SYSTEMATIC PETROGRAPEY. 341 
that ‘the idea of mineralogical classification, of this great con- 
temporary of Werner, did not spring from a wealth of geognostic 
observations; his letter | above referred to | was not dated from 
the central plateau of France, from Vesuvius, from the Rhone 
Valley, or from Predazzo, as were the classic letters of Leopold 
von Buch at an earlier day, but from the mineralogical cabinet 
in Paris.‘ Furthermore, the enlargement of the halls allotted to 
the collections and the consequent rearrangement of the latter 
was the immediate inspiration of the idea. Haty’s system is 
therefore characterized by Lossen as cabinet specimen petrog- 
raphy. 
The writer does not know whether or not Haiiy’s revised 
system was actually published prior to the appearance of the 
second edition of his Zvazté de minéralogie in 1822. As there 
presented, it expressed at least ten years’ development under the 
idea announced in 1811. Its principal feature is: a subdivision 
of rocks into classes, orders, genera, species, varieties, and modi- 
fications. Five classes of rocks are distinguished, viz.: (1) 
Stony and saline; (II) Combustible nonmetallic; (III) Metallic; 
(IV) Rocks of an igneous origin according to some, aqueous 
according to others; (V) Volcanic rocks. This grand divisien is 
clearly not logical or consistent. General, chemical, and physi- 
cal properties and mode of origin are all arbitrarily applied. 
The stony appearance used to produce the first class is recog- 
nized as possessed also by the questionable igneous rocks of the 
fourth class, and is the first factor used for their further sub- 
division. A ‘‘schist inflammable” is included in the first class 
in spite of the property applied to produce the second class. 
Except for the class of metallic substances Hatiy’s category of 
rocks is similar to that now recognized as the subject-matter of 
petrography; that is, he did not include with them geological 
formations, as did many of his contemporaries. 
The inconsequent construction of this system appears also in 
™K, A. Lossen. “Uber die Anforderungen der Geologie an die petrographische 
Systematik.” Jahrbuch der kinigl. preuss. geolog. Landesanstalt und Bergakademtie, 
1883. 
