254 PROCEEDINGS OF THE AMERICAN ACADEMY. 



20 : 1 : 9 Sodic Platino-tung state. In one experiment in which I 

 boiled a portion of pure sodic tuugstate with a considerable excess 

 of sodic hydrate, and added to the boiling solution chlorplatinic 

 acid (PtClglia) in small portions at a time, a fine yellow solution was 

 formed, after addition of an excess of acetic acid, which soon deposited 

 a mass of topaz-yellow crystals. This could be redissolved and re- 

 crystallized without decomposition. The mother liquor appeared to 

 contain one or two other salts. Of this salt : 



(1) 1.4847 grams lost on ignition 0.2453 gram = 16.52% 0+ H2O. 

 (4) 1.4154 grams lost on ignition 0.2349 gram = 16.61 % O + HgO. 



(2) 1.4847 grams gave 0.0466 gram platinum = 3.73% PtOg. 



(3) 1.0976 grams gave 0.0345 gram platinum := 3.65% Pt02. 

 x-N ( 1.4154 grams gave 1.0467 grams platinum ^= 3.83%. 



\ 1.4154 grams gave 1.0129 grams WO3 = 71.57%. 

 (6) 1.4847 grams gave 1.0619 grams WO3 = l\.bO%. 



The analyses lead to the formula, 



20 WO3 . PtOa . 9 Na^O -\- 58 aq., 

 which requires ; 



6468.5 100.00 



The solution of this salt has a strongly acid reaction with litmus. It 

 gives with ammonic chloride beautiful colorless scaly crystals, slightly 

 soluble in cold but soluble in boiling water, exactly resembling in 

 appearance the sodio-ammonic tungstate, 12 WO3 . IS^a^O . 4 (NHJgO? 

 and containing nd platinum. This reaction seems to support the view 

 that the compound is a double salt, and we may perhaps assume that it 

 is represented by the formula, 



10 WO, . 4 NaaO + 10 WO3 . PtOg . 5 NagO + 58 aq. 



The principal reactions of this salt are as follows : — 



With AgN03 ^ white fine grained crystalline precipitate settling slowly. 

 With TINO3 a similar precipitate in rather coarser grains. 

 With SO^Cu a very pale blue or bluish white fine grained precipitate. 

 With HgNOg a bright yellow amorphous precipitate. 

 With Co(NH3)f,Cl3 a pale bull precipitate quickly becoming crystal- 

 line in leaves. 



