Physiology. — “On the relation between the electrical phenomenon 
in cloudlike condensed odorous water vapours and smeli-inten- 
sity”. Bij H. ZWAARDEMAKER and H. ZeEHUISEN. 
(Communicated in the meeting of May 31, 1919). 
In earlier publications’) we set forth that all true odorous sub- 
stances, a large number of saponins and antipyretica possess the 
property of imparting an electrical charge. This phenomenon mani- 
fests itself most distinctly with the first group, less distinctly with 
the second, and again less with antipyretica. However, the result 
is largely dependent. on the solubility in water of the individual 
substances, as it can be of some significance only when, at the 
spraying, an adequate number of dissolved molecules are present 
in the water. Suspended particles are of themselves of no value 
for the phenomenon. Before proceeding we wish to call attention 
to a fourth group to be discussed later on, viz. the alkaloids. The 
phenomenon appears with many of them, but their solubility being 
very slight, it cannot reach a high degree of intensity. To give an 
idea of the great differences among the four groups, we observe 
that on comparison, eg. of the charge of a saturated camphor- 
solution with that of a saturated quinine-solution, the former appears 
to be at least twice as strong as the latter. It follows then that 
among the organic substances of physiological activity the electrifying 
power is always highest in the odorous substances, so that they 
are most appropriate for the study of the phenomenon. 
It has been established before, that in homologous series the in- 
tensities of electrifying power and olfactory capacity rise and fall 
concomitantly. In order to ascertain the relations of these intensities 
for odorous substances we selected at random 26 of them, distri- 
buted over various groups and series and we diluted their aqueous 
solution to such a degree that on spraying they yielded only in- 
appreciable electrical phenomena (with an electroscope of moderate 
sensitiveness 7) a deflection of from 0.1 to 0.2 scale-marks). When 
1!) K. Akad. v. Wetensch. Amst. 25 Maart 1916, 27 Mei 1916, 30 Sept. 1916, 
23 Febr. 1918, 29 Juni 1918. Arch. neérl. de physiol. T. 1, p. 347; Nederl. 
Tijdschr. v. Geneesk. 1918 II 980—982. 
2) A tension of 220 vlts made the instrument deflect 10 scalemarks. (It had a 
capacity of + 50 Electrostat.-units). 
