The Principles of Leather ManufactureProcter, H. R. (Henry Richardson)
History
The Principles of Leather Manufacture
Procter, H. R. (Henry Richardson)
Leather
_T. Chebula_ (Fig. 57), a tree 40-50 feet high, and yielding good
timber, is the source of all the ordinary varieties, which differ only
in the district from which they are obtained, and the state of maturity
of the fruit. The nuts contain from 30 to 40 per cent. of tannin. Of the
various sorts, probably those known as Bombays are least unripe, while
“lean greens” are the most so. The unripe fruit is the richest in
tannin. “Bombays” have a smooth skin in coarse wrinkles, and when cut
are porous and light coloured. “J’s” (Jubbalpores) and “V’s”
(Vingorlas), have finer and shallower wrinkles, and are harder, solider
and consequently darker looking, but do not give a darker liquor, while
“lean greens” are greener, have less yellow colouring matter, and
consequently more nearly approach in character to sumach, which the
tannin in many respects resembles, though probably containing more
ellagitannic acid in proportion to gallotannic acid than the latter.
The “nuts” should be bright in colour, not worm-eaten, nor “waxy” or
soft. If kept in a damp place they rapidly absorb moisture, and fall
into the “waxy” condition, in which they are very difficult to grind,
sticking to and choking the cutters or beaters of the mill.
Neither the large hard stones nor their kernels contain tannin, but the
latter have an oil which gives a peculiar odour to leather. The tannin
exists in large and rather thickly-walled cells, and is not very easily
extracted; the skin is wrinkled, but the uncrushed nuts swell up to
their original plum-like form when placed in water for some time. The
bark is almost as rich as the fruit, and the tree also yields galls.
_T. Belerica_ yields Beleric or “Bedda nuts,” which are downy, rounder
and larger than ordinary myrobalans, and contain about 12 per cent. of
tannin, used as adulterant of ground myrobalans. A sample of solid
extract made from the bark of T. Belerica contained 70 per cent. of
tannin.
_T. tomentosa_ has downy nuts, containing about 10 per cent. of tannin,
bark stated by de Lof to contain 36 per cent. of tannin. A sample of
solid extract contained 56 per cent. of tannin. The bark contains about
11 per cent.
There are several other Indian species.
_T. Catappa_, “Badamier bark” of Mauritius, contains 12 per cent. of
tannin.
_T. mauritiana_, “Jamrosa bark,” said to contain 30 per cent. of tannin.
_T. Oliveri_, Malay Archipelago, yields “Thann leaves,” from which an
extract is made as a cutch substitute. A sample of the extract from
Burmah examined recently in the Author’s laboratory, contained 62 per
cent. of tannin. The tannin is a catechol derivative, differing from
that of _Acacia catechu_ in containing no phloroglucol (p. 297).
A sample of bark from Mandalay contained 31 per cent. of tannin, while
the leaves from the same tree contained 14 per cent.
Emblic myrobalans, see p. 293.
RHIZOPHORACEÆ, Mangles or Mangroves.
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