H. L. Ward — Estimation of Lead, Nickel, and Zinc. 335 



tion, that precipitation is incomplete. If, however, glacial 

 acetic acid makes up one-half the volume of the solution the 

 results are accurate. 



Oxalic acid has been used as a precipitant for lead by a number 

 of investigators.* The determinations of Table II were made 

 by adding crystallized oxalic acid to a boiling solution of lead 

 nitrate, filtering, washing, and titrating the oxalate with per- 

 manganate as before. When no acetic acid is present, precip- 

 itation is not quite complete, but the errors are much less than 

 when ammonium oxalate is used as a precipitant, as may be 

 seen from a comparison with Table I. Acetic acid added in 

 equal volume to the solution secures complete precipitation 

 even in the presence of considerable amounts of ammonium or 

 potassium salts, provided the amount of lead salt present is not 

 too small. 



Table II. 



The Determination of Lead as Oxalate by Precipitation with Oxalic Acid 

 in the Presence of strong Acetic Acid. 



Lead 

 present 



Volume 

 at 













as 

 nitrate 



precipi- 

 tation 



Acetic 

 acid 



Oxalic 

 acid 



Salts 

 present 



Lead 

 found 



Error 



grm. 



cm 3 



cm 3 



grm. 



grm. 



grm. 



grm. 



0-0500 



50 



__ 



2 





0-0491 



— 0-0009 



0-0500 



100 







4 



_„ 



0-0488 



— 0-0012 



o-iooo 



50 



_. 



2 





0-0994 



— 0-0006 



o-iooo 



100 



-- 



4 



-- 



0-0990 



—o-ooio 



0-0050 



50 



25 



1 





0-0050 



+ 0-0000 



0-0250 



50 



25 



1 







0-0256 



+ 0-0006 



o-iooo 



100 



50 



2 



-- 



0-1002 



+ 0-0002 







Potassium Acetate present 





o-iooo 



50 





2 



•2 



0-0962 



— 0-0038 



o-iooo 



100 



-- 



4 



'2 



0-0988 



— 0-0012 



o-iooo 



100 



50 



2 



•2 



0-0997 



— 0-0003 



o-iooo 



100 



50 



2 



•2 



o-iooo 



±0-0000 







Ammonium Acetate present 





0-0050 



50 



25 



1 



3- 



0-0040 



— o-ooio 



0-0250 



100 



50 



2 



5- 



0-0227 



— 0-0023 



0-1000 



100 



50 



2 



2' 



o-iooo 



±0-0000 



f Bottiger & Pollatz, Chemical Abstracts, ii, 

 »uch der Chemische Analytische Titermetnode. 



645 : Mohr-Classen, Lehr- 

 , 228 ; Low, Jour. Amer. 



