32 THE WORK OF THE FOREST DEPARTMENT IN INDIA. 



Zizyphus Xylopy^us fruits. The fruits of Zizyphus Xylo- 

 pyrus have recently been examined at the Forest Research 

 Institute. They contain about 20 25 per cent, of tannin, toge- 

 ther with 20 per cent, of non-tannin, mostly consisting of pectom 

 substance. They yield good light coloured leather of fair 

 texture. Except that they tan slowly, taking about double the 

 time of babul bark, they are in every way a good auxiliary 

 tanning material. 



Caesalpinia digyna is a shrub found growing scattered in 

 Burma and elsewhere, the pods of which are very rich in tanning 

 material, containing as much as 50 to 60 per cent, of tannin. 

 If cultivation is possible this may prove to be a valuable tanning 

 material. 



Babul pods. The pods of the babul (A cacia arabica) are not 

 so extensively used as might be expected, the chief objection to 

 them being that they ferment badly in the tan yard. The con- 

 ditions under which they may be employed as tanning agents 

 are under study. From the work done so far it appears that 

 they can be utilized if tan liquors are prepared from them and 

 the refuse materials discarded before use. They contain 18 

 20 per cent, of a bloom yielding pyrogallic tannin, and if an 

 extract can be prepared from them it may be of considerable 

 value. 



Mangrove barks. The barks obtained from the mangrove 

 forests of littoral regions are rich tanning materials, containing 

 on an average 25 30 per cent, of tannin. They are used to a 

 limited extent by the native tanners of Burma and Calcutta. It 

 has been demonstrated that it is possible to make a saleable 

 mangrove tan extract but unfortunately a prejudice exists 

 amongst tanners in Europe and America against it as it gives a 

 red leather which is also inferior in other respects to leather 

 tanned with other materials. Unless its preparation is sub- 

 stantially improved and the cost of manufacture considerably 

 reduced, the commercial possibilities of working this product 

 are, to say the least, doubtful. 



Babul bark. The bark of the babul (Acacia arabica} is one. 

 of the commonest substances used for tanning, especially in 

 Northern India. This bark, which yields an essentially harsh 



