Prof. A. Des Cloiseaux on the three Types of ' Hum-it e. 289 



Dispersion tournante is fairly distinct, when seen in oil, 

 especially in pale yellow crystals. Seven thin laminae of a 

 more or less deep reddish brown showed the dispersion in a 

 manner moreor less marked ; and the separation of the axes in 

 oil varied for red rays from 86° 14' to 87° 20'. 



Type III. Pale yellow and white Humite from Monte Somma. 

 Oblique, with a prism-angle of 90° 24/. 



b : a : c : : 419575 : 907720 : 605135. 



Scacchi's 

 symbols. 



Symbols of 

 Des CI. 



Miller's 

 symbols. 



Calculated 

 angles. 



Observed 



angles. 



rA: C 



P9 X 



001:010 



90 



O I 



90 



A:i 



pe* 



00 1 :023 



136 38 



136 35 



A:i 2 



pe 1 



001:011 



*125 13 



125 13 



A:i 3 



pe 2 



00 1:021 



109 28 



109 30 





5 



pa 4 



00 1 :405 



149 48 







po l 



00 1:101, 149 48 





o 1 ar 



id a z found holohedral (v. Rat 



h). 



A:e 



pa 1 



00 1:10^ 143 12 30 



143 15 





po* 



00 1:40 3 143 11 





i 



't 1 and <ft holohedral (v. Rath) 





A : e 2 



3 



pci% 



1:403 



133 40 



133 44 



A : e 2 ' 



l 



po' 2 



001:201 



133 40 



133 44 



A:e J 



pa> 



001:201 



119 48 



119 50 





po* 



1:401 



119 48 







o T and a 2 holohedral (v. Rath) 





A:e* 



i 

 pai 



00 1:40 1 



100 49 



100 48 



L A : e 1 ' 



p h l 



001:100 



*100 48 



100 48 



A : rn 



P DC 



001:623 



114 55 



114 46 



- 



A : m- 



py 



001:621 



92 58 



92 50 



A :n 



pe 



00 1:212 



132 14 



132 7 



i 



-} and e h 



001:423 

 olohedral 



132 12 



(v. Rath). 





A : n- 



1 



^X | 00 1:4231 122 57 

 po., | 00 1 : 2 1 l| 122 56 



V, and o 3 holohedral (v. Rath). 



123 



A : n 3 



P a 3 



001:21 1 



Ill 15 



111 18 



A: w 3 ' 



pit 



1:421 



111 14 



111 18 





pn 



f, new 



1:14 1 

 form (v. 



105 10 



Rath). 





Phil Mag, S. 5. Vol. 2. No. 11. Oct. 1876. 



