O F F O S 5 I L S. 



CLXXIV. Jlhijlrathn of external Markt. 



THE chief external marks arc thofe taken 

 from the form of the outward furfncc ; the tex- 

 turc', in tlic appearance of its particles by a re-- 

 rent frachire ; the colour, hardncfr, and gravi- 

 ty- 



CLXXV. Amorphous Fv/fits. 



FOSSILS that have no determined fliape are 

 denominated amorphous. 



5 c i xx vi. Cbryjlalllne Foflils. 



BIT r thofe whofe circumference is included 

 \vithin plain iidcs meeting cacli other at various 

 angles arc called crystalline. 



In the foflil kingdom, \vc have five regular geo- 

 Tiictric figures, of plain, equal, ancl fimilar 

 ikies; as the tctraedra, cubes, oclacdra, docle- 

 caedra, and icoi'acdia ; helides many others dif- 

 tinguilhcd by their prifmatic columns and py- 

 ramidal terminations. In what manner the great 

 number of derivatives arifc from a few prima- 

 tivcs, and differing from each other at the firft 

 view, I have related elfewhcrc *. 



Salts, indeed, on account of their folubility 

 T 3 in 



*. fTay9 t vol. ii. p. I. 



