PHYSICS ABSTRACTS 
THE ATTENUATION FACTOR IN ACOUSTIC WAVE 
FILTERS 
- H. B. PEACOCK 
Abstract 
A theory has been formulated by Dr. G. W. Stewart by which 
it is possible to determine the selective transmission in three types 
of specially constructed acoustic wave filters. The theoretical at- 
tenuation factor also has been worked out and shows fair agree- 
ment with experimental results. Theoretical values of the attenu- 
ation were computed for one filter of each type and, from these 
values, the theoretical transmission curves were determined. The 
types of filters were the low-frequency and high-frequency — pass, 
and the single band. 
State University oe Iowa. 
COEFFICIENTS OF DIFFUSION OF SALT VAPORS IN 
THE BUNSEN FLAME 
GEORGE E. DAVIS 
Abstract 
The coefficients of diffusion of alkali salts in the Bunsen flame 
have been determined by a photographic method which is a modi- 
fication of the method used by H. A. Wilson. The values of the 
diffusion coefficients obtained for sodium, potassium, and caesium 
salts, are roughly proportional to the reciprocals of the atomic 
weights of the metals. This is what we should expect from kine- 
tic theory, if we consider the luminosity to be due to free metal 
atoms in the flame. Lithium salts, however, are found to have a 
lower coefficient of diffusion than sodium salts, and hence their 
metal atoms are probably free only a part of the time the vapor 
is in the flame. 
Department oe Physics. 
Iowa State College. 
