Browning, etc. — Tellurium, Arsenic, etc. 107 



Table I. 

 Test for Tellurium and Arsenic in Hydrochloric Acid Solution. 



Treatment of solution with Na v S0 3 + KI. 



r i 



P. Te F 



Treatment by boiling to remove 

 the S0 2 , by H 2 2 to break up the 

 iodide, by boiling to remove iodine, 

 by excess of NaOH and H 3 5 to 

 oxidize the arsenic to arsenate, 

 acidifving to remove excess of 

 NaOH, by NH.OH and MgCl,. 

 NH 4 C1 mixture, and filtration. 



P. NH 4 MgAs0 4 F 



Confirmation by Testing for Mo by 



AgN0 3 , forming red KSCN and Zn in HC1. 



brown Ag 3 As0 4 . Red Mo(SCN) 4 . 



Table II. 



Test for Iron, Thallium, Zirconium and Titanium Taken in the Form of 



Hydroxides. 



Solution of hydroxides in the least amount of H 2 S0 4 . Treat- 

 ment with H 2 2 , a red coloration indicating titanium. Treatment 

 with Na 2 HP0 4 in the presence of NaOH* and addition of H 2 S0 4 

 to acidity. 



P. ZrOHPO. ~F. 



Treatment with NaOH. 



P. Fe ) as hydroxides F. 



Tl j or phosphates Treatment with 



Solution in H s S0 4 . H,S0 4 , Na 5 SO, and 



Treatment with Na 2 S0 3 Na 3 HP0 4 and fil- 



-I- KI and filtration. tration. 



P. TiOHPO. 



P. Til F. 



Treatment by boiling (to remove 

 SO,), with H 2 O a to break up iodide, 

 by boiling to remove iodine, with 

 KSCN. Red coloration indicates 

 Fe. 



* This step is to prevent the excess of acid when sodium phosphate is 

 added which interferes with the ready precipitation of zirconium phosphate. 

 Gentle warming after the addition of the sodium hydroxide gives good 

 results, but in no case should the solution be boiled, and if warmed it 

 should be cooled and treated with hydrogen dioxide before acidifying with 

 sulphuric acid. 



Am. Jour, Sci.— Fourth Series, Vol. XL1I, No. 248. — August, 1916. 



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