62 REPORT OF SCHIMMEL & Co. OCTOBER 1915. 
quantitative proof, as A. Viehoever and C. O. Johns) have found. For this purpose, they 
added sodium hydroxide to the distillate containing hydrocyanic acid (it must contain 
about 1 to 2 mg.), until its reaction becomes slightly alkaline, and concentrated the 
solution, which had been placed into a round distilling flask of 200 c. c., by distilling 
the water over in vacuo, the flask being put during the process into a water-bath 
heated to about 70°. The flask must be provided with a similar condenser as used 
for the determination of nitrogen according to Kjeldahl. After the liquid has been 
boiled down to 1 cc., 0.2 to 0.5 cc. of freshly prepared 3 p.c. ferrous sulphate solution 
and about 0.05 g. of potassium fluoride are added, and the flask is evacuated. From 
5 to 10 minutes later the mixture is acidulated with nitric acid of 30 p.c., when the 
blue colour appears immediately. If only traces of prussic acid are present it is 
necessary to heat to 50°. One then dilutes with water until a colour is reached 
corresponding to that of a standard solution of 1 mg. of potash cyanide in 25 cc. - 
This method is said to be very suitable too for the qualitative determination of 
prussic acid, as it allows to ascertain quantities down to about 0.00001 g. 
7 
1 
a 
The evaluation of aniseed oil in liqueurs has been discussed on page 7 of this Report. 
As to the quantitative determination of cineol, see page 17 of this Report. 
The use of mercuric acetate for the investigation of terpenes in essential oil is 
described on page 77. 
Physical Notes. 
Relations between optical behaviour and constitution. 
We have repeatedly had an opportunity of reporting on the interesting spectro- 
chemical investigations of K. von Auwers and his collaborators”). Now again a volu- 
minous publication by von Auwers*) on his latest investigations in the spectrochemical 
domain has made its appearence. We need not here enter into details about the 
important theoretical considerations regarding the spectrochemical influence of the local 
isomerism in aromatic aldehydes, ketones and esters, nor about the spectrochemical 
relations between aromatic hydroxy-aldehydes, hydroxy-ketones and hydroxy-esters and 
their ethers. The rule is that in aromatic aldehydes, ketones and esters a methyl 
group in ortho position does not alter the exaltations of the mother substance; almost 
the same holds good for a methyl group in meta position. A methyl group in para 
situation, however, seems to increase the optical exaltation regularly. The rule previously 
established, that aldehydes show higher exaltations than the corresponding ketones 
and esters, finds confirmation also in the homologues. : | 
It further resulted that methyl takes a special place among the alkyles in that its 
disturbing action is somewhat smaller than that of its homologues. In consequence 
the exaltations of homologue ketones come near those of the acid esters in such a 
degree that the differences, which generally are very small for the methyl ketones : 
too, disappear for practical considerations. The action of methoxyl is considerably 
stronger than that of methyl. In the case of methoxyl the influence is very pronounced 7 
also in meta and ortho positions, above all in the dispersion values. The para derivatives | 
of the methoxyl compounds likewise take a special place, in that they again show 
higher exaltations. 
1) Journ. Americ. chem. Soc. 87 (1915), 601. — 2% Comp. Reports October 1910, 164; October 1911, 122; — 
April 1912, 158; October 1918, 124. — #4) Liebigs Annalen 409 (1915), 212. 
