200 ON THE DIFFERENT METHODS OF MAKING AND 



till it is either manufactured or consumed. In the udder, busy 

 absorbents which line the milk tubes carry into the general 

 circulation part of the nutrient properties it contains ; thus it 

 loses a portion of fat, albuminoids, sugar, and water, and possibly, 

 too, of its salts. But if drawn into a bottle or other vessel with- 

 out exposure to the air, and so kept, it will not spoil for an 

 almost indefinite length of time. Otherwise it attracts from the 

 air the seeds of a fungus plant wdiich grow, multiply, and pro- 

 duce souring — the arthrococcus cells of the savan. The boiling- 

 point temperatuie will certaffily kill them, but it is not con- 

 sidered that either cold or wet will, although the former will, 

 when intense, at least hinder reproduction. One or two left on 

 a milk vessel, or in one of its crevices, will, on being moistened 

 with warm milk, again spring into active life, quickly produce 

 millions, and premature souring results. There are also destruc- 

 tive agents which get into milk through the cow's body. These 

 are the micrococcus cells of the learned, very minute and every- 

 where abundant. Within the snow lines of high mountains, as 

 proved by the experiments of Tyndall on the Alps, they cannot, 

 in otherwise favourable circumstances, spring into life ; and, 

 according to other experiments, when once formed no amount 

 of cold will kill them. The heating to the boiling-point cer- 

 tainly disposes of them ; it is for this that green fruit is scalded, 

 and with the desired effect. Milk is extremely susceptible of 

 any ferment, it readily adopts its seeds, and even the flavour of 

 a tobacco pipe will be imparted to it hi a close compartment. 

 Diseases have through its means been transmitted, and the 

 peculiar smell of a cellar is readily detected in the milk which 

 has been set in it. A good butter-maker will object to cooling- 

 warm milk in the same room where other milk is set for the 

 cream to rise — the odour leaving the former being readily 

 adopted by the other. 



Souring. 



When souring once begins it contmues until the sugar is con- 

 verted into acid. The whey begms to separate from the thick- 

 ened milk, the vinous fermentation sets in, alcohol is slowly 

 formed and takes up the volatile oils, the strong acid ferment 

 acts upon the solid fats, and l)otli quantity and quality of pro- 

 duct are injuriously affected. Still longer will convert the 

 alcohol into vinegar with even worse results. But there is a 

 time in the souring process when the butter separates more 

 perfectly from the other constituents. Acidity is well known 

 to exert a powerful and beneficial action in the manufacture of 

 cheese, and, although different in butter-making, it can also be 

 turned to account. The acid as it develops thins and wears 

 away the membrane which covers the butter globule, and at the 



