81 



lines are apparent chiefly in the larger ellipsoidal grains, but 

 not in all of these, the smaller grains only occasionally showing 

 any trace of such lines." With specimens freshly scraped from 

 a potato and immediately examined in water there should be 

 no trouble, however, in seeing the concentric hues with a I'' 

 objective and a large axial cone of light from the condenser, and 

 we have never yet under such conditions seen one of the larger 

 grains A\^thout markings. Even the smaller grains, with the 

 exception of the most minute, more often than not exhibit a few 

 concentric hues. In deahng with wheat starch the author does 

 not allude to the peculiar reticulated sculpturing of a part of 

 the surface which a small percentage of the grains usually exhibit. 

 In regard to illustrations the author has been decidedly un- 

 fortunate. Compared with the direct prints from negatives 

 contained in Mr. Griffiths's book already referred to, they are, to 

 say the least, very poor. Whatever detail may have been shown 

 on the original negatives has practically entirely disappeared in 

 the half-tone reproductions. The difficulties of obtaining good 

 photographs of some of the starches are no doubt very great, and 

 we would suggest that the use of reagents producing a weak 

 yellowish or brownish tinge might probably be employed with 

 advantage to obtain the desired results. D. J. S. 



Das Mikroskop im chemischen Laboratorium. Elementare 

 ADleitung zu einfachen krystallographisch-optischen Unter- 

 suchungen. By Dr. F. Rinne. 101x7^ in., 74 pages, 

 202 figures in the text. Hanover, 1900: Janecke Bros. 

 Price 4 marks. 



This book is intended to serve as an introduction to the study 

 of the optical properties of crystals and the crystallographic 

 investigation of natural and laboratory products by means of the 

 mineralogical microscope. It is not written for would-be experts 

 in crystallography, but for those who, like chemists, may wish to 

 obtain, with a minimum of trouble, information concerning the 

 form and optical peculiarities of the crystalline substances with 

 which they have to deal. The author says—and the remark is pro- 

 bably even more to the point in this country than in Germany— that 

 although such information is generally acknowledged by chemists 

 to be of great value, the crystallographic method is very little 

 JouRN. Q. M. C., Series II.— No. 48. 6 



