder is, indeed, one of its recommendations, while a still more important chemical advantage which it possesses arises from its being perfectly resolved into gases on explosion; so that there is no smoke to obscure the sight of the soldier who is firing or to point out his position to the enemy, and no residuum left in the gun to be got rid of before another charge can be introduced.

Physical Report.-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

1 In ten years' experience it is proved that this temperature is sufficiently high to insure safety of manipulation; 277° Fahr. is an artificial temperature, and artificial temperatures accidentally produced are generally high enough to ignite gunpow der. The greater liability to accident from this cause can, therefore, scarcely be admitted.