1915] BOVIE—SCHUMANN RAYS 147 
glass tube. A gold wire was drawn down exactly to fit this space. 
The wire was coiled spirally around the quartz tube as shown at G. 
The distance between the inlet tube B and the outlet tube C was 
16 cm. The quartz tube was 5 mm. in outside diameter, and the 
gold wire made 15 turns about the quartz tube. The solution 
under treatment was thus spread into a thin layer, 0.3 mm. in 
thickness, and took a spiral course through the sterilizer. The 
discharge tube was filled with rarefied unwashed hydrogen, con- 
taining carbon dioxide as an impurity, since a discharge tube 
filled with pure hydrogen would not emit light of wave-lengths 
between 2000 and 1675 Angstrém units. The carbon dioxide 
which the tube contained filled in this gap. This is important, for 
it is highly improbable that the strong 1600 lines of the hydrogen 
spectrum, because of their small penetrating power, could be 
effective in sterilizing the water. Any virtue which the sterilizer 
might have must be due to its emitting light between wave- 
lengths in 1850 and 1675 Angstrém units. 
A discharge tube filled with carbon dioxide is short- lived. After 
the tube has been excited a few hours, the carbon dioxide dis- 
appears and is replaced by hydrogen. To insure a carbon dioxide 
spectrum, the discharge tube was filled and pumped before each 
experiment. 
The discharge tube was excited by a current of 14 milliamperes, 
and Cambridge city water was passed through the sterilizer at the 
rate of 10 cc. per minute. By this treatment the bacterial count 
of the water was reduced from 50 to 4 per cc., and the fungal count 
from 3 to r per cc. In none of the experiments was the water 
completely sterilized. 
It is apparent that a hydrogen discharge tube such as is 
described by BiLLoN-DAGUERRE is not an efficient source of light 
for photo-sterilization. 
LABORATORY OF PLANT PHYSIOLOGY 
HARVARD UNIVERSITY 
LITERATURE CITED 
1. BILLON-DAGUERRE, Stérilisation des liquids par les radiations de trés courte 
longuer d’onde. Compt. Rend. 149 and 150: 1909 
