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DYEING AND CALICO PRINTING.

quote the following:—White discharges on Turkey-red—i ga'lon of water;io lbs. of tartaric acid ; 7 J lbs. of pipeclay or china-clay ; 1 pint of gum:water;—x J lbs. of bichloride of tin ; 1 gallon of hot water; 9 lbs. of tartaric acid; 10 lbs.of pipeclay; 3 quarts of gum Senegal water. These can only be properlyapplied by blocking, but the following discharge for machine work may do forlight designs:—1 gallon of water; 6 lbs. of tartaric acid; i£ lbs. of starch.As an instance of discharge for red and the reprodudtion of blue on the dis-charged spot, we mention the following mixture:—2 gallons of muriate oftin ; 1 gallon of prussian blue pulp ;* 1 gallon of water; 5 lbs. of tartaricacid, to which, after having been dissolved and mixed together, are added2 gallons of thick tragacanth gum water. The excess of acid discharges offthe red, while the blue part not being adted upon, remains.

A resist (French, reserve) in calico printing signifies any suitable compositionapplied to the portions of the fabric in order to prevent the decomposition ofthe colour or mordant upon those portions of the cloth. The parts thus pro-tedled may be either the original white fibre of the cloth, or it may be somecoloured part which is required to be preserved unaltered, while the remainderis covered with some coloured design. Resist compositions intended for thislatter purpose are usually called pastes, and the colour so preserved is said tobe pasted ; resists may, moreover, be either chemical or mechanical, or bothcombined, according to the nature of the colour or mordant to be resistedand the manner in which it has to be applied. The best and only safe resistfor iron and red liquor mordants is lime-juice, chiefly citric acid. If of fairquality and of proper strength it leaves nothing to be desired. Good lime-juice at 15 0 Tw., thickened with calcined farina, will resist all the iron andalumina mordants in use for madder work, and at 30° Tw. it is strong enoughas a resist for garancin styles. Oxalic and tartaric acids and bisulphate ofpotassa will a< 5 t as resists, but are inferior to lime-juice or citric acid. Citrateof soda or potassa also form a good neutral resist, and are usually employedalong with pipeclay.

The reserves or protedting resists are commonly applied by the block, andadt chiefly mechanically, as may be inferred from the undermentioned resistpaste for chintz, made up of—Water, 6 gallons ; neutral arseniate of potassa,15 lbs.; pipeclay, 40 lbs.; calcined farina, 30 lbs. The arseniate of potassahas some resisting power, but its use in combination with pipeclay is owingto its drying up in a dense, somewhat gummy mass, which gives solidity tothe pipeclay, and makes it more capable of withstanding the effedts of fridtion.Another neutral paste is made from citrate of soda mixed with pipeclay andcalcined farina.

A most ingenious means of obtaining reserves on fabrics is the invention ofMessrs. Onfroy and Co., of Paris : this process is the more advantageous, becausethe chemical reserves in general use are imperfedt in composition, of difficultapplication, and still more difficult to remove. The process in question con-sists in punching out patterns from a sheet of cardboard lined with gutta-percha in such places as are intended to remain white or reserved. The card-board is then rolled on the pressing cylinder of the printing machine, so that

* Under this name are known to printers and dyers a variety of mixtures made up of yellowprussiate of potassa (ferrocyanide of potassium), protochloride of tin, or bichloride and water.