NOTES ON SCIENTIFIC RESEARCH. DF 
the beginning of the heating, a bluish-green colouring of the flame, though feeble and 
transitory only, due to the copper, was noticed, especially when the camphor was 
heated over a small flame. 
Kunz-Krause points out that from the appearance of a green or bluish-green 
colouring in Beilstein’s test one must not always conclude that halogens are present, 
as it may occur that the substance tested forms more or less volatile compounds 
with copper. This is the case e.g. with benzoic acid, the copper benzoate formed 
on heating with copper oxide being sufficiently volatile to colour the flame bluish-green, 
so that it looks as if halogens were present in the acid. Only a check test with a 
substance unquestionably free from halogens can give a clue as to the significance 
of such a colouring. 
Very interesting is the observation which Kunz-Krause made with camphoric acid 
and which shows the reciprocal pyrochemical decomposition in Beilstein’s test. Cam- 
phoric acid does not yield any volatile copper compound and therefore leaves the 
Bunsen flame unchanged. But if the acid, spread out on the cover of a porcelain 
crucible, is touched with glowing-hot copper oxide, even with the smallest fragment 
of a crystal, an intensely nickel-green spot is immediatelly formed. The reaction is due 
to the pyrogenous formation of copper camphorate. If terpine hydrate is used instead 
of camphoric acid, it is said that under the same conditions a decomposition product 
of a pronounced benzaldehyde odour results, an indication which we have not been 
able to confirm on checking the test. 
Critical examination of the most important methods for the evaluation of mustard oil. 
The prize problem of The Hagen-Bucholz Fund of the Deutscher Apotheker-Verein 
for the year 1912/13 was: Comparative investigations as to the evaluation of Semen 
Sinapis, Spiritus Sinapis, Oleum Sinapis and Charta sinapisata according to the various 
methods indicated for the purpose. With reference to this, H. Frerichs reports on the 
investigations of F. Wehrmann, K. Wegener, F. H. Braunwarth, and K. Meyer. The 
treatises of Wehrmann and Wegener contain a great number of practical experiments, 
but in which only the best-known methods have been taken into consideration. Meyer 
carried out but few practical experiments, and Braunwarth considered the problem 
more a literary than a practical one. Frerichs reports especially on Wehrmann’s 
treatise, leaving out everything superfluous. 
According to the 294 and 3rd editions of the German Pharmacopoeia, allyl mustard 
oil must be determined as thiosinamine’). From the results obtained by Wehrmann, 
it is evident that the method is fairly correct, but it can hardly be used in practice, 
because of the comparatively great waste of material and, on the other hand, because 
it is applicable almost exclusively to the evaluation of pure mustard oil and not for 
preparations of mustard seed. 
According to Forster’s method”), mustard oil is transformed into thiosinamine with 
the aid of ammonia, the sulphur precipitated with yellow mercuric oxide as mercuric 
sulphide and the oxydihydrargyriammoniumhydroxide, formed by the action of the 
excess Of ammonia, extracted with potassium cyanide solution or nitric acid from the 
thiosinamine solution, to which the mercuric oxide had been added, before it cools 
down completely. The remaining mercuric sulphide is collected on a dried and weighed 
filter and then weighed at 100°, after having been washed and dried. Wehrmann 
1) Comp. Gildemeister and Hoffmann, The Volatile Oils, 2.4 ed., vol. I, p. 605. — 2) Landw. Versuchs- 
Stat. 35 (1888), 209; Untersuch. d. Nahrungs- u. Genussm. 1 (1898), 235. 
