278 R. T. BAKER AND H. G. SMITH. 
The best fraction for eucalyptol content appears to be that 
obtained from the lighter coloured oils, consisting of about 60 per 
cent. of the crude oil, distilling between 172°4 and 182°8° C., but 
as from 10 to 15 per cent. distils between 171-4 and 172°4°C., 
much of which is eucalyptol, it is questionable whether this could 
be dispensed with commercially. If added to the large fraction 
the eucalyptol content would certainly be diminished, and this 
also applies to that portion boiling between 182°8 and 193:2°C., 
although this would increase the specific gravity, it having a sp. 
gr. °9253 at 16°C. The greatest quantity of this latter, however, 
was 7 per cent., but in some cases only half this amount was 
obtained, so that the loss would not be great if this portion was 
discarded. That portion boiling below 171°C. should not be 
added to the rectified oil because of the predominance of terpenes 
boiling at a low temperature, and because of the presence of 
aldehydes. 
The product of crude distillation of all eucalyptus oils should 
not be used medicinally as such, but the oil should be rectified, 
principally for the following reasons :— 
1. Aldehydes appear always to be present in a greater or lesser 
amount in the oil as first distilled, and these bodies are considered 
very objectionable, are cough producing, and in affections of the 
respiratory organs should not be used. They are not difficult to» 
remove, as they generally boil at a lower temperature than that 
of the principal constituents of the oil, and can thus be readily 
got rid of. . 
2. A portion of the terpenes boiling below the temperature 
required to distil eucalyptol can also be removed, thus consider- 
ably increasing the eucalyptol content in the portions boiling at 4 
higher temperature. 
3. The higher oxidised portions boiling above 193°C. are 
removed ; the colouring matter of the original oil is also retained 
in the residue, so that we obtain by rectification a clear, almost 
colourless product. The residue also retains those portions of a 
