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21 



rated upon was prevented from comlnir into direct contact with 

 the surface of the still. Tlie leaves luiving been introduced into 

 the basket, water was poured on, the still adjusted as for an ordi- 

 nary distilhition, and direct heat applied. The oil passes over 

 and condenses with the aqueous vapour, and from the watery 

 portion of the distillate is separated by mechanical means. 

 When steam is at command the above method can, it is needless 

 to say, be greatly improved upon. 



As previously stated, the J-Jiiva/i/ptiis g/ulnihoi is perhaps the 

 speci'js best known outside Australia, from the fact of its having 

 been introduced into Europe, etc., and has therefore been most 

 handy for investigation. It is consequently the oil from this 

 tree which has received most attention, and in alluding to it 

 further on, mention will be made of the experiments of M. Cloiiz, 

 who has studied its chemical properties. 



The following series of essential oils includes those from the 

 most common and important trees of the genus. Appended is a 

 short notice of their general behavior with re-agents. The scale 

 employed in taking temperatures was Fahrenheit's. 



1. Enaihiptus avii/gdii(ii(a, Labillardierc — one of the so-called 

 Peppermint-trees — occurs in Victoria, New South Wales, and 

 Tasmania. In the deep recesses of some of the Victoria Ranges 

 it is found c!' colossal size; in more open places it is a middle 

 sized tree. The foliage of this Eucalypt contains a larger per- 

 centage of essential oil than any of its congeners — 100 lbs. of 

 the freshly gathered leaves, including the small branchlets to 

 which they are attached, gave GO, 50 fluid ounces. 



The oil is a thin transparent iluid of a pale yellow color, having 

 a pungent odor, much resembling that of oil of lemons, but 

 coarser and stronger ; its taste is rather mild and cooling, pro- 

 ducing an after sens;' ' Ion in the mouth resembling camphor, witli 

 something of its bitterness. Its specific gravity is 0.881. It 

 boils freely at 330° ; but as the evaporation proceeds, the mer- 

 cury rises rapidly to 370°, where it remains almost stationary. 

 Cooled to 0° F., it at first becomes turbid, and then clearing, 

 deposits a white flocculent substance, which melts at + 27° F. 

 Suffered to evaporate spontaneously, it proves to be somewhat 

 less volatile than oil of turpentine. Conformably with other 

 essential oils, it leaves no stain on paper ; in shallow vessels it 

 absorbs oxygen, giving rise to a residual resinous matter. It is 



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