138 Extracts from the Jownals. [Jan., 



The milk in the morning amounted to 4| quarts. Sp. gravity, 

 1030, and yielded 



Casein, .... 3.5 

 Butter, .... 4.9 

 Sugar, .... 3.8 

 Ashes, .... 0.5 

 "V^'ater, .... 87.3 



100.0 

 The food upon which the cow was fed, is composed as follows: 

 Boussingault. Plmjfair. Boussi72gault. 



Kay. Oats. Beiiiis. Potalces. 



Carhon,. . . 38.47 41.57 38.24 12.30 



Hydrogen, . . 4.20 5.25 5.84 1.74 



Oxygen, . . 32.51 30.10 33.10 12.04 



Nitrogen, . . 1.26 1.80 5.00 0.32 



Ashes, . . . 7.56 3.28 3.71 1.40 



Water, . . . 16.00 18.00 14.11 72.20 



The question which Prof. Playfair discusses at this stage of his 

 paper is, whether the butter is derived wholly from what may be 

 considered the free fat or oil ready formed in the vegetables con- 

 sumed by the cow. This is determined in the negative, for while 

 the whole amount of fat in the food of one day amounts only to 

 0.486 of a pound, the milk yielded 0.964 lbs. butter; and so in 

 about the same proportion during the time the experiments were 

 continued. It is supposed that the excess of butter, over that in 

 the food is formed in the animal system by the action of oxygen 

 on the unazotised ingredients of the food. 



Another question discussed is, how it happened that the quan- 

 tity of butter should vary from day to day. This is accounted 

 for on the ground that when the cow was exercised much, either 

 in obtaining her food, or was hurried to and from the pasture, the 

 material which would have been converted into butter was con- 

 sumed in respiration. A supposition of this kind agrees with the 

 facts in this case, and also with the experience of all dairymen. 

 When an animal is quiet the respirations are fewer; less food is 

 consumed in respiration, and the animal, if not milked, fattens. 

 Hence, cows ought never to be diiven rapidly to or from pasture. 

 We see too why soiling cows increases the amount of butter — 

 or when they are kept in warm comfortable stables during the 

 winter. 



The conditions necessary for the production of cheese are dif- 

 ferent from those which produce butter. To make butter a rich 

 pasture is required, but for cheese poor lands or poor pastures are 

 the best. The travel which the cow has to perform wastes the 



