Chemistry and Physics. 229 



4. A Course in General Chemistry ; by William McPherson 

 and William Edwards Hexdersox. 8yo, pp. 737. Boston, 1921 

 (Ginn and Companv) . — This is the second edition of what may be 

 regarded as one of the best of onr text books for the use of college 

 students in this subject. It gives an excellent presentation of the 

 fundamental laws and theories of chemistry, together with a satis- 

 factory amount of descriptive matter in connection with the theo- 

 retical discussion. A good feature is the introduction of well- 

 selected lists of ciuestions and problems at the ends of the 

 chapters. 



The new edition has been largely rewritten in order to intro- 

 duce improvements that have been suggested by the use, since 

 1913, of the previous issue, and to bring the work up to the views 

 of the present time. There is an interesting discussion, occupy- 

 ing about nine pages, of the recent ^dews in regard to the struc- 

 ture of atoms. H. L. w. 



5. Introduction to Qualitative Chemical Analysis; by Th. 

 WiLHELM Fresex^ius. Seventeenth Edition of the Original Work 

 by C. Remigius Fresexius. Translated by C. Aixsworth 

 Mitchell. 8vo, pp. 954. New York 1921 (John Wiley & Sons 

 Inc. Printed in Great Britain). — This standard work on quali- 

 tative analysis which was begun as long ago as 1840. now appears 

 as an English translation of a considerably modernized and 

 enlarged German edition. The general plan and scope of the 

 work have been preserved, however, while most of the old illus- 

 trations have been retained, with few additions, and a large part 

 of the text remains practically unchanged, so that the book has a 

 very familiar aspect to those who are acquainted with the previous 

 English translations. Since the last English translation of the work 

 published in America was issued in 1897, nearly 24 years ago (by 

 the writer of this notice), it is e^ddent that a new edition was 

 needed, and there is no doubt that its appearance will be widely 

 welcomed as a very important work for reference and study. 

 The translation of the new edition appears to have been very well 

 done. H. L. w. 



6. Diaphragms Capable of Continuous Tuning. — In the field 

 of under-water acoustic signalling it is highly desirable to possess 

 a diaphragm capable of being tuned over a certain range of fre- 

 quency so as to utilize selective transmission and reception, analo- 

 gous to the method employed in radio-telegraphy. The design of 

 such an instrument has been effected by Professor L. Y. King of 

 McGill University. The diaphragTo. is accurately turned from a 

 single block of suitable metal, such as nickel-chrome steel, fash- 

 ioned so as to have a hea^'y rim of nearly square cross-section 

 connected to a relatively thick and rigid central disk by a much 

 thinner ring-shaped plate. The diaphragm so constructed serves 

 as a gas tight cover to a box which is essentially a hollowed bronze 



