148 COMPOSITION OF FEEDING STUFFS 



Analysis of Feeding Stufifs. 



140. (a) Moisture, 



Moisture is that portion of a food which disappears 

 on drying at ioo° C. In some cases the loss includes, 

 besides water, small quantities of volatile acids and 

 essential oils, but unless for some special reason, no 

 correction is applied for this slight error. 



Preparation of Sample. — The material is reduced, if 

 possible, to a fine powder and evenly mixed. If the 

 food-stuff is very moist, as in the case of green fodders 

 and roots, the material is chopped finely and the 

 estimation then carried out, the substance being 

 reduced to a powder subsequently. 



Estimation of Moisture. — Five to lo grams of the 

 material are heated in the steam-oven to constant 

 weight. The loss is moisture. 



In the case of substances which contain large 

 quantities of oil, which is found to oxidise readily at 

 the temperature of the oven, the material should be 

 dried in vacuo ^ or in a current of hydrogen or coal-gas, 

 in apparatus of the type shown in Fig. 20. 



141. {h) Ash and Sand. 



Five grams of the material are ignited to whiteness 

 at a dull-red heat. 



Phosphate. — Phosphate in the ash, when required, is 

 determined by extracting with HCl to which a little 

 nitric acid has been added, filtering off the insoluble 

 matter, and then estimating the P2O5 with ammonium 

 molybdate in the usual way. 



Sand. — The "crude ash" should be examined 

 qualitatively for fine earth, sand, gypsum, chalk, etc., 

 which may have been used as adulterants. The 

 insoluble matter remaining after extracting the ash 



