GOETZ AND PREINING 
N|O 
| (1109) | (mm) 
dels pli aanl anal Bee eee) 
3 4 6°78 (0 
Ly(cm) 
15°20 
30 ree 
Fig. 3—Particle diameter (log d) versus corresponding deposit length 
(log La) for various operating conditions N, O of the aerosol spectrometer 
Figure 4b demonstrates the laminarity of the 
flow in the channels by the linear ‘shadow,’ that 
is, absence of particles in the deposit, “down- 
stream’ from 1 or 2 inserted thin pins, protruding 
from the foil into the channel at P. 
ANALYSIS OF ABROSOL SPECTRA 
The analytic procedure used for the evaluation 
of the aerosol spectrum on a foil varies with the 
type of required information. This may be rela- 
tive, such as the size or mass distribution of the 
aerosol particles, or the distribution of certain 
chemical or radioactive constituents over the 
size range, represented by the spectrum; or it 
may be absolute, such as the numerical or mass 
concentration of aerosols. 
The basic considerations and the method of 
analytic procedure, resulting therefrom, are dis- 
cussed below. 
The geometry of the foil deposits—Since the 
Stokes’ diameter of a particle determines its locus 
of deposition, the geometrical relationships to 
which these deposits are subject represent the 
key to all analytic procedures. These relations 
are as follows. 
The dimensions of the foil correspond to those 
