114 Report of Schimmel § Co. April/ October 1917. 



2 or 3 drops of a 1 per cent, acenaphthene solution in the same solvent; the presence 

 of a cyclic aldehyde is then indicated by a green colouring which turns reddish- 

 violet. This colour remains permanent for a few days and disappears on pouring the 

 solution into water. It proved impossible to isolate the coloured substance. Benz- 

 aldehyde, salicylaldehyde, m-hydroxybenzaldehyde, vanilline, piperonal (heliotropine), 

 cinnamaldehyde, cuminic aldehyde, and furfurole show this reaction. Formic and 

 acetic aldehydes form dark-coloured addition products, without, however, producing 

 the characteristic reddish-violet colour; ordinary aliphatic aldehydes do not react at 

 all. Aldoses and other carbohydrates, including cellulose, which combine with cold, 

 concentrated sulphuric acid and produce furfurole or similar aldehydes indeed show 

 this reaction, but it lasts much longer until the characteristic reddish-violet colouring 

 appears. It is said to be possible by this means to detect such infinitesimal quantities 

 as 0.0078 mg. of benzaldehyde, 0.019 mg. of vanilline, and 0.006 mg. of furfurole. 



de Fazi has investigated the cryoscopic behaviour of binary mixtures of ace- 

 naphthene with vanilline, ^-nitrobenzaldehyde, and piperonal. In neither of these 



3 cases was it possible to detect the formation of addition products. The melting 

 points of the eutectics were 67.5, 66.8 and 29.9° respectively. 



On the determination of vanilline in vanilla extracts, vide page 102. 



On the saponification of iso-valeric esters, vide page 89 of this Report. 



Some colour reactions of indole and scatole have been described on page 157 of 

 this Report. 



Physical Notes. 



Electrical (charging) phenomena produced by the atSmization of solutions of perfumes. — 

 Perfumes offer abundant scope for investigation to the most various branches of 

 natural science. Not only chemists but also physiologists, bacteriologists, botanists, 

 medical men, etc. find in this branch a most productive field for their activities. 

 That physicists can also take up the subject of perfumes with advantage is apparent 

 from the publications of H. Zwaardemaker 1 ). In company with H. R. Knoops and 

 M. N. van der Bijl, he investigated the electrical phenomena produced by atomized 

 perfumes as well as the spec, strength of scent and the phenomena of odoroscopic 

 charging in homologous series, besides the possibility of charging mixtures of per- 

 fumes by means of secondary electrical currents. Zwaardemaker employs a larger 

 • atomizer for the purpose of producing a mixture of atomized perfume and air, such 

 as was built some years ago by G. Gradenigo 2 ). If we atomize a watery solution of 

 non-volatile substances with this apparatus, one obtains a fairly stable kind of mist, 

 watery solutions of perfumes, however, form a mist which disappears already in a few 

 minutes. By means of an ultramicroscope one can observe small drops of water in 

 the mist and active Brownian motion. The scent is even observable after the mist 

 has disappeared which proves that perfumes act on the nasal organs not only in the 

 shape of mists but also in a gaseous state 3 ). 



x ) Koninkl. Akademie van Wetenschappen te Amsterdam 24 (1916), 1630; 25 (1916), 3, 512. (Meetings of 

 March 25 th , May 27 th and September 30 th .) According to separate impressions kindly forwarded to us. Other 

 publications by the same author have formerly been discussed by us. Vide Report October 1904, 104; October 

 1908, 160. — 2 ) A description of this apparatus is to be found in the Arch. int. de laryngologie, d'otologie et 

 de rhinologie 1911. Vide also H. Zwaardemaker, Arch. Neerland. de Physiol, de Vhomme et des animaux 1 (1917), 

 347. — 8 ) J. Gaule expressed, in 1900, the idea that perfumes in Nature occur generally in the form of mists 

 or vapours and that they are only perceptible to us in that state. 



