THE ANALYSIS OF CHOPS 



Ash. In this case, as in all vegetable and animal matter, the ash 

 left on incineration has not the composition of the inorganic com- 

 pounds present in the plant or animal. This objection, however, is 

 not a very important one. 



Fat. Since this is really the matter soluble in ether, it is better 

 described as "ether extract". In the case of many substances, choro- 

 phyll, resins, waxes and organic acids, e.g., lactic acid, are dissolved 

 by ether and are included in the "ether extract ". In some instances 

 the amounts of these non-fatty substances may be considerable in 

 proportion to the true fat. 



Nitrogenous matter. However accurate the determination of nitro- 

 gen may be, the figures given under this head can never be very 

 trustworthy. In the first place, all the nitrogen in a substance is not 

 usually present as albuminoids, but may be partly as simple amino- 

 compounds, ammonium salts, or nitrates. Then, too, all albuminoids 

 do not contain the same proportion of nitrogen, and therefore multi- 

 plying by 6'25 does not give a correct measure of their amount. A 

 method of distinguishing between the nitrogen existing as true albumi- 

 noids and that as amides, etc., has already been described. 



Crude fibre. The method used in the estimation of this item is 

 obviously based upon an assumption that from a material freed from 

 fat by ether extraction, dilute sulphuric acid and dilute sodium hydrate 

 will effect the solution of all matter which could be removed in the 

 digestive processes of an animal ; it evidently cannot yield any really 

 satisfactory results. Moreover, the amount of the "fibre" obtained 

 depends very much upon the state of subdivision of the material and 

 upon other circumstances, and the residue obtained often contains 

 nitrogenous substances. 



Non-nitrogenous extractives. This item, like all those obtained by 

 difference, is liable to the accumulated errors of all the direct deter- 

 minations, some of which, e.g., the fibre, are probably very great. 



According to Stone L the results obtained by the Weende method are 

 very incorrect. He examined specimens of wheat and maize, both by 

 the usual conventional methods and by determining the various carbo- 

 hydrates actually present. Some of the results by the two methods are 

 given below. 



Air-dry material (per cent) : 



Under the last column (obtained by difference) it is generally as- 

 sumed that starch, digestible cellulose and sugars are included. 



1 Bull. No. 34 (1896), Office of Experiment Stations, U.S. Dept. of Agric. 



