Fig. "2," represents also an elevational section of a similar vessel with the top open. The body of the can is constructed, and the bottom attached thereto in the ordinary manner; but in place of using materials of the same tenacity and thickness for the top, thin brass or other soft metal is used, and a ring or rim thereof (see "a," fig. "1,") secured to the top of the can by solder. For sealing the can after it shall have received its contents, a disc (see "B," fig. "1,") of the same material as the body of the vessel is used, and soldered to the rim or ring, "a," leaving between the said disc, "B," and the edge of the can, sufficient space for the passage of a penknife blade.

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Having now described the nature of the said invention, and the manner in which the same is or may be carried into effect, I declare that what I claim and desire to have secured to me by the above in part recited letters patent, is the construction of a metallic vessel for hermetically sealing paints and other substances, one end of which shall be composed in part or wholly of thin brass or other soft metal, in such manner that the top or cover may be removed by severing the said end of brass or other soft metal with a penknife or other sharp instrument, substantially in the manner and for the purposes herein before described.In witness, &c.

WILLIAM KIRKBY PEACE.

Specification of the Patent granted to FREDERICK COLLIER BAKEWELL, of 6, Haverstock-terrace, Hampstead, in the County of Middlesex, for Improvements in the Manufacture of Caustic Alkalies.-Dated September 5, 1859.(A communication.)

WITH AN ENGRAVING.

To all to whom these presents shall come, &c., &c.This invention consists in a method of separating caustic alkalies from the lime or other precipitate used in the process of their manufacture by means of filtration through fire-bricks or other solid porous substance capable of resisting the caustic action of the alkaline liquid, whereby a more perfect separation is effected than by the processes heretofore known and practised combined with a great

saving in time and fuel. In describing this invention, so as to enable others skilled in the art to practise it, I will take for example the process as applied to the manufacture of caustic soda. A solution of carbonate of soda is treated with hydrate of lime in excess in the usual manner, whereby the carbonic acid is separated from the soda, and uniting with the lime in the form of insoluble carbonate, the lime is precipitated, and the soda solution is left in a caustic state. This solution of caustic soda is decanted from the precipitated carbonate of lime and is reduced by evaporation to a solid mass. After as much as possible of the solution of caustic soda has been decanted from the precipitate, there remains a large quantity of the solution mixed with the lime, forming a pulpy mass which requires further treatment to extract the soda from it. By the ordinary process of manufacture this remaining portion of the soda solution is separated from the insoluble lime by the addition of a quantity of water which is mixed thoroughly with the lime, and the latter is allowed to settle. The diluted solution of soda thus produced is then decanted from the lime, and the process of washing and decanting is repeated ten or twelve times until nearly all the caustic soda is removed from the lime. By this process the quantity of liquid to be evaporated becomes very great before the caustic soda is obtained in a solid state. The filtration of the solution through matting or other fabric might in some degree overcome this difficulty, were it not that the corrosive property of the caustic soda rapidly destroys any vegetable or animal textile fabrics, and even a filter made of sand or other similar substance would require renewal after each operation, would be difficult to construct and to keep in order, and a large quantity of the alkaline solution would be retained by capillary attraction among the particles of the lime. The obstacles to the ordinary use of filtration for the separation of the caustic soda from the residuum of carbonate of lime are entirely removed in this invention by causing the solution of soda, after it has been mixed with the hydrate of lime, to pass through a filter composed of porous bricks or tiles, or other similar material. The construction of such a filter is shown in the accompanying drawing.

In fig. 1, the letter a represents a shallow tank constructed of stone, brick, or other suitable material about eighteen inches in depth, and of any required length and

width, twenty-five feet by forty being a convenient size. This tank is made water-tight, and is supported on a wall or on props; the bottom of the tank is made to incline from the sides towards a hole in the centre, or in some other point from which a pipe, b, conducts the filtered liquid to a cistern or other receptacle. On the bottom of the tank are placed joints, c, c, c, parallel to each other about twelve inches apart; these joints need not be more than one inch thick, and two or three inches in height, and should have a number of openings close to their lower edge to allow the liquid to pass through to the exit pipe, b. Across these joists are placed supports, d, d, of suitable material, about one inch square, and distant from centre to centre the length of the bricks or tiles to be laid upon them. The bricks or tiles, e, e, e, to be used for the filter are made of fire-clay or other suitable material consisting essentially of a difficulty fusible siliceous clay, or clay and sand united into a mass by partial vitrification, or the reciprocate action of the silicates on each other. These bricks or tiles are laid flat, side by side, care being taken to cover the ends of them, wherever they touch each other, or the sides of the tank, with a thin mortar of hydraulic cement mixed with water to the consistence of cream, with or without sand, so as to leave no interstices between the bricks or tiles themselves, nor the sides of the tank, through which any liquid could pass. When the mortar has set, the bricks or tiles form a firm floor which can be walked upon without injuring it. The solution of caustic soda having been prepared by treating carbonate of soda with hydrate of lime in excess, the lime is allowed to precipitate, and as much clear liquor as possible is drawn off. The solution of soda. that remains mingled with the lime is afterwards filtered through the porous floor of the tank, and escapes by the pipe, b, being thus separated from the lime without dilution. The lime left on the floor of the tank is about three or four inches deep, and of the consistence of thick mortar. The portion of caustic soda that still remains mingled with the lime is then removed without diluting the solution by the gradual addition of pure water poured gently over the lime to a depth of two or three inches, care being taken not to wash away the lime from any part so as to uncover the floor of the tank. The water, which thus forms a stratum above the lime, then gradually displaces the alkali from the lime by forcing it through the porous floor into

the space below, whence it runs through the pipe, b. This operation is performed by the mechanical pressure of the water, which forces the alkaline solution through the porous floor, and occupies the place of the caustic soda without mixing with and diluting it. Nearly the whole quantity of soda in solution is thus extracted from the precipitated carbonate of lime, which is left in nearly a dry state, and may be used for other purposes. By this method of extracting the solution of caustic soda from the lime, the quantity of liquor to be evaporated is at least two-thirds less than by the ordinary mode of washing the precipitate with water, and it thereby effects a great saving in time, in labour, and in fuel, the economy of fuel in a manufactory making twenty-five tons of soda per week being not less than ten tons of coal per diem. After the filters have been used for some time, the porous bricks become partially choked, so that the filtration becomes less rapid. When this is observed, the bricks or tiles may be replaced with new ones, laid as before. The old bricks are not at all injured by the filtration, and after being washed, may be used for the purposes for which fire-bricks are usually employed.

Having thus described the improvements in the manufacture of caustic soda and other caustic alkalies, what I claim and desire to secure by letters patent is, the mode hereinbefore described of separating the solution of caustic soda or other caustic alkaline liquids from an insoluble precipitate by the use of a filter constructed substantially in the manner herein before described.—In witness, &c.

FREDERICK COLLIER BAKEWELL.

Specification of the Patent granted to GEORGE DANNETT ROBINSON, 15, Church-street, Islington, for Improvements in Apparatus for Regulating the Pressure of Gas and other Fluids.-Dated September 21, 1859.

WITH AN ENGRAVING.

To all to whom these presents shall come, &c., &c.-My invention relates to improvements in apparatus for regulating the pressure and flow of gas and other fluids, firstly, to apparatus for regulating the pressure and flow of

gas through pipes or other chambers, so as to maintain a uniform and steady pressure to the burners, and consists in the adaptation of a valve; in this particular the apparatus does not differ much from other gas regulators now in use; for this purpose the gas is introduced by a supply pipe into the inlet chamber or compartment of the apparatus; from this chamber or compartment the gas passes into a second chamber or compartment, but the amount of gas passed or passing from one chamber to the other is regulated by means of the valve which is caused to close or open a passage between the two compartments more or less as circumstances may require, that is, according to the number of lights burning; the valve for regulating the pressure of gas between the inlet and outlet chamber or compartment of the apparatus is carried by a cover with turned down edges, which enters a trough containing a fluid, by preference quicksilver, and the cover moves on points or fulcrum one inch or more from the end of the regulator, which causes the regulator to be self-governing, and at the same time acting as a break, so that when a high pressure comes on from the main, it cannot close the valve and cut off the gas and put out the lights, so common in gas regulators; the cover is supported by two pieces of brass on the sides that the screws or joints work upon; the cover is also supported by an iron or brass rod upon the top over the points or fulcrum, which makes the cover under a high pressure steady, and cannot oscillate as is common in gas regulators, and also acts as a safety rod.

Fig. 1, shows a longitudinal section of my gas regulating apparatus, constructed and combined according to my invention.

Fig. 2, is a plan of the regulator; the top and valve being removed shows the cover hung upon its points in the trough which contains quicksilver.

Fig. 3, shows a transverse section with the valve hung upon the cover with the rod, L, upon the top of the

cover.

Figs. 4 and 5, show a longitudinal section of the regulator, with the lid and valve reversed; similar letters of reference indicate corresponding parts in the several drawings.

A, shows the inlet; B, the outlet for the gas; G, a trough one inch or more deep; D, shows the cover with turn-down edges, and works in quicksilver, which makes a gas-tight