PART II 



THE MORE COMMON ESTIMATIONS 

 OCCURRING IN AGR1CUITURAL ANALYSIS 



21. No one can expect to attain proficiency in any 

 branch of quantitative analysis unless he first acquire confi- 

 dence in the accuracy of his work. The most simple way of 

 acquiring confidence is to practise the different estimations on 

 pure substances of known composition. The results are in 

 this way easily checked. By working systematically through 

 this section, using always the substance recommended, the 

 student will gain the necessary confidence and at the same time 

 acquire a knowledge of all the simpler operations used in 

 agricultural analysis. 



Always read through the whole oj a paragraph before com- 

 mencing the work described therein. 



Section I.-GRAVIMETRIC ESTIMATIONS 

 ESTIMATION OF IRON 



22. Substance used. — Ferrous ammonium sulphate, 

 Fe(NH 4 ) 2 (S0 4 ) 2 .6H 2 0. 



Method employed. — The iron is precipitated as ferric 

 hydrate and weighed as ferric oxide, Fe 2 3 . 



Weigh out in a watch glass about '5 gram of pure ferrous 

 ammonium sulphate which has been finely powdered and 

 pressed between folds of filter paper. Transfer this to a 10-oz. 

 beaker, washing the last traces of substance from the watch 

 glass by means of the wash bottle, and dissolve in about 



