444 
PHYSICS: NICHOLS AND HOWES 
or salts are the means by which these stimulations are brought about, 
as suggested in my ion-protein theory and by the investigations of 
Lasareff. 
1 Loeb, The dynamics of living matter, New York, 1906. Physiologische Tonenwirkung, 
Oppenheimer's Handbuch, Vol. 2, Jena, 1909. 
2 Loeb, Amer. J. Physiol., 3, 434 (1899); 6, 411 (1902); and /. Biol. Chem., 1, 427 (1906). 
3 Lasareff, Arch. ges. Physiol., Bonn, 135, 196 (1910). 
^Lasarefif, Arch. ges. Physiol., Bonn, 154, 459 (1913). 
6 Loeb, Science, 40, 316 (1914) ; Amer. Nat., Boston, 49, 257 (1915). 
THE POLARIZED FLUORESCENCE OF AMMONIUM URANYL 
CHLORIDE 
By E. L. Nichols and H. L. Howes 
PHYSICAL LABORATORY. CORNELL UNIVERSITY 
Read before the Academy. April 20. 1 9 1 5. Received June 2.1915 
The remarkable fluorescence spectrum of ammonium uranyl chloride 
(U O2 CI22NH4CH-2H2O), which has been described in a recent paper 
read before the American Physical Society, consists of several equidistant 
groups of bands. Each group 
contains five nearly equidis- 
tant bands, b, c, d, e, and a 
(fig. 1) and the spacing re- 
peats itself with such preci- 
sion in successive groups that 
the homologous bands, bi, 62, 
bs, — Ci,C2, C3 (see fig. 2) form 
series having a common and 
constant frequency interval. 
Observations at the tem- 
perature of liquid air show 
that these bands are really 
doublets, unresolved at -|- 20° 
but separated at low tempera- 
tures; a dim companion of 
the band as observed at 
-1-20° increasing greatly in 
brightness as the temperature 
falls while the dominant member becomes relatively feeble or in some 
instances disappears altogether. At low temperatures, as is usual with 
the uranyl compounds, all the bands are very narrow so that overlap- 
ping components which are entirely indistinguishable at the tempera- 
