MEDIUM BLUE.
Prepare your feathers by washing and rinsing thoroughly in hot water; light faded out colors need not be bleached, but thoroughly washed in hot soap suds instead. Prepare your bath as follows: Take one teaspoonful of concentrated cotton blue and one teaspoonful of oxalic acid, dilute it in one gallon of boiling water. Be careful to see that the blue crystals are well dissolved. Enter your feathers, and let them remain in bath about four minutes, keeping them well under the surface. Meantime keep them gently agitated to insure an even color; after which take out, rinse, starch and dry.
If your feathers be found too dark for sample, or too much on the purple, rinse off, starch in cold water thoroughly, and pass through a bowl of boiling water, starch and dry, using a few grains of oxalic acid diluted in starch bath.
If a very light shade be desired, use but half the quantity of cotton blue, and do not allow them to remain in bath quite so long a time. If a much darker shade be required than the foregoing recipe will produce, then rinse off your feathers thoroughly in cold water, to remove all starch, and pass feathers through a medium strong bath of logwood at boiling temperature for a few seconds, and rinse off twice in cold water; dilute a half ounce of bichromate of potash in a gallon of boiling water, and pass your feathers through for a few seconds only; rinse, starch and dry. Should you get your color too dark by this process, pass your feathers through a solution of half a teaspoonful of oxalic acid in a gallon of boiling water, and rinse off in boiling water twice; then dilute a small quantity of starch in luke warm water, add a few grains of oxalic acid to it, pass feathers through and dry as usual.