BALSAM PERU. 259 
Professor Fliickiger ; for instance, in the ‘ Pharmacographia’ and 
in the Professor’s article above quoted from, 38 per cent. of resin 
is stated as the amount contained in the balsam. Schlickum 
states the resinous residue obtaimable by the same method (treat- 
ment with three times its volume of carbon disulphide) to be 16 
per cent. at most, and that an admixture of benzoin increases the 
insoluble proportion. Mac Ewan, ina paper read before the British 
Pharmaceutical Conference, 1884, corroborates Schlickum’s obser- 
vation as regards the maximum being 16 per cent., and adds, 
“Tt is apparent that the United States Pharmacopeia has 
fixed upon too high a maximum which might be profitably 
amended, since the test affords a good indication of the presence 
of benzoin.” The maximum fixed by the U.S.P. is 40 per cent. 
Muter states the percentage at 38; Attfield 33 as maximum. 
The results of experiments made by Mac Ewan differ in some 
respects in a marked manner from those of Schlickum, and they 
also disagree with Professor Fliickiger’s “ Lime test” + and Dr. 
Grote’s modification thereof ; consequently great doubt arises as to 
the purity of the samples operated upon by Messrs. Mac Ewan 
and Schlickum, and the mind has a tendency to rely on the inves- 
tigations of the author of the ‘ Pharmacographia,’ at least until 
further researches are made with samples of undoubted purity and 
known age. 
The following process is recommended by Messrs. Gehe & Co. 
as convenient for determining with certainty the presence or 
absence of benzoin or storax in Peru balsam :— 
Five grams of balsam, five grams of soda solution (sp. gr. 1°160), 
and ten grams of water mixed together are shaken with two suc- 
cessive quantities of ether of 15 grams each, and the ether poured 
off as completely as possible. The residue is heated to boiling and 
acidulated with hydrochloric acid; cold water is then added, and 
the resin which separates is removed, dissolved in about 3 grams 
of soda solution, diluted with 20 grams of water, heated to 
boiling, and precipitated with solution of barium chloride. This 
precipitate is drained on a filter, dried on a water-bath, extracted 
with alcohol, the alcohol extract evaporated, then taken up with 
* Pharm. Journ. [3] xv. p. 238. 
+t Pharm. Zeitung, 1881, p. 222; and Pharm. Journ. [3] xii. p. 45, 
S2 
