15 
the condition of this supernatant liquid and residue as regards sterility. 
In order to ascertain this, inoculations were made from the super- 
natant portion af each flask by transferring with a sterile pipette -1 or 
5 drops of it to nutrient bouillon and placing it in the incubator at 
37^ C. Considering the absence of growth under these conditions as 
evidence of sterility, the following tables will show the results obtained 
with the supernatant portion of the difl'erent series of flasks containing 
various percentages of zinc chloride: 
Table A . — Germicidal influence upon the supernatant liquid when zinc chloride is added 
to ordinary sewage and kept at room temperature. 
[— means growth; — means no growth.] 
Table B , — Germicidal influence upon the supernatant liquid when zinc chloride is added 
to equal volumes of ordinary sewage and tap water and kept at room temperature. 
Percentage ZnCU. 
Time of exposure in days. 
6. 7. 9. 
10. 
12. 
1 14. 
1:500 
+ . + 
+ 
1:200 
-i- 
+ , + 
-i- 
+ 
1.100 
+ 
-f + 
+ 
--F 
— 
1: 75 
-h + 
+ 
— 
— 
1:50 
+ 
-i- + 
— 
— 
— 
1:45 
+ 
-f - 
— 
— 
— 
1:40 
+ 
— “■ 
Table C . — Germicidal influence upon the supernatant liquid u'hen zinc chloride is added 
to ordinary sewage and bouillon and kept at room temperature. 
From the above results it will be observed, as might be expected, 
that the microorganisms remained viable longer in the flasks contain- 
ing the most nutrition, other things being equal. The supernatant 
portions of the two series of flasks containing no nutrient bouillon 
were sterile at the end of 14 days in a proportion of zinc chloride of 
