306 



BUTTER. 



thickening of tte cream, wticli is in accord with the facts ; as 

 the nuclei increase in size, the layer condensed by surface energy 

 round them will rapidly become less, so that the cream will 

 gradually decrease in thickness ; this decrease in thickness of 

 the cream should take place later than the increase mentioned 

 above, which is also the case. 



When the butter is taken from the churn it is in fine grains, 

 which are the nuclei referred to. On working, the fat globules 

 are brought still closer to each other, and the butter is formed 

 into a nearly homogeneous mass ; small amounts of liquid are, 

 however, left distributed throughout the mass, and as these 



Fig. 39.— Churn. 



liquid globules are very small and contained in a medium which, 

 though solid, is still viscous, they are by surface energy trans- 

 formed into spheres. The microscopical examination of butter 

 shows a number of spherical globules of aqueous liquid in a 

 nearly homogeneous medium consisting of fat; there are, how- 

 ever, many fat globules left, which, by careful examination with 

 little light (best by dark stage illumination), can be made out. 

 The whole of the globules usually seen, which are of all sizes, 

 consist of aqueous liquid ; in many cases where the globules are 

 of sufficient size for the surface energy to become small, they 

 cease to be spherical. 



