(1658) Making Common Ink Indelible.

Manufacturer and Builder 10, 1876

—Yes; the remedy is the addition of potassium sulphid. But it will not work so well in ink already made of logwood and copperas; it is better to dissolve the copperas (iron sulphate) 4 ounces, in an equal quantity of water; the potassium sulphid, 4 ounce, in 2 ounces of water, and mix until it becomes black, then add to the logwood extract 1 pound dissolved in 1 gallon of boiling water, and boil again. It is remarkable that potassium cyanid, ½ an ounce added, improves and fixes the ink, while this same substance dissolves the nitrate of silver ink, and obliterates the writing made with the same.

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