Chemistry and Physics. 275 



nection with ordinary chemical topics, and in general it is an 

 excellent and useful book. h. l. w. 



6. Quantitative Chemical Analysis ; by Clowes and Cole- 

 man. 8vo, pp. 577. Philadelphia, 1914 (P. Blakiston's Son & 

 Co. Price, $3.50 net). — This is the tenth edition of a well-known 

 and widely-used text-book, which discusses general processes, 

 gives courses in simple gravimetric estimations and in volumetric 

 analysis, and gives an extensive treatment of many kinds of 

 industrial analysis, including the examination of ores, alloys, 

 fuels, silicates, water, foods, soaps, oils, gases, etc. Ultimate 

 organic analysis and molecular weight determination are treated 

 also. Besides a revision of the text, several important additions 

 have been made in the form of an appendix. h. l. w. 



7. Industrial Organic Analysis/ by Paul S. Aeup. 12mo, 

 pp. 340. Philadelphia, 1913 (P. Blakiston's Son & Co.).— This 

 book is intended for the use of advanced students in chemistry, 

 giving them some insight into methods of industrial analysis. 

 The materials included within the scope of the volume are coal 

 and coke, coal tar and its distillation products, fats and oils, 

 soap, petroleum products, milk and butter, starch and its prod- 

 ucts, and food preservatives and colors. A list of references is 

 appended to each chapter. The point of view is English, which 

 rather detracts from the value of the book for American students' 

 use. A. L. D. 



8. The Radioactive Origin of the Color of Zircons. — Some in- 

 teresting properties of the zircons are discussed in a very recent 

 paper by the Hon. R. J. Strutt. The communication deals only 

 with the brown crystals of which two kinds maybe distinguished : 

 the common opaque brown variety which occurs in Norway and 

 North Carolina, and the transparent reddish brown kinds known 

 as "hyacinth" which may be obtained, for instance, from 

 Expailly in Auvergne, from Unkel on the Rhine, and from Camp- 

 bell Island, New Zealand. It is a noteworthy fact that the opaque 

 variety occurs in plutonic rocks, such as syenites, and the trans- 

 parent only in basalts and other lavas. Furthermore hyacinths 

 lose their reddish brown color completely when heated to a tem- 

 perature of about 300° C. Since zircon strongly resists chemical 

 attack the question at once arises as to how this mineral acquired 

 its color, when the high temperature of its original matrix is taken 

 into account. Again, the transparent zircons are thermolumines- 

 cent. These crystals, when moderately heated, give out a phos- 

 phorescent glow and simultaneously lose their tint. Also this 

 glow does not recur on subsequent heating of the same specimen. 

 Hence the query : How has the capacity of native unheated 

 crystals to glow been recovered ? — for presumably it was not 

 possessed by the crystals when they first cooled down in the 

 molten lava. 



The keynote to the explanation of the apparent difficulties just 

 suggested is given by the fact that crystals decolorized by heat 

 have their color restored by exposure to the radiations from 



