- 38 - 



For the bacteriological experiments two different bacteria of high 

 resisting power were employed, viz., the stronger Staphylococcus pyogenes 

 aureus, and the weaker Bacillus coli communis. 



The experiments made by Hall showed that eucalyptol as such, 

 with regard to its antiseptic properties, is inferior to all other constit- 

 uents of the eucalyptus oils, and that aromadendral, piperitone 1 ), and 

 phellandrene are here particularly active. 



For example, Bacillus coli communis is only destroyed after 8 hours 

 by eucalyptol, whilst the same effect is obtained with aromadendral 

 in 10 minutes, with piperitone in 40 minutes, and with phellandrene 

 in 1Y2 hours. Somewhat less powerful, but stronger than eucalyptol, 

 are d- and 1-pinene and aromadendrene. Eudesmol also proved to 

 be a strongly antiseptic substance, as it enhanced the activity of 

 eucalyptol and piperitone, which served as solvents for this body. 



The conditions are decidedly more favourable for eucalyptol when 

 it contains ozone which is formed by the slow oxidation of the terpenes, 

 especially phellandrene and aromadendrene 2 ). Under such conditions 

 the vitality of Bacillus coli communis ceases already after 15 minutes, 

 so that here eucalyptol is only exceeded in activity by aromadendral. 



The results of the action on Staphylococcus were entirely analogous. 



The results of the tests with eucalyptus oils naturally correspond 

 to the content of the above-named constituents in the oils. To this, 

 however, a further essential factor must be added, consisting of the 

 presence of free acid (acetic acid) and consequently of a possible content 

 of iron or copper originating from the vessels in which the oil is kept, 

 by which the antiseptic activity of the oils is increased in a marked 

 degree. However, as a rule this does not carry much weight, as the 

 oils intended for medicinal purposes are always rectified and neutral. 



As it is for the rest still an open question whether oil containing 

 aromadendral can be used with advantage for medicinal purposes, 

 and as moreover eucalyptol is the constituent which occurs chiefly in 

 eucalyptus oil, Hall arrives at the conclusion that in the first place 

 "ozone" is of very considerable importance for the antibacterial power 

 of eucalyptus oils, and that the oils, in order to enhance their anti- 

 septic properties, should be "ozonised" by allowing light and air to 

 act upon them for a prolonged period (at least two months); this is 

 done by closing only loosely with plugs of cotton-wool the vessels 

 in which the oil is kept, and frequently shaking up the oils which 

 are exposed to sunlight. 



*) With regard to piperitone, see p. 33, note. 



2 ) It is a long-known fact that in the slow oxidation of terpenes not ozone, 

 but organic peroxides and hydrogen peroxide occur. If further on we continue 

 to speak of "ozonised" eucalyptol, etc. this is only done for the sake of simplicity. 

 Comp. Gildemeister and Hoffmann, "The Volatile Oils", p. 231. 



