Review of Recent Geological Literature. 325 
8 glass (imitation emerald), and 9 five fragments of diamond 
and one small grain of glass. The diamond grains are much 
thicker than the thin sections of rocks but are seen to be 
much more transparent. Carbon and its compounds, are in 
general, more transparent than inorganic substances. The 
presence of some other elements in compounds has a similar 
effect to that of carbon on their transparency, but to a less 
degree. Crystals of hydrated compounds appear to be gen¬ 
erally less opaque than those of the corresponding anhydrous 
materials. 
Besides having compared the relative transparencies of a 
large number of crystals, the members of the staff of this 
institution have examined a number of liquids. For this pur¬ 
pose equal volumes of the liquids were placed in small paraf¬ 
fin vessels of exactly the same dimensions. The differences 
in their transparencies proved to be very great. Sulphuric 
acid was found to be the most opaque of any of those ex¬ 
amined and water the least so. 
School of Mining, Kingston, March 23d, 1896. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
Life, Letters , and Works of Louis Agassiz. By Jules Marcou. (Two 
vols.; I, pp. xxi, 302; II, pp. ix, 318; with portraits and other illustra¬ 
tions. Macmillan and Co., 1896.) The foremost place among American 
investigators and teachers in zoology and biology, and one among the 
foremost of all the world in all time, must be accorded to Louis Agassiz. 
Before his coming to America, by his great work on fossil fishes, and by 
his adoption and earnest advocacy of the glacial theory of Venetz and 
Charpentier to account for the boulders and striation of Switzerland 
and of Scotland, Agassiz had made his most important contributions to 
the advancement of natural history and geology, and, in the opinion of 
his biographer, had attained the zenith of his life work. This may well 
be true in respect to the increase of knowledge by original investigations; 
but in the New World, from 1846 to his death in 1873, the great scien¬ 
tist continued to exert an increasingly powerful influence in the true 
work of the teacher, to discover and train students worthy to aid and 
finally to inherit wholly, and to carry forward unchecked, the work of 
the master. 
