and 
Bae 
It will be well though, to take caproie acid instead of valerianie 
acid, the latter being too soluble and also lowering the surface- 
tension to such an extent that in less than no time it spreads over 
all surfaces that are moist at all. The persistent adsorption largely 
encumbers the technical conduct of the experiments. Generally 
speaking adsorption is a serious impediment in odorimetry, whatever 
method may be followed. With caproic acid its influence is felt far 
less than with valerianic acid. 
The stimulus limen of my olfactory organ is for terpineol at about 
1 mm. of the cylinder-length; for guaiacol at about 2 mm.; for 
caproie acid at about 1 mm. on the double olfactometer just described. 
The terpineol limen corresponds with 4 micrograms per litre of air, 
that of guaiacol with +; microgram, that of ecaproie acid with st> 
microgram (1 microgram = 1.10-© gram). 
The odorometrical coefficients *) of the saturated solutions are respect- 
ively 10, 5 and 10, i.e. the smell stimuli, evoked by means of the 
olfactometer and expressed in the centimeters to which the cylinders 
have been moved out, must be multiplied respectively by 10, 5 and 
10 to ascertain the number of ‘‘olfacts” with which they correspond. 
The compensation-point is arrived at when in the double olfac- 
tometer the odorous cylinders are pushed off the inhaling tubes 
over lengths that stand to each other: 
for terpineol and guaiacol, as 4 cm. to 5 em. 
a 55)» HORE DIE LACIE Sg? ene lng Se Neg 
EE) guaiacol 2: LE) > EE) 1 2 2 1 LE) 
A somewhat greater length of one odorous cylinder makes its 
smell come to the front and vice versa. Equilibrium is also found 
with multiples of the proportions, though a weak antagonism some- 
times occurs. 
When mixing in the same proportions the saturated solutions 
that are decanted off into a separator, we obtain mixtures none of 
which will be inodorous, as stated above. It is true, their scent is 
considerably weaker than that of the original concentrated solutions 
from which they have been derived. The odorimetrical coefficients 
proved to be: 
for the terpineol-guaiacol liquid mixt. 3—4 
5 + »  -caproic acid al aoe 
5) zv Suaaede= al x; sid Dae 
all being obviously smaller than the coefficients found for each of 
the constituents (terpineol 10, guaiacol 5, caproic acid 10). 
1) H. ZWAARDEMAKER, Physiol. d. Geruchs, Leipzig, 1895 p. 185. 
