450 
Ink, 
weight of oil of vitriol, will yield 250 parts of chrystal- 
lized green copperas. 
INK. 
This is the gallat of iron, which turns black by ex- 
posure to oxygen, and then precipitates. The preci- 
pitate for the purpose of writing is suspended in water by 
means of mucilage of gum arabic. White sugar gives 
a gloss to the ink, but renders it more slow in drying. 
Hence it is an useful addition to copying ink. 
I do not know a better composition for common ink 
than the following. 
Logwood rasped or finely chipped, 1 ounce 
Nutgalls in powder, 3 ounces 
Green copperas calcined to whiteness, I ounce and a 
quarter 
Blue copperas, * of an ounce 
Gum arabic pounded, 1 ounce and a half 
White sugar, i of an ounce 
Water one quart; vinegar one pint. 
The vinegar and water should be poured hot upon the 
ingredients in a close vessel. When, cool it should be 
frequently stirred with a stick, for a fortnight. It may 
then be strained through a cloth, and put in a bottle. 
Mr. Watt’s receipt for the ink used for his copying 
press, and the preparation of the paper, is as follows. 
Take a piece, or pieces, of thin paper which contains 
no size, or glue, or gummy or mucilaginous matter, or 
which at least does not contain so much size, or other 
matter, as would make it fit for being written upon. Cut 
this paper, or papers, to the size and shape of the writing 
of which a copy is wanting : moisten or wet the said 
thin paper with water, or other liquor, by means of a 
spunge or brush, or by dipping, or otherwise. Having 
moistened or wetted the thin paper, lay it between two thick 
