36 



DYE STUFFS AND TANNING SUBSTANCES. 



UTILISATION OF MANGROVE BARK. 



The name "mangrove" was applied by Lindley to the trees belonging to 

 the natural order Rhizophoracese. These trees or shrubs inhabit the muddy swamps 

 close to the seashore in tropical climates, where they frequently form forests of 

 vast extent. The mangroves are of particular interest, owing to their peculiar 

 habit of growth, which is described by Hamilton as follows :— " In the economy of 

 nature the mangrove performs a most important part, wresting annually fresh 

 portions of land from the dominion of the sea. This is effected in a twofold manner, 

 by the progressive advance of their roots and the aerial germination of their seeds, 

 which do not quit their lofty cradle until they have assumed the form of actual 

 trees, and drop into the water with their roots prepared to take possession of the 

 mud, in advance of their parent stems. The progression by means of the roots is 

 effected by fresh roots, which issue from the trunks at some distance above the 

 surface of the water, and arching downwards, enter the mud. In this manner, the 

 plants, after their descent from the parent trees, continue during their early years 

 to advance steadily forward till they have attained a height of about fifteen feet, 

 and gained a position considerably in advance of their parent trunks. After this 

 fewer additions are made to the roots, but the head begins to expand in every 

 direction, spreading its branches on all sides. These branches in turn send down 

 long slender roots like those of the banyan tree (F'icus indica), which, rapidly 

 elongating, descend from all varieties ot height, and, reaching the water, penetrate 

 the mud, becoming in time independent trees ; thus a complicated labyrinth 

 is formed." 



It has long been known that all parts of the mangroves, and especially 

 their barks, contain tannin, but it is only comparatively recently that mangrove 

 bark has been systematically collected and imported into Europe for the use 

 of tanners. 



MANGROVE BARKS SUITABLE FOR TANNING PURPOSES. 



The mangroves best known as yielding barks suitable for tanning purposes 

 are Rhizophora mucronata, Rhizophora Mangle, Bruguiera gymnorrhiza, Ceriops 

 Candolleana and Roxburghiana, and Kandelia Rheedii. 



Mangroves yielding barks rich in tannin are fairly widely distributed iu 

 tropical countries, and in recent years a good deal of attention has been paid to the 

 exploitation of these materials in various countries, notably Germany and Belgium. 

 The best-known mangrove barks in European commerce are probably those of 



GERMAN EAST AFRICA, 



which have ^been made the subject of special study by Dr. Busse (Ohem. Centr. 

 1899. I. (4), p. 315), and by Professor Korner, whose analyses are recorded in 

 Jahresberichte Gerbschule, Freiberg, 1899-1900. 



These results show that the richest mangrove barks obtainable from German 

 East Africa are the " Mkaka," derived from Rhizophora mucronata, which may 

 contain as much as 48.0 per cent, of tannin, though samples containing only 21*3 

 per cent, were examined. The "Msinzi" bark, derived from Bruguiera gymnor- 

 rhiza, contained from 44 to 53 per cent, of tannin, whilst the "Mkandaa" and 

 " Mkamavi " barks, obtained from Ceriops candolleana and Xylocarpus granatum 

 respectively, contained 42 , !-> and 40"5 percent, of tannin. Quite recently a similar 

 series of barks from 



