TANNING MATERIALS 



TANNING MATERIALS 



627 



boiler, heated, with water, till the liquid, which is con- 

 stantly stirred, becomes sirupy. The leaves are removed, 

 drained, and the liquor returned to the boiler. The liquor 

 is strained into small shallow tubs, where it is allowed to 

 cool, with constant stirring, until the catechin crystallizes. 

 When cool, the pasty mass is turned out of the tub, dut 

 into one-inch cubes and dried. A commoner quality, 

 called " block-gambier," is marketed in large, oblong 

 blocks of about 250 pounds weight, which are wrapped in 

 matting and exported in a pasty condition. These contain 

 35 to 40 per cent of tannin, while the best cubes reach 

 50 to 65 per cent. The tannin is a catechol-phlorglucol 

 derivative and is used with other materials in tanning 

 light and heavy leathers. 



The myrobalans. 



Myrobalan (Terminalia Chebula), the fruit of a tree 

 forty to fifty feet high, which is found in India, Ceylon, 

 Burmah and elsewhere, is the source of all the ordinary 

 varieties, which differ only in the district from which 

 they are secured and the state of maturity of the fruit. 

 The nuts contain 30 to 40 per cent of tannin. Those 

 known as Bombays are the ripest, while " lean greens " 

 are least ripe. The unripe fruit is the richest in tannin. 

 Neither the stones nor kernels contain tannin, but the 

 latter have an oil which gives a peculiar odor to leather. 

 The tannin exists in the pulp which surrounds the kernel, 

 and is not very easily extracted. The bark is almost as 

 rich as the fruit, and the tree also yields galls. Myro- 

 balans are used in combination with other materials. By 

 itself it produces a soft and porous leather. T. Bellerica 

 yields Beleric or " Bedda nuts," which contains about 12 

 per cent of tannin. It is used as an adulterant of ground 

 myrobalans. The nuts of T. tomentosa contain about 10 

 per cent of tannin and the bark 10 to 36 per cent of 

 tannin. "Badamier bark" (T. Catappa), of Mauritius, 

 contains 12 per cent of tannin. "Jamrosa bark" (T. 

 Mauritiana) contains about 30 per cent of tannin. 

 " Thann leaves " (T. Oliveri), of Malay Archipelago, yield 

 an extract used as a cutch substitute ; the tannin is a 

 catechol derivative. The bark contains about 31 per cent 

 of tannin, the leaves about 14 per cent. 



Mangrove tannins. 



Mangrove, or Mangle (Bhizophora Mangle), grows on 

 tropical coasts all round the world. In the United States 

 it is grown on the southern coast of Florida, the Missis- 

 sippi delta, Texas coast, on the east and west coasts of 

 Mexico and Central America, and in the West Indies. It 

 is now being used in Florida for making extract. The 

 barks vary much in strength, from 15 per cent up to 40 

 per cent in different species. The leaves, used in Havana, 

 are said to contain 22 per cent of tannin. Young plants 

 contain the highest proportion of tannin. B. Mangle 

 seems to yield a bark inferior to several other species. 

 The catechol tannin, which is easily extracted, is of deep 

 red color, and allied to that of ttie mimosas. In admixture 

 with other materials the red color has a much smaller 

 effect, and mangrove bark is now largely used in combi- 

 nation with pine, oak and mimosa. Bhizophora mucronata, 

 of India and Burmah, has bark that contains 4 to 50 per 

 cent of tannin. 



Bakau or Tengah bark of the East Indies, "Goran" 

 of Bengal. It contains up to 27 per cent of tannin and 

 yields an extract which promises well as a substitute equal 

 to cutch, for dying purposes. The solid extract contains 

 up to 65 per cent of tannin, making a good but dark 

 red leather. Ceriops Boxburghiana bark is very similar 

 in strength and character to the above. 



Eucalyptus barks. 



Blue gum (Eucalyptus Globulus) and other species of 

 Eucalyptus are common in Australia. Blue gum has been 



introduced into the United States, in southern California 

 and Arizona, and is found in Algeria and southern Europe. 

 The Eucalyptus is more or less rich in catechol tannms, 

 the sap being the source of Botany Bay or Australian 

 kinos, which contain up to 79 per cent of tannin. Sev- 

 eral species of Eucalyptus afford astringent extracts ; 

 those from the "red," "white," or "flooded" gum {E. 

 rosiraia'), the "blood-wood" (S. corymbosa), and E. eit- 

 riodora, being quite suitable for replacing the ■official 

 kind. The bark of E. occidentalis contains 35-50 per 

 cent of tannin and is now being used under the name 

 Mallet bark, from which the tannin is readily soluble. It 

 makes a light brown leather. The bark of E. longifolia, 

 the "woolly-butt" of Australia, contains 8.3 per cent of 

 tannic acid, and 2.8 of gallic acid. The bark of the 

 "peppermint" tree contains 20 per cent of tannic acid. 

 The "stringy-bark" {E. obliqua) gives 13J per cent of 

 kinotannio acid. The Victorian " iron-bark " (E. leucoxy- 

 lon) contains 22 per cent of kinotannio acid, but is avail- 

 able only for inferior leather. 



Ccesalpinia. 



Divi-divi (Ccesalpinia Coriaria). This is a tree of 20- 

 30 feet high, native in central America and introduced suc- 

 cessfully into India. The dried pods contain 40-45 per 

 cent of a pyrogallol tannin, mainly ellagitannic acid, and 

 would be a most valuable tanning material but for a lia- 

 bility to fermentation and sudden development of a deep 

 red coloring matter. If used in strong liquors it gives a 

 heavy and firm leather, but is principally employed as a 

 partial substitute for gambler on dressing leather. The 

 seeds do not contain tannin. Tari or teri pod (C. digyna) 

 occurs in parts of India and Burmah, where it is used as a 

 drug. The pod-case is said to yield over 50 per cent of 

 tanning material. C. digyna promises to become a valuable 

 tanning material if it proves free from the tendency to 

 ferment. It yields a leather quite as white as sumac. Cas- 

 calote (C. Cacalaco) is found in Mexico. The pods are rich 

 in tannin, in some instances containing 55 per cent. The 

 tannin is similar to that of divi-divi. 



Algarobilla (C. [or Balsamocarpon'] brevifolia) is 

 found in Chile. This is one of the strongest tanning ma- 

 terials known, containing an average of 45 per cent of a 

 tannin very like that of divi, but less prone to discolora- 

 tion. The tannin lies loose in a very open skeleton of 

 fiber, and is easily soluble in cold water ; the seeds con- 

 tain no tannin. 



Logwood (C. [or Hmmatoxylon,] Campechianum) is 

 found in Central America. It contains about 3 per cent 

 of tannin. Its principal use is in dyeing blacks with iron 

 or chorme mordants. 



Turwar or Tanghadi bark (Cassia auriculata) is 

 found in southern India. It is used for tanning so-called 

 " Persian " sheep and goat-skins, and contains about 17 

 per cent of a catechol tannin. Leather tanned with it is 

 of a pale yellow color, but rapidly reddens in sunlight. C. 

 Fistula is found in India. The husk of the pod contains 

 17 per cent tannin. 



Mimosas. 



" Babool," or "Babul " (Acacia Arabica), is found in 

 India and Egypt. The bark contains about 12 to 20 per 

 cent of catechol tannin and considerable red coloring 

 matter. It is extensively used in India for tanning kips 

 and heavier leathers. The pods contain about the same 

 amount of tannin as the bark but of a different kind. 



Cutch is derived from the wood of A. Catechu of India. 

 A lighter colored variety called kath is made in northern 

 India, and used principally for chewing with betel. The 

 extract or cutch is made by boiling the chips with water 

 in earthen jars over a mud fireplace. As the liquor 



