omate of potash and 3 lb.
of acetic acid, for half an hour at 170 deg. to 180 deg. F. Bichromate of potash
used alone gives a reddish shade of black, sulphate of copper a greenish
shade, a mixture of the two gives a greenish shade.

There are three brands of Immedial black, _viz._, V extra, G extra and
F F, which vary a little in the tone of black they produce. The method
of using is identical for all three. The dye-bath is not exhausted of
colour and so should be kept standing, for each subsequent lot of cotton
add 8 lb. Immedial black and 3 lb. sulphide of soda, and to every 10
gallons of water added to bring the bath up to volume 1/2 lb. soda and 3
lb. salt.

These blacks are very fast to washing, light, etc. By using smaller
quantities of dye-stuff good greys can be dyed.

_Black._--Prepare the dye-bath with 10 lb. soda, 10 lb. sulphide of
sodium, 60 lb. salt and 25 lb. Vidal black, work at the boil for one
hour, then rinse and fix with 3 lb bichromate of potash and 2 lb.
sulphuric acid.

_Black._--Prepare the dye-bath with 30 lb. Cross-dye black B, 10 lb.
soda, 150 lb. salt. Dissolve the dye-stuff in boiling water, then add
the soda crystals and finally the salt. Enter the previously well-boiled
cotton at about 175 deg. F. After a few turns raise the temperature to the
boil as quickly as possible, and work for one hour (just at the boil).
Lift and thoroughly rinse without delay. (The better the cotton is
washed the clearer the ultimate shade.) After washing, wring up and let
air age for about one hour; the intensity of the black is thereby
increased.

Meanwhile prepare a bath with 5 lb. bichromate of potash, 4 lb.
sulphuric acid (168 deg. Tw.). Enter at 150 deg. to 160 deg. F., and work at this
for about ten minutes. After chroming, wash thoroughly to remove all
traces of acid. At this stage, the usual softening may take place if
desirable, and finally dry at a low temperature.

The bath is kept up for further lots, and three-fourths the quantity of
colouring matter, and about half soda and one fourth salt are used.
Wood, or iron cisterns are most suitable, and copper pans or pipes must
be avoided.

The dye-bath should be kept as short as possible, about twelve to
fifteen times the amount of water on the weight of cotton is advisable.
The cotton when in the dye-bath should be exposed as little as possible
to the air.

There are several brands of these Cross-dye blacks varying in the tone
of black they gi