STERILIZATION OF DRINKING WATER—COURMONT. 237 
tericidal properties of the ultra-violet rays from the quartz mercury- 
yapor lamps), *.(*.i* 
Let us state our method of procedure. At first we used the classical 
lamp of Kromayer. A metallic tube, provided with several test 
holes, and closed at one end by a quartz window (fig. 1), was placed 
face to face with a Kromayer lamp. The tube, filled with polluted 
water, was thus subjected to the radiation from the lamp for various 
lengths of time. Samples of the water were taken from each test 
hole by means of sterilized pipettes. Preliminary tests showed us 
that the water was very rapidly sterilized to about 0.30 meters from 
the lamp. Water was therefore permeable to the bactericidal rays 
from the lamp, and especially to those which killed very rapidly the 
microbes contained in the water. The most important fact for our 
purpose was therefore established. 
We next had constructed some long lamps (0.15 to 0.30 meters) of 
the form shown in figure 2. These lamps were hung in the axis of a 
metallic cylindrical box, about 1.20 meters in diameter, and holding 
110 liters (fig. 2). This box could be filled through an orifice in the 
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UPUPRRREPEREY! i : 
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LANNY 
Fia. 1.—Tube for determining to what distance water may be sterilized. 
top; a cock was provided at the bottom. Through a large glass win- 
dow could be safely noted what happened within. The box was 
mounted on a pivot, so that it could be tilted for lighting the lamp. 
When we would experiment with thin layers of liquid, a glass basin 
could be introduced through the window and placed under the lamp. 
Finally, a single lamp was placed in the axis of a portion of a tube, 
0.60 meter in diameter, so that the walls of the latter were nowhere 
farther than 0.30 meter from the luminous source. In fact, the dis- 
tance could have been made much greater; we were convinced of that 
later. 
With this metal box we have made a great number of experiments, 
which enable us to affirm the rapid and complete sterilization of 
water, no matter how polluted, provided only that it be transparent. 
Later my collaborator, Th. Nogier, constructed a set of apparatus 
for the application of our discovery. 
The problem of the sterilization of potable water in private houses 
and in small public establishments (hotels, barracks, hospitals, etc.) 
