406

DYEING AND CALICO PRINTING.

authors agree generally in this, that the wood contains two entirely distindprinciples, one of which is nearly insoluble in water, while the other is ratherreadily soluble therein. The former is named morin, and the latter morin-tannic acid, or maclurin. Hlasiwetz and Pfaundler thus describe the opera-tions required for the separation of these substances from each other and fromthe other matters contained in the wood :—The wood, previously rasped, istwo or three times exhausted with boiling water, and the mixed liquors are-after having been concentrated by evaporation—left to stand for several days.A crystalline matter is slowly deposited, which has to be rapidly washed bydecantation with cold water, and is next placed in a cloth and stronglypressed. This substance, which contains the principles just named, is fre-quently thrown down from the strong decodtions of the wood (sp. gr. I'oyo),as prepared for use in dye-houses, and that deposit may serve, with great ad-vantage, for the preparations to be mentioned. The strongly-pressed drymass is first pulverised, and next repeatedly treated with boiling water; theremaining insoluble residue, crude morin, mixed with a small quantity of thatsubstance combined with lime, is therefore first adted upon by dilute hydro-chloric acid, well washed, and next dissolved in alcohol, from which latter—after the addition of two-thirds of its bulk of hot water—the morin separatesin the form of yellow acicular crystals, which are further purified by repeatedcrystallisation from dilute alcohol. The morintannic acid is left in the wateremployed for the exhaustion of the original deposit from this solution. It isseparated partly by the concentration of the solution by evaporation, andpartly by the addition of hydrochloric acid ; it is purified by means ofrepeated crystallisations from an acidulated aqueous solution. This sub-stance is the chief constituent of the crystalline deposits seen by M. Chevreulin the blocks of the fustic.

Morintannic Acid.—The crystals of this body, as obtained by the mode ofpreparation just described, are yellow, but may be obtained entirely colourlessby adding to the aqueous solution acetic acid and acetate of lead, and nextpassing a current of sulphuretted hydrogen through the liquid ; the sulphideof lead, while falling down, carries along with it the small quantity of yellowcolouring matter which contaminates the crystals.

This acid is very soluble in hot water, i part of the acid requiring 2'I4 partsof hot and 6-4 parts of cold water for its solution ; it is also soluble in alcohol,wood-spirit, and ether, fuses at 200°, and is decomposed at 250°. Sulphate ofiron yields with it a greenish-black, and acetate of lead a yellow, precipitate;the latter soluble in acetic acid. It does not completely lose its water below140°. Its composition is C I3 Hi 0 O6. By the adtion of concentrated and warmsolutions of caustic alkalies it is split up into phloroglucin and protocatechuicacid. A moderately concentrated solution, boiled with zinc and dilute sul-phuric acid, rapidly becomes intensely red: this colouration gradually,however, fades away, leaving a wine-yellow colour (colour of Lunel orFrontignac so-called white wine). By this operation phloroglucin and a newprodudt, machromin, are formed. The last-named substance is isolated in thefollowing manner:—To the liquid decanted from the excess of zinc is firstadded the third part of its bulk of alcohol, and it is next shaken up with etheras long as that liquid becomes coloured ; the ethereal solution is evaporated,the residue diluted with water, and precipitated with acetate of lead; the