176 
examined in a simple olfactometer these solutions yielded a very 
weak sensation of smell, which could readily be determined by the 
length to which the olfactometrical cylinder had to be moved out, 
in order to procure a minimum perceptibile. 
Table Ia shows the olfaction-values of the solutions when we 
try to find the “Reizschwelle”. Table 15 gives of the same substances 
the lengths to which the cylinder has to be moved out when we 
search for the “Erkenntnisschwelle”’. 
TABLE la. TABLE 10. 
The odorous substances arranged in the | The odorous substances arranged accord- 
ing to the “Erkenntnisschwelle” in solu- 
order of the smell-intensity of solutions 
yielding an approximately equal, extre- 
mely weak electrical charge tions yielding an approximately equal, 
(0,1—0,2 scale-marks). extremely weak electrical charge. 
S : … | “Reizschwelle” »Erkenntnis- 
ubstances (arranged in a ate Substances arranged \schwelle”incen- 
ascending order of which the cylin- in ascending order of ae i eae 
-i i : -j i e n is 
smell-intensity). der is moved out. smell-intensity. ren nk 
Caproic acid 5 Caproic acid 9 
Artificial moschus 1 Artificial moschus 8 
Valerianic acid 1 Valerianic acid 5 
Amylalcohol 1 Amylalcohol 5 
Cumidin 1 Cumidin 5 
Allylalcohol 1 p. Xylenol 5 
Iso-amylacetate 0.5 Allylalcohol 3 
Terpineol 0.5 m. Xylidin 2.9 
Skatol 0.5 o. Toluidin 155 
Indol 0.5 p. Toluidin AGS) 
Pseudocumol 0.3 Iso-amylacetate 153 
Xylol 0.3 Terpineol 1 
o. Toluidin 0.2 Skatol 1 
Anilin 0.2 Pseudocumol i 
p. Xylenol 0.1 Anilin 1 
m. Xylidin 0.1 Thymol 1 
m. Toluidin 0.1 Benzol 1 
Thymol 0.1 Toluol 1 
Benzol 0.1 Xylol 0.6 
Toluol On! Indol 0.5 
Naphthalin 0.1 Naphthalin 0.5 
m. Xylenol 0.1 m. Xylenol 0.4 
Guaiacol 0.1 Guaiacol On 
Nitrobenzol 0.1 Nitrobenzol 0.1 
Pyridin 0.1 Pyridin 0.1 
Vanillin 0.05 Vanillin 0.1 
Average 0.54 c.m. Average 2.16 c.m. 
In the latter case, it is true, the values are based upon the inten- 
sity of the sensation, however the psychological consciousness of the 
quality had been previously established. 
