23 
111 the more concentrated solutions so much of the zinc chloride 
is carried over on the thread that it was found better to use two 
tubes of bouillon for each thread, one being used to wash out most of 
the zinc chloride, after which the thread is planted in another tube. 
Both tubes were then incubated at 37^ C. The results obtained with 
the tubes in which the threads were placed after washing were much 
more uniform and satisfactory than those in which the threads were 
washed. 
The following are the tabulated results with 7 days old spores of 
B. anthracis on silk threads exposed in various percentages of zinc 
chloride prepared in distilled water: 
[-f- means growth; — , no growth.] 
Percentage 
Time of exposure in days. 
1 
ZnCl,. 5 
10. 
15. 20. 25. 
40. 
5 + 
10 - 
-f 
. ill 
4- ' 
25 - 
' 50 - 
i I T 
The spores of B. suhtlUs on silk threads exposed in a 100 per cent 
solution of zinc chloride were viable at the end of the tenth day, after 
which time the silk threads were so completely destroyed by the action 
of the zinc chloride that further planting was impossible. 
By substituting linen threads, which are not destroyed by a 100 per 
cent solution of zinc chloride, for silk threads in the above experiment 
it was found that, the spores of B. suhtilis were still viable after thirty 
days exposure. 
SU.VMARY AND CONCLUSIONS. 
Chloride of zinc has had more or less reputation as a deodorant, 
antiseptic, and disinfectant for manv years, but it has gradually been 
realized, that it was much overrated, particularly as an antiseptic and 
disinfectant, and its use for these purposes is becoming more and more 
limited. 
It is used as an ingredient of some proprietary preparations found 
on the market and vaunted for their disinfectant powers, but its role 
is principally that of a deodorant. Even as a deodorant there are 
certain objections or limitations to its use. but for the sanitarian it is 
the only property of any practical value that it possesses. 
hen zinc chloride is added to sewage in dilutions as high as 
1:10,000 a diminution of offensive odors is appreciable: but this effect 
is only transitory. As the percentage of zinc chloride is increased its 
deodorizing effect becomes more marked and more permanent. It is a 
fairly reliable deodorant in proportions varying from 1:500 to 1:200. 
but the exact percentage to be used in each case depends upon the 
kind and condition of material to be acted upon. 
