h a small quantity of oil of vitriol,
add a little chalk and stir well. Go on mixing gradually till all is
used up. This should take an hour or two. Stir a few times each day
for 4 or 5 days, adding about 1/2 oz. more of chalk by degrees. It is
best mixed in a glass stoppered bottle or jar, and stirred with a
glass rod. It must be kept from the air.

INDIGO EXTRACT (4 to 6 lbs. wool).

Mordant[E] 25% Alum. Stir 2 to 3 ozs. Indigo extract into the water of
dye bath. The amount is determined by the depth of shade required.
When warm, enter the wool and bring slowly to boiling point (about 1/2
an hour) and continue boiling for another 1/2 hour. By keeping it
below boiling point while dyeing, better colours are got, but it is
apt to be uneven. Boiling levels the colour but makes the shade
greener. This is corrected by adding to the dye bath a little logwood,
10 to 20 per cent which should be boiled up separately, strained, and
put in bath before the wool is entered; too much logwood dims the
colour. Instead of logwood a little madder is sometimes used; also
Cudbear or Barwood.

INDIGO VAT (TIN) FOR WOOL

To 2 quarts of water add 1/4 lb. lime, and make hot. Then add 1 oz.
indigo pounded up with a little of the lime water; let it stand and
get warmer. Pound up 1/2 oz. tin, _Stannous Chloride_, in a little
lime water and add, together with 1/2 oz. zinc. Add more lime water or
tin according to the state of the vat. There should be a streaky scum
on the surface, and the water underneath clear with a green tinge.
Pearl ash can be used instead of lime.

HYDROSULPHITE-SODA VAT FOR WOOL

2 ozs. powdered indigo.
7 fluid ozs. Caustic Soda solution (SG 1.2).
4 pints Sodium Hydrosulphite (SG 1.1).

_The Stock Solution._--Take 2 ozs. of well pounded indigo, with enough
warm water (120 deg.F.) to make a paste, and _grind_ in a pestle and
mortar for 10 minutes. Empty into a saucepan, capacity 1 gallon. Take
12 fluid ozs. of water adding gradually 3 ozs. of commercial caustic
soda 76 per cent. This will give a solution of SG 1.2, which can be
tested with a hydrometer reading from 1000 to 2000, the 1000
representing SG 1 as for water.

Next take 5 pints water, add hydrosulphite slowly, stirring gently
until a reading of 1100 is shown (SG 1.1) on the hydrometer. If the
hydrosulphite be weighed beforehand and the stock of the same be kept
free from damp air, or great heat, for future vats the hydrometer can
be dispensed with; it is