These four objections may be just or they may not. What I do submit is that they are matters of policy to be determined by Parliament in open debate rather than settled autocratically by the most conservative of our trade unions.-Yours, &c., JAMES SEXTON.

House of Commons, S.W.1.
July 16, 1923.

NOTICES OF BOOKS.

Quantitative Chemical Analysis and Inorganic Preparations, by R. M. CAVEN, D.Sc. (LOND.), F.I.C. Part I. Pp. VI. + 156. London: Blackie & Sons, Ltd., 50, Old Bailey, E.C. 1923. 3s. 6d. net. The author has aimed at including in one volume all the essential practical exercises that a student should carry out. He has not included any superfluous matter-at least in the first part now under review.

Part I. includes a description of the preparation of certain typical salts and their gravimetric analysis, followed by exercises in volumetric analysis. It is intended that Part II. will contain a more extensive selection of preparations.

In general, the book follows the lines that have been found most suitable in presenting the subject to students. It possesses,

however, one or two features that call for special mention. The introductory instructions are particularly well presented, and it is to be hoped that all students using the book will master them at the beginning of the course.

Another point of interest is the use of standard oxalic acid as the basis of standardisation in acidimetry and alkalimetry. By following this procedure, the teacher has a good opportunity to press home a number of interesting theoretical and practical points. It might be pointed out here that the short note on the Use and Theory of Indicators does not go very far and seems inadequate.

Also, whilst most of the matter in the section on preparations is good, the method suggested for ferrous ammonium sulphate could be much improved.

The book, as a whole, fulfils its intention for the use of students who have passed the elementary stage, and it will prepare such students, in practical work, up to degree standard.

Abstract Published this Week. 197863-Phosphorus pentoxide.-Threlfall, Sir B., of Oakhurst, Church Road, Edgbastor, Birmingham.

Phosphorus pentoxide made by burning phosphorus in a stream of dry air is condensed at a temperature of 125 to 200° C. in a compact, crystalline form. To avoid the presence of a small amount of the amorphous, bulky variety a portion of the vapour at about 160° C. is led through a filter containing glass wool to a second condensing chamber.

Messrs. Rayner & Co. will obtain printed copies of the published specifications and abstract only, and forward on post free for the price of 18, 6d. each.

X-ray line spectra have a much simpler structure than the optical line spectra. The characteristic X-ray spectra of the different elements are built up in nearly the same way, which is due to the great similarity of the inner groups of electrons of the atom for the different elements. They consist of but very few strong lines and a relatively small number of weaker lines. For the Xray lines the following simple relation holds: the square root of the frequency of a definite line is to a first approximation proportional to the atomic number of the emitting element. Roughly speaking, we could say: If the X-ray spectrum of a definite element is known, those for the next elements with higher atomic number are found by shifting the whole group of lines a certain amount to the short wave-length side. This fact may be illustrated by the following figures.