ig05 .] HALL AND SMITH— COLUMBIUM. 181 



On dissolving in water more platinum sulphide was found, but 

 when hydrogen sulphide was conducted through the filtrate no 

 further precipitation took place. The first crop of crystals got by 

 the evaporation of this solution showed the usual form of potassium 

 columbium oxyfluoride. They were allowed to dry in the air and 

 labeled crystals No. i (A). The filtrate from them was reduced 

 to a small bulk. Strong hydrofluoric acid was added when -the 

 needles of potassium columbium fluoride (K 2 CbF.) separated. 

 These were dried between bibulous paper and labeled crystals No. 

 2 (B). Samples from these two crops of crystals were analyzed. 

 Analysts of No. i (A) : 



0.53 gram of salt gave 0.2346 gram of oxide and 



0.3 16 1 gram of potassium sulphate 

 0.2346 : 0.3 1 61 :: x/2 : 174 x = R. 2 5 = 258.2. 



Calculated. 

 K 2 CbOF 5 H„0. Found. 



K. 2 S0 4 57.81 59.64 



Oxide 4452 44.26 



The crucible in which the ignition of oxide occurred was stained. 

 This was undoubtedly due to the presence of tin, which had not 

 been removed, although hydrogen sulphide had been conducted 

 through the solution of the double fluoride. 



Analysis of No. 2 (2?) : 



0.S428 gram of salt gave 0.3635 gram of oxide and 



0.4803 gram of potassium sul- 

 phate. 



0.481 1 gram of salt gave 0.2082 gram of oxide and 



°- 2 7 75 1 gram of potassium sul- 

 phate. 



0.3635 : 0.4803 :: .v/2 : 174 x = 263.4. 



0.2082 : 0.2775 :: xJ2 : 174 x = 250.1. 



Calculated 

 K 2 CbF 7 . Found. Found. 



K 2 S0 4 57.05 56.99 57.68 



Oxide 43.93 43.13 43.28 



1 Probably too high because it was not heated enough to expel all of the sul- 

 phuric acid. 



