74 GERMICIDAL ACTIVITY OF EUCALYPTUS OILS, i., 



two inches of wire further up with tin by means of a soldering 

 iron. This extra tinning was found to be necessary to prevent 

 the wire rusting and vitiating the tests. A strand of thick 

 darning cotton (Chad wick, No. 10) was looped on the eye of the 

 wire with a wire hook, and the loose ends were cut, leaving two 

 strands about a centimetre in length. The wires were sterilised, 

 the cotton was touched with a loop of infected serum and put 

 into the diluted oil. The wire loops could be used over and over 

 again, but the cotton had to be renewed after every test. 



The infected cotton remained in the diluted disinfectant for 

 two hours at 20", when the wire was withdrawn, and the excess 

 of oil was removed from the cotton by twirling the wire against 

 the inner sides of the tube. The cotton and wire were then 

 dropped into a tube containing three c.c. of meat-extract broth,* 

 after passing the stem of the wire through a name. The tubes 

 of broth were incubated at 37°, and were observed daily for four 

 days. 



The Eucalyptus oils do not appear to have previously been 

 tested by means of their dilutions in a neutral oil. Some years 

 asro, Cuthbert Hall examined the activities of the undiluted oils. 

 His paper was presented as a thesis for the doctorate of Sydney 

 University, and was subsequently issued as a private publica- 

 tion.! From the booklet, I have in the following paragraphs 

 abstracted the main items which bear upon this investigation. 



The action of the oils upon the staphylococcus and the colon 

 bacillus was investigated, and it was found that the constituents 

 of the oils possessed individual activities. Aromadendral was 

 most active, as it destroyed the staphylococcus in 15 minutes. 

 The other constituents took much longer — phellandrene 2| hours, 

 piperitone and dextro-pinene each 4 hours, la±vo-pinene b\ hours, 



* This was Mar-time broth; it had no peptone. A litre of tap-water 

 contained 20 grams of Lemco meat-extract and 5 grams of common salt; 

 the reaction was made decidedly but not strongly pink to phenolphthalein. 

 It gave a ery satisfactory growths. 



I On Eucalyptus Oils especially in relation to their Bactericidal Power. 

 By Cuthbert Hall, M.B., Ch.M. [Little and Co., The Argus Printing 

 Works, Parramatta, 1904). 



