21 
Part VI.] Preparation of Turpentine , Rosin and Gum. 
From the above results it is evident that collections should not be 
made during the rains, as the excess of moisture produces a peculiar 
treacle-like mass, which is the result of the gum swelling by absorption 
of watef. Moreover, extraction is rendered difficult owing to the swollen 
wet gum forming a coating on the resin impermeable to solvents. An 
average sample of the gum-oleo-resin may thus be taken to be 10-11 per 
cent, moisture, 4-5 per cent. Insolubles, 8-9 per cent, oil, 55-57 per cent, 
j Boswellia rosin, 20-23 per cent, of gum. 
3. Constants of Boswellia serrata gum-oleo-resin. 
(t) Turpentine. 
The oil as distilled by steam on a large scale, at the Institute distillery, 
on redistillation ancl after eliminating all the fraction of high boiling 
residue, was examined with the following results :— 
Bulk Fraction, Sp. Gr. @ 22°C. . . . 0-8371 aD+32° 30' 
High boiling Fraction, Sp. Gr. @ 22°C. . . 0-8675 aD-{-12- 0 12' 
The fractional distillation of the original oil before rectification gave 
the following results, in an ordinary fractional distillation flask at Dehra 
Dun (Barometric pressure 27-8 inches) :— 
Below 160°C. . 
160°-167°C. . 
167°-180°C. . 
Above 180°C. . 
Per cent, (by volume) 
50 
17-5 
11-0 
22-5 
The bulk fraction gave the following results :— 
Below 155°C. ...... 87 
155°-160°C.8 
Above 160° C. ...... ^ 
Besidue left by the Boswellia turpentine on spontaneous evapora¬ 
tion after 3 months amounted to 0-8 per cent, as compared with 6*03 per 
cent, residue from the American and 8*42 per cent, from the French 
turpentine oils, the latter as obtained in the Indian markets, the oils 
having been allowed to evaporate under identical conditions. 
From these results, it is evident that the constants of Boswellia 
turpentine closely resemble those of superior American and French 
turpentines. As already stated, this Boswellia serrata oil differs in some 
respects from the oil of African frankincense, consisting mainly of 
Dextropinene mixed with /3-pinene. 
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