48 
gauze, whereas the large positive nuclei, loaded with waterdrops, 
dash against the disc and creep down along it. Also in GRADENIGO's 
and STEFANINIs experiments with salt-clouds the larger drops splash 
against the glasswall and the smaller escape to the inhalatorium. 
With their salt-clouds, contrary to our odour-containing vapours, 
however, the positive charge cannot be rendered visible on an inter- 
cepting dise, though both positive and negative charges can, also 
with salt-clouds be demonstrated when another method is employed 
viz. through special contrivances. 
In what we have said above we assumed that the odour-containing 
water condenses round the negative as well as round the positive 
ions, also, however, that the former disappear sooner, because the 
drops evaporate more rapidly. It goes without saying that we may 
also assume the vapour to condense, under the experimental condi- 
tions, only round the positive ions. (See the above references to the 
literature). 
The excess of charge in odorous cloudlike condensed vapours is 
in every sense the counterpart of the odoroscopic phenomenon 
(camphor movement on perfectly pure water), as it requires for its 
arousal : 
1's". volatility of the substance ; 
2d. an effect of reducing the surface tension of the water. 
The phenomenon of electrification is, however, more general, as 
it applies to odorous liquids as well as to odorous solids, that are 
soluble in water, whereas the odoroscopic phenomenon holds only 
for the latter. 
Special attention should be given to the fact that a 2°/, alcohol- 
solution, when sprayed, gives a distinct charge, which gradually 
diminishes with 5°/,, 10°, and 25°/, solutions, the latter giving 
only a trace, while a 50°/, solution gives no charge at all. A similar 
ratio with slight differences in the percentages is found in the case 
of acetone, pyridin and a number of other substances examined on 
this point. 
Even surprisingly small quantities of true odorous substances 
suffice to generate electricity as e.g. 25,10 ® grms of geraniol taken 
up in 25 cc. of a 2°/, salicylas natricus solution (giving no charge 
of itself), is sufficient to produce a distinct charge. A similar result 
is obtained with a quantity of trinitrobutyltoluol (artificial moschus) 
of the same order. Such liquids have (as determined after Travss) 
a lower surface tension than water. If we bear in mind that the 
25 cc. of liquid were diffused in a large volume of air, it is easy 
to realize how vivid the electrica) reaction is. Still it is far distanced 
