STERILIZATION OF DRINKING WATER—COURMONT. 241 
Bacillus mesentericus ruber, whose refractory spores will resist the 
temperature of boiling water sustained for several hours.’’ In Table 
IIT is given a typical example of his results. 
TABLE III.—Sterilization of water polluted with Bacilli mesentericus. 
Common bacilli 
per liter in Bacilli mesenterici per liter 
: in water— 
Flow per water— 
Dec. 30, 1909. jG 
Before. After. Beiore. After. 
Liters. 
POON. ee. aa egal hart en YA Set BGKOmeaeticeie ese cect us 128, 200, 000 0 in 400 c.c. 
MD OOSSS Ae SEE EREL LS. oo 5S ae oA 78.0 | 3,615,000 | ~ 0 76, 900, 000 0 in 400 c.c. 
iTS GUS oye ee ee Oe ee oe See ce GEO CY | BR eee ey (mei ME 50, 000, 000 0 in 400 c.c. 
Motaltand meant. 22 . SA 81.6 | 3,615,000 0 85, 033, 000 0 in 1,200 c.e. 
| 
Thus, with water polluted with 128,200,000 bacilli per liter and 
whose spores will resist boiling for several hours, sterilization is almost 
immediate (in the time necessary for the water to pass through the 
apparatus at the mean rate of 81 liters per hour. This experiment 
should be of special interest to surgeons. 
Such are the results. Let me repeat my earlier conclusions, which 
have been but strengthened: The sterilizing power of the ultra- 
violet rays emitted by a quartz mercury-vapor lamp immersed in 
water, face to face with the microbes contained in that water, is so 
great that the problem of the integral, rapid, and economical steril- 
ization of clear water by this procedure may be considered as solved. 
MUST THE QUARTZ MERCURY-VAPOR LAMP BE IMMERSED IN THE WATER ? 
Should the lamp be immersed in the water or merely placed just 
above it? Immersion is certainly preferable. 
Naturally we tried an apparatus in which the mercury-vapor 
lamp was placed just above a thin sheet of water for sterilization. 
The water was sterilized. However, practically and economically, 
immersion is necessary. The reasons for this are easily given. 
The greatest reason is that the utilization of the sterilizing power 
of the lamp is infinitely more perfect when within the mass of water 
itself. The water is then in close contact with the source of the rays; 
all of the rays emanating in all directions are used. A lamp conse- 
quently sterilizes a far greater volume of water when it is immersed 
than when merely placed close to the water—that is surely clear. 
Economically, therefore, immersion is very advantageous. 
And yet further: Immersion seems necessary for the life of the 
lamp as an emitter of ultra-violet rays. The quartz tube of such a 
lamp, working in the air, is warmed to some 700° or 800°C. H. Bor- 
38734°—sm 1911——16 
