Vlll 



Especially is this noticeable in the great variety of timbers and oils, 

 the latter of which is specially treated in this work, the former being 

 monographed in a separate publication by one of us, and issued from this 

 Museum: No. 23 of the Technical Education Series. 



Since the publication of the 1st edition, the Eucalyptus oil industry 

 has expanded considerably its scope of usefulness in the industrial world, 

 as for instance the utilisation of certain oils in the mineral flotation process 

 for the extraction of metallic sulphides, for perfumery purposes, for solvents, 

 and the preparation of proprietary articles. 



Besides the amplification of the letterpress and subject matter in the 

 first edition, many new features will be noticed, as, for instance, the sections 

 of leaves in colour photography, magnified by various diameters, which will 

 give some idea of the position of the oil in the leaf. Chromatic photography 

 was employed in this way in order to show more clearly the differentiation 

 of the anatomical structure of the leaf. The bark illustrations also give some 

 idea of the natural groups into which the trees are divided on a cortical 

 system. 



A series of plates is added, showing the various systems or methods of 

 extracting the oil from the leaf in Australia. 



As we have now reached the age limit for retirement as laid down 

 by the Government Service Regulations, and so will shortly leave this field 

 of our scientific activities in which we have laboured so long, and, we hope, 

 with some small measure of success, this will be the last joint monograph 

 by us. We therefore take this opportunity of placing on record our appre- 

 ciation of the far-sighted policy of our Department of Education (of which 

 this Museum is an integral part) — a policy that has encouraged and enabled 

 us in our research work, to endeavour to bring to light for the benefit of 

 pure and applied science some of the hidden mysteries of Australia's unique 

 and wonderful Flora. 



R.T.B. 

 November, 1920.' H.G.S. 



