FATTY ELEMENTS OF FOOD, AND ON FATTENING. 423 



entire quantity of dry matter contained in the moist excrement was 

 readily ascertained : 



Dates. Moist excvement. Dry excrement. Milk in pints. Milk in lbs. 



Jan. 24 40.7 lbs. 6.8 lbs. 10.5 13.5 



25 41.8 7.3 10.5 13.5 



26 62.1 0.0 10.5 13.5 



27 43.4 7.1 10.5 13.5 



188.0 30.2 42.0 54.0 



To ascertain the quantity of fatty or waxy substances contained 

 in the food, the several samples were first treated with hot water, 

 then with ether, and finally with a mixture of ether and alcohol boil- 

 ing. The fatty element of the butter was determined by Peligot's 

 method. 



Fatty Matters in the 

 Food per cent. 



< 1st E.xperiment 3.6 



^ 2d ditto. 3.9 



\ 1st E.xperiment 2.4 



< 2d ditto 2.0 



Hay... 

 Straw 



Fatty Matter in the 



Excrements and 



Milk per cent. 



Excrements (dry, j J' •^Xr'"';:;; .::; ^.I:? 



Milk 3.7 



Let us say, that the proportion of fatty substance contained per 

 cent, in the several articles consumed as food', was as follows — 



Hay 3.7 



Straw 2.2 



Beet 0.1 



Dry excrements. 3.6 



Milk 3.7 



and we shall have the results of the experiment in this shape : 



FOOD CONSUMED IN FOUR DAYS. EXCREMENTS AND MILK IN FOUR DAYS. 



Fattv matter. * Fatty matter. 



Beet 237.6 lbs. 1667.3 grs. Excrements 30.4 lbs. 7688.1 grs. 



Hay 66.0 1776.1 Milk 54.3 14125.7 



Straw 39.6 6113.4 



Fatty matter in excrements 



Fatty matter in food.. 24956.8 and milk 21813.8 



I'he excretions 21813.8 



Fatty matter fi.xed or 



burned 3143.0 



The natural conclusion from this experiment appears to be this : 

 that the cow extracts from her food almost the whole of the fatty 

 matter it contains, and that she converts this matter into butter. 



It would perhaps be possible to make the proportion of butter 

 contained in the milk to vary within certain limits. It is well known 

 that the butter of cows in the same district varies notably according 

 to the nature and abundance of the forage ; the butter of the same 

 country-side, for example, has been ascertained to contain 66 of 

 margarine to 100 of oleine in summer, and 186 of margarine to 100 

 of oleine in winter. In the first case, the cows are grazing on the 

 mountains, (the Vosges ;) in the second they are eating dry fodder 

 in the stall. I have besides had an opportunity to make a direct 

 experiment upon this subject, which appears to me quite conclusive^ 

 Having substituted for one half the allowance of hay an equivalen 



