16 
1:100, while in the series to which bouillon was added it was sterile at 
the end of the same time (11 days) only in a proportion of 1: 75. 
Inoculations from the residue in the bottoms of these same flasks 
made into nutrient bouillon in the same way as the above showed that 
some microorganisms, probably spore-bearing, were still viable and 
capable of multiplying in all the flasks after standing 21 days. As can 
be observed, the largest percentages of zinc chloride used in these 
series of experiments were 1 : 10. 
A series of flasks was next prepared containing ordinaiy sewage, to 
which was added particles of vegetable matter, such as cabbage, etc. 
Zinc chloride was added in derinite quantities varying from 1: 1,000 to 
1:10. The flasks were kept at room temperature. At the end of 11 
days the particles of floating cabbage were still well preserved and the 
supernatant liquid was a straw color in those flasks containing zinc 
chloride in a proportion as large as 1:200. 
In the flasks of this series containing zinc chloride in the proportion 
as small as 1: 300 the liquid took on a brownish cloudy appearance and 
the particles of cabbage gradually disappeared. This decay and dis- 
appearance of the vegetable matter was of course more rapid in the 
higher dilutions of zinc chloride. 
In the foregoing experiments for ascertaining the antiseptic prop- 
erties of zinc chloride the solutions always became decidedly acid, 
which has a certain tendency to inhibit decay and the growth of micro- 
organisms. 
GERMICIDAL PROPERTIES. 
For determining the germicidal value of chloride of zinc various 
deflnite percentages were prepared in distilled water and about 1.5 
c. c. of each strength placed in a test tube. These were then inocu- 
lated by adding 0.5 c. c. of an emulsion, in distilled water, of the 
organisms to be used, carrying over as little organic matter as possible. 
Cultures of the diflerent organisms used for this purpose were 
grown on agar slants for 21 hours at a temperature of 37° C. 
Plants were then made in sterile bouillon at definite intervals by 
means of a wire loop. They were then placed in the incubator at a 
temperature of 37° C. and the results noted from day to day. 
The results of the germicidal action of zinc chloride upon pure cul- 
tures of the diflerent organisms used are shown in the following tables: 
[ + means growth ; — means no growth.] 
BACILLUS COLI COMMUNIS. 
Percentage 
Time of exposure in minutes. 
used. 
5. 
7. 
8. 
10. 
15. 
20. 
25, 
30. 
40. 
50. 
60. 
5 
+ 
+ 
+ 
-1- 
+ 
']- 
+ 
+ 
+ 
+ 
+ 
10 
j + 
-1- 
+ 
4- 
+ 
4- 
— 
— 
— 
— 
— 
15 
! -h 
+ 
4 - 
4- 
— 
— 
— 
__ 
— 
— 
•25 
1 + 
+ 
+ 
