12 ESSENTIAL OILS PROM THE 



vapcairs, in which the colours yellow, red, violet, green, and blue are 

 very beautifully visible, particularly in bright sunlight. 



The essential oil of E. amygdalina is soluble in all proportions in tur- 

 pentine, both fat and drying oils, benzine, naphtha, ether, chloroform, and 

 absolute alcohol. Spirits of wine also dissolves it pretty freely ; and 

 water, on being agitated with an excess, takes up 1"1 per cent, by weight, 

 or two drachms to the imperial pint. 



This oil, when exposed in a shallow vessel, is ignited with great diffi- 

 culty, by means of a burning match of wood or paper : in this way it 

 cannot be made to take fire by contact "with a flame until it has become 

 quite hot. When it does burn under these circumstances, it produces a 

 bright flame, with much smoke. When burned in a kerosene lamp, it 

 gives a flame very nearly as luminous as that from American 

 kerosene, but somewhat yellower, and inclined to smoke : a slight 

 addition to the height of the chimney obviates this defect. The solvent 

 powers of this and other oils from the genera Eucalyptus and Melaleuca 

 constitute one of their most important characteristics, which will, doubt- 

 less, be turned to account in the preparation of varnishes and lacquers, 

 provided the cost of production does not exclude their use for such 

 purposes. 



To enable manufacturers and technical men to estimate the capa- 

 bilities of this as compared with the liquids usually employed for dis- 

 solving resinous substances, an extended series of experiments have been 

 undertaken, the residts of which are embodied in the subjoined table. 

 In reference to this table, it is necessary to state that the exact satu- 

 rating quantity of some of the substances there specified is obtained with 

 much difficulty and loss of time, because the solution gradually in- 

 creases in viscidity, while the solvent power of the oil proportionally 

 diminishes ; but in every case the resin undergoing investigation was 

 added until a portion of it remained for two three days unacted upon. 

 It will also be seen that the solutions were effected at ordinary tem- 

 peratures, and the results produced by the action of different degrees of 

 heat are not included in the category of facts, because to have done so 

 would haA T e extended this portion of the inquiry beyond all reasonable 

 limits. Those persons who are conversant with this subject will, it is 

 believed, be able to deduce from what is here stated the information 

 they require. In those cases in which only part of a resin is taken up 

 by the essential oil, the determination of the quantity dissolved has been 

 made by evaporating carefully a measured portion of the solution to 

 dryness, and weighing the residue, after heating it until deconrposition 

 had just commenced. 



Mr. Hugh Gray, of Ballaarat, exhibits an oil distilled by him from one 

 of the Eucalypti, which Dr. Mueller believes to be the E. amygdalina, 

 judging from leaves of the tree forwarded to him. In yield this tree is 

 very inferior to that which has just been described, 100 lbs. of the leaves 



