Part IV.] Puran Singh : Preparation of Tannin Extracts. 13 
the expert tanner does in his tannery, an extract capable of 
yielding almost colourless leather. 
(4) The serious defect in leather tanned by many tanning materials, 
i.e., its harshness, can be successfully eliminated by mixing 
them with materials yielding soft tannage; in the case of 
chemical treatment, however, this defect becomes more pro- 
notinced. 
(5) In the manufacture of mixed extracts, there are advantages 
peculiar to this country which are worth consideration. It 
is extremely difficult to procure cheap the fresh and pure 
chemicals required for the manufacture of tannin extracts, 
and it is inadvisable to stock them largely, since the chemicals 
used in this industry are liable to deterioration, and, further, 
by their use, the cost of production is considerably increased. 
(6) In this and other tropical countries where there is a great 
abundance of tanning material of all kinds containing vary¬ 
ing percentage of tannin, it is the manufacture of mixed 
extracts alone, which offers an outlet for their profitable 
exploitation. Instead of preparing extracts from materials 
poor in tannin on a large scale, as it is done in Europe, and 
placing such on the market by themselves, a procedure which 
could not be undertaken on a paying basis in India, extracts 
from a suitable admixture of materials of varying richness 
in tannin, and of varying degrees of colour, might well be 
prepared; with a mixture containing 20 to 30 per cent, of 
tannin, the process could be made to pay on a comparatively 
small scale. For example, it will not pay to prepare an extract 
on a small scale from a bark which has only 10 per cent, of 
tannin, but if 30 parts of this 10 percent, bark and 70 parts 
of Mangrove barks (of 30 per cent, tannin) are mixed, we will 
obtain a mixture which would have on the whole a tannin 
content of about 24 per cent, and which will produce an 
extract of superior colour and value to that producible from 
Mangrove alone. 
For the reasons given above, the writer is of opinion that the future 
of the tannin extract industry at least in tropical countries does not lie in 
chemical decolonisation of extracts but in the preparation of mixed 
extracts of standard colour and strength. 
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