Crossword-Solution: ZAFFRE 6 letters, 1 clue 🏆 scrabble score: 21

Zaffre, digested in aqua regia, and diluted with four times its weight of water, is sometimes employed; a green tint results.

Zaffre, digested in _aqua regia_, and diluted with four times its weight of water, is sometimes employed; a green tint results.

The sympathetic inks made by Zaffre dissolved in the marine and nitrous acids have this curious property, that being brought to the fire one of them becomes green, and the other red; but what is more wonderful, they again lose these colours, (unless the heat has been too great,) on their being again withdrawn from the fire.

The process of making these inks is very easy, take Zaffre, as sold by the druggists, and digest it in aqua regia, and the calx of Cobalt will be dissolved; which solution must be diluted with a little common water to prevent it from making too strong an impression on the paper; the colour when the paper is heated becomes of a fine green-blue.

The Saxon mines have till very lately almost exclusively supplied the rest of Europe with cobalt, or rather with its preparations, zaffre and smalt, for the exportation of the ore itself is there a capital crime.