1894.] Mineralogy. 699 
axis are generally lopsided. Figures 70, 138, 224, 255 and 322 area 
few of the incorrectly drawn crystals. Another bad feature of the 
illustrations is that crystals are not always properly set up but are seen 
from all directions. The best portions of the work are those which 
treat optical mineralogy and mineral synthesis. The former is treated 
without mathematics and in a simple and practical manner. The 
section on the classification of minerals is very unsatisfactory. What 
purports to be a history of the subject isgiven. The systems mentioned 
are those of Werner, Hauy, Beudant, Delafosse and Dana. Groth’s 
system is not mentioned nor is that of any other modern German 
mineralogist. A considerable number of pages is devoted to detailed 
ists of minerals as they appear in the schemes of Werner, Delafosse, 
and Dana. With theexception of the latter, which Friedel adopts as 
the one most in harmony with the present state of the science, these 
lists seem out of place. The book is not provided with an index, but 
has a somewhat extended table of contents. 
As a text-book the work is subject to criticism on account of its 
classification and arrangement of subject matter, its lack of perspec- 
tive in the treatment of the different divisions of the subject, its ten- 
dency to utilize mainly French investigations and systems, and its 
faulty illustrations. 
Relation between Atomic Weight and Crystal Angles.— 
In a paper entitled, “Connection between the Atomic Weight of con- 
tained metals and the magnitude of the angles of crytals of isomor- 
phous series, a study of the potassium, rubidium and cesium salts of 
the monoclinic series of double sulphates R,M (SO,), 6 H,O,” Tutton' 
has given the results of a most careful and thorough erystallographi- 
cal study of an isomorphous series of salts, to determine the kind and 
degree of effect which the different bases exert upon the crystal angles. 
The results are very interesting since they seem to show a relation be- 
tween the atomic weights of the contained bases and the crystal 
angles. "The work involved no less than 9,500 measurements. The 
crystals were obtained by slow crystallization from cold solutions and 
ten good crystals of each salt were selected for measurement from a 
dozen or more different crops. The double salts of the formula RM 
(809), 6 H,O containing as univalent metals either potassium, rubid- 
ium, or cesium, and as bivalent metals either magnesium, zinc, 
iron, manganese, nickel, cobalt, copper, or cadmium, were always pre- 
‘Jour. Chem. Soe, London, Trans., Vol. LXIII, (1893), pp. 337—423. 
