April 22, 1922] 



NA TURE 



509 



elements ; the rest of the discussion is on more in- 

 dividual and less standard Hnes. Dr. Chree devotes 

 reat attention to the important subject of the magnetic 

 ■ activity " — its variations from day to day and from 

 iiour to hour, and its connection with other magnetic 

 characteristics. He finds, for instance, that the 

 remarkable differences existing between the Antarctic 

 diurnal magnetic variations on quiet and on disturbed 

 days are by no means merely proportionately intensified 

 forms of the corresponding differences in temperate 

 latitudes. Again, he investigates the tendency for 

 a given state of magnetic activity to recur after twenty- 

 seven days, a phenomenon long ago suggested by 

 Broun and others, and independently established and 

 brought into prominence more recently by Mr. Maunder. 

 Dr. Chree uses his own admirable method based on 

 daily character figures, and finds the tendency to be 

 as clearly shown by the Antarctic as by the Kew 

 records. The variation of the magnetic activity 

 throughout the day, and even over short periods of 

 an hour or so, has also been studied, the latter with 

 the aid of the quick-speed records arranged to be 

 taken simultaneously for " term hours " at the 

 Antarctic and at many co-operating observatories. 

 While these records have proved useful for the purpose 

 named. Dr. Chree expresses doubt as to the desirability 

 of including this arrangement in the programme of 

 future polar expeditions. 



Another subject discussed in much detail is magnetic 

 disturbance of various kinds, including " sudden 

 commencements," whether followed by a magnetic 

 storm or not, large disturbances (studied from Antarctic 

 and other records) and short-period disturbances. 

 Some cases of the repetitions of disturbances at about 

 the same hour on successive or adjacent days, such as 

 were first noticed by Seiior Capello in the Lisbon 

 curves, were found in the Antarctic records, and are 

 illustrated ; it is to be regretted that the corresponding 

 curves from other observatories were not obtained 

 for these as well as for the larger disturbances discussed. 



With the co-operation of Mr. C. S. Wright, an 

 interesting chapter on the relation between aurorae 

 and magnetic disturbance is included. In this chapter 

 various definite numerical criteria are applied to test 

 the view generally held that there is a close connection 

 between the two phenomena. It is so difficult, on 

 account of daylight, clouds and moonlight, to get 

 records of aurorae at all comparable with the magnetic 

 records in continuity or completeness that it requires 

 some ingenuity to devise satisfactory numerical tests 

 of the connection ; Dr. Chree's tables succeed in 

 confirming it, as they show that 41 per cent, of the 

 " first-class " aurorae observed were associated with 

 days of character-figure 2 (connoting a magnetically 

 NO. 2738. VOL. 109] 



disturbed day), while no single aurora of the fourth 

 class was so associated. It appears also that aurorae 

 are probably rarely, if ever, totally absent, even at 

 the times most quiet magnetically. 



In order to utilise the results to the best advantage, 

 Dr. Chree has not shrunk from entering upon enormous 

 pieces of arithmetical computation, and the preparation 

 of this report has been an enterprise which even those 

 naturally most inclined towards numerical work 

 might have shirked. The volume is necessarily 

 restricted in its appeal, but magneticians will every- 

 where be grateful to Dr. Chree for the clear and accurate 

 way in which he has ascertained and presented so 

 many of the leading facts regarding the magnetic 

 phenomena of the Antarctic. 



The Analysis of Drugs. 



The Chemistry and Analysis of Drugs and Medicines. 

 By H. C. Fuller. Pp. ix + 1072. (New York: John 

 Wiley and Sons, Inc. ; London : Chapman and 



' Hall, Ltd., 1920.) 555. net. 



THE number of drugs in use at the present day 

 runs into thousands, and each of them is a 

 component of one or more, often many more, " medi- 

 cines." The materials used as drugs include such 

 diverse products as plants the constituents of which 

 are unknown, elementary substances such as colloidal 

 copper and sulphur, and complex but well-defined 

 compounds like " salvarsan." To prepare a com- 

 prehensive account of the analysis of drugs and medi- 

 cines is therefore a difficult task, and one may doubt 

 Mr. Fuller's wisdom, but not his courage, in tackling it. 



He has produced a book which is inclusive rather 

 than useful, and is unnecessarily large, owing to faults 

 in the arrangement of matter and to needless repeti- 

 tion ; thus the assay of the principal crude drugs is 

 described in chap. 2, and drugs which contain alkaloids 

 or glucosides are discussed again in the chapters 

 devoted to these constituents, with the result that 

 the determination of morphine in opium is dealt with 

 on pp. 53-60, and a second set of processes for this 

 operation is given on pp. 211-13, a cross-reference 

 being provided in neither case. 



Many authors inadvertently repeat themselves, but 

 it must be unusual to find such a case as that of sali- 

 genin in this book, which is described twice, each time 

 under a central heading in heavy type on the same 

 page (553); and a third time on p. 787 ; the headings 

 are different each time, viz. " ortho-oxybenzyl alcohol," 

 " salicyl alcohol," and " saligenin," but a chemist, 

 with his daily experience of vagaries in nomenclature, 

 should be prepared for such pitfalls. 



