i blacks, etc.; for dark blues from
Diamine blues, Diazo blues, etc.; for greys from Diamine blues, Neutral
grey, etc. Alpha-naphthol for dark reds from Primuline, greys from
Diamine blues, Neutral grey, etc. Phenylene diamine for blacks from
Diamine blacks, Diazo blacks, Zambesi blacks, Triamine blacks, etc.; for
dark browns from Diamine browns, Diazo browns, etc.; for light browns
from Cotton browns, Diamine cutch, Primuline, etc. Naphthylamine ether
for blues from Diamine blacks, etc. Phenol for claret from Diamine
cutch, and for gold yellow from Primuline, etc. Resorcine for orange
from Primuline, etc. Soda for browns from Diamine cutch, Diazo browns,
Zambesi browns, for orange from Diamine orange, and yellow from
Primuline.

=Beta-naphthol.=--This is by far the most important of the developers.
It is a white body, insoluble in water, but readily soluble in soda lye,
and a solution is easily made by taking 10 lb. beta-naphthol and heating
it with 10 lb. caustic soda lye of 70 deg. Tw. and 60 gallons of water. This
bath may be used as the developing bath, or it may be diluted with more
water. It is not desirable to use any more caustic soda than is
necessary to dissolve the beta-naphthol, so that the bath is not too
alkaline. To produce full shades it usually takes 1 per cent. of the
weight of the cotton of the beta-naphthol, but it is best to use the
bath as a continuous one and for the first lot of cotton use 2 per cent.
of naphthol, while for each succeeding lot only 1 per cent. more
naphthol need be added to the same bath.

This bath is alkaline, while the diazotising bath is acid, unless,
therefore, the cotton be well washed when it is taken from the latter
bath there is a risk of the alkali of the one being neutralised by the
acidity of the other, and the naphthol being thrown out in an insoluble
form. This, of course, is easily remedied should it occur.

Developer A (Bayer) is a mixture of beta-naphthol and caustic soda in
the powder form, so that a solution is obtained by simply adding water.
Rather more (about 1-1/2 per cent.) of this is required than of
beta-naphthol.

=Alpha-naphthol= has similar properties to, and is used in the same way
as, beta-naphthol; it develops much darker and rather duller colours,
which are less fast to washing.

=Resorcine=, like naphthol, is insoluble in water, but it can be
dissolved by using either soda ash or caustic soda. The latter is
preferable, as the former is lia