19 
Table B . — Germicidal results when the B. pyocyaneus was exposed in percentages of zinc 
chloride prepared in distilled icater. 
Time of exposure. 
Percentage ZnCL. 
10 min- 
20 min- 
30 min- 
2 
3 
5 
7 18 ■ 
utes. 
utes. 
1 utes. 
hours. 
hours. ' 
hours. 
hours, hours. 
I 
■ 5 
' 10 
+ 
_ J 
+ 
1 
+ 
~r 
- 
, ^ 
i ^ i 
- 
-F 
— 
Table B1 . — Same as Table B, when nutrient bouillon was used instead of distilled waters 
Time of exposure. 
Percentage ZnCl-:. 
1 
10 min- 
utes. 
20 min- 
utes. 
30 min- 
utes. 
2 
hours. 
3 
hours. 
5 
hours. 
hours. 
18 
hours. 
5 
_ 
_u 
+ 
1 -F 
; IB 
-i- 
-j- 
-F 
— 
— 
— 
' — 
' 25 
1 
-F , 
+ 
“ 
i “ 
These results, confirmed by repeating several times, show that when 
zinc chloride is prepared in nutrient bouillon its germicidal value is 
not appreciabh" infiuenced by the organic matter contained therein as 
compared with its value when prepared in distilled water. 
As has alread}^ been stated, zinc chloride produces a heavy white pre- 
cipitate when added to nutrient bouillon. Consequently experiments 
were performed to determine the relative germicidal properties of this 
precipitate as compared with those of the clear transparent portion 
that remains above. A 10 per cent solution of zinc chloride in nutrient 
bouillon was prepared and allowed to settle. The clear supernatant 
portion was then siphoned off and 10 c. c. of it placed in a test tube. 
Ten cubic centimeters of the precipitate was placed in another test 
tube. Beth tubes were then inoculated with a 21-hours-old agar culture 
01 Bacillus jyyocyarieus^ after which plants at definite intervals were 
made from each tube into nutrient bouillon in the usual wa}'. 
The results of the inoculations made every hour show that the 
Bacillus pyocyaneus was killed within 3 hours in the tube containing 
the supernatant portion, and within 1 hours in the tube containing 
the precipitate, indicating that the supernatant portion has slighth' 
greater germicidal powers than the precipitated portion. A similar 
experiment in which Bacillus typhosus was substituted for Bacillus 
pyocyaneus shows that this organism was killed in both tubes within 
2 hours. 
GERMICIDAL INFLUENCE OF ZINC CHLORIDE ON SEWAGE. 
For this work an average sample of sewage was selected. Definite 
quantities were placed in Erlemneyer ffasks and heavily inoculated 
with a watery suspension of a 21-hours-old agar culture of Bacillus 
pyocyaneus. Various definite percentages of zinc chloride were then 
