74 PRACTICAL AGRICULTURAL CHEMISTRY [259 



coloration will be seen if K is present. Potassium may 

 also be detected by platinum chloride (188) or sodium 

 picrate (188a). 



259.— Example of Method of Entering the Results op 

 an Analysis in the Note-book 



Examination of pale brown earthy substance 



Preliminary Examination for Metals 



Wet Examination 



Boiled substance with water ; did not dissolve. Treated with 

 dilute HC1, all dissolved. Evaporated to dryness, moistened with 

 HC1, added water, filtered off trace of SiO i} and tested filtrate for 

 metals. 



Heated a few drops of solution with ammonium molybdate, obtained 

 no precipitate ; hence phosphates were absent. To bulk of solution 

 added AmCl and AmHO. 



No pre- 

 cipitate ; 



.*. Fe 

 and Al 



absent 



To solution added Am 2 C 2 o filt ered 



White pre- 

 cipitate 

 Ca present 



Evaporated to dryness, ignited, dissolved 

 residue in dilute HC1, divided into two 

 portions 



1. Added AmHO 



and Na,HP0 4 , 



white crystalline 



precipitate 



Mg present 



2. Tested on Pt wire 

 in Bunsen flame, faint 

 yellow flame, no crimson 

 colour through prism 

 ,\ Trace Na present 



