285 



the calculated quantity oi ferri-sulfate. The heaufifully green solutions, 

 after evaporation on the water-bath, deposited crystals of the salts 

 here described. 



§ 4. POTASSIUM-FERRI-MALONATE. 



Splendid, pale emerald-green, ordinarily flattened, very big and 

 perfectly transparent crystals. They are well developed, but in the 

 zone of the prism and that of the clino-doma they often show 

 oscillations of the angular values to an amount of ^°. Analysis 

 proved the composition to be 



(13,1 % HJJ; 10,3 »/, Fe) -. K, \ Fe {C\H,0,), \ + 4 H,ü. 

 The salt possesses therefore 2 H^O more than mentioned by Scholz^). 



Triclinic-pinacoidal. 

 a:h:c = 0,4924 : 1 : 0,4897. 

 A= 96°33' 

 B = 103^43' 



C= 84°41' 



tri 



a = 98° 5' 



ii — 104°30' 



r= 82°b2 



Forms observed : h = jOlOj, large and lustrous; 

 ;/?, =z|110|, and rt ^ jlOOj, almost equally large; 

 ^> = jl20|, somewhat smaller than ni; t = {\10\, 

 narrow, but well reflecting; o ^= {111|, and 

 ^ = I 01 J I, well developed, and like r = |T01 1, 

 giving perfect images; c = |001j, small; s=z\021\, 

 well-developed ; a> = {11 Ij, as a narrow truncation 

 of the edge r-.h. The external habit is elongated 

 parallel to the c-axis, and in most cases some- 

 what flattened parallel to jOlOj. 



•Fig. 1. 

 Potassium-Ferri- 

 Malonate 



Angles: 



a:b =(100): (010) =* 95°19' 



b:c =(010): (001) =* 83 27 



c:a =(001) (100) =* 76 17 



a:m = (100):(110) =* 26 39 



b:q =(010): (Oil) =* 59 13 



6:m = (010):(110) = 68 40 



c.q =(001): (Oil) = 24 14 



b:p =(010): (120) = 48 16 



/):m = (l20):(lK)) = 20 34 



a:t =(mO):(lU)) = 25 



t:b' =(110): (010) = 59 43 



Observed : Calculated -. 



68°40' 



24 14 

 48 6' 13 

 20 332/3 



25 7 

 59 34 



1) A. ScHOLz, Monatshefte f. Chemie, 29. 445. (1908). 



