(1) Bichloride of copper, 8-1/2 grains, dissolved in distilled water, 30 grains; then add common salt, 10 grains, and liquid ammonia, 9-1/2 grains. A solution of 30 grains hydrochlorate of aniline in 20 grains distilled water is then added to 20 grains solution of gum-arabic, containing 2 pts. water, 1 pt gum-arabic, and 10 grains glycerine. Four parts of the aniline solution thus prepared are mixed with 1 part of the Copper solution. This ink can he used with a steel pen. It is green at first, hut becomes black in a few days or by application of hot iron. It is absolutely indelible, and the finest devices can be written with it. It is better to mix the two solutions only just before using. (2) For very fine linen, take a solution of nitrate of silver, 1 pts., in distilled water, :24 pts. Add liquid ammonia until the precipitate formed is dissolved. Then a little sap-green and indigo are ground together and mixed with a solution of gum-arabic, 4 pts., and this is mixed with the nitrate of silver solution. The whole is then diluted until it occupies 32 parts. It turns black as No. 1 does.