330 Mr. W. J. Sell and Prof. W. J. Lewis. [Feb. 14, 



The principal zones measured were those containing poles a, /, s, 

 and these angles were alone depended on in determining the element. 



Calculated. Observed. 



O I 01 



of = 41 2^ 41 2-^, mean of 14 observations. 



fs = 48 57} 48 58" 12 



"bf = 29 26 Approximations to these angles were 



fr = 36 40 obtained on a somewhat altered 



rs = 65 27 crystal. 



\Jb = 48 27 



D = or = 23 54 

 No cleavage was perceived. 



The Iodide. 



This salt was prepared from the dichlordichromate by precisely 

 the same method as the bromide, only that potassium iodide replaced 

 the bromide. It crystallises from water in long brilliant green 

 prisms, free from water of crystallisation. It is insoluble in the usual 

 organic solvents. 



The compound has the composition (CON 2 H 4 ) 12 Cr 2 I 6 , and gives 

 the following results on analysis : 



1. 0*750 gram salt lost no appreciable quantity of water in vacua 



or at 104 C., and is therefore anhydrous. 



2. 1'18 gram salt dissolved in water and made up to 250 c.c. The 



mean of four concordant titrations with silver nitrate on 

 portions of 50 c.c. each required 8'95 c.c. ; each c.c. AgNO 8 

 = 0-0035293 01. 



Percentage calculated. Percentage found. 

 I 48-02 47-88 



The crystals are of a brilliant green colour, in long prisms termi- 

 nated by rhombohedral planes, often unequally developed. 



The forms observed were a{10l} well developed, b {211} very 

 minute, and r{100}. 



The element D = or was found by calculation to be 24 30J'. 



Calculated. Observed. 



o / o / 



ar 68 57 68 58, mean of 3 measurements. 



rr ]= 42 6 42 5J 3 



00! = 60 59 59 



