56 : REPORT OF SCHIMMEL & Co. OCTOBER 1914/ APRIL 1915. 
technics, in a book written by him on microscopy’). It is used merely as a medium, 
mixes clearly on the one hand already with 90 p.c. alcohol, but on the other hand, 
as regards resins, only with euparal’) and gum turpentine, not with Canada balsam. 
It does not dissolve paraffine wax and celloidine. 
An instance for the use of benzyl alcohol in microscopic technics is to be found 
in a description, published by H. Ambronn®), of an experiment to demonstrate Abbe’s 
theory of microscopic perception. He found that benzyl alcohol and a certain kind 
of cinnamon oil are the best mediums for the immersion of the fibre of the inner bark 
of the ramie plant, as their exponents of refraction tally almost with those acting in 
the longitudinal direction of the fibre. The exponent of refraction of benzyl alcohol 
was 1,040; that of cinnamon oil, 1,597. As the latter value lies between those found 
for pure Ceylon cinnamon oil and pure cassia oil, Ambronn presumes that the oil he 
used was perhaps a mixture of the two. In any case, it is easy to make a mixture 
of the two oils that has the desired refractive power. The difference between the two 
figures indicates at the same time the intensity of the double refraction, i.e. 0,057. 
This figure agrees very well with the estimations carried out nearly 25 years: ago by 
V.von Ebner with similar fibre in a totally different way, by determining the differences | 
of the phases and of the thickness of the membrane. 
Concerning an inferior artificial Bergamot oil, we have reported on page 18. 
Copaiba Balsam. According to E. Deussen‘), the determination of thexacid and 
saponification numbers is only of secondary importance for the estimation of officinal 
copaiba balsam. The determination of its solubility in chloroform, absolute alcohol 
and light petroleum may serve as a criterion. However, the most important part of the 
work is the distillation of the balsam with steam for testing the essential oil thus 
obtained. The optical rotation of the oil must be determined. The limits for the ap 
of the oil of Maracaibo balsam are between —2,5 and — 14°. It may be advisable 
at times to make Turner’s colour test with the modifications indicated by Deussen and 
Eger®) and, should the result be doubtful, to split the oil up into 3 or more parts by 
fractionated distillation in vacuo. The residue in the vacuum still should likewise be 
tested in the same manner. 
Deussen analysed, under the considerations exposed above, 12 samples of officinal 
copaiba balsam, bought in the retail trade. He determined the density of these samples, 
the a) of the volatile oil, the ¢p of the resinous residue and further investigated the 
several fractions as well as the distillation residue. He gave his results in the form of 
tables. It was found that 5 of the 12 samples were adulterated with either gurjun balsam 
or gurjun balsam oil, whereas two others proved to be pure gurjun balsams. Only with 
the two last, Turner’s colour reaction, as indicated in the German Pharmacopoeia V 
gave no result. Three balsams had been adulterated in another way, as the volatile 
oil was dextro-rotatory. In order to establish whether there is any adulteration with 
illurin balsam, the essential oil is split up into about 4 fractions, and their rotatory 
power determined. Illurin balsam oil yields on simple, not repeated fractionated 
distillation only dextro-rotatory components. 
1) Einfihrung in die Mikroskopie, Berlin, 1914, p. 183. — *%) A mixture, the composition of which is not " 
exactly known, but which among other substances contains eucalyptus oil and paraldehyde. — %) Zeitschr. f. 
wissensch. Mikrosk. u. mikroskop. Techn. 80 (1913), 289. As per a special copy kindly sent us. — *) Arch. der ~ 
Pharm. 252 (1914), 590. — 5) Chem. Ztg. 86 (1912), 501; Report October 1912, 49. : 
