[717] Analyzing Ink.

Manufacturer and builder 8, 1873

Boil down a given quantity of the ink, say 100 grammes, until dry; the residue is tannate of iron, which in good ink (that is, such in which there was no excess used of either tannin or iron sulphate) consists of equal parts of both. If gall-nuts were used, the quantity of them was about double that of the iron sulphate, as gall-buts contain about 46 per cent of tannin.