12 
Indian Forest Records. 
[Vol. lit. 
Mixed Extracts. 
It is a well-known fact that in the tannery, the expert tanner does not 
work with any one single tanning material. He makes a judicious mixture 
of tanning materials of different colours, dark and light, to get his leather 
of the right colour. For example in India, the Babul^ {Acacia arabica) 
bark, which is decidedly the best tanning material, is never used alone 
as it gives leather of red colour, but it is mixed with myrabola ns in suit¬ 
able proportions for decolourising leather and rendering it suited to the 
employment of the most delicate shades of aniline dyes. In modern tan¬ 
ning, the use of bark has given place to tannin extracts of various descrip¬ 
tions, some of which are prepared from very deep coloured materials like 
Quebracho wood, malletto and Mangrove barks. The tendency has been, 
and still continues, to chemically decolourise these high coloured tannin 
extracts. But, as mentioned above, both the practical experience of the 
tanners and scientific research have shown that treated extracts give far 
from satisfactory results in the hands of the tanner. The experienced 
tanner, therefore, prefers to have pure extracts of tanning materials with 
which he is well acquainted and to use them to the best advantage by 
mixing them with other light coloured materials in his tannery. The 
interesting question, therefore, arises whether the future of the tannin 
extract industry does not lie in the manufacture of mixed extracts . In 
mixed extracts it will be only necessary to reduce them down to a standard 
colour, sufficiently light for the purposes of the tanner. For example, 
barks like those of Mangrove, Shored robusta , Terminalia tomentosa , etc., 
occurring abundantly in India may well be mixed with myrabolams, leaves 
of the Bhus species, Babul pods, etc., and other abundant products of this 
country. Thus all sorts of tanning materials of different colours can be 
utilised for the manufacture of extracts of standard colour and strength. 
This procedure has the following advantages over the chemical treat¬ 
ment :— 
(1) The percentage of tannin in mixed extracts is higher than in 
similar extracts treated chemically. 
(2) The tanning properties of the original material suffer no deterio¬ 
ration in the mixed extracts. 
(3) The colour of the extracts from the highly coloured materials 
can be reduced to the desired degree by altering the pro¬ 
portions of the ingredients to be mixed so as to produce, as 
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