138 



CHEMICAL CONTROL OF DIPPIXG TANKS. 



the new tank at Cedara, and the second group including those 

 tanks in which only plain arsenite of soda is used. 



The results of all the analyses are given in the following 

 tables : — 



II. Tanks on Cedaua Farm. 



(a) Neiv TcDtk (using an arsenical dip containing coal tar 

 derivatives in addition). This tank was cleaned out and filled 

 with the clean dip on May 17th, 1921. 



(b) Old Tank (using plain arsenite of soda), 

 cleaned out and refilled on July 18th, 1921. 



This tank was 



Note. — The solid arsenite of soda used for filling this tank 

 had been in stock for several years and had an unusually high 

 percentage of oxidised arsenic (arsenate), hence the high per- 

 centage (6'9) of oxidation in the tank immediately after filling. 



