ESSENTIAL OIL OF EUCALYPTUS SMITHII. 163 



various stages might be determined. From accumulated 

 results obtained with a very large number of Eucalyptus 

 species, collected during a quarter of a century of experi- 

 mental research, it has been conclusively shown that the 

 same species of Eucalyptus always yields a similar product, 

 although the percentage amounts of the constituents 

 characteristic of the species may vary under particular 

 conditions. Not only is this true for trees grown under 

 natural influences, but it appears to hold when they are 

 cultivated. Numerous instances of this fact have accu- 

 mulated, and the one now given is a good example of this 

 constancy. It has long been known that the pinene in the 

 cineol-pinene oils varies in amount under special conditions, 

 and in the leaves of mature trees diminishes during the 

 winter months, while the cineolatthe same time increases 

 correspondingly in amount. The yield of oil is also less at 

 that period, the maximum content being present in the 

 early spring and summer months. To determine what 

 alterations may be expected in the percentage amounts 

 of the chief constituents in a rich cineol-pinene oil has 

 been the object of the present investigations. 



Eucalyptus Smithii is a well defined species and has a 

 somewhat extensive range. The oil obtained by steam 

 distillation is one of the richest in cineol content of all 

 Eucalyptus species so far examined. The yield of oil is 

 also good, as much as from twenty to twenty-six pounds of 

 oil being obtainable commercially from the leaves and 

 terminal branchlets which can be packed in a four hundred 

 gallon tank. The oil consists very largely of cineol, and the 

 terpene is dextrorotatory pinene. In commercial samples 

 the amount of high boiling constituents is often very small 

 indeed, the original distillation not being carried to the 

 end, and 96 per cent, or more of crude commercially distilled 

 oil may come over below 190° O. With one sample of the 

 oil distilled in January, 40 lbs of crude oil were steam 



