Phyllanthus emblica, India, yields emblic myrobalans, which in immature condition contain considerable tannin. Leaves (18 per cent.) and bark used for tanning.
Phyllanthus distichus and nepalensis both yield tanning barks.
COMBRETACEÆ.
Anogeissus latifolia, India. Bark and leaves rich in tannin.
GUTTIFERÆ.
Garcinia mangostana, India. The rind of the mangosteen fruit contains much tannin.
CHAPTER XIX.
THE CHEMISTRY OF THE TANNINS.
The essential constituents of tanning materials are members of a large group of organic compounds known as “tannins” or “tannic acids,” which are widely distributed throughout the vegetable kingdom, and said to have one representative among animals, in the body of the corn-weevil. Their use in vegetable physiology is as yet uncertain, and indeed they appear in some cases to be waste products of organic change. The tannins, though varying considerably in their chemical constitution, and in many important characteristics, are all marked by the power of precipitating gelatine and some allied bodies from their solutions, of converting animal skin into the imputrescible material known as leather, and of forming dark-coloured compounds with ferric salts which are often utilised as inks. They are also precipitated by lead and copper acetates, stannous chloride, and many other metallic salts, and form insoluble compounds with many organic bases, such as quinine, and with the basic aniline colours. They are possessed of feeble acid character.
All tannins are soluble in water to a greater or less degree; they are also soluble in alcohol, in mixtures of alcohol and ether, in ethyl acetate, acetone, and a few similar solvents, but are not dissolved by dry ether alone, nor by chloroform, petroleum spirit, carbon disulphide, nor benzine.