Calculated 



290 



Angles : Observed 



a:r =(100): (102)=* 69 52' 



a: o =(100): (111)^* 59 4 



r:r =(102):(T02) = 



0:o> =t (111): (122) = 



o,:,> =(122):(T22) = 



a:a^ = (100):(221) = 

 W.t =(221): (121) = 



a:t =(100):(121) = 



a:p =(100): (120) = 



a: w = (100): (110) = 

 m:m = (100) : (TlO) = 

 m:p =(110): (120) = 

 m:b =(110): (010) = 



o-.r =(111):(102) = 



No distinct cleavabilitj. 



The crystals are noticeably dichroitic: on jJOOj yellow-green for 

 vibrations parallel to the c-axis, and pale green for those perpen- 

 dicular to the former. The plane of the optical axes is JOOJj, with 

 the ^ï-axis as first bisectrix of positive character. The apparent 

 axial angle is very small. 



Thallo-malonate. 



Crystallised from water, the salt is deposited in very big, trans- 

 parent crystals; they are 

 a7ihydrous{79,m°/, Tl- calc: 

 8OV0). The compound is very 

 soluble, and crystallisation 

 starts only in highly super- 

 saturated solutions. 



Monoclinic-prisma tic . 

 a:6:C=:0,5707:l:l,0833; 



i3=81°30i' 

 Forms observed: c = }001|, 

 very lustrous; b = |010|, 

 gives good reflexes; in the 

 same way: ??i = |110}, and fig. 6. 



= {111} ; s = jlOlj, narrow Anhydrous Thallo-Malonate. 



and often badly measurable ; r = S102J, not measurable, because the 

 faces are either concave, or strongly cui-ved. Besides the forms 



