28 



GENERAL BEHAVIOUR OP THE ESSENTIAL OILS OF EUCA- 



LYPTINE ORIGIN WITH KEAGENTS. 



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Sulphuric acid, in the cold, causes a gradual darkening in 



color: the. tint varying somewhat according to the oil operated 

 upon, but the final result is in all cases a deep brown. When 

 heat is employed these changes are rapidly brought about : the 

 acid is decomposed with evolution of sulphurous acid, the oil 

 being converted into a charred mass, a part of which is soluble 

 in water, affording a liquid so dark as to be almost black. 



Nitric acid in the cold acts but slowly : when concentrated it 

 produces numerous shades of brown, olive, purpb, violet and 

 grey: when heated the action is very violent: Nitrous acid fumes 

 are given off in great abundance, the oil is converted into a brown 

 resinous body possessed of a pungent odor, hard and brittle yet 

 becoming plastic-like pitch soluble in alcohol, and ether : fusing 

 at a moderate heat and inflammable and possessed of marked acid 

 properties, as it forms colored salts with the bases, and the alco- 

 holic solution reddens litmus. 



Hydrochloric acid, does not give rise to any very marked 

 results : but the action of this reagent on these oils has not as 

 yet been sufficiently studied. 



Iodine : when brought into contact with these oils causes no 

 explosion, even when the temperature is raised : but a dark 

 colored solution is created, which, when heated, emits peculiar 

 variegated vapors, in which the colors yellow, red, violet, green 

 and blue are very beautifully visible, particularly in bright sun 

 light. 



Sodium : a piece of this metal introduced into one of these 

 oils, causes an instant evolution of gas upon its surface, the 

 action is aided by heat : it is not under any circumstances so 

 energetic as that caused by the same treatment of some other 

 essential oils, such as oil of cloves. The soda formed is taken 

 up by the oil giving rise to a dark brown liquid from which 

 water extracts the color, and acquires alkaline properties. 

 Caustic potassa aided by heat, and an alcoholic solution of 

 potash produce a very similar result so far as color is concerned. 



