68o

DYEING AND CALICO PRINTING.

The “reduction paste” is prepared as follows:—

Acetate alumina.. gallon.

Water. i ;1

Starch.3 lbs.

Boil till dissolved, cool, and add—

Arsenic solution .i pint.

Mix well together.

The arsenic solution is thus obtained:—■

Glycerin . i gallon.

Arsenic.4 lbs.

Boil till dissolved.

When printed, the pieces are steamed for thirty minutes.

28. Naphthols, or Naphthylic Alcohols.—If the alkaline salts of sulpho-naphthalic acid are fused with the hydrate of soda we obtain the naphthols,

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Aniline Grey (Castelhaz).

which bear the same relation to naphthalin as does phenol to benzine. Onepart of dry sulphonaphthalate of soda is melted in an iron, copper, or silvercapsule, with two parts of dry hydrate of soda; the mass is dissolved inboiling water, cooled, and the clear solution decanted, and mixed with hydro-chloric acid. Sulphurous acid is given off, and naphthol is thrown down in acrystalline state. It is filtered, slightly washed, and re-crystallised fromboiling water.

Naphthol a can be sublimed, and crystallises in brilliant white needles. Itmelts at 94° C., and dissolves readily in alcohol, ether, and benzine, andsparingly in water. The aqueous solution takes an intense violet colour ifmixed with a solution of chloride of lime, and deposits brownish-red flocks ifheated.