SY) A. Kk. PENFOLD AND R. GRANT. 
In preparing the emulsions for determining the germicidal 
value of the different units 1% in 7% rosin soap solution was 
decided upon as being the most suitable for working pur- 
poses, particularly with regard to its commercial applica- 
tion. The soap solution alone was tested for an hour with the 
Bacillus typhosus culture and was found to have no germi- 
cidal properties. In arriving at this decision it is as well to 
bear in mind that two lines of investigation are available 
in this particular branch of research. Firstly, to find out 
whether the substances under examination have any germi- 
cidal value; secondly, to establish a value for those proper- 
ties. The former is valueless from an economic standpoint 
unless the latter is obtained. Dr. Cuthbert Hall in his 
experiments on “‘ Hucalytups oils, especially in relation to: 
their bactericidal power’’ (1904), according to our con- 
clusions, only dealt with the former. Dr. R. Greig Smith’ 
in following on the work of the former used Micrococcus 
aureus and Bac. coli communis for determining the bacteri- 
cidal powers of eucalyptus oils. A continuation of this work 
by the same author, Vol. 42, part 11, page 311, same Pro- 
ceedings, entitled ‘‘The germicidal activity of the Huca- 
lyptus oils,’ gave co-efficients to the various species of oil 
using B. coli commumis as the test organism. 
In all our experiments we used the standard organism 
B. typhosus as adopted by Ainslie Walker and known as 
the Rideal-Walker test for determining the germicidal 
value of disinfectants. B. typhosus is a more resistant 
type of organism than B. coli communis from an epidemio- 
logical point of view. The strain used was one that has 
been used for a number of years by the Department of 
Public Health, Sydney, for determining the Rideal-Walker 
values of hundreds of disinfectants submitted there. The 
suspensions of bacilli used were standardised 24 hours broth 


1 Proc. Linn. Soc. N.S,W., Vol. 44 (1919), part 1, p. 72. 
