337 
also by sprayed water to the heavier particles of a cloud '). For the 
present I prefer, for technical reasons, to take roughly, empiri- 
cally in taking the axis of the cone for index, on the one hand 
because its length corresponds with the distances to which the large 
positive and the smaller negative ions are dashed away or rebound, 
when sent adrift by a constant force, on the other hand because it 
enables us to realize that the space is large enough to balance, at 
least on a distant disc, the contrast between positive and negative 
electricity evoked by the odorous substance. 
In‘carrying out the experiment care was taken to allow sufficient 
time for the determination of the faint charge, since it is obvious 
that, in view of the large size of the disc, its capacity should not 
be neglected, so that several seconds will elapse before a sufficient 
amount of electricity has been obtained to be visible on the electroscope. 
The results are to the following effect : 
EABLE NE Arth 
Critical distance (cm.) 
Aliphatic BRE pe OE 
alcohols | | | 
On, 02. 0.1 n 
hers 
: Methylalcohol 46 26 3 
Ethylalcobol | 103 TE ds 
Propylalcohol | 145 80 | 12 
Butylalcohol = | «17010017 
Isoamylalcohol 187 135 130 
Alcohols. 
_---+ critical distance 0.3 norm, 
smell int, (logarithm.) 
ed 
methyl ethyl propy| butyl amyl 
Dig, 1. 
1) No manner of charge was given in our experiments by pure water under 
the experimental conditions, carefully observed, viz. an overpressure of two atmos- 
pheres, perfect cleanness of sprayer, glass vessels, air-chamber of 2 m?. capacity. 
long metallic pressurecircuit. 
22 
Proceedings Royal Acad. Amsterdam. Vol. XIX. 
