ve.

_Black._--Prepare the dye-bath with 5 lb. soda ash, 200 lb. salt and 20
lb. Amidazol black G, this is heated to 150 deg. F., the cotton is entered,
the heat raised to the boil, and the dyeing done for an hour at that
heat. Lift, rinse well, then pass into a chroming bath, made from 5 lb.
bichromate of potash and 3 lb. sulphuric acid, used at 160 deg. F. for
twenty minutes, then lift, wash well and dry. The bath may be kept
standing and used for other lots of cotton by replenishing with about
two-thirds of the original weight of dye-stuff and a little soda. There
are four brands of these Amidazol blacks which dye from a jet black with
the G to a deep blue black with the 6 G brand. The G, 2 G, and 4 G, used
in small quantities, 2-1/2 to 3 lb., dye good greys of a bluish tone,
the 6 G gives a dull blue, the 4 G and 6 G, used in the proportions of
7-1/2 to 10 per cent., give dark blues.

All these blacks may be combined with aniline black with good results as
shown in the following recipe:--

_Black._--Prepare the dye-bath with 10 lb. Amidazol black 2 G, 5 lb.
soda and 100 lb. salt. Work at the boil for an hour, then rinse, pass
into a cold bath made from 2-1/2 lb. aniline oil, 2-1/2 lb. hydrochloric
acid, 6-1/2 lb. sulphuric acid, 7-1/2 lb. bichromate of potash, and
5-1/2 lb. perchloride of iron, 66 deg. Tw. This is used cold for an hour,
then the heat is slowly raised to 160 deg. F., when the operation is
finished, and the cotton is taken out well rinsed and finished as usual.
Any of this class of black may be so topped with aniline black if
thought necessary A very fast black is thus got.

_Black._--Make the dye-bath with 15 lb. Sulfaniline black G, 60 lb.
salt, 10 lb. soda, and 5 lb. sulphide of sodium. Work at a little under
the boil, then lift, rinse well and pass into a hot bath of 3 lb.
bichromate of potash, 3 lb. sulphate of copper, and 4 lb. acetic acid
for half an hour, then lift, rinse well and dry.

It has been observed in the practical application on a large scale of
these sulphur blacks that the cotton is liable to become tendered on
being stored, although there are few signs of such after the dyeing is
finished. The exact cause of this is somewhat uncertain, the most
probable reason is that during the process of dyeing a deposit of
sulphur in a fine state of division has been thrown down on the cotton
by decomposition of the dye-stuff, and that this sulphur has in time
become oxidised to sulphuric