On Crystallographyi, 273 



point of direction or the measurement of the decre- 

 ments. Ex. Apophanoiis feldspar, apophanous sul- 

 phurated antinionialed silver, apophanous gray copper. 



L Blunted {e?nousse)y when it has facets which intercept, 

 and render as it" bkinted, some parts which would 

 otherwise be sharper than the rest. Ex. Blunted 

 axinite, bhuited carbonated lime. 



m, Contracted^is a dodecabedral variety of carbonated lime, 

 in which the bases of the extreme pentagons undergo 

 a kind of contraction, in. consequence of the incli- 

 nation of the lateral faces. 



?;. DUatady is said of another dodecabedral vanety of car- 

 bonated hme, in which the bases of the extreme pen- 

 tagons undergo a kind of dilatation, in consequence 

 of the inclination of the lateral faces. 



0. Acutemigled, is a variety of carbonated lime in a hex- 



ahedral prism, the solid angles of which are inter- 

 cepted by very sharp triangular facets. 



/?. Defective, is a variety of borated magnesia, in wliich 

 four solid angles of the primitive cube are intercepted 

 hy facets, while ihe opposite angles remaining un- 

 touched, are subject to a kind of defect. 



q. Superabundant, is another variety of borated magnesia, 

 in which the solid angles which were untouched in th« 

 defective variety, are intercepted each by four facets, 

 in such a way as to make a superabundance where 

 there was a defect. 



4. Secondary forms considered relatively to the laws of 

 decrement on which they depend* 



The crystafi is called, 

 «. Unitary, when it undergoes only a single decrement by- 

 one row. Ex. Unitary telcsia. If there are two, three, 

 four decrements by one row, we say bisunitary, tri- 

 unitary, quadriunitary. Ex. Triunitary peridot, bis- 

 unitary carbonated lime. 



1. Binary. LiOifiary, trihinary, &c. in the case of one, 



two, and three decrements by two rows. Ex. Binary 

 oligistous iron, bibinary feldspar. 



c. Ternary, biiernary, &c. in the case of one, two decre- 



ments, &c. by three rows. 



d, Unihinary, if tliere are two decrements, the one by one 



row, the other by two ',un'i ternary, if there is one by 

 one row, and the other by three ; hinoternary , if there 

 is one by two, and the other by three, &c. Ex. Uni- 

 ternarv carbonated lime, binotcrnary carbonated lime^ 

 Vol. 35/No. 144. April J 8 10. S The 



