10). Saxon Blue. (Berthollet).
Prepare the wool with alum and tartar. A smaller or greater proportion of the Indigo solution is put into the bath, (1 part of Indigo with 8 parts of sulphuric acid, digested for 24 hours), according to the depth of shade wished to be obtained. For deep shades it is advantageous to pour in the solution by portions, lifting out the wool from the bath while it is being added. The cold bath acts as well as the hot.
11). The Cold Indigo Vat with Urine.
Take 4 lbs. of powdered Indigo and put it into a gallon of vinegar, leaving it to digest over a slow fire for 24 hours. At the end of this time the Indigo should be quite dissolved. If not dissolved pound it up with some of the liquor adding a little urine. Put into it ½ lb. madder, mixing it well. Then pour it into a cask containing 60 gallons of urine (fresh or stale). Mix and stir the whole together; this should be done morning and evening for 8 days or until the surface becomes green when stirred, and produces froth. It may be worked immediately without any other preparation than stirring it 3 or 4 hours before-hand. This kind of vat is extremely convenient, because when once prepared it remains so always until it is entirely exhausted. According as you would have your vat larger or smaller you reduce or enlarge the amount of the ingredients used in the same proportion as the original. This vat is sooner prepared in summer than in winter.
12). Indigo Vat on a small scale for Woollens and Cottons.—
Have a strong 9 gallon cask, put into it 8 gallons of urine, have a 4 quart pickle jar, into which put 1 lb. ground Indigo and 3 pints of best vinegar; put the jar into a saucepan filled with water, and make it boil well for 2 hours, stirring it all the time. Let it stand in a warm place for 3 days, then pour it into the cask; rake it up twice a day for a month. It must be covered from the air.
13). Blue Vat for Woollens.—
For every 20 gallons of water add 5 oz. ground Indigo, 8 oz. of potash, 3 oz. madder, and 4 oz. bran. Keep the solution at 140°F.; after 24 hours the whole will have begun to ferment, then add 2 oz. madder, stir and allow the whole to settle, after which the vat is ready for use.
14). To Dye Indigo Blue. Urine Vat.—
Prepare vat as follows:—To 3½ gallons of stale urine add 4½ oz. of common salt, and heat the mixture to 125°F. (as hot as the hand can bear). Keep at this heat for 4 to 5 hours, frequently stirring, then add 1¼ oz. thoroughly ground Indigo and 1¼ oz. Madder, stir well and allow to ferment till the Indigo is reduced. This is recognized by the appearance of the vat, which should be of a greenish yellow colour, with streaks of blue. Allow the vat to settle, when you can proceed with dyeing. Process of dyeing the same as in No. 15.