12 THE STOCKFEEDER'S COMPANION 



in acid of standard strength. The amount of acid 

 neutralised measures the ammonia which has been 

 driven off, and from this the amount of nitrogen 

 is calculated. Protein is found to contain on an average 

 1 6 per cent, of nitrogen, hence by multiplying the 

 nitrogen in food by 6J (-W -)* the amount contained in 

 the food is obtained, and the percentage calculated. 



The albuminoid part of the protein is precipitated 

 when copper hydrate is added to a solution of protein, 

 but the amides remain in solution. This precipitate 

 contains only the albuminoids, and the estimation 

 of the nitrogen is as above described. Hence if 

 the protein (nitrogenous matter) is ascertained in a 

 food, and the albuminoids also found in the same food, 

 the difference will give the amides. 



Oil. This includes that part of the food which is 

 soluble in ether, and on this account is more correctly 

 called " ether extract." A known weight of the finely 

 ground food is taken and treated with hot ether for 

 probably a couple of hours to dissolve the oil out. 

 The ether is then evaporated off, and the oil which is 

 left behind is afterwards weighed. In bulky fodders 

 this ether extract may include waxy matters, etc., in 

 addition to oil, which makes the fat credited to these 

 fodders less valuable for feeding purposes. 



Fibre. The food is boiled for half an hour in weak 

 acid and then for half an hour in weak alkali ; the part 

 which still remains undissolved is called " fibre." 



Ash or Mineral Matter. The part which remains 

 after the food has been burnt in the air till the residue 

 ceases to lose weight is called " ash." 



Carbohydrates include sugar, mucilage, starch, etc., 

 and are obtained by ascertaining the total percentage 

 of the above constituents and subtracting the aggregate 



