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



1. O4658 gram gave on combustion 0*18025 gram CO 2 and 



0"168 gram water. 



2. A modification of Liebig's process gave equal volumes of CO 2 



andN. 



3. 0*4005 gram precipitated by mercurous nitrate gave 0'0906 gram 



O 2 3 . 



4. 0-5294 gram, treated as in 3, gave 0'1199 gram Cr 2 s . 



5. 0*4925 gram dissolved in H 2 0, excess of KI and HC1 added, and 



the iodine titrated with thiosulphate, required 44'6 c.c. ; each 

 c.c. thiosulphate = 0'00328 gram CrO 3 . 



6. 0*374 gram reduced by sulphurous acid, excess of latter expelled 



by heat, AgNO 3 added, and the whole strongly acidified with 

 HNO 3 , gave 0*0789 gram AgCl. 



7. 0'4554 gram, treated as in 6, gave 0'09853 gram AgCl. 



8. 0-42415 gram lost in vacuo over H 2 S0 4 0'0114 gram H 2 0. 



9. 0-3243 gram lost at 100 C. 0*00845 gram H 2 0. 



10. Two separate experiments gave 33*68 per cent. Cr 2 3 on ignition. 

 Deducting Cr found as CrO 3 , gives 7*56 per cent. Cr. 



The crystals have a distinct oblique habit, but are very ill 

 developed, and few of the planes are truly parallel, or in their true 

 zones. The measurements and elements are, therefore, but approxi- 

 mations. They were obtained from six of the best crystals 1 could 

 find. The crystals are dark green and have a fairly good cleavage, 

 w(IOl), perpendicular to the plane of symmetry. 



The system is oblique, and the elements are (100, 101) = 49 2' ; 

 (010, 111) = 45 6' ; :(101,001) = 35 20'. 



The planes observed are a(100), /(101), c(001), w(101), and m(110). 

 The planes Z are generally those most largely developed. 



Observed 

 Calculated. means. Extremes. 



al 49 2 49 10 48 3550 17 



ac 84 22 84 13 82 1484 51 



en ...... 39 30J 39 20 



wo! 56 7i 55 59 55 34^56 22 



am 59 45 59 37 58 4661 19 



mm l 60 30 59 51 57 5560 33 



ml 70 43 70 



me 92 50 92 44 



m^i 73 411 73 11 



