264: ODOROGRAPHIA. 
quantity of solution of potash, it loses its own characteristic odour 
and acquires that of the Clove-Pink; also (by Alix) that the 
balsam, if heated with sulphuric acid, dissolves without disengage- 
ment of sulphurous acid, and yields a cherry-red liquid. 
To detect storax or colophony in balsam Tolu, the following 
process is recommended by Cripps *:—About 30 grams of the 
sample are digested in carbon disulphide for about 15 minutes, 
keeping it gently warm by occasional immersion in hot water. 
The clear liquid is poured off, evaporated to dryness, and when 
cold, sulphuric acid added to dissolve the resinous extract. A 
bright red-rose coloration is produced, which in the case of 
genuine tolu remains of a distinctly rose hue for some considerable 
time. If, however, the sample be adulterated with either storax 
or ordinary resin, the rose colour rapidly becomes more brown in 
tint. The best way to apply the test is by performing the opera- 
tion upon a genuine sample by the side of the suspected one. In 
this way, a distinct difference in tint can be observed if only one 
per cent. of the adulterant be present; with 4 per cent. of colo- 
phony, or rather more of storax, the difference in tint can be 
readily distinguished without the blank experiment. If to the 
sulphuric acid solution a fluid ounce of water be rapidly added, the 
colour of the resulting liquid is much duller and paler when 
colophony is present than with the pure balsam. 
* Pharm. Journ. [3] xix. p. 422, 
