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NEW BOOKS
Le Soufflage du Verre. B y H e n r i rligreuz. 16 X 11 em, p p . 276. Paris: Librairie Ditnod, 1930. Price: 3.5 jrancs. I t is somewhat surprising that opportunities for learning glass blowing even by advanced students in physics and chemistry scarcely exist in England and reliance has to be placed upon self education and experience. Under these conditions any book which describes methods of glass bloving which really can be followed and acted upon would prove invaluable. There are but few text hooks on this subject and nearly all of these suffer from the defect that it is difficult to follow the directions. Dr. Vigreux's little book on glass blowing is a good book although it might be regarded from the English point of view as somewhat old fashioned. The directions given in the book are clear and intelligible. I t contains an interesting history of early operations in glass, continues with practical methods for making first simple and then more complex apparatus and terminates somewhat surprisingly with cements, X-ray bulbs and artificial eyes. This book is already in its third edition and is to be warmly commended both to physicists and to chemists. Eric K. Rideal Optical Rotatory Power. A General Discussion held b y the Faraday Society. 25 X 16 cm; pp. ii 187. London: Gurney a d .Jackson, 1530. Price: 10 shillings, 6 pence. This volume is a separate issue of that part of the Transactions of the Faraday Society which contains the papers read a t the general discussion held in London during last April and the comments that arose from the papers. The papers are classified on four groups, the physical basis of optical rotation, apparatus and methods, the rotatory power of solutions and finally the chemical aspect,s of rotatory power. In all there are twenty one papers together with an introduction and a concluding summary by Professor Lowry. Reading through this volume gives one a very good impression of the present position of many of the diverse problems that await solution in this subject. The majority of the papers are summaries of investigations already published and, as such, will be of the greatest valiie. To the reviewer two of the most intermt.ing are those of Kuhn and of Wolf. The former is a simplified exposition of Kuhn's theory of the physiral basis of rotatory power which appeared in the Zeitschrift fuiil. physif:aZische Chemie last year; it is presented in an extremely able way and can be followed by those who do not possess an extensive mathematical equipment. The latter, that of Wolf, deals with the question of free rotation in saturated carbon compounds, and indicates a new method of investigating the extent of the freedom of rotation. As Wolf points out, rlassical stereochemistry was based on three postulates, of which two, constancy of atomic distances and constancy of valency angles, have been justified as first approximations by all recent methods of physical investigation. The third postulate, free rotation, however, has had to be abandoned in a few cases by even the most classical of stereochemists, so that this preliminary account of a physical investiga7". TV. J . Taylor tion into the extent of free rotation is of the greatest interest.
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Biological Applications of Absorption Spectrophotometry. 15 X 24 cm; p p . 12. London: A d a m HiZger L t d . , 1930. Issued gratin. The study of absorption spectra has in recent years occpuied an important place in biochemical investigation, particularly with regard to vitamin A and vitamin D. Very interesting results have also been obtained with proteins, blood sera, biological pigments and the respiratory ferments. There are probably few fields of research in which hasty deductions and inadequate technique present greater dangers, and this publication is useful both in calling attention to the possib spectrophotometry and to the need for accuracy in gathering data and care in interpretation. R. A . Morton Erratum Owing to an oversight on the part of the editor the legends were omitted from the cuts in the article by Levene and Rothen (34, 2567). Fig. I . The concentration of mandelic acid is o,ojK throughout, except in the case of Ca(OH)%where the concentrations are indicated in brackets on the curve. Fig. 2. The concentration of sodium mandelate is constant and equal to 0.05N. Fig. 3. The concentration is o.05N in mandelic acid and in HC1.
