the AblZ Ha'ihfs Theories of Crystallography. \ 03 



orders, genera and species,) united all that has hitherto been 

 discovered on mineralogy, without falling into that confu- 

 sion which lias ever been imputed to other mineralogical 

 writers, we are almost astonished at his success. 



" To class mineral bodies ;" " to furnish the means of 

 discovering to which class, genus, and species a mineral 

 under examination belongs/ are the two great problems 

 which the Abbe Hauy proposes for solution. 



He solves the first in following Bergman's method (found- 

 ed on chemical properties), much improved by the immense 

 progress which chemical analysis has made since the days 

 of that great chemist. In the solution of the second he 

 follows Werner's method (grounded on exterior characters), 

 but corroborated by a multitude of new experiments, easily 

 made, and brought to a surprising degree of correctness by 

 the Abbe's own labours, on the forms of crystals. But I 

 perceive that the immensity of matter contained in this 

 treatise is leading me from that point which I had particu- 

 larly in view, I mean crystallography. 



In the description of crystals the Abbe employs three 

 different means. 1st, He draws their figure ; he does not 

 give crystallographical tables, as Rome de l'lsle, which are 

 only general representations, but draws separately each spe- 

 cies and variety. Every form given in the plates has been 

 examined by himself; he has calculated every angle, and, 

 nevertheless, his plates contain one-third more figures than 

 De l'lsle's tables. 2d, He makes use of symbolic *,gns, than 

 which nothing can be more simple, and which were invented 

 not to recall the form of the crystal to the mind, but the laws 

 by which it had been produced. Yet I have met with per- 

 sons who were so accustomed to these signs, that at the first 

 sight of them they could immediately figure to themselves 

 the form of the corresponding crystals. These signs can 

 also be spoken, and much circumlocution in consequence 

 avoided. 3d, A significative nomenclature, subdivided into 

 general and particular. The general is for the minerals, and 

 comprises onlv substantives ; the particular for the crystals, 

 and is entirely composed of adjectives. He studiously 

 avoided introducing new names, and nevertheless has been 

 obliged to introduce many, where new substances, names 

 capable of giving false impressions, or others void of signi- 

 fication, and unsupported by long usage, required it. He 

 then substituted names taken from the Greek; a language, 

 be says, that eminently enjoys the faculty of combining se- 

 yeral words together, so as to form one representing con- 

 cisely the object to be named. The adjectives used m the 



nomen- 



