28 
Indian Forest Records. 
[VOL. IV. 
B. 
155°—160° C.15 per cent. 
160°—165° C .65 
Above 165° C. ...... 20 „ 
Sample A that showed at Bhowali about 95 per cent, passing below 
.165° C. showed only 90 per cent, at Dehra Dun. This may be partly 
due to the difference between the atmospheric pressure at the two 
places, which at Bhowali is 25 " and at Dehra 27 ^". Besides the oil 
was exposed for about 15 days to the air at Bhowali before packing, 
and at Dehra for about a month in the half empty canisters in which 
it was kept. 
It seems that the Indian oil distilled from Chir resin is liable to 
rapid polymerisation if air is not excluded as soon as it is distilled, 
washed and filtered. The time allowed between the first distilla¬ 
tion and final packing should be reduced to a minimum. 
The experiments conducted at Bhowali on a fairly large scale 
indicate the advantages of working with the methylated spirit process, 
always provided that great care is taken to distil slowly and to keep 
up the original strength of the spirit used, otherwise, as shown above, 
the results are somewhat indifferent though they are always better 
than in the case of water distillation. 
(iv) Summary of Results obtained. 
From the Laboratory experiments, it is clear— 
(1) That the oil as it occurs in the oleo-resin is of much better 
quality than that usually produced by water dis¬ 
tillation, which has necessarily to be carried out at 
high temperatures, but it is liable to a greater amount 
of polymerisation under the influence of high tempera¬ 
ture and aerial oxidation, and that the 20 per cent, of 
the heavy turps occurring in the water distilled crude 
oil are due to the decomposition that takes place in the 
process of distillation. 
(2) That oil of the best and of a uniform quality can be 
obtained by one distillation only, if the acetic acid or 
methylated spirit method be combined with simple 
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