Notes on scientific research. 87 



substances must be dissolved, down to the gaseous state of aggregation, in fact, so 

 as to be able to excite the cells of special conformation in the nose into which they 

 penetrate and which cause the sensation of smell. 



An apparatus for the automatic separation of immiscible liquids, especially of essential 

 oils from aqueous distillates, is described by H. E. Watson 1 ). The liquid is placed into 

 a cylindrical vessel which is provided with a float fitted with a vertical rod. The rod 

 passes through a hole in the lid and terminates at the bottom of the cylinder in a 

 conical needle valve. Care must be taken to keep the weighted float in the interface 

 between the two liquids and to introduce the distillate in the horizontal position. As 

 soon as the level of the heavier liquid rises, the float is raised and the valve is opened. 

 The liquid may then flow off, until the original level has once more been attained. 

 The lighter liquid collects in the upper portion of the cylinder and is drawn off through 

 a lateral tube. An apparatus of 8" diameter and 10" high can deal with 100 lb. of 

 distillate per hour. 



Bibliography. 



R. T. Baker and H. G. Smith 2 ) have published the second edition of their work 

 "A Research on the Eucalypts especially in regard to their Essential Oils",, which first 

 appeared in 1902. The republication and completion of this work, which is valuable 

 not only for those interested in the subject, was as justified as necessary and will 

 generally be welcomed, considering that the exploration of the species of eucalyptus 

 and their oils and their utilisation in perfumery, medicine and the arts have seen many 

 a novelty since the first publication of the work. In the present edition the original 

 arrangement and division of the subject matter into a general, a botanical and a 

 chemical part, with special regard to technics, have been maintained. New are the 

 series of coloured illustrations examplifying the habitus of branches and flowers and 

 cross and longitudinal sections of barks and leaves, which will be welcome to the 

 botanist. The groups of the cognate eucalyptus species have been supplemented; 

 altogether 176 different varieties are enumerated and are described in detail together 

 with their oils. Since the species of eucalyptus of nearly all Australia and Tasmania 

 have better been studied within the last 20 years — formerly the explored territory was 

 confined to the south-east of the continent — the authors have also paid attention to 

 the geographical distribution of the species and have elucidated by good maps, how 

 the species are interconnected in geological, botanical and chemical respects. The 

 chemical part which contains above all the results of their own experiments has been 

 supplemented and amplified in every way. We might especially mention the chapters 

 on piperitol and piperitone to which we have already alluded on page 23. A special 

 chapter has also been devoted to the industrial utilisation of eucalyptus oils in which, 

 among other things, the ore flotation process is discussed in detail. 



The older methods for the determination of cineole are compared with one another, 

 and their defects and advantages are discussed at some length. The view of the 

 authors, that an accurate method applicable under all conditions has not yet been 

 found and that, according to the quantity of cineole present, sometimes the one, and 

 sometimes the other method would give better results, may be correct. We can, 

 however, not quite agree with the opinion of the authors in favour of the modified 



] ) Journ. Sac. chum. Ind. 40 (1921), A. 26. — 2 ) Sydney 1920. We take this opportunity once more to 

 thank the authors for obliging us with a copy. 



