Part VI.] Preparation of Turpentine , Rosin and Gum. T 
From the above statement it is clear that the collection of the gum- 
oleo-resin and “freshing” of the cuts should be carried out at least 
every fourth day. 
It was also found that only 47 per cent, of the trees yielded in large 
quantities, so that probably when working on a large scale it will be 
found necessary to eliminate a fairly large proportion of the trees from 
the operations. Mr. Benskin also drew certain conclusions from 
observations while at work, which deserve consideration. He considers 
that, as a general rule, it will be found that the following trees yield no 
gum-oleo-resin 
(1) A large number of healthy trees of small girth. 
(2) Old trees with black bark. 
(3) Dwarfed and suppressed trees. 
(4) Trees with a short bole. 
The following yield well:— 
(1) All sound and vigorous trees of 30 inches girth and over. 
(2) All trees attacked by borers or otherwise diseased. 
(3) Generally all hollow trees. 
As the tapping carried out during the hot weather in the Siwaliks 
had proved a failure, and that carried out in January and February in 
Nimar had given fair but not conclusive results, it was determined to 
carry out a further series of experiments during the rains, i.e., during 
July and August. These experiments were conducted by Mr. A. 
Dunbar-Brander, Divisional Forest Officer, Nimar. Two lots of 50 
trees were tapped, the first from the 1st to the 31st July 1916, the second 
from the 31st July to the 30th August 1916. The method of tapping 
was the same as that adopted in the previous experiments. The process 
of collecting and freshing was repeated every three days, making a total • 
of ten collections and freshings per month. The first 50 trees yielded 
15-6 lbs. and the second 50 trees yielded 23-6 lbs. or 5-0 and 7-6 oz. of 
gum-oleo-resin per tree per month. These results compare favourably 
with former results ; but, on the other hand, it was found that owing 
to absorption of water in the rains, the crude “ drip was difficult to 
deal with in the solvent stills, in which the gum is separated from the 
rosin and turpentine. Should it prove possible to overcome this 
difficulty, at no great expense, it would allow tapping to continue for 
a longer period of the year. 
(ii) Experiments in the Bombay Presidency. 
The Bombay Authorities having under consideration the possibi¬ 
lity of starting the Boswellia industry instituted three sets of 
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