Clarence A. Smith and Philip B. Hawk 



187 



and aluminium phosphate is but very little (1.3 mg.) larger than the 

 calculated weight of the ferric phosphate alone. These findings indi- 

 cate a failure of complete precipitation of either the iron or the 

 aluminium, or both. The exact reason for this failure was not 

 determined. It would seem probable that it was due to the addition 

 of an insufficient quantity of sodium phosphate, although the amounts 

 added were considerably larger than the amounts called for in the 

 method. The explanation for the high values noted in Det'ns 25 

 and 26 is not apparent. 



TABLE I 



Results obtained with the method of Steel {and Kahn), expressed in milligrams 



