344 WHITMAN CROSS 
8. The Diamictonic, ‘in which substances are mingled.” 
g. The Anomalous, ‘or those which contradict the common order of 
nature.” 
to. The Transilient. 
11. The Decomposed. 
12) dhe) Volcanic: 
This outline will indicate sufficiently that the Petralogy has no 
real importance to the present review. Pinkerton does not 
appear to have been taken seriously by his contemporaries, as 
there is little or no reference to his elaborate system in succeed- 
ing publications of his countrymen. 
Alexandre Brongniart, 7813.—In 1813 Alexandre Brongniart* 
published a Classification minéralogique des roches mélangées. The 
writer has not seen the original, but von Leonhard gives a tabular 
view of the scheme proposed by Brongniart, which shows it to 
have been crude, and not worthy of special discussion here, 
because of the much more elaborate and mature work by this 
author issued a few years later, to which some space must be 
given. But comparatively crude as this outline was, it gave 
much evidence of the logical mind of its author. 
P. L. A. Cordier, 7575.—Contemporaneously with the con- 
structive labors of Haiiy and Brongniart, another French master 
was also struggling with the same problem. It is to the pains- 
taking researches of P. L. A. Cordier that we owe the first great 
step in deciphering the composition of volcanic and other rocks 
of such fine grain that their constituents could not be recognized 
by the simple methods of examination then in use. He insti- 
tuted chemical, microscopical, and mechanical researches of 
much ingenuity, and arrived thus early at the conclusion that 
volcanic rocks were made up of known minerals in microscopic 
crystals or grains, and of glass, which he believed contained the 
same elements. In 1815 Cordier presented to the Academy of 
Science in Paris the results of his investigations in an important 
work upon the substances composing volcanic rocks.* The 
t Journal des Mines, Vol. XXXIV. 
2P. Louis CORDIER, “Mémoire sur les substances minérales dites ev masse,” etc., 
followed by “ Distribution méthodique des substances volcaniques dites e masse,” 
