1823.] 



Crystalline Forms of Artificial Salts. 



39 



Acetate of Soda, 



The primary form deduced from cleavage is an obUque rhorrt- 

 hie prism, tlie cleavages being parallel to the 

 planes P, M, and M', of the annexed figure. 

 Some or all of the secondary planes on that 

 figure occur on many of the crystals. On 

 some crystals only the planes ky or k and/, 

 accompany the primary planes, and on 

 others only the planes a and g, with the 

 addition sometimes of the planes A. 



All the planes except / have been mea- 

 sured by the reflective goniometer. 



PonMorM' 104° 25' 



P on/ 136 nearly 



Von a' 103 35 



MonM' 84 30 



Mon/c 137 45 



Mon/« 132 15 



M on gt 156 54 



Mong, 135 50 



Acetate of Zinc, 



The crystals are very thin, flexible, and 

 soft, and fissile parallel to P, but do not af- 

 ford any other measurable cleavage planes. 



The primary form indicated by the natural 

 planes of the crystals is an oblique rhombic 

 prism, measuring as follows : 



PonM,orM' .... 112° 28' 



M on M'. 67 24 



P on A 133 30 



P on c 100 00 



P on c' 80 00 



Pong, org' 75 30 



Binacetate of Copper, 



The primary form developed by cleavage 

 is an oblique rhombic prism, the cleavages 

 being parallel to the planes P, M, and M', 

 of the subjoined figure; the secondary 

 planes c and g are the only ones J have 

 observed on the crystals, which are some- 

 times produced in pairs, and united by the 

 planes c, in such a manner as to exhibit a 

 second entire plane P, joined by an acute 

 angle to the lower acute angle of that which 



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