35 
Part VI.] Preparation of Turpentine , Rosin and Gum. 
Results of examination. 
The rosin was analysed and gave the following results, compared with those 
obtained from the previous samples dealt with in the Imperial Institute reports 
on Boswellia serrata rosin from India dated the 31st May 1915.:— 
— 
Present 
sample. 
Previous Samples. 
A. 
B. 
Moisture per cent. 
. 
0*7 
0-7 
0*9 
Ash per cent. 
. 
0-03 
0-5 
0*4 
Melting point, C. 
68-0 
72-0 
56*0 
Acid value* 
. 
55-1 
51-5 
250 
Saponification value* 
90-2 
92*0 
66-0 
* Milligrams of potassium hydroxide per gram of rosin. 
Like the previous samples, the rosin was completely soluble in alcohol as well as 
in turpentine oil, and varnishes made by its solution in these liquids gave on rying 
a fairly brilliant but rather soft “ coat ” similar to that given by good grades ol 
ordinary colophony, but less brilliant and softer than those yielded by dammar 
and other typical spirit varnish rosins. 
The rosin was not completely soluble even on prolonged boiling in sodium car¬ 
bonate solution, and as pointed out in the previous report could not be used as a 
substitute for colophony in making ro, in soap or rosin size. 
Remarks. 
It is clear from the foregoing results that Boswellia rosin could only be used as a 
substitute for colophony, and then only in cases where the use of colophony does 
not depend on its complete solubility, in alkaline solutions. 
Technical trials will be required to determine precisely the commercial value ol 
the Boswellia rosin, and these are now in progress. It does not seem likely, however, 
that the material will at best fetch higher prices than the colour grade G ol 
colophony to which it corresponds, and which is at present worth 22s. per cwt. 
and is normally worth about 14s. per cwt. 
(ii) Further Report from the Imperial Institute of the United Kingdom , 
the Colonies and India. 
With reference to your letter No. 925-18 of the 4th ultimo and previous corre¬ 
spondence on the subject of Boswellia rosin, I have to inform you that a firm oi 
importers to whom the rosin v as submitted valued it at about £20 per ton in 
London (July 1916). . . . 
A firm of spirit varnish manufacturers described it as equal in all respects to 
American rosin and quite suitable for making certain qualities of spirit varnishes 
[ 337 ] 
