The Purchase oe Feeding Stufps. 



13 



be employed with so much ease and certainty in the case of 

 feeding stuffs, it is the only one that admits of the use of 

 definite and detailed figures, and, if applied intelligently, it 

 is capable of furnishing useful information. 



In the case of manures three substances only are valued, 

 namely, nitrogen, phosphates, and potash. Similarly, in 

 the case of foods, the valuer has regard to but three con- 

 stituents, which in this case are albuminoids, oil or fats, and 

 carbohydrates. 



In comparing the three main constituents of food, albu- 

 minoids and oil are generally credited with a value which is 

 about 2 J times as great as that of carbohydrates, so that, to 

 get the number of units in a food, we multiply the percentage 

 composition as regards albuminoids and oil by 2 J, and to the 

 product add the percentage of carbohydrates. As a formula 

 it may be thus expressed : — 



2 J (albuminoids + oil) + carbohydrates = total food units. 



Suppose that a sample of linseed cake guaranteed to contain 

 32 per cent, albuminoids, 11 per cent, oil, and 34 per cent, 

 carbohydrates is offered at £g per ton, the number of units is 

 z\ (32 + 11) + 34 = 141 J, an d the value of a unit is there- 

 fore — = is. 3jd. 



Assuming that another sample of si milar cake is offered 

 whose composition is guaranteed at 28 per cent, albuminoids, 

 9 per cent, oil, and 35 per cent, carbohydrates, the number 

 of units in this case is 2\ (28 -f 9) + 35 = 127 J, and this, at 

 is. 3jd. per unit, comes to £8 2s. per Ion. , 



The value of different brands of the same kind of cake, say, 

 linseed, does not depend altogether on the chemical composi- 

 tion ; other circumstances, such as hardness, freshness, etc., 

 being not without material influence. And if there are diffi- 

 culties in the way of depending entirely upon the system of 

 units in determining the value of different samples of the 

 same kind of feeding- stuff, the difficulties are so great as to 

 render the system practically inapplicable where different 

 kinds of feeding stuffs are compared. 



The Chief Feeding Stuffs. 



Linseed. — The chief sources of the supply of linseed are 



