244 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
ACTION OF THE ULTRA-VIOLET RADIATION UPON TOXINES. 
It may be asked whether the poisons resulting from the microbes 
and which may be contained in the water (in small quantities, of 
course) are destroyed by the ultra-violet rays. We are in a position 
to answer this question. 
The toxines such as we have been able to obtain in our bacteriolo- 
gical laboratories can not be destroyed by the ultra-violet rays since 
they form a liquid very rich in colloidal matter and therefore not 
transparent to this radiation. It would therefore be necessary to 
work with very thin strata of the liquid. We have demonstrated this 
with the tetanus toxine.!. A very long exposure (one hour under | to 
2 cm.) scarcely weakened the toxic power of a fibrous culture of the 
Nicolaier bacilli. If the toxine is sufficiently diluted with water, say 
1 part in 2,000, it is neutralized in a few minutes.? Cernovodeanu 
and V. Henri have obtained similar results.® 
Toxines are, therefore, very sensitive to the action of the ultra- 
violet rays provided they are so diluted as not to be protected from 
them by their colloidal state. Such toxines as are apt to be found in 
potable water will, therefore, be destroyed as well as the micrcbes. 
PRACTICAL APPLICATIONS. 
Are the preceding results capable of practical application? Surely. 
They give rise to a simple and very powerful new method of steriliza- 
tion, applicable wherever an electrical current (continuous or trans- 
formed) is at hand. 
The water is not changed or warmed. Nor is it harmful for drink- 
ing. 
The only condition necessary for the successful sterilization is the 
transparency of the water; filtration would, therefore, be necessary 
for muddy water. 
Our apparatus can serve three purposes: First, household steriliza- 
tion (special small-sized apparatus adapted to the supply pipe of 
an apartment). Second, sterilization for larger establishments (appa- 
ratus with greater flow of water placed at the entrance of the water 
into the building and furnishing sterile water to all the faucets of a 
hotel, barracks, hospital, school, etc.). Third, sterilization of water 
for a city (apparatus capable of purifying, if necessary, several 
thousand cubic meters of water per day; apparatus with which trials 
are actually being made). 
For household apparatus, and even for such as is destined for larger 
establishments, it is desirable to have some automatic device to stop 
1 5! Courmont et Th. Nogier. C. R. Ac. des Sciences, 2 mars 1909. 
2J. Courment et Th. Nogier. C. R. Ac. des Sciences, 2 aofit 1909. 
3 Cernovodeanu et V. Henri. C. R. Ac. des Sciences, 2 aofit 1909. 
