is rather adapted for a dye than an artist-colour. It is furnished by acting on quinine with hypochlorite of lime, hydrochloric acid, and ammonia, successively. Thus prepared, the green resembles a resin, insoluble in water, but soluble in alcohol, and turned blue by acetic acid. Its alcoholic solution dyes silk green, and also woollen and cotton when mordanted with albumen. 203. _Roman Green_, brought from Rome some years back by a President of the Royal Academy, appeared to be a mixture of Prussian blue and Dutch or Italian pink. It was a fugitive compound, which became blue in fading. 204. _Silicate of Baryta._ One part of silica heated to whiteness with three parts of baryta, yields a pale green solid mass, permanent, but deficient in colour when ground. It might be employed in enamelling. 205. _Titanium Green_ has been proposed as a substitute for the green arsenical pigments in common use; but, apart from its expense, the colour is very inferior to Scheele's green, &c. Titanium green is a ferrocyanide of that metal, produced by adding yellow prussiate of potash to a solution of titanic acid in dilute hydrochloric acid, and heating the mixture to ebullition rapidly. The dark green precipitate is washed with water acidulated with hydrochloric acid, and dried with great care, since it decomposes at temperatures above 100°. 206. _Uranium Green_ is an oxide of a deep dull green colour, inclining to olive, and nearly black when in lumps. A durable but unattractive preparation, equalled in permanence and far surpassed in beauty by many cheaper compounds. 207. _Vanadium Green_ falls when ferrocyanide of potassium is added to vanadic acid dissolved in a strong acid. It is a beautiful green precipitate, but at present simply a curiosity, owing to the rarity of the metal vanadium. * * * * * Adopting our usual custom of separating the wheat from the chaff, we point to the opaque and transparent oxides of chromium, Veronese green, viridian, emerald green, Scheele's green, and terre verte, as more or less worthy of being dubbed durable. As semi-stable, malachite green, bronze, Hooker's green, and Prussian green, must be classed. Verdigris, chrome greens, and sap green, should be branded as fugitive: the chrome greens, because they are always commercially composed of chromate of lead and Prussian blue, two compounds which are semi-stable in themselves, but become fugacious when compounded.