I 



i 



19 



^L'ioal purposes considered equul to Kino: that from Eitcahjptus 

 rostrata is preferred to others as a therapeutic, and as an astrin- 

 gent is parUcuhirly administered in Europe and India in cases of 

 chronich diarrliuju. The solvent action of water upon these gum- 

 resins differs according to the species operated on. Tlie aqueous 

 solutions give an acid reaction ; in these solutions acetate of lead 

 gives copious gelatinous precipitites; solution of gelatin causes 

 precipitates, which however do not in any c;ise appear ' • be so 

 abundant as might have been anticipated from the intense astrin- 

 gent taste of these gum-resins. Ferric s ilts give precipitates of 

 various shades of green and black ; mineral acids produce bulky 

 flocculent deposits. 



These jodies, so far as I am aware, have hitherto been but very 

 cursorily examined : they offer an interesting field for chemical 

 investigation. 



IV. Essential Oils from the Eucalypts. 



To Biron Von Mueller is due the credit of having been the 

 first to draw attention to this important f-ubject, important, 

 whether regarded from a scientific point of view, or one of indus- 

 trial importance, as will be conceded on becoming acquainted 

 with their valuable properties. At his suggestion, Messrs. 

 Bosisto and Johnson entered upon the preparation of the essen- 

 tial oils from a number of species of the genus ; in each case 

 determining the yield, etc., etc., the material upon which their 

 C'xperini nts were conducted having been supplied by Baron Von 

 Mueller, all uncertainty regarding the true botanical name of 

 the trees from which the samples were obtained has been re- 

 moved. The supply of material from which the.se oils are pre- 

 pared, is almost unlimited : the plants furnishing it constituting 

 the great bulk of the forest vegetation of the country. Speaking 

 of Victoria alone, the area in that colony occupied by forest 

 trees and scrubs has been estimated at 73,000 square miles, of 

 which 71,500 square miles are occupied by Eucalypti of various 

 species ; and wherever these trees are felled for timber (this more 

 especially applies to Eucalyptus globulus, the timber of which is 

 always in great demand), the foliage which otherwise is wasted, 

 would be available in great abundance for the extraction of the 

 oil. 



Mr. Jas. Bosisto, with a praiseworthy spirit of enterprise, 



