[ 286 ] 



XXXVI. Memoir on the three Types of Hum tie. 

 By Professor A. Des Cloiseaux f. 



SCACCHI (Pogg. Ann. Erganzungsb. iii. 1851) and vow 

 Bath (Pogg. Ann. Erganzungsb. v. 1871) have referred 

 the different forms of Hiunite to three types belonging to the 

 orthorhombic system, all reducible to the same elements. An 

 examination of the optical characters, however, has led me 

 to separate the three types, and to transfer the crystals belong- 

 ing to types II. and III. to the clinorhombic system, as shown 

 in the following pages. 



Type I. System orthorhombic, with a prism-angle of 130° 19 / . 

 a : b : c : : 907497: 420059 : 1849650. 



Scacclii's 

 symbols. 



Symbols of 

 Des 01. 



Miller's 

 symbols. 



Calculated 

 angles. 



Observed 

 angles. 

 Scacchi. 



- A:B 



P9\ 



001:100 



90 



O 1 



90 



A:e 



pe* 



001:205 



140 49 



140 47 



A:e 2 



pe 2 



001:102 



134 27 



134 30 



A:e 3 



3 



pe 2 



001 :203 



126 21 



126 17 



A-.e 1 



pe 1 



1:101 



116 8 



116 13 



L A : e 5 



i, 



pe 2 



001:201 



*103 47 



103 47 



r A:i 



pa 5 



1:015 



138 38 



138 41 



A:P 



pa 3 



001:013 



*124 16 



124 16 



L A : i 3 



pa 1 



001:011 



102 48 



102 50 



r A.r 



5 

 pb' 2 



1:115 



135 52 



135 48 



A:r 2 



pb 2 



1:114 



129 30 



129 32 



A:r 3 



3 



pb 1 * 



001:113 



121 44 



121 44 



A:r" 



pb 1 



001:112 



112 24 



112 23 



A:r 5 



pb 2 



001:111 



101 39 



101 41 



lA:o 2 



pvi 



1:10 



90 



90 



r B:o 



9 l 9 2 



100:310 



144 14 



144 11 



1 



g 1 f 



100:210 



132 48 





L B:o 2 



g x m 



100:110 



114 50 



114 48 



p A : n 



pex 



001:2 13 



116 34 



116 SO 



L A : w 2 



Ph 



1:211 



99 28 



99 28 





pf 



1:210 



90 



90 0D. 





plS 



001:212 



108 26 



108 20 D. 



N( = ^^^) and (f observed by vom Rath and myself. 

 ^ 3 (=6 1 &V) and ^(sspfcfy*) are the x and fi of figure 227 

 t Communicated by the Cry stallome trie Association. 



