290 CM A NATURAL SYSTEM 



CLXX. Species of organic FoJJUs impregnated 

 'with metallic Particles. 



VERY few metals aflame an organic form. 

 The calx of iron, but (lightly cohering, or con- 

 creted like a ilone, penetrates roots, wood, anil 

 even whole trees, preferving Hill the fibrous 

 texture, which may fo me time 8 be fc raped with 

 the nail. 



Pyrotaccous iron, indeed, now and then forms 

 nuclei ; but it commonly adorns the organic 

 iirufturc witli lines or little fpots, and ieldoru 

 occupies it entirely. 



Copper, in the form of a calx is fuppofed fre- 

 quently to enter into bones and teeth, giving 

 them a blue colour, especially after they are 

 calcined. This colour, however, is often ow- 

 ing to iron. 



Pyritaccous copper alfo refemblcs the anemia 

 in the magnet oi'Iurliberg in Norway, and iiihe* 

 in feveral places. 



Spots of native gold or filver are fumetimex 

 feen on the furface of foifil Ihells. 



The grey ore of filver at Frankenthal in Hcfle 

 is found in the form of ears of corn, and com- 

 monly called kobrn-ubrcn\ and under the ap- 

 pearance of leaves and italks of fume ^ranife-* 

 rous vegetable. 



Ciniiubariue ihclls are exceedingly rare. 



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