( 351) ) 



importance. I then prepared also all (he oilier i-alls of Ihc series, 

 whose general formula is represented hy H' CO^. CCl^-\-HC(J, . CCI^. 

 The results of the investigation are given helow. A detailed description 

 of these compounds, also thai of the acid thallhnn-fr/hroiiuxiccftfi,' 

 (investigated bv way of comparison) will be given lii-sl. 



§ ,3. 1. POTASSIUM-SALT : KCO.td, . HCO.CC/, . 



The analysis gave 10,(>() 7„ K- calculated 10,68 7„. 

 Sp. Gr.: at 18° C, 2,005; molecular volume: 182,04. 

 Large clear, vevy iusli-ons crystals, which are generally llaltened 

 along two parallel |)lanes. Small isometrically developed, colourless 

 octahedra also occur. The crystals are represented in fig. 1. 



THragoiinl-trapezohedric. 

 a -c = 1 : 0,7808. 



Potassium-salt. 

 Fig. 1. 



Forms observed: o == |111|, large, with a high lustre and well 

 developed; ,i'=:|311|, with four planes above and fouj- below in the 

 alternate spacial-oclanls, but often wanting, and in all cases small 

 and rather dull; ~ = |511|, very small and narrow, dull aud mostly 

 quite absent. 



Angular rallies: 

 : = {111) : {111) =-^ 



: d^= {111) : {111) = 

 : ,r = (111) : (311) = 

 0:,/=(JJI):(311) = 

 A':,r=;311):(131)=.- 

 X:0 = {;Sn) : (111)=: 



