55 
Physiology. — “Specific smell intensity and the electrical pheno- 
menon of cloudlike condensed water vapours in chenacal series.” 
By Prof. Dr. H. ZWAARDEMAKER. 
(Communicated in the meeting of May 27, 1916). 
In the meeting of the 25" of March 1916 we set forth that all 
true odorous substances have the property of imparting an excess of 
electro-positive charge to the cloudlike condensed water-vapour, 
generated by spraying an aqueous solution under an overpressure 
of two atmospheres. The attending negative charge is in the air. 
Contrary to this, pure water *) and aqueous solutions of salts, inodo- 
rous substances, sugars, ureum ete. sprayed in the same way, 
give a cloud containing both charges, which persist in the case 
of salts. 
A sereen, arranged to block the way of the spray, intercepts a 
very strong charge in the case of the odorous substances, but is not 
electrified in the case of the above-mentioned inodorous liquids, 
unless under special circumstances that give rise also to waterfall- 
electricity. Not before the sereen approaches the insulated sprayer 
very closely, or before the surrounding air has been purposely ionized 
(e.g. through an electric field), does a charge appear; in the latter 
case, also on the distant screen. This charge is identical with the 
charge arising spontaneously if the water in the earth-connected 
sprayer had been impregnated with even the merest trace of an 
odorous substance. 
This odoroscopie phenomenon | have correlated with : 
1) Pure water, diffused through a sprayer, going obliquely upwards, gives a 
positively charged spray, as has been shown in experiments by P. Lenarp in 1898. The 
amount of electricity was per gram of sprayed water 7.10—1" coulomb. (P. Lenarn, 
ii, Wasserfallelektricitiit, Ann. d. Physik (4). Bd. 47, 1915, p. 479). Eve’s water- 
sprayer gave distinct electricity of either sign (negative to excess) only to a pur- 
posely charged electrometer. (A. S. Eve, Jonization by spraying, Phil. Mag. (6) 
Vol. 14 p. 382 1907). J. C. Pomrroy again succeeded in catching up the positive 
drops while the negative electricity remained in the air. (Phys Rev. Vol. 27 p. 492, 
1908). It attracts notice that he also placed the sprayer above the reservoir. In 
all these cases, however, very small, just noticeable quantities of electricity were 
dealt with (A. Beeker. Jahrb. d. Radioaktiv. u. Elektronik, Bd. IX, 1912, p. 79). 
The electroscope (Exner-lype', used in my experiments, was not sensitive at all. 
The aluminium-leaves were of the usual width, but rather short. They deflected 
at a charge of 220 Volts 10 scale-divisions of a milimeter scale. The charges pro- 
duced by the odorous clouds induced much larger, even maximal deflections within 
some moments. They were of the order of 100.10—1° coulomb per gram of sprayed 
solution, with an earthed sprayer. 
