350 



species, and how large a proportion of these contain a predominance of terpenes, 

 principally pinene and phellandrene. The yield from trees giving terpene oils 

 is often large, especially those in which phellandrene predominates, and this fact 

 has naturally led to the exploitation of these species for mineral separation and 

 other industrial purposes. 



By referring to the table it will be seen that such species as E. polybractea, 

 E. Morrisii, E. Smithii, E. cor data, &c., all of which yield oils rich in cineol, almost 

 hold their^own, in regard to yields, with many of the " peppermint " or phellan- 

 drene-bearing species. 



It is to be expected that the yields of oil will influence largely the com- 

 mercial consideration of distillation, and for this reason we append the following 

 table, which in almost every case records the results of our own distillations ; 

 included are a few the authenticity of which there is no doubt. The figures 

 given represent the mean of the results obtained with the leaves of any individual 

 species recorded in the list, and in many cases these spread over more than twenty- 

 five years. The leaves and terminal branchlets were taken in all instances as 

 would be done for distillation on a commercial scale, and the leaves in all cases 

 were as fresh as it was possible to obtain them. Of course, in some instances, 

 evaporation had taken place, as some of the material came hundreds of miles, 

 both by land and sea, packed closely in bags. We have given the average yields 

 in preference to that of any one distillation, because this more nearly represents 

 the actual amount of oil that would be obtained if the species was commercially 

 distilled. 



In practically the whole of the species recorded in the table the oil was 

 distilled from the mature leaves and not from abnormal leaves, so that in these 

 cases the results may be considered to represent the minimum yields. 



The yield per 1,000 pounds of material has also been calculated, as 

 the statement in pounds and ounces appeals more directly to the commercial 

 world. 



