Wood-Tar as a Source of Coloring Materials.

Manufacturer and Builder 11, 1874

Although no method for the utilization of wood-tar is likely to prove of as much practical importance, as the discoveries in coal-tar, on account of the comparatively limited quantity of wood-tar produced, experiments have recently been conducted with this in view. Attention was first directed, some years ago, by Reichenbach to a red crystalline precipitate, obtained by treating beechwood-tar with bichromate of potash and tartaric acid, or a solution of sesquisulphate of iron, and named by hint cedriret, which afforded an indigo blue solution with concentrated sulphuric acid, and a purple one with creosote. More exact recent investigations by Prof. Liebermatot have led to the production of several new compounds fromwood-tar, one of reddish-blue color being named cærulignon, on account of the blue solution it affords with sulphuric acid. Further experiments by C. Fischer led to a very simple process for printing a lively orange on silk or wool, by dissolving this substance in hot alcohol, and precipitating it again with water, then thickening the paste with gum water of the proper consistency, and printing, drying, and steaming the fabrics. In steaming, the slight color of the printed portions disappears, and after washing out the thickening, a lively orange may bo developed on them, by treating the goods in a bath of bichromate of potash, or of sesquichlorid of iron. They may then be washed and finished. Attempts to print with it on cotton have not thus far proved successful. Experiments on a large scale are of course necessary to determine the practical value of the method.