955 
of one odorous substance are neutralized by 5 olfacts of another, 
na and nx 6 olfacts will similarly neutralize each other. What 
strikes us as novel and remarkable, is that a typical compensation 
was found with odorous substances of one and the same homologous 
series. 
Complete compensation may of course also be obtained among 
four homologues. We subjoin the results of an experiment with the 
quadruple. olfactometer 
Number of olfacts Hon EGE | gn 
ST Sean Sensation 
Benzol Xylol Toluol Pseudocumol 
ne 11.4 | 12 5D (none) 
12 11.4 10 a. pseudocumol-like 
12 8.6 12 5,0 benzol-like 
12 13:07 411 12 55 xylol-like 
12 0 | 12 Oh benzol-toluol-like 
Another similar compensation is e.g. benzol 12, pseudoeumol 4.2, 
toluol 12 and xylol 6.5 olfacts. This combination also gives complete 
compensation. Likewise toluol and pseudocumol can compensate 
xylol alone, e.g. 14 olfacts of toluol and 3.9 olfacts of pseudocumol 
with 13.5 (7.4 + 6.0) olfacts of xylol. 
SUM a ARN: | 
1. The liminal stimulus of the odorous substances of the methyl- 
benzol series exhibits for the first four terms a fairly proportional 
decrease with increasing methylation. Consequently the liminal smells 
intensify as the series advances. Moreover they pass from a marked 
empyreuma (benzol-toluol) to a predominating aroma (xylol-pseudo- 
cumol) until ultimately a phenol-like odour (durol) comes to the front. 
Meanwhile the smell-intensity lessens, so that a prolonged methyl- 
ation may perhaps give rise to inodorous compounds. 
2. The rate at which the odour is spread by diffusion is nearly 
the same for the four homologues examined. 
3. The electric charge produced by spraying an equimolecular 
sohition of the substances augments slowly at first, afterwards more 
rapidly as the series advances. 
