24 



DISCOVERY 



spiration) and a bone button bearing the address Batavia 

 and a name, probably that of a tailor. Portions of the 

 waistcoat were soaked in distilled water, and the solutions 

 obtained examined chemically. These contained various 

 compounds of calcium, magnesium, sodium, etc., in about 

 the same proportion as they exist in sea water. It was 

 also concluded that a very fine quartz sand, found in 

 each pocket, was dune sand. The deductions from these 

 facts were as follows : 



The owner of the waistcoat had bought a ready-made 

 suit of clothes in Batavia. The stain proved that the 

 lining had been used before, since the stain had not been 

 acquired while the lining was in its existing position. 

 An old lining on a new-looking waistcoat suggested a 

 ready-made suit rather than a second-hand one. The 

 man had travelled to Egypt in a Dutch steamer (the only 

 steamers which then called at Batavia and passed through 

 the Suez Canal). He had left the boat surreptitiously 

 while it was passing through the Canal, and had swum to 

 shore. He had not waded, because the presence of sea- 

 water salts even at the top of the waistcoat suggested 

 entire immersion. He had landed from the Canal at a 

 place where there were sand-dunes. This was indicated 

 by the nature of the sand found in the pockets. 



These conclusions were subsequently proved to be correct. 



One of the most interesting chapters in the book is the 

 account of the methods used in the detection of counter- 

 feit coins. In this particular work the camera and the 

 microscope are particularly valuable adjuncts. The 

 chemist is required not only to analyse the counterfeit 

 coins, but also the materials seized on the premises of 

 suspected persons, which may include metals, moulding 

 composition, and miscellaneous chemicals. It is also 

 part of his job to know the most up-to-date methods and 

 apparatus employed by coiners, as well as the methods 

 employed in minting the genuine article. 



In one case, in the house of a man suspected of pro- 

 ducing counterfeit coins, were found several pieces of 

 white metal and some similar-looking metal adhering to 

 the end of an iron rod, which had manifestly been used 

 as a stirrer. The defence was that these articles had been 

 used merely for tinning copper saucepans, a common 

 practice. Analysis, however, proved that both the pieces 

 of metal and the metal on the rod were identical in com- 

 position with the counterfeit coins, and differed consider- 

 ably from the material ordinarily employed for tinning 

 saucepans. The man was convicted. 



The reader will find especially interesting the chapter 

 on the detection of forgeries in documents, which includes 

 also an account of secret writing and sympathetic inks ; 

 also the chapters on poisons, on the preservation of the 

 human body, and on the detection of robbery from 

 letters and parcels. 



It is a good book, and verv interesting. 



A. S. R. 

 Radio-activity and Radio-active Substances. By J. 

 Chadwick, M.Sc, Ph.D. (Sir Isaac Rtman, 3s. 6^;.) 



This, the latest volume of Pitman's Technical Primers 

 series, is the most up-to-date exposition of the physical 

 side of radio-activity in English, and no better book on the 



subject could be recommended for the senior class of 

 schools and to university students reading for honours in 

 physics. It is an introduction to the study of radio- 

 active substances and their radiations, the nature of radio- 

 activity, and the bearing of radio-active transformations 

 on the structure of the atom. It follows in the main the 

 lines of Sir Ernest Rutherford's great book. Radio-active 

 Substances and Their Radiations, published in 1913. but 

 it is very much shorter, it omits references to authorities, 

 and time has enabled it to include an account of the 

 valuable additions that have been made to the subject 

 during the last eight years. Dr. Chadwick has one ad- 

 vantage over many writers of textbooks — he knows his 

 subject from the inside. This is useful knowledge, for 

 it helps an author to write on occasion a book which is 

 not merely informative, but arresting and stimulating ; 

 one, like this one, that is worth buying, reading, and 

 keeping. 



The author has included the results of the most recent 

 work on radio-activity in this book. The treatment is 

 simple, concise, and strictly scientific. He bases his ex- 

 position on the modern conceptions of atomic structure, 

 and does not pay much attention to the historical order 

 of discovery. This is no doubt wiser and makes for clear- 

 ness, but a short historical description, if it be genuine, 

 may pro\'ide an excellent opportunity for an author to 

 recall to his readers' minds the main facts and theories 

 with which he assumes them to be familiar before he 

 begins his self-appointed task. It would have been a 

 gain, I think, if Dr. Chadwick had led off in Chapter I with 

 a diagram demonstrating the place of the radio-elements 

 in the periodic system, and followed it up with a short 

 description of atomic number. 



A. S. R. 



Taboo and Genetics. By M. M. Knight, Ph.D., Iv.\ 

 LowTHER Peters, Ph.D., Phyllis Blanchard, 

 Ph.D. (Kegan Paul, Trench, Trubner & Co., Ltd., 

 los. 6d.) 



This book is a survey for the general reader of the sexual 

 factors that influence the life of the community ; it is 

 divided into three sections, a biological, sociological, and 

 psychological, each of which is written by a separate 

 author. 



The biological section, by Dr. M. M. Knight, is an elabo- 

 rate but lucid summary of the more modern work on the 

 biology and physiology of sex, from which the author 

 draws the conclusion that the difference between the sexes 

 is a quantitative one, i.e. a question of degree rather 

 than the expression of an absolute qualitative difference. 



The sex of the individual is determined at a very 

 early stage by a bias impressed upon the chemical pro- 

 cesses of metabolism, a bias that is maintained through- 

 out life by the chemical secretions of the ductless glands ; 

 so that the sexual character comes to depend immediately 

 upon the balance of the endocrine or ductless gland sys- 

 tem, and if this is disturbed, corresponding changes in 

 the sexual characters will ensue. 



From the qualitative nature of the sex differences it 

 follows that considerable variations are found in the degree 



