582 



NATURE 



[October 20, 192, 



carvacrol is said to be the only phenol present in 

 Spanish oil of tl.\i<ii-. whereas Mastbaum has shown 

 that the Sp;ii of Thymus vulgaris, T. Zygis, 



T. hiemalis, and Corydothymus captains all contain 

 notable proportions of thymol ; in this case at least 

 the discrepancy may be due to the length of time that 

 has elapsed between the completion of the work and 

 its publication. To clove oils i8 pages are devoted, 

 and here also the description is accompanied by a map 

 of the islands of Pemba and Zanzibar showing the 

 distribution of the clove plantations. For the deter- 

 mination of the percentage of eugenol in the oil a 

 3 per cent, solution of sodium hydroxide is recom- 

 mended, whereas in the " British Pharmacopoeia " 

 a 5 per cent, solution (of potassium hydroxide) is 

 given. 



Eucalyptus oils are very fully represented, no fewer 

 than 141 being mentioned, the great majority of them, 

 however, being of scientific rather than economic value. 

 The commercial oil of E. amygdalina is now referred to 

 E. amygdalina, Labill., var. Aiistraliana, Baker and 

 Smith. 



The task of translation, always a rather tedious one, 

 has been admirably accomplished by Dr. E. Kremers, 

 of Madison, Wis. The work is couched in excellent 

 English, reads very easily, and shows only occasionally 

 a somewhat literal rendering of the German original. 

 Both paper and type are good, and clerical errors are 

 seldom to be found. 



Viewing the work as a whole, one cannot but be 

 surprised at the mass of information which has been 

 collected by the author, sifted in the laboratories of 

 Messrs. Schimmel, and is now offered to the scientific 

 world. Notwithstanding the disadvantages under 

 which the book has been compiled, translated, and 

 issued, it must be regarded as one of the most complete 

 in existence on the subject. It will doubtless prove 

 a mine of information for all workers on volatile oils, 

 and it is difficult to see how any scientific library can 

 be complete without it. 



Low Temperature Carbonisation of Coal. 



Low Temperature Carbonisation of Bituminous Coal. 

 By A. McCulloch and N. Simpkin. Pp. xii + 248. 

 (London : H. F. and G. Witherby, 1923.) 185. net. 



THE low temperature carbonisation of bituminous 

 coal is a process which has received much 

 attention from writers, speakers, and experimenters, 

 and Messrs. McCulloch and Simpkin have made a use- 

 ful summary of the work that has been carried out. 

 The preface insists quite rightly upon the importance 

 of the subject in connexion with atmospheric pollution 

 by smoke. If commercial success can be attained 

 NO. 2816, VOL. I 12] 



" Not only will it be possible to ensure a smokeless 

 atmosphere, but, at the same time, a considerable 

 conservation of our coal resources will result, and the 

 country will be provided with a home supply of fuel 

 oil." 



The constitution of coal, the history of attempts 

 dating from Parker's " Coalite " proce-ss to soh » 

 problems of low temperature carbonisation, the < 

 culties arising from the expansion of coal on heating 

 and its low thermal conductivity, the pro*' 

 nected with the names of McLaurin, Del Moni' 

 and Gluud, lUingworth and others, the nature of coal 

 tar and of low temperature tar in particular, are dis- 

 cussed in turn in the seven chapters of the work. 

 The printing is clear, and forty-three illustrations arc- 

 given, most of them useful line drawings of plant, but 

 some of Sir George Beilby's microphotographs of coke 

 are included. 



It is very difficult to write a book of this kind 

 judicially and critically as regards large-scale opera- 

 tions, unless from a first-hand experience, to which 

 the authors do not seem to make any claim either 

 in the preface or the text. The account of each 

 process in existing circumstances remains to a great 

 extent a repetition of the claims made for it, although 

 an exception must, of course, be made of those experi- 

 ments which have been made and fully described by 

 the Fuel Research Board. 



The more theoretical portions of the book make 

 mention of many researches, apparently more than 

 have been digested. Thus, perhaps, the most striking 

 result obtained by Messrs. Greenwood and Hodsman 

 in their work on " The Factors Influencing the 

 Yield of Ammonia during Carbonisation " was that 

 oxygen did not decompose the ammonia, but was 

 used up in the preferential combustion of other sub- 

 stances. The work is referred to by the authors on 

 p. 33, but on p. 34 they say that " the presence of 

 oxygen is detrimental to the formation of high ammonia 

 yields since it decomposes the ammonia produced." 



On the whole, however, the book stands as a good 

 and readable account, brought well up-to-date, of a 

 very important side of modem experimental develop- 

 ments in the utilisation of coal. J. ^\ (. 



Complex Space. 



Prolegomena to Analytical Geometry in Anisotropic 

 Euclidean Space oj Three Dimensions. By Prof. 

 E. H. Neville. Pp. xxii + 368. (Cambridge: At 

 the University Press, 1922.) 305. net. 



WERE a Greek from the Academy of Plato to visit 

 England, it would surely please him to find a 

 title he could read without using a dictionary. Should 



