254. ODOROGRAPHIA. 
solution of neutral acetate of lead. Kachler, in 1869, found that 
by melting this resin with potash, about 3 of its weight of proto- 
catechuic acid was obtained. By destructive distillation it yields 
benzoic acid, styrol, and toluene. 
From the researches above recorded it may be concluded that 
the balsam contains one-third more of a resin and probably nearly 
two-thirds of benzyl cinnamate, which undergoes some modification 
consequent on the method employed to obtain the balsam—a 
method which is certainly the cause of the presence of free acids 
and a black colouring-matter in the balsam. The balsam also 
contains 3 or 4 per cent. of cinnamic acid. The proportions of 
these constituents vary somewhat (but only to a small extent) in 
different parcels of balsam, and are probably accompanied by small 
quantities of other bodies such as benzylic alcohol, styracin, and 
benzoic acid. 
The thick consistence and dark brown colour of the balsam 
render sophistication very easy. The principal adulterants are 
castor oil, purified storax, copaiba balsam, an alcoholic solution of 
benzoin brought to the consistence of a balsam, and a similar 
solution of colophony. The specific gravity is a very important 
criterion of unsophisticated balsam. All the substances above 
mentioned are lighter than the true balsam, the sp. gr. of which 
at 15° C. varies, as above stated, between 1°140 and 1°145, or 
perhaps 1:138 may be taken as the extreme minimum and 1°147 
as the extreme maximum; therefore, as soon as the sp. gr. of a 
sample is found to be below 1:140, and certainly when below 1:188, 
the article becomes suspicious. The sp. gr. of castor oil varies 
between 0°95 and 0°97, and that of copaiba balsam between 0°94: 
and 0°99. The sp. gr. of purified storax, obtamed as a brown 
transparent balsam by extracting liquid storax with alcoholic 
ether and evaporating the clear filtrate, was determined by 
Schlickum * as 1:093, that of the colophony solution as 1-016, 
and that of the benzoin solution as 1°080; therefore an addition 
of one of them would markedly lower its sp. gr. The plan re- 
commended by Hager, of observing whether a drop of balsam floats 
or sinks in a saline solution of known density, is considered 
to be defective, as the behaviour of the drop is affected by the 
conditions under which it reaches the surface of the solution. 
In estimating the purity of this balsam, Professor Flickiger 
* Archiv. der Pharm, [3] xx. p. 498. 
