236] WET SEPARATION OF METALS 69 



SEPARATION OF THE METALS 



ammonia gas will be evolved which turns turmeric-paper brown. To the 

 drops of strong HN0 3 , evaporate to dryness in a porcelain dish, and very gently 

 add water and filter. 



Fe, Mn, Ca, Mg, K, Na 



molybdate solution and warm ; if a yellow precipitate forms, phosphates 



(231), heat to boiling, and then add AmHO in excess ; filter. If a phos- 

 absent, examine the precipitate as below. In any case the filtrate must be 



Filtrate may contain Mn, Ca, Mg, K, Na 



Add Am 2 S until the solution has a distinct yellow tinge. Warm and filter 



Buff precipi- 

 tate will 

 beMnS 

 Confirm by 

 heating on 

 platinum foil 

 with Na 2 CO s 

 andKN0 3 ; a 

 green mass 

 shows 

 Presence 

 of Mn 



Filtrate may contain Ca, Mg, K, Na 

 Add ammonium oxalate (Am 2 C 2 4 ) solution in fair 

 excess, filter 



White 



precipit ite 



will be 



CaC 2 0, 



showing" 



presence 



ofCa 



Filtrate may contain Mg, K, Na 

 Evaporate the filtrate to dryness in a 

 porcelain dish, scrape out the residue on to a 

 piece of platinum foil, ignite until all fumes 

 cease to be evolved. Boil the foil in a very 

 small quantity of water containing a few 

 drops of HC1. Divide into two portions. 



Examination 

 for Mg 

 Add AmCl, 

 Am HOin excess, 

 and Na 2 HP0 4 

 and shake well ; 

 a white crystal- 

 line precipitate 

 shows 

 Presence of Mg 



Examination for K 



and Na 

 Take up a little of the 

 solution on the loop of 

 platinum wire and hold in 

 the Bunsen flame. 



(1) A pale violet flame 

 shows 



Presence of K and 

 absence of Na 



(2) A bright yellbw 

 flame shows presence of 

 Na. Examine this flame 

 through the indigo prism 

 or cobalt glass ; a crimson 

 flame shows 



Presence of K (235) 



