DYEING AND CALICO PRINTING.

55 °

amount of genuine argol or tartar should be used along with the substitute.One of these compounds, the so-called “ tartar cake," is made by mixingsulphate of soda with some free sulphuric acid and a small quantity of whiteargol or tartar. The mixture is melted, run into thin layers, and broken upwhen cold. It is deliquescent, corrosive, and intensely sour. In stuff-dyeingit is used for the so-called sour browns.

Super-Argol is white argol to which sulphuric acid has been added,enough to combine with all the potash present. It is, therefore, a mixture ofsulphate of potash and of free tartaric acid.

The following is a mixture, patented by B. Barcroft, as a substitute for tar-taric acid “ in the production of blues and in the reduction of pinks in dyeingand printing—Mix 14 quarts of sulphuric acid, at 170° Tw., with 12 quartsof cold water, and allow it to stand till cool. The inventor then “ takes alarge vessel and places it in a water-bath, and pours into it 20 quarts ofboiling water, and adds 48 lbs. sal-ammoniac and 6 lbs. of white arsenic,”boiling till all is dissolved. The solution is then cooled down to 70° F. Thefirst mixture (dilute sulphuric acid) is then added, and the whole allowed tostand till quite cold: 3 quarts of oxymuriate of tin, of 120° Tw., are thenadded, and in a few days it will be ready for use.

A. E. L. Bellford attempts to prepare, from the reaction of sugar and 1 nitricacid, a body less highly oxidised than oxalic acid. Gatty patented the use ofladtic acid as a substitute for tartaric. These preparations, however, havenever come into general use, and are probably now completely abandoned.

Royal Blue Spirits.

Under this name is known a mixture of acids, used in dyeing Prussian bluesupon wool, for the purpose of decomposing the prussiate of potash. It con-tains neither tin nor any other base. Where the yellow prussiate is employedthe following mixture is given as one in adtual use:—

Sulphuric acid, at go° Tw. . 1 gallon

Spirits of salts, at 32 0 Tw.2 quarts

Double aquafortis, at 64° Tw. 1 quart.

Some dyers prefer to diminish the latter ingredient by one-half. The wholeof the acids are well mixed together, carefully avoiding the fumes.

If the red prussiate of potash is used, the nitric acid (aquafortis) is omittedaltogether.