288 AGRICULTURAL ANALYSIS 



b. There may be present nitrogen in the organic form mixed 

 with nitric nitrogen. 



c. Ammoniacal nitrogen may replace the nitric in the above 

 combination. 



d. The sample may contain no organic but only nitric and 

 ammoniacal nitrogen. 



e. Only nitric or ammoniacal nitrogen may be present. 



249. Seeds and Seed Residues. The proteid matters in seeds 

 and seed residues, after the extraction of the oil, are highly prized 

 as sources of nitrogenous fertilizers, either for direct application, 

 or for mixing. Typical of this class of substances is cotton- 

 seed-meal, the residue left after the extraction of the oil, which 

 is accomplished at the present time mostly by hydraulic pressure 

 but also by the use of a solvent. The residual cakes in the former 

 case still contain some oil, but nearly half their weight consists 

 of nitrogenous compounds. The following table gives the com- 

 position of a dry sample of hydraulic pressed cottonseed-meal : 



Ash 7.60 per cent. 



Fiber 4.90 " 



Oil 10.01 " 



Protein 51.12 " 



Digestible carbohydrates, etc. . - 26.37 " 



While the above shows the composition of a single sample of 

 the meal, it should be remembered that there may be wide varia- 

 tions from this standard due either to natural composition or to 

 different degrees of the extraction of the oil. 



The composition of the ash is given below : 



Phosphoric acid, P 2 O 5 31.01 per cent. 



Potash, K 2 35.50 " 



Soda, Na 2 0.57 " 



Lime, CaO 5.68 " 



Magnesia, MgO 15.19 " 



Sulfuric acid, SO S 3.90 " 



Insoluble 0.69 " 



Carbon dioxid and undetermined. 7.46 " 



The cakes left after the expression of the oil from flaxseed 

 and other oily seeds, are also very rich in nitrogenous matters ; but 

 these residues are chiefly used for cattle-feeding and only the 

 undigested portions of them pass into the manure. Cottonseed 



