1445 
In subsequent experiments this was repeated for guajacol. 
The minimum perceptibile in ZWAARDEMAKER’S camera amounted 
for my olfactory organ with guajacol to 6.4.10—'° grms per ce. of 
air. This concentration corresponds with the value of 1 olfactie. 
After one drop of guajacol was evaporated the camera of 400 liters 
contained 8.2.10-§ grms per cc. of air, in other words 128 of my 
olfacties. [ remained for 7 minutes in the perfumed air. 
The same was repeated with caproic acid in a third series of 
experiments. 
The minimum perceptibile for caproic acid in ZWAARDEMAKER’S 
camera per cc. of air was 3.3.10—!° germs, corresponding with one 
olfactie. | 
After evaporation of 0.5 drop of caproic acid the camera which 
encloses the observer’s head, contains per c.c. of air: 3.35.10—§ grms 
of this odorous substance. This concentration represents 118 of my 
olfacties. I remained for 6 minutes in the perfumed air before 
making measurements. 
In these 6 minutes my organ got completely exhausted, so that 
no observations could be made either when breathing deeply or 
when sniffing. 
When making a measurement in an inodorous surrounding with 
the olfactometrical cylinders that I used, the min. pere. for my 
organ corresponded with 
airy lacetale.: samen wedt Ue eeu: 
NUTOURNZO! ne OSR 
(erpimeol sn ae eh 
Artif. MOSChUB: A Sn EO 
allvialeoha! … torn Tanen OREN 
gaapacol:” nr irt OLS Eee 
CABEDICSAEId, ha ah Urata: 
AOL REESE DEE 
BERDE rs Re eee 
However, performing the same determination in the perfumed air 
of the camera, the results are quite different. 
With a view to making these determinations in the camera an 
olfactometer is attached to the bottom, through which an inspiration- 
tube of the olfactometer projects. This inside tube of the olfactometer 
can be freed from adhering odour by means of a current of air 
passing through the long movable glass-tube, which can be inserted 
or disconnected at will. During the measurement the turned up part 
