The Natural Organic Colouring Matters
By
Arthur George Perkin, F.R.S., F.R.S.E., F.I.C., professor of colour chemistry and dyeing in the University of Leeds
and
Arthur Ernest Everest, D.Sc., Ph.D., F.I.C., of the Wilton Research Laboratories; Late head of the Department of Coal-tar Colour Chemistry; Technical College, Huddersfield
Longmans, Green and Co.
39 Paternoster Row, London
Fourth Avenue & 30th Street, New York
Bombay, Calcutta, and Madras
1918
Kaikki kuvat (kemialliset kaavat) puuttuvat // None of the illustrations (of chemical formulas) included.
Valonia (Valonée, Fr.; Valonea, Ackcrdoppen, Orientalische Knoppern (Ger.)), an important tanning material, is the acorn cup of certain species of oak, usually Quercus aegilops (Linn.), and probably Q. macrolepsis, Q. graeca, Q. ungeri, and Q. coccifera (Linn). The former is most prolific in the highlands of Morea, Roumelia, Greek Archipelago, Asia Minor, and Palestine, whereas the Q. macrolepsis forms great forests in Greece. These acorn cups have a diameter up to about 1½ inches, and in good condition possess a bright colour.
The fruit ripens in Asia Minor about July or August, and the trees are then shaken, and the material left on the ground to dry; this is subsequently collected into heaps, and allowed to ferment for some weeks, until the acorn contracts and falls from the cup. The acorn, which contains but little tannin, is employed for feeding purposes.
In Greece distinct qualities of valonia are known, the best (chamada) collected about April before the fruit is ripe, a second (rhabdisto) in September or October, and a third little-used inferior variety (charcala).
Smyrna valonia may contain 40 per cent., Greek 19-30, and Candia valonia 41 percent, of tannin matter, which consists of a mixture of a gallotannin and an ellagitannin. Valonia is, indeed, an excellent source for the preparation of ellagic acid, because it so readily yields a product easy to purify. Extract of valonia frequently undergoes fermentation with deposition of ellagic acid, and to avoid this the employment of antiseptics is to be recommended.
Valonia is especially suited for the manufacture of sole leather, and together with gambier and other materials for dressing leather, but is little employed for dyeing purposes (cf. Procter, "Principles of Leather Manufacture," 259).
Ei kommentteja :
Lähetä kommentti