68 PRACTICAL AGRICULTURAL CHEMISTRY [236 



236.-TABLE II. FOR THE 



Test for ammonium by heating the original solid with KHO solution, 

 original solution (229) if not already acid add HC1 in excess. Add a few 

 ignite over the Bunsen flame (230). Treat with a little strong HC1, warm, 



Residue is 

 SiO, 



This resi- 

 due should 

 be quite 

 white 



The filtrate may contain Al, 

 Add a few drops of this solution to some ammonium- 

 are present ; if not, phosphates are absent. 



To the rest of the solution add Am CI in moderate quantity 

 phate is present, examine this precipitate by Table III. ; if 

 examined as below. 



Precipitate may contain Fe 2 (HO) 6 , Al 2 (HO) 8 (232) 

 If the precipitate is quite white, aluminium only 

 will be present ; if coloured, iron will probably be present. 

 Dissolve the residue in hot dilute HC1, add pure KHO or 

 NaHO in excess, then add more KHO so as to have con- 

 siderable excess. Warm and filter 



Residue will be Fe 2 (OH) 8 

 Dissolve in hot dilute 

 HC1 and add KCNS, a 

 blood-red coloration shows 

 Presence of Fe (233) 



Filtrate will contain 

 Al 2 (OH) 6 dissolved in ex- 

 cess of KHO 



Add strong HC1 until 

 the solution is distinctly acid, 

 then add Am HO very 

 cautiously until the solution 

 is faintly alkaline. A white 

 gelatinous precipitate shows 



Presence of Al (234) 



