ANILINE BLACK.

213

This process was very successful in block-printing, and came into use to agreat extent, especially in Switzerland. For roller-printing it was lessadapted, as the acid chloride attacked both the copper rollers and the steeldodtors. These defedts were partially remedied by using a neutral chloride ofaniline, substituting sulphate of copper for the chloride. It is still employedin hand printing and dead-roller work.

Lauth’s improvement, patented in England by Hughes, substitutes sulphideof copper for either the chloride or sulphate ; his proportions being—16 ozs.salt of aniline, 4 ozs. sulphide of copper, and 4 ozs. chromate of potash.

The sulphide of copper for this purpose is prepared as followsFlowers ofsulphur are dissolved in caustic soda; the liquor obtained is poured into asolution of sulphate of copper, at the temperature of 75 0 C. The precipitatedcopper sulphide is colledted upon a filter, and washed.

Kcechlin proposes the following formula :—Boil together—

Water. 10 litres.

Starch. 2 kilos.

Torrefied starch. 2 ,1

Aniline. 2 „

Sal-ammoniac . 4 „

Chlorate of potash. 1 kilo.

When it is to be used, add cold—

Sulphide of copper paste. 1 kilo.

Tartaric acid . 2 kilos.

The following processes have been found useful in pradtice :—

Dissolve 300 grms. starch in 2 litres of water, 150 grms. tragacanth inanother 2 litres, and 750 grms. of light burnt or torrefied starch in a third2 litres. Mix together equal weights of these three solutions, and add withheat the ^th or j'gth part of the weight of this solution of chlorate of potash;let it cool, and add twice as much muriate of aniline as was used of chlorateof potash. If the colour is required for printing, sulphide of copper is addedin the same quantity as chlorate of potash.

The appended recipe has done good service :—

5 kilos, of starch solution ;

5 „ light burnt starch solution;

5 „ tragacanth solution;

J kilo, chlorate of potash ;

1 ,, muriate of aniline;

And in the application J kilo, of sulphide of copper.

Spirk boils together 1 litre of starch-paste (made by dissolving 150 grms. ofstarch in 1 litre of water) with 1 litre of gum solution (7J grms. of tragacanthto 1 litre of water) and 1 litre of gum substitute solution (42 grms. of dextrineto 1 litre of water. He then adds to the hot mass go grms. chlorate of potashan< i 75 grms. of sal-ammoniac. The mixture is allowed to stand till cold,when 240 grms. of chloride of aniline are dissolved in it, and 73 grms. ofsulphide of copper are added just before printing.

For a deep body colour the same author recommends the following:—Boiltogether, for fifteen minutes, 6 litres of water, 1000 grms. of aniline oil, 625of chlorate of potash, and 625 of sal-ammoniac. When nearly cold add to it,