MORINTANNIC ACID.

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ensuing precipitate is at first yellow, but gradually turns green. The filtratecontains the phloroglucin ; the lead compound is suspended in boiling water,and decomposed with sulphuretted hydrogen ; after filtration the liquid isevaporated in vacuo over sulphuric acid. During the evaporation the liquid,which deposits small crystals, becomes coloured ; the crystals are first washedwith cold water, and next dissolved in boiling dilute alcohol, from which, oncooling, they are deposited in brilliantly shining needles.

The most interesting property of machromin is its great facility of turningblue in solution, as well as in the solid state, on contact with air or under theinfluence of oxidising substances. The solutions of this substance yield, withhydrochloric acid, an indigo-blue precipitate ; with perchloride of iron andbichloride of mercury this body developes a beautiful violet colouration, whichturns gradually blue ; the alkaline and ammoniacal solutions also become blueon contact with air. Machromin in solution reduces nitrate of silver to themetallic state, while the liquid assumes simultaneously a violet colour. Con-centrated sulphuric acid dissolves machromin, yielding a liquid at first orange,next yellow, but which on heating turns deep green, which hue remains afterdilution of the acid with water. This green liquid is turned violet by alkalies.The formula of this body is C I4 H I0 O 5 -|-3H2O; the blue material formed bythe oxidation of the machromin is most readily obtained by adding to anaqueous solution of that body an excess of perchloride of iron. The bluematter precipitates in the shape of a flocculent mass, is collected on a filter,washed with water, dried and pulverised, and exhausted with ether, when itappears as an amorphous dark blue mass, soluble in alcohol, the solutionhaving also a blue colour. This alcoholic solution, acidulated with sulphuricacid, is decolourised by the addition of zinc and sodium amalgam. Thecomposition of this blue substance appears to be C14H8O5, or machrominless H 2 .

Dr. Hlasiwetz has dire&ly prepared machromin from protocatechuic acid byreduction. When machromin in alkaline solution is treated with sodiumamalgam the liquid becomes first deep brown, then red, turning finally yellow.After saturating this alkaline solution with hydrochloric acid, and shaking upwith ether, the new result of the decomposition may be separated by evaporatingthe ethereal solution, taking up the residue with water, and precipitating itwith acetate of lead. The precipitate, after having been well washed, andbeing decomposed with sulphuretted hydrogen, yields, on evaporation of theaqueous filtered liquid, an amorphous body, soluble in water, alcohol, andether, and composed of C^H^O^.

A solution of moritannic acid in sulphuric acid deposits, after having beenallowed to stand for some time, a new acid called rufimoric, in the shape of abrick-red crystalline precipitate, soluble in ammonia, with a purplish colour.On being boiled with caustic potassa, rufimoric acid is re-converted into morin-tannic acid. Moritannic, or morintannic acid, is by some termed Maclurin.The plan of naming chemical compounds after their discoverers, or afterother chemists, even if eminent, is highly obje&ionable, and if toleratedwould become a greater nuisance than the sesquipedalian nomenclature ofcertain modern authorities.

Morin is nearly insoluble in cold, and very slightly soluble in boiling, water;soluble in alcohol, very slightly soluble in ether, insoluble in sulphide of