It was at first thought to be unnecessary to give a formula for the preparation of pyroxiline or gun cotton, as no individual not in the business can possibly produce an article that can be in any way compared to that made by manufacturers of skill and experience.
For the benefit of any one wishing to experiment, this formula is given:
Sulphuric Acid 6 oz. Nitric Acid 4 " Water 2 "
Mix and the temperature will rise to 170° F.
Inmerse dry cotton wool (best long fibre), be sure wool is dry, draw it in long flakes and pull it under acids with a stout glass rod; do not crowd in too much, take care that each tuft is well wetted with the acids before putting in a fresh tuft. Carefully cover the vessel and put it where any slight fumes may escape; leave it for at least 12 hours--20 hours will not spoil it. When ready, lift cotton out and plunge it [p029] into a large quantity of water, quickly separating the tufts with glass rods, wash in changes of water, until no acid is left, then wring the cotton in a coarse towel until dry as possible and pull it all apart and place in the air to dry.
Alcohol 5 oz. Ether 10 " Cotton 100 grains
Alcohol 5 oz. Iodide Ammonium 60 grs. Iodide Cadmium 30 " Bromide " 20 "
Dissolve the iodides in the 5 oz. alcohol or in the whole 10 oz., if desired, then put in the 100 grains cotton, shake well, then add the 10 oz. ether and shake till the cotton is all dissolved; it will be ready for use in a few hours, and will improve with age.
The silver solution for a negative bath is prepared in substantially the same manner as for a positive.
Two thirds of the amount of silver nitrate intended to be used, should be dissolved in the quantity of water required to make the bath, and a grain or two of iodide of potassium added and placed in the sunlight until the solution has changed color, become turbid, and again clear and colorless. This change is caused by a minute portion of the silver combining with the organic matter and with other impurities in the water, if there are any; a molecular change then takes [p030] places, oxygen is evolved and the infinitesimal portion of silver changes to a metallic state and sinks to the bottom, carrying with it the impurities, which induced the chemical action or change.