698 The American Naturalist. [August, 
MINERALOGY.’ 
Friedel's Cours de Mineralogie.'— The first part of a text-book 
of mineralogy by Charles Friedel covers the field of general mineral- 
ogy. In the preface it is stated that a second part, devoted to special 
or descriptive mineralogy, will be prepared with the assistance of M. 
George Friedel, the author’s son. The book does not claim to be, the 
author states, a treatise on crystallography or crystal physics, but a 
practical method of determining minerals on the basis of their mor- 
phological, physical, and chemical properties. It is intended for the 
use of those students who are preparing for the examinations for 
licentiate in physical sciences, and should therefore be adapted to the 
needs of college students. 
The book contains 416 pages with the subject matter distributed as - 
follows: introduction (giving history of science and fundamental 
definitions, 16 pages); organoleptic properties, 16 pages; crystallo- 
graphy, 238 pages ; physical (and optical) properties, 59 pages; chem- 
ieal composition occupies the remainder of the book and includes the 
divisions, blowpipe methods, mineral synthesis, and mineral classifica- 
tion. Under organoleptic properties are included among others, 
structure, color, lustre, density, external form (with a consideration of 
pseudomorphs), hardness, and streak. In treating crystallography 
eight pages are devoted to an exposition of Hauy's théorie des décroisse- 
ments. This is followed by sections on the law of rational indices 
andsymmetry. After deriving the crystal systems, the author gives 
eight pages to an exposition of Bravais’s theory of crystal structure. 
No mention is made of the work of later writers on this subject, and 
throughout the book a tendency to utilize mainly the work of French 
writers seems manifest. The difficulties of translating Levy’s symbols 
into those of Weiss, Naumann, Dana and Miller, makes it necessary 
to devote thirty-seven pages to crystallographic notation. Twelve of 
these are consumed by a table giving the equivalents of Levy’s sym- 
bols in the other notations. An usually large amount of space for a 
book of this sort is devoted to the representation of erytals, but those 
which illustrate the book are very poor. Many of the figures are not 
merely carelessly, but incorrectly drawn. Crystals having a principal 
'Edited by Dr. Wm. H. Hobbs, University of Wisconsin, Madison, Wis. 
"Cours de minéralogie professé a la faculté des sciences de Paris, par Charles 
Friedel. Minéralogie générale, pp. iii and 416. Paris, 1893. 
Eo MM Se equ ES ANB eee M m 
trm Berg E d ue rel, UE TE UC be PAPER ERE REM UR set ai 
