AGRICULTURAL EXPERIMENT STATION. 211 



usual manuer, while in a duplicate set the action of the pepsin 

 was limited to twelve hours. The nitrogen found in the undigested 

 residues is shown below. 



24 hs. pepsin, 12 hs. pepsin, 



12 hs. pancreas, 12 hs. pancreas, 



per cent undigested, per cent undigested. 



Corn Meal, XX, .26 .42 



White Clover, XIIL .49 .54 



A sheep excrement, after 6 hours with pepsin alone, gave nitrogen 

 1.12 per cent; after 12 hours, 1.02 ; 18 hours, .98 ; 24 hours, .93. 



It would appear from these figures that the full effect of the pepsin 

 is not obtained in 12 hours — at least, in the case of the materials 

 named. In this work much depends upon the complete separation 

 of the digestive fluids from the residue, and the careful washing of 

 the latter. As a rule, the filtrations were effected with extreme 

 difficulty, and a few anomalous results were manifestly due to ihe 

 fact that a part of the digested material remained upon the filtei-. 



The best results were obtained by the use of the "Best German" 

 filter paper. Soft filters, 13 c. m in diameter, were selected and 

 pleated. After the final washing no attempt was made to separate 

 the residue from the paper. When dry, the tops of the filters were 

 cut away, and the nitrogen determined in the whole by the Kjeldahl 

 method. 



LOSS OF NITROGEN FROM NITROGENOUS SUPERPHOSPHATES. 



Andouard* calls attention to the loss of nitrogen which many 

 superphosphates suffer through the decomposition of nitrates. This 

 decomposition he believes to be due to the presence of free phos- 

 phoric, sulphuric or fluorhydric acids. The niiric acid thus set free 

 escapes either unchanged or after reduction by the iron sulphide, 

 ammonia salts or organic matters present 



The statement has also been made that sodium nitrate undergoes 

 decomposition in the presence of free sulphuric acid together with 

 large quantities of iron sulphate and organic matters.! 



In August 1887 six nitrogenous superphosphates were prepared 

 in the station laboratory'. Thej' were mixed as follows : 

 1. 500 grams Dissolved Bone Black. 

 100 " Sodium Nitrate. 



*Comptes renduce. Tome CIV, Nr. 9, S. 583-585; Abs. Bied. Oeutralbhitt, Mai, 18S7, S. 

 304-305. 



tOhemikerzeitung, 1887, Nr. 36; Abs. Bied, Centralblatt, Mai, 1SS7, S. 305. 



