1892.] Mineralogy and Petrography. 953 
and igneous rocks, and then describes briefly the principal members of 
each class. The little book is well illustrated, and its contents are con- 
veniently arranged for the student of the museum’s collections. 
All of the natural manganese oxides except pyrolusite and manga- 
nite yield red or violet solutions when digested with a mixture of sul- 
phuric acid and water in equal proportions.” 
%Thaddeef. Zeits. f. Kryst., xx, 1892, p. 348. 
