METHOD OF DE ROODE FOR KAINIT 563 



The mixture is boiled for 20 minutes and treated with some 

 hydrogen peroxid to oxidize any ferrous iron that may be pre- 

 sent. Afterwards the solution is made alkaline with ammo- 

 nia. After cooling, it is made up to a given volume (half a liter) 

 and filtered. An aliquot part of the filtrate is evaporated to dry- 

 ness, ignited, extracted with hot water, and, after the addition of 

 a few drops of hydrochloric acid, the potassium is precipitated 

 with platinic chlorid, and collected and weighed in the usual 

 manner: Or the ignited residue may be dissolved directly in 

 dilute hydrochloric acid and the rest of the process carried out 

 as indicated. 



In kainit the process is conducted as follows : Ten grams of 

 the powdered sample are treated with a hydrochloric acid solu- 

 tion of the barium oxalate containing 10 grams of the salt. 

 The rest of the operation is conducted as described above. In 

 the use of this method it is important that always enough of the 

 barium oxalate solution be employed to fully saturate all the 

 sulfuric acid which may be present. 



475. Method of de Roode for Kainit. All the potash contained 

 in kainit, according to de Roode, passes readily into aqueous 

 solution. 43 On evaporating this aqueous solution to a pasty 

 condition with enough platinic chlorid to unite with all the halo- 

 gens present, all the other bodies can be washed out of the potas- 

 sium platinochlorid by ammonium chlorid solution and the pure 

 platinum salt thus obtained, which is washed and dried in the 

 usual way. De Roode therefore, asserts that it is quite useless 

 to previously precipitate the solution of kainit with barium chlo- 

 rid, ammonium oxalate, or carbonate. Before the addition of alco- 

 hol to the residue obtained, by evaporation with platinic chlorid 

 the sodium sulfate present renders the platinum salt sticky and 

 difficult to wash, but the disturbing sodium compound can be 

 readily removed by washing with ammonium chlorid solution. 



The method of direct treatment has the advantage of avoiding 

 the occlusion of potash in other precipitates and the danger of 

 loss on ignition. The method as used by de Roode gives results 



43 Journal of the American Chemical Society, 1895, 17 : 85. 



