purpose of admitting the key. The screens are so arranged, that, when in a quiescent state, they only present a very small opening for the admission of the key, but will admit a much larger key than the proper one.-This arrangement is made for the purpose of misleading any person who may attempt to examine the interior of the lock, for the purpose of making a false key. The barrel or shaft of the key, for opening a lock of this description, is pointed, so as to enter the small opening between the screens, which are radually expanded as the key is introduced.— [Inrolled in the Inrolment Office, June, 1840.]

To CHARLES ADOLPHE ROEDERER, of Wellington-street, City-road, for an improved method or process of manufacturing or preparing the chemical salts, called acetates.-[Sealed 9th April, 1839.]

THE patentee commences his specification by stating that in the various processes hitherto employed in the production of acetates, and particularly in the manufacture of the acetate of lead, the base is mixed with liquid acetic acid, either in a weak or concentrated state. This mode of operating, has, however, many disadvantages, such, for instance, as the expense of fuel, labour, and apparatus, also a serious loss of time and acid, as well as the difficulty of producing acetates of pure quality, capable of perfect crystallization.

By the improved process, hereafter described, most of these disadvantages are entirely obviated, and the remainder considerably ameliorated.

The present invention consists in employing the acid in

the state of vapour, instead of using it in the form of a liquid. The apparatus, employed for carrying the improved process into effect, consists of a vessel of a suitable size, according to the quantity of acetate required to be made at once. This vessel must be made of such materials as are not acted upon by the acid, and the top thereof is hermetically closed by a cover, which is fastened down in any convenient manner. In the lower part of this vessel a false bottom, perforated with minute holes,'is placed, or a coiled tube, minutely pierced with holes, may be employed instead of the perforated false bottom. Through this tube or false bottom, the vapour of acetic acid is allowed to pass freely, and in order to prevent the loss of acid, several perforated shelves or diaphragms, (similar to the false bottom,) may be placed at different altitudes throughout the vessel. On each of these shelves or diaphragms, a layer of litharge is spread, if acetate of lead is to be produced,—or other base, according to the acetate required; after which, the cover must be hermetically closed; then, by means of a distilling apparatus, of the ordinary construction, liquid acetic acid, strong or weak, pure or impure, must be converted into vapour, and conveyed by a suitable pipe into the coiled tube, or between the false and real bottom of the vessel containing the base, which is to be converted into an acetate; and as the vapour rises up through the perforated bottom and shelves, and diffuses itself throughout the vessel, the acid enters into combination with the base employed, and thereby forms an acetate, which falls to the bottom of the vessel; and as, in its descent, it meets with the ascending vapour, it becomes completely neutralized by the acid. When the acid combines with the base, the more aqueous parts of the vapour become liberated; and, as they maintain their

temperature, they ascend, and in their passage, pass through the successive layers of the base, thereby becoming deprived of acid that may remain; the vapour being thus reduced to simple steam is allowed to escape at the top of the vessel, from whence it is conveyed by a pipe to a worm placed in the vessel containing the mother liquor or acetic acid, and thereby assists, by its heat, in evaporating the said acid.

The distillation of acid is continued until the base in the vessel has become thoroughly saturated, and has arrived at a proper degree of concentration for crystallization; as the operation of saturating the base draws to a close, the vapour issues from the top of the vessel, highly charged with acid; this vapour is, therefore, conducted into another vessel charged with a superabundant quantity of the base, so that no acid is wasted, and the operation may continue in the first vessel until completed.

The patentee says that, it is evident, a great saving of fuel is effected, as by this improved process, the operation finishes where the ordinary one begins, and the mother liquor is evaporated by the latent heat of the aqueous vapour. The apparatus is very cheap and simple, and as it is self-acting, much labour is dispensed with; and, finally, as the temperature of the acetate never exceeds that of the vapours, the crystalline product is of a much finer quality than is generally obtained.—[Inrolled in the Inrolment Office, October, 1839.]

ount of the Performances of the Locomotive Engines on don and Birmingham Railway, during the year 1839." By Edward Bury, M. Inst. C. E.

gines used on the London and Birmingham Railway are ructed on the same principle as to the main parts, the ng upon four wheels, and only differing from each other of the minor details. The engines used for the conof passengers have cylinders 12 inches diameter, with an stroke; the driving wheels are 5 feet diameter, and the wheels 4 feet diameter. The merchandize engines have 13 inches diameter, with an 18-inch stroke, and differ others in having all the wheels of 5 feet diameter, and together. The framing is of wrought-iron, fixed inside els for the greater convenience of connecting it with the The cylinders are attached to the frame by two strong iron bars, passing beneath the lower semi-diameter, and y bolts to the ears cast on them. The cranks and forealso fixed to the frame. By this arrangement, any conreceived directly by that part of the machine best cal› bear it; and when the force of the engine is exerted pushing or drawing, it is done directly through the line aming, and thus any strain is diverted from the boiler,

or from those parts of the machine liable to be injured. There are only two bearings on the axles, and they are inside the wheels. Any tendency towards depression in the centre, from the weight, would be counteracted by the continual upward pressure, arising from blows received by the flanch of the wheels striking against the rails on curves, passing crossings, &c. The bushes, which the axles run in, are fitted into the frame in such a manner as to allow the springs to play vertically, but have flanches, which prevent any tendency to lateral action beyond that necessary for the irregularities of the road, and they are of such a length as to enable them to hold up the engine in case of the breakage of one of the axles. It would appear that the breakage of the axles is a very rare occurrence, and that even when it has happened, the engines have performed the remainder of the journey, and brought home the train with only a slight diminution of speed. The engines differ in weight according to the class they belong to. A passenger engine, with its coke and water in the fire-box and boiler, weighs 9 tons 13 cwts. 1 qr.

A merchandize engine, with coke and water, weighs 11 tons 13 cwts. 1 qr.

This form of engine was adopted by the author as early as the year 1829, when he constructed the "Liverpool," which was the original model engine, with horizontal cylinders and cranked axles. It was set to work on the Liverpool and Manchester Railway in July, 1830. This form of engine has been invariably used on the London and Birmingham Railway since its opening.

The paper is accompanied by complete drawings of the engines, and tabular statements of their performances during the year 1839, showing the number of miles traversed by each engine,