288 Report OF THE CHEMIST OF THE 
THE CAUSE OF MOTTLES IN BUTTER. 
The fact that we have no mottles in butter when we have no 
salt! has led to the belief that the salt is the sole cause of mottles 
and produces mottles as the result of its uneven distribution. It 
is held that the salt deepens the color of the butter-fat, the 
lighter portions containing little or no salt, the darker portions 
containing salt. 
Effect of salt on color of butter-fat.—We desired to test experi- 
mentally the question whether salt brine has any influence on 
the color of butter-fat. We took some fresh, colored, unsalted 
butter, melted and filtered it, in order to separate the butter-fat 
from the other constituents of the butter. The filtered portion 
was allowed to harden and then cut into cubes and immersed in 
30 per ct. brine in such a way that a part of the cube was in 
brine and a part out. There was not the slightest increase of 
depth of color or any other change in color noticeable. 
In another experiment, some butter-fat was stirred with salt. 
The mixing produced a variegated color, not a true mottling, 
due to the grains of undissolved salt. The same effect is pro- 
duced by mixing any white substance, sugar for instance, with 
butter-fat. 
It would, therefore, appear that the mottling of butter is not 
produced by salt in the way generally held, viz., by affecting the 
color of the butter-fat itself. 
Amount of salt in mottled and unmottled butter.—We took sam- 
ples of butter by means of a trier, taking a plug through the 
ends of the prints examined. In one sample of unmottled butter, 
the amount of salt at opposite ends of a pound print was 3.65 
and 2.61 per ct. In another unmottled butter, the salt varied 
from 4.6 to 5.3 per ct.; and in still another, from 1.86 to 2.59. 
In some badly mottled butter, the salt at different ends of some 
prints varied from 5.13 to 5.19 and 4.66 to 4.78, which showed 
very even distribution of salt. We may, then, have mottles where 
the salt is evenly distributed, and no mottles when the salt is 
unevenly distributed. Samples taken in the manner indicated 
by a trier give only the average of the mass but do not enable 
one to distinguish the amounts of salt in the lighter and darker 
portions separately. 
Amount of salt in light and dark portions of butter—It is a 
matter of common experience that the lighter portions of mottled 
