— H4 — 



chemical action; finally, identification, constitution, isolation, and history. 

 To those who are interested in the historical side of this domain, 

 the constantly emphasised relationship of the individual, genetically 

 closely allied members, and the very numerous references to the liter- 

 ature on the subject, which go back to the very commencement of 

 chemical work, may particularly possess lasting value. Whoever wishes 

 to be scientifically informed on a constituent of an essential oil, its 

 occurrence in nature, in other oils, its production, constitution, the 

 history of its investigation, finds an abundance of material in this 

 work of an author, who has already been known for a long time 

 as a successful investigator of the domain of the terpenes. 



The essential oils themselves are considered in so far, as in 

 every compound discussed occurring in Nature, the individual mother 

 plants, their families, and the oils containing the compound in 

 question are mentioned. A table arranged according to the families 

 of the plants also gives information on the plants and the individual 

 parts thereof which come under consideration for the production of 

 essential oils. In compiling the very voluminous material, which has 

 been treated with typical thoroughness, the author was not, as in the 

 case of other works, guided by practical requirements to deal with 

 the oils as such; his leading idea was to give a description of the 

 components of the various oils more for the purpose of research work. 



Bran del 1 ) continues abstracting (to which we have repeatedly 

 referred) the publications in the domain of the terpene chemistry 

 in the course of the year 1905. Up to the present he has, in the 

 order of Gildemeister's and Hoffmann's work, dealt with the oils 

 up to those of the Myrtaceae. 



Analytical notes. 



In a previous Report 2 ) we have already referred to the cryoscopic 

 method for determining the essential oil in spices, etc., worked out by 

 Beckmann and Danckwortt; we now return to this, as a more 

 detailed treatise on the subject by Beckmann 3 ) has made its 

 appearance. Ethylene bromide, which possesses a sufficiently high 

 molecular depression K = 1 1 8°, and solidifies at -J- 8°, was found 

 to be the best solvent. It is desirable to mix the ethylene bromide, 

 before determining its freezing point, by way of trial with a few drops 

 of water, and also to submit the solution prepared with dry ethylene 

 bromide to the same test only after a few drops of water have been 



x ) Pharm. Review 25 (1907), 64, 121. 



2 ) Report October 1906, 104. 



3 ) Arch, der Pharm. 245 (1907) 211. 



