JOB CUTLER, of Spark Brook, Birmingham, civil engineer, and CHARLES ROBINSON, of the same place, gentleman, for certain improvements in welding iron pipes or tubes, to be used as the flues of steamboilers. Patent dated January 13th, 1848. Enrolled July 13th, 1848. THE invention described in this specification has for its object the production of tubes or pipes, formed of wrought-iron, for use as flues for steam-boilers, which shall possess the advantages of being enabled better to bear the unequal wear and tear to which the tubes are exposed when in use in steam boilers. The ends of them nearest the fire being subjected to greater heat, and, consequently, wearing away faster than the ends more remote therefrom, in the case of the use of tubes of the usual construction, namely, when they are cylindrical and parallel from end to end, and the tubes of equal thickness throughout, the result is, that when the end nearest the fire is worn out and rendered unfit, the other end will still be in good condition, and might, if dependent on itself, be still used without removal, but it will, in consequence of the worn-out condition of the one end, be necessary to remove the whole tube; it is intended by the present invention to remove this inconvenience and disadvantage, by the employment of tubes so made and constructed that the part of the tube most subject to the wear and tear shall be in a better condition to resist it, and cause the tube throughout its whole length to be so affected by the wear and tear as to be worn out or rendered unfit for further service equally. This the patentees effect by increasing the thickness of the substance of the tubes at the parts most exposed and subject to the wear and tear, and, at the same time, reducing in thickness the parts less exposed-in fact, forming them of a gradual taper upon their interior, while their exterior still remains cylindrical, and of the same diameter as when constructed as usual; by this mode of construction, the tubes will be worn out or rendered unfit for further use equally. Although this mode of forming the tubes renders them capable of sustaining a greater degree of wear and tear, and last much longer, and consequently more economical, it is not attended by any increase of

weight of the whole of the tube, as the quantity of the metal necessary to increase the thickness of the one part of the tube will be obtained from the other part, by the reduction of the thickness there. The annexed engravings will illustrate the invention, as also the mode of manufacture; fig. 1, being a sectional elevation of rollers for forming, welding, and drawing the tubes. Fig. 2, shows the mandrel employed, with the bulb upon it; and, fig. 3, the tube, when manufactured, in section; both the last figures being drawn to an enlarged scale. The skelps, B, of iron plate, for forming the tubes, are of equal thickness throughout, the same as are used in manufacturing tubes in the ordinary manner; these skelps, after being brought to a welding heat, are submitted to a pair of rollers, A, A, of the usual construction, set in suitable frames, C. These rollers at once, while the skelp is at a welding heat, turn over the sides of the skelps, and bring the edges in contact, and then weld them. This operation is effected upon the bulb, D', of the mandrel, D, over which the newly-formed tube, B', is drawn towards the other end of the mandrel, the length of the skelp being dependent upon the length of the tube to be manufactured. The tube thus formed is, however, notwithstanding the taper form of the mandrel, cylindrical in shape and equal in substance throughout, the interior diameter being equal to the diameter of the bulb, which will be about equal to the greatest diameter of the mandrel. The outer end of the mandrel, D, is supported and held by the standard, E, abutting against the stop, F, thereon, thereby maintaining the bulb, D', at the other end of the mandrel, in its proper position between the rollers, A,A. When the whole of the skelp is passed through the rollers, and the tube passed over the mandrel, the stop, F, is lowered, and the tube (with the mandrel within it, but the bulb at the end removed) passed on to another pair of rollers, similar to the last, between which the tube is drawn. These rollers have somewhat smaller grooves upon their peripheries, and thereby reduce the thickness of the tube at the end where the thickest end of the mandrel is situated, and roll the superabundant metal therefrom towards the other end, where the metal thickens, thus forming the tube

ness required, it is passed to the drawbench, for the purpose of extracting the mandrel; but should it not be considered properly finished and smooth, it may be again passed through another similar pair of rollers, for further reducing it and completing it. The drawbench employed is of the usual construction; and should there be any difficulty in removing the mandrel from the tube, the patentees recommend the re-heating the tube, and then submitting it to the action of the drawbench, or by means of cold rolling the tube between three rollers, as is well known, and thereby loosening the tube upon the mandrel. The patentees do not claim the reducing or welding of iron skelps or tubes, or the exclusive use of rollers, dies, or mandrels, or other apparatus, as described or referred to, unless when such be employed in and adapted for the said invention; but they claim the manufacturing, by thickening on a mandrel, of iron tubes or pipes, cylindrical on the exterior and conical or taper on the interior, as described.

ALEXANDER ROBERTSON ARROTT, manager of the Union-place Glass Works, St. Helen's, Lancashire, for improvements in manufacturing common salt. Patent dated January 5th, 1848. Enrolled July 5th, 1848.

THE improvements described in this specification relate to the manufacture of common salt, and consist, first, of a method of manufacturing common salt from brine by an improved process; and secondly, also, a mode of manufacturing common salt from rock salt. The first of these improved processes consists in mixing with the brine from which the salt is to be manufactured, muriate of lime (chloride of calcium), or muriate of magnesia (chloride of magnesium), and producing thereby such a solution containing salt, as may be concentrated by heat to a considerable extent, without any deposition of salt therefrom taking place while subject to such heat, and then by transferring the solution, when so concentrated, into a shallow vessel or vessels, where the solution will be allowed to cool, that common salt will be deposited in such vessel or vessels upon the solution so cooling. The patentee is enabled by this addition to the brine of muriate of lime or muriate of magnesia, to concentrate the solution to the extent required in closed boilers or vessels, without any deposition of salt therein. The apparatus described by the patentee in his specification, and of which he also gives drawings, for carrying out the process of

manufacture and producing the salt, is illustrated by the annexed engravings. Fig. 1, being a sectional elevation of part of the apparatus, containing what he calls the condenser; and fig. 2, a sectional plan of the same, the letters of reference apply to the same parts in both the figures. A, the condenser, which consists of a vertical cylinder having at top and bottom tube plates, which are secured steam-tight to the ends of the vertical tubes which pass through the condenser, and form a communication between the lower chamber, B, below the condenser, and the upper chamber, C, above the condenser; a pipe, D, passes through the condenser, A, and the upper chamber, C, and forms a communication between the lower chamber,B, and the large shallow vessel or pan, E, of which only a small portion, however, is shown in the engraving. There are two of these vessels or pans in the apparatus, the second of which communicates with the first by means of a short pipe. The second of these vessels or pans also communicates, by means of another short pipe, with a long cylindrical boiler, in every respect the same as a steam-boiler; from the other end of this boiler proceeds the pipe, F, which communicates with the chamber, C; from the boiler also proceeds the pipe, G, which communicates with the condenser, A; this pipe is for the purpose of passing over all the vapour generated in the boiler from the boiler to the condenser, where,

by contact with the tubes, it will be condensed. It must be of sufficient cross sectional area to be capable of carrying off the whole of the steam as soon as generated, so that there shall be in the boiler no pressure of steam, or only so much pressure as not to exceed two inches of water; the water, the result of the steam condensed in the condenser, A, is carried off therefrom by means of the pipe, H, which passes in several coils through the vessel, I, for the purpose of heating the solution with which the vessel, I, is charged previous to its introduction therefrom into the apparatus by the pipe, K, which communicates between the vessel, I, and the lower chamber, B; there is a stop-cock provided to this pipe for the purpose of regulating and determining the supply of the solution; the vessel, I, is supplied with solution by the pipe, L; previous to the supply of the solution into the apparatus, the muriate of lime or the muriate of magnesia is added to the brine; the apparatus is so arranged that the solution therein will stand at the same height in all the vessels, namely, the condenser, A, the shallow vessels or pans, E, and the closed boiler, so that the solution will flow through the pipes of communication between those vessels; the mode of operation is thus: the closed boiler being raised to the required temperature, steam is generated and allowed to flow through the pipe, G,