FIXITY OF PHYSICAL PKOPERTIES. 337 



form. And though none of the other properties have yet been 

 referred to standards so definite as that which geometry supplies for 

 crystals, a system has been introduced which makes their measures 

 far more constant and precise than they are to a common undisciplined 

 sense. 



The author of this system was Abraham Gottlob Werner, who had 

 been educated in the institutions which the Elector of Saxony had 

 established at the mines of Freiberg. Of an exact and methodical 



o 



intellect, and of great acuteness of the senses, Werner was well fitted 

 for the task of giving fixity to the appreciation of outward impressions; 

 and this he attempted in his Dissertation on the external Characters 

 of Fossils, which was published at Leipzig in 1774. Of the precision 

 of his estimation of such characters, we may judge from the following 

 story, told by his biographer Frisch. 1 One of his companions had 

 received a quantity of pieces of amber, and was relating to Werner, 

 then very young, that he had found in the lot one piece from which 

 he could extract no signs of electricity. Werner requested to be 

 allowed to put his hand in the bag which contained these pieces, and 

 immediately drew out the unelectrical piece. It was yellow chalce- 

 dony, which is distinguishable from amber by its weight and coldness. 



The principal external characters which were subjected by Werner 

 to a systematic examination were color, lustre, hardness, and specific 

 gravity. His subdivisions of the first character (Color), were very 

 numerous ; yet it cannot be doubted that if we recollect them by the 

 eye, and not by their names, they are definite and valuable characters, 

 and especially the metallic colors. Breithaupt, merely by the aid of 

 this character, distinguished two new compounds among the small 

 grains found along with, the grains of platinum, and usually con- 

 founded with them. The kinds of Lustre, namely, glassy, fatty, ada- 

 mantine, metallic, are, when used in the same manner, equally valu- 

 able. Specific Gravity obviously admits of a numerical measure ; and 

 the Hardness of a mineral was pretty exactly defined by the sub- 

 stances which it would scratch, and by which it was capable of being 

 scratched. 



Werner soon acquired a reputation as a mineralogist, which drew 

 persons from every part of Europe to Freiberg in order to hear his 

 lectures ; and thus diffused very widely his mode of employing 

 external characters. It was, indeed, impossible to attend so closely to 



1 Werner's Leben, p. 26. 

 VOL. II. 22. 



