Angular Values : 

 a: b =(100): (010) 

 b:c =(010): (001): 

 a:c =(100):(001)= *77 

 a: r = (100) : (101) = 

 q:c =(01 1): (001) = 

 q:b =(011):(010) = 

 r:c =(101): (001) = 

 rt:m = (100):(230) = 



\ dislinct dicliroisin was not obsei'ved. On all faces tlie exlincliuii 

 was oblique, but the extinctiou-angle on the prism-faces was o]\\y 

 small with respect to the direction of the c-axis, — which is in 

 agreement with the evident approximation to monoeliiiic symmetry, 

 this last one can be easily seen, if the forms n and b are taken as 

 |lïü!, resp. {llOj, while c remains j001|. 



/). dd'-Liiteo-Trlethi/lenedlainlne-Cobnltihroiuotavlrate. 

 Forinnla: \Co {Aein)^\ ., ^^ ri ■. 



Big, very histrons, perfectly transparent crystals (tig. 4), which 

 are wholly analogous to those of the corresponding cidorotartrate. 

 The angular valnes oscillate here still a little more than in the 

 preceding case ; bnt nndoubtedly the crystals are completely isonior- 

 phous with the above-mentioned ones. 



Triclin ic-pedial. 

 a:b: c = 0.6208 : 1 : 0.6528. 



(1=102° 507,' 

 ^=100° 35' 

 y= 95° 14' 



.4 = 104° 8' 

 5=102° 7' 

 C= 97° 55' 



Observed forms ■■ b = JOIO! and b' = |01Ü| large 

 and lustrous ; a = llOOj and a' = jIOO!, c = |Oüli 

 and c' = jOOl), all about equally well developed 

 and giving good images; y^jlOlj, well develo- 

 ped and lustrous; r' = jl01! commoidj' absent; 

 (t =z \\Vo\ small, but allowing exact measure- 

 ments ; (/ ^ |{)32} narrow and somewhat dull. 

 The angular values oscillate with different indivi- 



Fis. 4. 



duals not nnappreciably, with differences of about I'. Cobaltibiomola.lrate. 



