22 



Copaiba Balsam. For the purpose of examining and estimating 

 the value of copaiba balsam Utz 1 ) recommends the determination of 

 the index of refraction. He employed for his examinations a re- 

 fractometer of Abbe's construction, and determined the refractive 

 index at 15 . The values ascertained for commercial balsams derived 

 from the most diverse sources lay between 1,5088 and 1,5258. Utz 

 is not prepared to fix definite limits of value for the individual com- 

 mercial qualities, as he had no authentic pure copaiba balsams at his 

 disposal. An adulteration of the official balsam with gurjun balsam 

 cannot be detected by the determination of the refraction, as the 

 two balsams have approximately the same refractive power. An ad- 

 mixture of fatty oils and oil of turpentine, which possess considerably 

 lower refractive indices, can, according to Utz, be detected by deter- 

 mining the refraction. The determination of the polarisation of copaiba 

 balsam, which was carried out by Utz in a solution of carbon tetra- 

 chloride 1 : 5 did not afford any definite data for a valuation. 



We would caution against attaching too great a value to the 

 determination of the refractive index by itself: when it is a question 

 of the detection of slight adulterations, this method will fail more 

 readily than the usual one. The same applies to Rosenthaler's 

 test, which appears useful to Utz in many cases. Rosenthal er 2 ), 

 as is well known, uses a solution of vanillin in hydrochloric acid as 

 reagent, and observes the colorations which occur with the balsams 

 to be examined, both in the cold and when heated. As a violet 

 coloration occurs both with pure copaiba balsam, and with gurjun 

 balsam, which in the former case is feeble and disappears within a 

 quarter of an hour, but in the latter is stronger and of longer duration, 

 this method naturally fails where mixtures are examined. 



Copal Oils. From a communication by L. Schmolling 3 ) on 

 copal oils, we abstract the following: — The most commonly used copals 

 met with in commerce are Kauri and Manila copal, whose oils, 

 separated from them by ordinary distillation, are employed for the 

 manufacture of varnishes. The two kinds differ somewhat considerably 

 in respect of content of resin acids, essential oil, etc. For further par- 

 ticulars we would refer to the work done by Walla ch 4 ) and Tschirch 5 ). 

 Schmolling now has examined the essential oils of both resins, and 

 from this it appears that they also show considerable differences. The 

 Kauri oil is mobile, bright yellow, has a pleasant aromatic odour, 



x ) Apotheker-Ztg. 21 (1906), 72. 



2 ) Zeitschr. f. anal. Chem. 44 (1905), 292. Report October 1905, no. 



3 ) Chem. Ztg. 29 (1905), 955. 



4 ) Liebig's Annalen 271 (1892), 308. 



5 ) Arch. d. Pharm. 239 (1901), ^145; Report October 1901, 56. Arch. d. 

 Pharm. 240 (1902), 202; Report October 1902, 31. 



