A stout frame of wood must be made, about 3 yards long and about 1 1/4 yards wide. Within this frame must be placed two sides of another frame, running longitudinally and across, so fixed in the outer frame that the two pieces may slide independently of each other backwards and forwards about 6 inches. Tapes of canvas must be tacked round the inside of the inner frame and the corresponding sides of the outer frame, so as to form a square for the material to be sewn in, which when done, the two loop frames must be drawn tightly to the outer by means of a twine passed round each, in order to stretch perfectly free from irregularities the silk or satin previous to laying on the composition. To make the plaster. Dissolve india rubber in naphtha or naphtha and turpentine, lay it on with a flat brush on the opposite side to that which is intended for the plaster. When the silk is perfectly dry and the smell in a great measure dissipated, it will be ready for the adhesive material; to make which take equal parts of Salisbury or fine Russian glue and the best isinglass, dissolve in a sufficient quantity of water over a water-bath, and lay on with a flat hogtool while warm. It is reqidsite to use great caution to spread 'the plaster evenly and in one direction, and a sufficient number of coatings must be given to form a smooth surface, through which the texture of the fabric is not perceptible. Each coating should be perfectly dry before the succeeding one is given, after which the frame is to be placed in a situation free from dust, and where a draught of air would facilitate the drying. The quantity of water used and the weight of the two materials must be a little varied according to the season and the gelatin strength they possess. Lastly, the plaster being ready to receive the polishing coat, which gives also the balsamic effect to it, a preparation is made in nearly the same manner as the Tinct. Benz. Co. of the P. L., with the addition of more gums. This preparation must be laid on once only, and with a brush kept for the purpose. For making plasters on coloured silks it is only necessary to select the silk a shade deeper than the colour required, as the plaster causes it to appear a little lighter. Indigo. The principal preparations of indigo are described under Chemic Blue, and Dyes. Indigo may be purified by several methods, 'of which the following is the most simple: - Mix indigo with half its weight of Paris plaster and sufficient water to form a thin paste. Spread this evenly on an iron plate, about two inches wide, to the depth of one eighth of an inch, and let it dry in the air. Then apply the flame of a large spirit lamp to the under side of the plate, beginning at one end and advancing it to the other as the sublimation proceeds. The violet vapour condenses on the surface in brilliant prisms or plates. Good indigo yields from 15 to 17 per cent. - Mr. T. Taylor.

Purified indigo is also obtained from the alkaline solution of reduced indigo, described under Dyes; or by dissolving indigo in a mixture of 1 part of caustic soda, 1 of grape sugar, and 20 of water. To the clear solutions thus obtained add hydrochloric acid to throw down the indigo, wash this perfectly with pure water, and finally with alcohol. If care be taken to exclude the air before and after adding the acid, and to wash it with recently boiled water, to drain it rapidly and dry it in vacuo, the indigo is obtained nearly white, but becomes blue on exposure to the air. Ink?. The following are specimens of the most useful kinds: