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



The oxalate of zinc obtained by the method of Classen* was 

 contaminated with potassium oxalate and therefore could not 

 be used to determine the amount of zinc present. On ignition 

 and washing of the oxide obtained, it was shown that all the 

 zinc was recovered. 



Summary. 



Experiments have been given to show that lead may be 

 determined by precipitation, either with ammonium oxalate or 

 oxalic acid, in the presence of large volumes of acetic acid and 

 titration of the oxalate formed with permanganate. 



Nickel has been estimated by precipitation by oxalic acid in 

 water solution, the addition of acetic acid to separate the metal 

 remaining in solution, and titration with permanganate. 

 Errors may occur in this method from inclusion of the pre- 

 cipitant or indefmiteness of the end point. 



Zinc may be estimated very accurately by the method used 

 for nickel. 



* Classen, Zeitschr. anal. Chem., xvi, 470. 



