CYANOGEN COLOURS. 165

The tin pulp is prepared from a mixture of the two following solutions, wellstirred, and filtered to a pulp :—

a. 1 gallon of hot water;

1 lb. of yellow prussiate of potash.

b. 1 gallon of water;

1 lb. muriate of tin crystals.

The cloth when printed is steamed for 40 minutes, aged during one night, andrinsed in a weak solution of bichrome and alum at 120° F. It is then washed,dried, and finished, when it presents the appearance of the specimen.

The light steam blue is printed from the following standard mixture :—

45 lbs. prussiate of potash ;

30 lbs. alum ;

20 gallons of boiling water ;

10 gallons of cold water;

3 pints of vitriol. ♦

1 quart of this standard is added to 3 quarts of water; there is then added—i£ lbs. of starch ; the bath is boiled, cooled, strained, and then is ready.

When printed the cloth is steamed for 40 minutes, then aged during onenight, and rinsed in a weak solution of bichromate of potash and alum on themangle. It is then passed through water, dried, and finished.

A beautiful Berlin or royal blue, almost approaching the aniline blues inlustre, is produced upon wool by the following process :—For 36 lbs. of wool,take yellow prussiate, 4 lbs., and oxalic acid, 6 lbs. Dissolve in water, andenter the wool at ioo° F.; work well for 2 hours, raising the temperature gra-dually to 180 0 F. Take out and cool. Cool the liquor with 2 pailfuls of coldwater; add 21 lbs. alum; re-enter the wool, and work for £ an hour. Thenadd £ pint of yellow spirit, and work for 1 hour, raising the temperature slowlyto 180 0 F., at which heat work for i} hours longer. Take out and add 1 to 2pints of nitrate of iron, according to shade required. Re-enter the wool, andgive five or six turns. Take out, cool, and wash very well.

The yellow spirit referred to maybe made as follows:—Take 18 ozs. tincrystals, 4^ lbs. hydrochloric acid, 2 lbs. strongest sulphuric acid, and 2 lbs.water. Dissolve the tin salt in the hydrochloric acid ; mix in a separate vesselthe sulphuric acid and water, and when cool mix altogether. Let down withwater to 6o° Tw.

Turnbull’s blue is obtained by the a&ion of ferricyanide of potassium (redprussiate) upon solutions of proto-salts of iron. These colours, as such, arenot used in printing and dyeing. Alkalies destroy them. They are insolublein water; and their so-called solution, used as blue ink, is merely the finely-divided solid matter in a state of suspension. These colours are fixed upontextile materials chiefly by two reactions. The goods are mordanted with asolution of iron,—in other words, the hydrated oxide of iron is deposited inthe pores of the fibre,—and are then passed through a bath consisting ofacidulated prussiate of potash. Or ferro- or ferri-cyanhydric acid, or a mixtureof both, is applied to the tissues by passing them through an aqueous solutionof the potassium salts mixed with an acid, and the blue colour is brought outby the simultaneous adtion of steam and the oxygen of the air. The additionof preparations of tin in these processes is not required for developing thecolour, but only for modifying its shade. For dyeing wool a so-called royal