158 



NATURE 



[August 4, 1923 



pages, and offer no novel features. Owing to the 

 drastic condensation employed, difficulties may occur 

 in endeavouring to follow the directions. The alka- 

 linity test for refined methyl alcohol is on the line of 

 the Government " methyl orange alkalinity test " for 

 wood naphtha for use as a dcnaturant, though this is 

 not stated. In the abstracted form in which the test 

 is described it may be misleading if applied generally. 



The separate treatment of physical properties is a 

 welcome feature in a technical volume of this type. 

 The scope, ho\v(\ir, is restricted, density and humidity 

 only receiving consideration. The factor of wind 

 velocity as an influence on humidity has not been 

 indicated. More accurate practical means of measuring 

 humidity {e.g. Assmann's hygrometer) are available 

 than that described. The main source of reference 

 appears to be the publications of the United States 

 Forest Service. 



On the assumption that wood cellulose first forms 

 Isevoglucosan on distillation, the author indicates how 

 the two rings in this carbohydrate might be broken 

 up to give many of the usual products obtained on the 

 industrial plant. Pictet, however, obtained his laevo- 

 glucosan from a pure cotton cellulose, while it has yet 

 to be shown that the cellulose from broadleaf or conifer 

 trees will give appreciable amounts of Isevoglucosan 

 even on vacuum distillation. It must be recognised 

 also that the non-cellulose portion of the wood has a 

 profound influence on the nature of the decomposition. 

 The author states that "it is now established that the 

 complex carbohydrates found in plants are produced 

 in the first place from formaldehyde which is photo- 

 synthesised in the leaves from CO2 and water," and 

 two references are given to the work of Baly and 

 Heilbron. Possibly the word established is too strong 

 at this stage in the chemistry of plant structure. The 

 chemistry of wood is restricted to eighteen pages, and 

 of necessity is incomplete. Two structural formulae 

 proposed by Irvine for cotton cellulose are given, but 

 it is not made clear that even the resistant cellulose in 

 wood has yet to be shown to be of similar constitution. 

 Indication should be made to the fact that Irvine 

 obtained his 2:3:6 trimethyl glucose from the highly 

 methylated cellulose by hydrolysis. 



It is stated that charcoals can be represented as 

 C16H1QO2, and in a footnote it is implied that the formula 

 is not intended to represent a single chemical com- 

 pound. Again, in another connexion C10H5O is in- 

 dicated to be " primary charcoal," and C30H20O3 to 

 be " secondary charcoal." Giving definite molecular 

 formulae, rather than percentage composition only, to 

 these residual products is not considered sound in the 

 present state of our knowledge. 



Charcoal was originally the main product sought 



NO. 2805, ^'OL. I 12] 



after in wood distillation for metallurgical needs, but 

 a substitute has been found in coke. Acetic acid and 

 methyl alcohol are now the principal products desired. 

 Organic and biological chemistry are, however, makint- 

 rapid strides, and soon these products may possibly 

 be produced more cheaply by processes other than 

 the thermal decomposition of wood. The gases once 

 considered unimportant may yet become the mainstay 

 of the wood distillation process. 1 he outlook, how- 

 ever, at present is not very hopeful, at least in coal- 

 producing countries. Recent developments, which are 

 very well described by the author, have been along 

 two lines — the carbonising of wood in gas retorts and 

 in gas producers or generators. 



The text shows the mark of careful editing, and onl\ 

 a few errors and misprints have been noticed. In some 

 instances a lack of uniformity in units occurs. Again, 

 such statements as " Add HaOj to decompose the re- 

 maining KMn04," or " i gram €02=1.045 grams of 

 H , COOH," might be expressed otherwise. There is 

 too great a tendency to use molecular formulae as a 

 kind of shorthand in the text. 



The volume is more in the nature of a well-written 

 compilation of current literature than a record of the 

 author's personal experiences. It contains one hundred 

 and twenty tables, many of them full-page, as well as 

 more than a hundred illustrations and photographs 

 all excellently reproduced. In the printing and 

 arrangement of the book there is little further to be 

 desired. The only serious complaint that can be 

 offered is that the price tends to restrict the book to the 

 reference librar}- rather than to place it on the shelves 

 of the industrial chemist and technical student, where it 

 would be extremely useful. Joseph Reilly. 



Clinical Pathology. 



A Manual of Clinical Diagnosis by Means of Laboratory 

 Methods, for Students, Hospital Physicians and 

 Practitioners. By Dr. Charles E. Simon. Tenth 

 edition, enlarged and thoroughly re\-ised. Pp. 

 xxiv + 1125 + 23 plates. (London : Henry Kimpton, 

 1922.) 425. net. 



N any branch of knowledge actively progressing 

 in many divergent directions it is of course 

 difficult to keep the whole field of investigation in 

 proper perspective, and the very keenness of the 

 workers in the different diWsions tends to keep them 

 immersed and somewhat solitary in their owti grooves. 

 This disadvantage specially concerns medicine, in 

 which it is most desirable that the clinicians and the 

 laboratory workers should be in close and constant 

 touch with each other ; to some extent this is effected 

 by clinical pathology, and the clinical pathologist 



I 



