47 
anethol, anilin, anisaldehyd, apiol, acetic acid, benzaldehyd, borneol- 
bromin, bromoform, isobutylaleohol, carvone, chinolin, chloroform, 
cinnamylaldehyd, citral, citronellol, cumol, decylaldehyd, duodecy lal- 
dehyd, eucalyptol, eugenol, formaldehyd, guaiacol, heliotropin, ionone, 
iron, iodin, linaloöl, menthol, mercaptan, methylanthranilate, methyl 
butyrate, methylsalicylate, formic acid, myrtol, naphtalin, nonylal- 
dehyd, paraldehyd, paraffin-ether, propylamin, pulegon, pyridin, safrol, 
skatol, styron, thymol, trimethylamin, undecylaldehyd, valerianic 
‘acid, vanillin, xylol. 
As yet we did not come across any exception among the true 
odorous solids. 
All odorous vapours charge a metal or glass wall positively, when 
it is placed in their way. With the true odorous solids ethylmelonic 
acid, benzaldehyd, citral, eugenol, geraniol, heliotropin, ionon, cam- 
phor, menthol, trinitrobutyltoluol, (artificial moschus) this effect can 
be produced even in extremely weak dilutions. With other substances 
the charge is less strong, sometimes weak. With ammoniac it was 
so weak that we almost supposed we had to do with an exception. 
Rowever, even with this substance a positive charge is not alto- 
gether wanting. Aqua cholarata does not electrify appreciably. No 
more does ozone-containing water. 
Of course, the quesiion arises where the other charge is located. 
It may be rendered visible by replacing the disc by a wire gauze. 
This shade will be charged positively, while in the cases examined, 
the negative drops fly through it and are caught up on a disc 
drawn up behind the shade. The positive drops streaming down the 
shade emit a stronger scent than the negative ones collected on 
the dise. 
It seems to me that what we have observed so far may be ex- 
plained as follows: 
Suppose that somewhat larger drops form round the positive ions 
than round the negative, then the smaller negative drops will, in 
the case of odorous watervapours, evaporate sooner and thus leave 
the negative nuclei denuded. ') 
These negative nuclei will slip through the meshes of the wire 
1) Also when we take odorous paraffin a spraying occurs, though not through 
condensation. The dense cloud then forming is again electro-positive, and continues 
for some time. The cloud smells of the substance dissolved in the paraffin, of 
tallow if the paraffin be pure. In this case the odour can volatilise from the 
drop, but the drop itself cannot evaporate. 
An odorous substance dissolved in glycerin does not give a charge, unless the 
solvent is diluted with three times its volume of water. 
