Gr. S. Robertson 



19 



Florida Pebble Phosphate. 

 Twenty half-hour extractions with 500 c.c. of 2 per cent, citric acid 

 were made with various portions of this phosphate. The results 

 obtained by extracting two portions are given below. 



Refuses "30" sieve 



Passes "100" sieve 



23 



21 



19 



17 



15 - 



13 



11 



12 3 4 5 



Extractions 

 "100" sieve. 2. Refuses '30'' sieve. 



3. Calcined phosphate. 

 Fig. 2. Florida Pebble Phosphate. 



2—2 



