New York AGRICULTURAL EXPERIMENT STATION. 291 
whether the proteid is calcium casein, casein or casein lactate. 
This action appears to be a purely physical one; the brine seems 
to harden the particles of proteid and cause the proteid mass to 
contract into less space in the tubes. 
Relation of time to formation of mottles——It is well known that 
the light-colored portions do not: appear in butter at once after 
adding salt and working the butter, but several hours are required 
to develop them and the maximum development occurs in about 
24 hours in our experience. In the experiments in which we 
treated buttermilk with salt, the separation or condensation of 
the proteid by the brine was not at its greatest until 24 hours 
had elapsed. 
RELATION OF PROTEIDS OF BUTTER TO MOTTLES. 
The facts presented in the foregoing pages appear to us to fur- 
nish a satisfactory explanation of the causes of mottles in butter. 
Reviewing these facts, we have seen that: 
(1) Salt brine does not change in any way the color of butter- 
fat. 
(2) The amount of salt may vary considerably in different por- 
tions of butter that is not mottled. 
(3) In different portions of badly mottled butter, the distri- 
bution of salt may be very uniform throughout the mass of butter 
as a whole. 
(4) In mottled butter, the light portions usually contain less 
salt than the darker portions. 
(5) Mottles proper do not occur in unsalted butter. 
(6) The amount of proteid in mottled butter is greater in the 
light portions than in the portions of normal color. 
(7) Unsalted butter, containing buttermilk adhering to the 
outer surface of the granules, mottles on the surface when sub- 
merged in concentrated salt brine. 
(8) Mottling does not occur in butter when the buttermilk, 
adhering to the outer surface of the small granules, is mostly 
removed. 
(9) Small butter-granules (rice-size) washed with water at 
low temperature lose most of the adhering buttermilk and no 
mottles appear in the finished butter in the presence of salt. 
