of water),
1-1/2 oz. zinc dust,
4-5 oz. quick lime,
4-5 pints of water.

Mix the zinc dust to a paste with a little of the water, gradually add
the indigo and the rest of the water. The heat of the water should be
not less than 160 deg.F. as it will cool while the lime is being
prepared. Slake the lime in a separate vessel by pouring about 5 oz.
of water over it. When it begins to hiss and break, add more water
little by little. When all the lumps have cracked up stir till a thick
even cream is made. Add this to the other ingredients in the stock
vat. Stir well. The stock vat should have a temperature of 120-140
deg.F. It should be stirred at intervals. The vessel should be stood
in hot water to keep the temperature as near 120 deg.F. as possible.
In about 5 hours the mixture has a pure yellow colour and is ready to
add to the dye vat. (There is of course a blue-black scum of indigo on
top.)

_Preparation of the dye vat._ The vessel used should be deep and
upright so that an unnecessarily large surface is not exposed to the
air, and a sufficient space for dyeing is obtained above the sediment.
A galvanised dust bin, or a barrel (provided it is not of oak or any
other wood which contains tannin), make good indigo vats. Put 16
gallons of water in the vat at a temperature of 65-70 deg.F. In order
to counteract the effects of the atmospheric oxygen contained in the
water of the vat, additions of zinc dust and lime are made some hours
before the stock solution is added. A pinch of zinc dust and an ounce
of lime, previously slaked, should be added and the vat stirred.
Stirring must always be done gently and smoothly, every effort being
made not to take air into the vat. At the same time it must be stirred
up from the bottom so that the sediment is mixed with the liquor above
it. The best tool for this purpose is a broom stick, to one end of
which a piece of wood is nailed, like a garden rake. When all is
ready, carry the stock solution to the dye vat, and, to avoid
splashing through the air, hold it in the water of the vat while
gently pouring out half its contents. Stir up the vat and cover it
until it shows a clear yellow colour under the surface of the scum.
This may not happen for 24 hours. A good way to test the colour of the
vat is to push back the scum with the edge of a saucer or plate, then
dip it halfway into the liquor. Against its white surface the colour
of the liquor will be plainly seen. It sho