io6 ARTIFICIAL NITROGENOUS MANURES 



Chlorides . . Test with silver nitrate in 

 acid solution. 



Thiocyanates . Blood-red colour produced 

 with ferric chloride. 



Ferrocyanides . Prussian blue formed with 

 ferric chloride. 



All of these substances are likely to be present, as 

 well as tarry matter, organic bases, etc. 



{b) Total Ammonia. — Ammonia in ammoniacal 

 liquor amounts in the average to 2 per cent. It is 

 estimated by distilling 20 c.c. of the liquor with caustic 

 soda, and collecting the ammonia evolved in 50 c.c. of 

 N.H2SO4. The apparatus used is that previously 

 described in the Kjeldahl estimation (7, p. 12). 



The free ammonia may be estimated by similarly 

 distilling 20 c.c. of the liquor without the addition of 

 caustic soda. 



90. Sulphate of Ammonia. 



A commercial sample of the manure is chosen, its 

 colour and general appearance noted, and a small 

 portion heated on platinum foil in the Bunsen flame. 

 A good sample should volatilise without leaving any 

 residue. 



{a) Sand and Insoluble Material. — Ten grams of the 

 fertiliser are weighed out, dissolved in water in a beaker, 

 and filtered into a 250 c.c. flask. The residue, if any, 

 is washed thoroughly, and the filtrate and washings 

 made up to the mark. The insoluble material is dried 

 in the oven, and ignited in a crucible together with the 

 niter paper, and its amount expressed in percentage of 

 "the original material. 



{b) Ammonia. — Twenty- five c.c. of the solution from 

 {a) are distilled in the Kjeldahl distillation apparatus 



