loo THE POPULAR SCIENCE MONTHLY. 



water can be transferred from earth to air, it may be possible that an 

 atmosphere, which without such aid would be laden with malarious 

 exhalations, may be rendered pure by this process of leaf distillation : 

 the putrescible constituents of the stagnant water are absorbed by the 

 roots, and become i^art of the vegetable tissue of the tree. 



But this is not all. Like those of the pine, the leaves of all species 

 of eucalyptus secrete large quantities of an aromatic essential oil. It 

 has recently been shown and the statement has been very impressively 

 put by Mr. Ivingzett that, under the combined action of air and 

 moisture, oils of the turpentine class are rapidly oxidized, and that, as 

 a result of this oxidation, large quantities of peroxide of hydrogen are 

 produced. Now, peroxide of hydrogen is being itself one of the 

 most potent oxidizers known a very active disinfectant ; and, as the 

 leaves of some species of eucalyptus contain in each hundred pounds 

 from three to six pounds of essential oil, we can hardly avoid the con- 

 clusion that the oxygen-carrying property of the oil is an important 

 element in the malaria-destroying power of the genus. Moreover, the 

 oxidation of the oil is attended by the formation of large quantities 

 of substances analogous in their properties to camphor, and the reputa- 

 tion of camphor as an hygienic agent seems sufficiently well founded to 

 allow us to admit at least the possibility of these bodies playing some 

 part in so beneficent a scheme. 



Before closing this paper, it may be well to note that the Trappist 

 monks of the Tre Fontane attach much importance to the regular use 

 of an infusion of eucalyptus-leaves as a daily beverage. The tincture 

 of eucalyptus is said to be useful in intermittent fevers, though of 

 course inferior to quinine. As we threaded the coast-line via Civita 

 Vecchia to Leghorn, we could not help being struck by the fact that 

 the precincts of all the railway-stations were thickly planted with eu- 

 calypts. Since our return, I learn with much gratification that the 

 Italian Government have given a grant of land to the Trappists, and 

 have also afforded them the aid of convict-labor to a considerable ex- 

 tent for the establishment of a new plantation. And looking back 

 not only at what has been actually accomplished during the past 

 ten years, but to the important fund of information which has 

 been accumulated, one can only look forward hopefully and with en- 

 couragement to the future of the eucalyptus in the Roman Cam- 

 pagna. Chambers's Journal. 



