, and below is given a recipe illustrating this
method; it is one, however, rarely adopted.

_Blue-Black on Wool_.--Prepare the dye-bath with 10 lb. Glauber's
salt, 2 lb. Patent Blue, 6 oz. Brilliant Orange, 4 oz. Amaranth, 4 oz.
Acid Violet N, 4 lb. sulphuric acid. Enter the goods at about 150 deg. F.,
raise to the boil and work to shade; lift, wash and dry. It may be of
interest to note that by using a mixture of Azo Rubine and Acid green
good blacks can be got.

There is a range of Acid and Azo dyes which are capable of dyeing from
the usual acid baths on to wool, and yet can be developed and fixed on
the fibre to good, full blacks. Types of such dyes are Anthracene
Chrome Black F F, Diamond Black F, Chrome Patent Black D G and D G G,
Fast Chrome Black, etc. Generally the blacks dyed on wool with these
dyes are very fine, have a full, bloomy appearance, and are very fast.
They are much used in dyeing hat bodies and fine cloths which have to
be very fast to the weather.

The method of application will be gleaned from the recipes given
below.

_Black_.--Prepare a dye-bath with 5 lb. Chromotrop S, 1/4 lb. Azo (p. 093)
Yellow, 50 lb. Glauber's salt. Work for one and a half hours at the
boil, then add 4 lb. sulphuric acid. Work at the boil for another half
hour, then lift. Add to the same dye-bath 3 lb. bichromate of potash.
Re-enter the goods and work at the boil for half an hour, then lift,
rinse and dry.

_Jet Black_.--Mordant the wool by boiling for one hour in a bath made
from 4 lb. bichromate of potash and 3 lb. of tartar. Then rinse, and
dye in a bath containing 3-1/2 lb. Diamond Black, 1-1/4 lb. Alizarine
Cyanine R R R double, and 1 lb. Gambine Yellow, working at the boil
for from one to one and a half hours.

_Diamond Black on Wool_.--Mordant by boiling for one hour with 3 lb.
bichromate of potash, 1 lb. oxalic acid. Wash and dry in a bath made
with 2 lb. Diamond Black, 2 lb. acetic acid. Work at 120 deg. F. for one
hour, then heat to boil, and work until the dye is fully fixed. Lift,
wash and dry.

A more common method of using the Diamond Black is given in the
following recipe.

_Diamond Black_.--Prepare a dye-bath with 10 lb. Glauber's salt,
2-1/2 lb. Diamond Black, 1/2 lb. Diamond Green. Boil for an hour, then
pass through a fresh bath of 2 lb. bichromate of potash for
three-quarters of an hour at the boil; wash and dry.

This gives a fine jet shade of black, quite fast to a strong milling,
and