108 Analysis of Feeding Materials [163-165 



freshly dried substance, and estimate the nitrogen by the acid 

 process (paragraphs 90-95). The flask must be carefully 

 watched whilst heating, as the acid is apt to froth. Should 

 the solution take a long time to clear, it may be hastened 

 by adding a drop of mercury. If this be done, the mercury 

 must be precipitated by adding sufficient potassium sulphide 

 along with the caustic soda before distilling off the ammonia. 

 Otherwise mercury ammonium compounds are often formed 

 which are not completely decomposed by NaHO (see para- 

 graph 93). 



163. Total Albuminoids. — Weigh out 2 grams of freshly 

 dried ' dry matter,' place it in a 4-oz. beaker, and fill the beaker 

 with 4 per cent, carbolic acid solution in water. Add a drop of 

 meta-phosphoric acid and allow to soak for twenty-four hours. 

 Decant the liquid through a filter paper, and boil up the residue 

 with a fresh portion of the carbolic acid solution. Filter, wash 

 three or four times with carbolic acid, and dry. This treatment, 

 whilst coagulating all the albuminoids and rendering them 

 insoluble, dissolves all the amides. 



When the substance is dry introduce it, together with the 

 filter paper, into an 8-oz. flask, and estimate the nitrogen by the 

 acid process (paragraphs 90-95). 



164. Total Ash. — Weigh out 2 grams of freshly dried 

 substance into a platinum dish, and determine the ash as in a 

 sample of oil cake. 



Analysis of the Crude Fibre 



165. Insoluble Albuminoids.— All the amides being 

 soluble in water, the insoluble albuminoids may be calculated 

 from the nitrogen in the crude fibre. Weigh out 2 grams of 

 freshly dried crude fibre, and determine the nitrogen in the 

 same way as has been done in the dry matter. 



