Maech 4, 1921] 



SCIENCE 



215 



such a system of control of imports for a 

 limited period seems preferable to anything in 

 the nature of a permanent tariff. It is not 

 likely to have on the industry the emascu- 

 lating effect of a protective tariff; provided 

 that the period be limited, and that the 

 licensing committee adopt an enlightened 

 iwliey, prohibition of imports, except under 

 license, is rather calculated to act as a stimu- 

 lus on the development of the industry. 



There is, finally, one poiat not dealt with 

 in tlie proposals outlined above. In return 

 for this shield from danger during a limited 

 period, the country may well ask: What 

 guarantee is there that the manufacturers are 

 taking due measure to promote and prose- 

 cute the scientific research and scientific 

 methods on which alone ultimately these, or 

 any other, industries can be made efficient and 

 able to stand against foreign competition ? 

 The leading manufactui-ers have combined to 

 form a scientific instrument research associa- 

 tion, and in addition many of them are en- 

 gaged continuously in scientific reseach. But 

 it is not clear that all the manufacturers who 

 are demanding the legislative measures out- 

 lined above are contributing in either or both 

 of these ways to the advancement of the in- 

 dustry. It is worth considering whether the 

 proposed licensing committee should not take 

 this factor into consideration in any specific 

 case in which it is asked to grant or to refuse 

 a license. — Nature. 



SCIENTIFIC BOOKS 

 Mineralogy : An Introduction to the Study of 

 Minerals and Crystals. By Edward H. 

 Kraus and Walter F. Hunt. McGraw- 

 Hill Book Co., New York. 1920. 561 

 pages, about 700 figures. 

 When a new book enters a field supposed 

 to be already rather thoroughly covered, the 

 first thing that wiU be inquired about it is, 

 wherein does it differ from previous books? 

 A hasty glance through the present volume 

 yields one answer: in the character and qual- 

 ity of the illustrations. The usual line-draw- 

 ings of crystals are abundantly supplemented 



by half-tone views of crystal models, which en- 

 able the reader to gain an imusually good idea 

 of the shaftes of the crystals described. Then 

 there are portraits of leaders in mineralogy 

 and allied sciences, both past and present, 

 and representing various nationalities. And, 

 finally, there are numerous photographs of 

 mineral specimens, bringing out typical 

 features of the 150 mineral species covered. 



Other noteworthy features are a readable 

 chapter on the polarizing microscope, one on 

 gems and precious stones, and one in which 

 the minerals are classified according to ele- 

 ments present, and their uses are discussed. 

 The last 150 pages of the book are devoted to 

 an elaborate determinative table, based on 

 physical properties. Every effort has been 

 made to taring out the practical side of the 

 subject, to show wherein the facts given bear 

 on the everyday experiences of the reader, 

 and to make the subject matter interesting as 

 well as informing. 



In certain respects, moreover, the book is 

 more up-to-date than is usual in an intro- 

 ductory text. For instance, in the definition 

 of a mineral, allowance is made for recent 

 discoveries as to variability in composition, 

 and for the occurrence of colloid minerals, 

 thus : " A mineral is a substance occurring in 

 nature with a characteristic chemical compo- 

 sition, and usually possessing a definite 

 crystalline structure. . . ." Further, a table 

 is furnished for the use of the Merwin color 

 screen in identifying elements by flame tests; 

 and special tests to distinguish calcite from 

 aragonite and from dolomite are given. 

 Modernized formulas are listed for pyrrhotite, 

 limonite, and bomite. 



The make-up of the book is on the whole 

 good. The crystal models would have shown 

 up better if they had been coated with am- 

 monium chloride before photographing. There 

 are a number of places in which the tj^pe has 

 evidently become pied after the last proof was 

 corrected, but these can be readily set right on 

 reprinting. Through a change in the vowel 

 in the last syllable, the birthplace of scientific 

 mineralogy appears as a castle, rather than 

 the more appropriate mountain; mierocosmic 



