384 



OP THE FETTSTEIN. 



either emptey- 

 cd to sophisti- 

 cate it, or na- 

 tural to it j 



but probably 

 the latter. 



which does not combine with it at all, though of a resinous 

 nature. 



Do these two substances exist at the same time with the 

 balsam of Mecca in the tree that furnishes it, the amyris 

 opobalsamum ? are they formed at the expense of the balsam, 

 by a change effected by keeping? or are they fraudulently 

 mixed with the balsam ? 



To solve these questions it would be necessary, to examine 

 genuine balsam of Mecca, both when fresh, and after it is 

 old. If the resinous substances abovementioned were not 

 found in either, there would be reason to ascribe them to 

 fraud: but it is probable, that they are natural to the bal- 

 sam of Mecca, since Mr. Halle, who has had frequent oc- 

 casions of dissolving this balsam in alcohol, always obtained 

 the same result. 



Character of 

 the fettstein. 



Of the Fettstein : by Count Dunin Borkowski *. 



JL HE colour of this stone is sometimes seagreen, some- 

 times blueish. It is likewise found of a deep fleshcoloured 

 red. 



Externally it has but little lustre: internally it is very 

 shining, with a greasy lustre. From this appearance its 

 name, which signifies /«£ stone, is derived, 



Its fracture is lamellar ; not very determinate, though a 

 double cleavage, with oblique junctures is perceivable ; and 

 a little scaly. 



It is very translucid on the edges ; hard, so as to strike 

 fire with steel ; and brittle. 



Its specific gravity is 2-563. 



Heated before the blowpipe its colour changes to an ashen 

 gray; and it fuses, though with difficulty, into a white 

 enamel. 



It is found accompanied with feldspar and amphibole at 

 Arendahl, in Norway. 



When the fettstein is cut into a spherical form, it ex> 

 hibits the same play of colours as the cat's-eye. 



* Journal de Physique, vol. Ixix, p. 159. 



