16,659. Chaumat, H. Aug. 29,1907, [date applied for under Section 91 of Patents &c. Act 1907]. Dyeing.-Wool free from grease, or any other raw or spun textile material, is dyed with indigo, particularly with the leuco-indigo baths electrolytically produced according to Specification No. 19,027, A.D. 1907, in a vacuous apparatus of the type in which the liquid is raised by a screw &c. from the bottom centrally through the woolcontainers, and is distributed upon the latter at the top, flowing down through the contents to the bottom again. The wool is contained in baskets L, L', L<11>, which have perforated annular bottoms and sides constituted by two perforated cylinders having a common axis. The superposed baskets are hooked together for easy removal, rest upon bosses b cast with the bottom E of the treating vat or cylinder, and are surrounded by a steam coil H placed against the inside of the double wall D of the cylinder. The cylinder is closed by a cover A, balanced by a weight B, the supporting-chain of which is guided by a grooved rib A' shaped so that the cover shall be balanced in nearly all positions. A bronze pipe I secured to the cover contains a thermometer J. The upper part C of the cylinder is provided with a tube Z, which has a three-way cock (not shown) for evacuating, and re-admitting air to, the cylinder. A water-gauge is also provided. The cast-iron bottom E has a pipe E', provided with a three-way cock (not shown), for the admission and discharge of the indigo solution, a pipe E<2> for any special liquids that may be required and a pipe E<3> to admit steam. In operation a vacuum is produced in the cylinder, and a solution of leuco-indigo, produced as described in the above-mentioned Specification, and diluted either with hot water only or with hot water de-oxygenated with alkali or alkaline-earth sulphites, bisulphites, or sulphides, is introduced. The solution is raised by a vertical screw conveyer G through a tube T, occupying the central space surrounded by the baskets, and is discharged over the surface of a perforated cone K covering the top basket L so as to secure uniform distribution. After sufficient treatment, air is admitted, the baskets are withdrawn, and the dyed material is finished as usual. It is stated that, no reducing-agent having been used, any suspended blue insoluble indigo produced by air oxidation can be collected and again electrolytically reduced.