Proceedings of the Farmers' Club. 435 



from the weight of the product just named ; the difference indicates 

 tlie weight of the milk-sugar, which was consumed in the burning. 

 What remains is casein mingled with a portion of the salts ; in 

 order to separate the casein the material is burned. By taking 

 the weight of the asli from that of the material we have the weight 

 of the casein, and by adding together the weight of the two portions 

 of ashes we have the total of the inorganic salts or saline matter. 



Butter, which is a fatty substance, containing no nitrogen, exists 

 in milk in the form of minute globules, which are not opaque, as 

 might be supposed, but transparent. Each globule is surrounded 

 by a thin covering or skin believed to consist of casein, and, instead 

 of being of spherical form, the globules are lens-shaped. This 

 gives them the propert;)j of dispersing light in all directions, and, 

 as they exist in immense numbers this dispersion of rays communicates 

 a white color to the milk. Some cowa give blue and others an 

 unusually yellow milk. This arises in each case from an unnatural 

 cause. According to some investigators, from the presence of micro- 

 scopic vegetation that draws its sustenance from the milk as 

 ordinary plants do theirs from the soil. Others assert that the 

 abnormal tints are due to animalcules, and have given them hard latin, 

 names, that found in the blue milk being termed mhrio cyanogenus^ 

 and that in the yellow vibrio xanthogenus. As to the casein we 

 have seen that a portion of it is probably comprised in the cover- 

 ings of the butter globules, the greater part of it, however, exists in 

 solution in combination with the soda, the province of this alkaline 

 salt being to thus hold the casein in the proper condition. The milk- 

 sugar is simply dissolved in the liquid, it is not very sweet compared 

 with ordinary sugar, although it gives the sweetness peculiar to fresh 

 milk. Its great characteristic is the facility with which it is con- 

 verted into lactic acid, which serves a most important part in the 

 production of the butter, as will presently be seen. This trans- 

 formation of the milk-sugar is excited by the incipient decomposition 

 of the casein. 



When milk is set away at ordinary temperatures the butter globules, 

 being the lightest rise to the top, and thus aggregated constitute the 

 cream. At from fifty-live degrees to fifty-nine degrees the milk is 

 more limpid than when of a lower temperature, and the cream rises 

 more readily. If made warmer than fifty-nine degrees the incipient 

 decomposition of the free casein is unduly hastened ; this causes the 

 premature conversion of the sugar into lactic acid. The acid 



