142 MIXED MANURES AND CALCIUM COMPOUNDS 



184. Examination of other Mixed Manures. 



{a) Fish Meal and Fish Guano. — The following 

 characteristics should be noticed : — 



(i) Oiliness — shake a few grams with ether, and 

 note whether much oil is left after filtering 

 and evaporating the solvent. 



(2) Condition — the manure should be finely- 



divided, must not contain much sand or 

 shell, and be free from larger stones, etc. 



(3) Smell — distinctive fishy odour and well 



decomposed. 



The manure should be tested for ammoniacal and 

 organic nitrogen and nitrates, and for phosphates and 

 potash in the usual manner. 



{U) Rape Dust. 



(i) Oil — tested for as above. 



(2) Potash and Phosphates — rape dust fre- 

 quently contains appreciable quantities of 

 these constituents, which may be detected 

 in the usual way after destroying the organic 

 matter. 



{c) Sewage Sludges^ etc. — These should be examined 

 as to their condition — fineness, etc., and for organic 

 matter by estimating the loss on ignition, which in 

 some cases is very small. 



135. Artificial Mixtures — Incompatible Manures. 



In making up mixtures of artificial manures it must be 

 remembered that certain fertilisers are incompatible owing to 

 the reactions which are set up, possibly causing the loss of some 

 valuable constituent. 



{a) Superphosphate and Nitrates. — A few grams of 

 superphosphate are mixed with a little nitrate of soda 



