forming the flue or flues; and one or more fire-places are placed at the end of the decomposing chamber. The salt and acid are placed together on the lower bed of the chamber, in the side of which there are two doors, one near the centre of the bed, the other close to its end next the upper bed, for the greater convenience of moving the charge from the lower into the upper bed, when the materials become sufficiently stiff to allow of this being done, which generally takes place in a few hours.

A fresh quantity or charge of salt and acid are put into the lower bed, when that last introduced is changed to the upper; and at the expiration of ten or twelve hours from the commencement of the operation, the sulphate of soda in the upper bed may be drawn out, when another removal of partially decomposed salt takes place, and a fresh charge is put into the lower bed; so that although the materials are kept in the furnace ten or twelve hours, yet a fresh charge of salt and vitriol are put into the lower bed, and the decomposed salt or sulphate of soda is drawn out of the upper bed every five or six hours.

Figs. 10 to 16, in Plate VI., will serve to further illustrate these improvements in the construction of apparatus. Fig. 10, is a perspective representation of the decomposing furnace and condensing apparatus as seen looking toward the front of the fire-places; fig. 11, is a similar representation looking at the side of the furnace; fig. 12, is a vertical section taken longitudinally through the furnace, to show the closed oven or decomposing chamber, fire-places, and flues; fig. 13, is another similar section taken transversely: a, a, is the brickwork of the furnace; b, the fire-places; c, the fire-doors; d, the ash-pits; e, e, the flues leading to the

chimney; f,f, the arch of fire bricks separating the flues from the oven or decomposing chamber g, g; h, is the lower floor or bed of the chamber, and i, the upper; k, l, are the charging doors for introducing the salt and acid, through the latter of which the partly decomposed salt is transferred to the upper bed or floor; and m, is the door for removing the sulphate of soda.

A slight variation of the foregoing is shown in figs. 14, and 15, which are similar sections to figs. 12, and 13, the same letters of reference being marked on corresponding parts, the only difference of construction being that the flues are in this instance separated from the decomposing chamber by means of fire tiles or fire bricks placed at an angle, instead of an arch or curve; and the top of the flues are made flat or horizontal. Fig. 16, is a longitudinal section of one of the condensing apparatus or troughs which will be more fully

described hereafter.

The condensing apparatus consists of a trough or troughs, constructed either of stone, slate, or wood, or of any other material or materials which may be found best to resist the action of muriatic acid. Wood, well covered with boiled tar, pitch, or rosin, or a mixture of such substances, have been found to answer well; and the most convenient size is from about 9 to 12 feet long, by 3 feet wide, and from 12 to 15 inches deep: 0, 0, are the troughs within which conducting pipes p, p, formed of earthen or stone ware are introduced, as seen in the drawings.

A quantity of water sufficient to rise within a few inches of the mouths or apertures of the pipes p, p, is to be put into the troughs; and over the mouths of the pipes are inverted earthen or stone ware jars or vessels q, q. These inverted jars form water lutes or joints.

The gas is conducted from the furnace by pipes r, r, into the conducting pipes p, p, and is passed from vessel to vessel, until by the time it reaches the fourth or fifth jar, there is remaining little or no gas uncondensed, the interior of the jars allowing a sufficient surface of water exposed to the gas.

The last conducting or exit pipe s, is connected with a flue leading to the chimney, the draught of which contributes to bring the gas forward from the furnace, and assists the condensation.

To the bottom part of each of the conducting pipes p, small branch pipes or nozles t, t, are attached (see fig. 16): these nozles pass through the bottom of the trough, and any gas which becomes condensed in its passage, is allowed to drop into a jar or any suitable receptacle placed below. The water in the troughs may be changed as often as is found desirable; and if there be a good supply of water, and the acid be not required of any particular strength, it may be allowed gradually to receive a fresh supply of water upon the upper surface at one end of the trough, and may be drawn off from the bottom part at the other end; but if the acid be required for manufacturing purposes, the water may remain in the troughs until it acquires sufficient gravity, or until the fumes arising therefrom become inconvenient, or the condensation be impeded.

The Patentee concludes by saying, "Having thus described the nature of my invention, and the manner of carrying the same into effect, I would remark that I do not confine myself to the exact form and dimensions of the decomposing furnace shown in the drawing, nor in the construction of the arches, or the part which separates the fire-place and flues from the decomposing chamber, or the medium over which the fire passes, as

this medium may be of fire bricks or fire tiles, or other fit and proper materials, placed obliquely or horizontally, or in curved figures over the materials under operation for the formation of the sulphate of soda : nor do I confine myself to the size or number of the condensing troughs, jars, vessels or conducting pipes, the same being capable of modification, or being varied according to the quantity of salt required to be decomposed in a given time. But I claim as my said invention, the improved construction of decomposing furnace, with the mode of applying the fire through a medium of fire bricks, fire tiles, or other fit and proper materials, in the manner as before described; thus separating the muriatic acid gas from the smoke and gaseous products arising from the combustion of the fuel. And I also claim as my invention and improvements, the improved construction of condensing apparatus, and the application of the mode or method of conducting the muriatic acid gas in pipes under water, and inverted jars, as before described, in the said condensing troughs or apparatus."-[Inrolled in the Rolls Chapel Office, April, 1837.]

Specification drawn by Messrs. Newton and Berry.

TO FREDERICK EDWARD HARVEY, of the Horsley Ironworks, in the parish of Tipton, in the county of Stafford, mechanical draftsman, and JEREMIAH BROWN, also of Tipton, in the same county, roll-turner, for their certain improvements in the process and machinery for manufacturing metallic tubes, and also in the process or machinery for forging or rolling metal for other purposes.-[Sealed 3rd February, 1836.]

THESE improvements in the process and machinery for manufacturing metallic tubes, and also in the process

or machinery for forging or rolling metal for other purposes, consist, first, as regards the manufacture of cylindrical tubes in preparing iron for skelps, by rolling it in a heated state to particular forms suited to the production of such tubes; secondly, in partially bending or turning over a portion of the edges at the end of each prepared skelp, by means of rolls having excentric and peculiarly formed grooves, and afterwards completing the bending of the whole length of the skelp (whilst still in a heated state) upon a stationary mandrel, between a pair of rollers having semi-circular grooves; or the same effect of bending may be obtained by passing the skelp through suitable forming moulds; and, thirdly, after again heating the skelp to a welding heat in a hollow fire or air furnace, closing or welding the edges or junctions of such bent skelp upon a stationary mandrel by the external pressure of a pair of grooved rollers, between which the skelp is made to pass.

Plate VII., fig. 1, represents the flat side and transverse section of an iron skelp A, prepared, by rolling, for forming a cylindrical tube to be closed at its edges when welded, by what is technically called a jump joint. Fig. 2, is another skelp, also prepared by rolling, shown in flat and sectional views, bevelled on its edges, and intended to be closed by what is called a lap joint. It is not necessary to show in the drawings, figures of rollers suited to produce these skelps, as the forms of the skelps being exhibited, the manner of producing them by rolling will be well understood.

Having prepared the skelp A, as shown at figs. 1, or 2, we introduce its end edgewise through a free passage between a pair of rollers B, B, having segment grooves formed by excentric or convolute curves, and tapering in width, as shown in the front elevation at fig. 3, and

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