382 
with a view of correcting and controlling this particular form of 
adulteration and Avatering that laws ha\^e been enacted in many 
countries and in many States throughout our own country fixing the 
amount of milk fat which a milk offered for sale should contain. 
It will be seen from the compilation of milk standards giA^en on 
page 378 that the amount of fat required in different States varies 
from 2.4 to 3.5 per cent. All things considered, it seems reasonable 
to require that all milk offered for sale should contain at least 3.25 
per cent of fat, although it should be borne in mind, of course, that 
unadulterated milk, especially of certain breeds of cattle, sometimes 
contains less than this amount of milk fat. The color of skimmed 
milk is also more or less characteristic, tending more to dead white 
or bluish white than normal milk, which is distinctly yelloAvish white 
in color. 
WateHng . — The addition of water to milk is probably the com- 
monest practice in milk adulteration. Obviously, this is done in 
order to increase the output of the dairy. The effect of Avatering is 
to alter the physical properties and chemical composition to a greater 
or less degree, depending on the quantity of water added. The addi- 
tion of water to milk has been found to loAver the specific graAuty 
and raise the freezing point of milk. It also lowers the index of 
refraction and probably the Auscosity. It causes a diminution in the 
amount of fat, total solids, and ash. Ordinarily it is not a difficult 
matter to determine whether a giA^en sample of milk has been watered. 
This is done by comparing its specific graAuty and refractometer 
reading, together Avith the amounts of fat, total solids, and ash, Avith 
those of normal milk or with standards Avhich have been based upon 
the results of thousands of analyses and years of experience Avith 
the milk of different herds of daily coavs and that produced in differ- 
ent countries. In the detection of Avatered milk advantage is also 
taken of the fact that natural Avaters frequently contain substances 
not ordinarily present in milk, such as nitrates and nitrites. If these 
substances are found in a samj^le of milk the chances are that water 
has been added to it. It has been proposed by Steinegger (2) to 
employ the aldehyde A^alue as a means of detecting the addition of 
water to milk. The aldehyde A^alue for normal milk in Soxhlet- 
Henkel degrees varies betAveen 5.8° and 8.5° and is loAvered by the 
addition of water to milk, but not by the remoA^al of fats. According 
to Commanducci (3) the Avatering and skimming of milk may be 
determined by the lowering of what he proposes to call the index 
of oxidation of milk. This he determines by means of tenth-normal 
potassium permanganate in acid solution. The number of cubic 
centimeters of potassium permanganate solution required to oxidize 
1 cubic centimeter of milk is what this author calls the index of 
oxidation. This has been found to be different for the milk of differ- 
