702 
stants not affecting its specific graritY. and estimating the proteids i 
from our knowledge of the fat content of the specimen. Xow. the j 
specific gravitY will Yary directly with the proteids and inYersely to j 
the fat. Yiz. high proteids. high specific graYity; high fat. low spe- 
cific graYity. The following table shows the application of this 
principle : 
Variations in the composition of xconmms milk as deduced hy observation of 
the specific gravity and the fat content (Holt). 
Specific gravity, 70° F. 
Cream, 24 hours. 
Proteids, estimated. 
Averaare 
... 1,031 
7 percent 
1.-50 per cent. 
Xormal variation^ 
... 1.02S-1.032 
8-12 per cent 
Xormal (rich milk). 
Xormal variation5 
... 1.031 
5-6 per cent 
Xormal (fair milk). 
Abnormal vaxiations 
. . . Low (below 1,028) 
High (above 10 per cent) . 
Xormal or slightly 
below. 
Abnormal variations — 
. . . Low (below 1.028) 
Low 1 , below 5 per cent) . . 
Lo w (very poor milk) . 
Abnormal variations — 
... High (above 1,032)... 
High 
Y ery high (very rich 
milk). 
Abnormal variations 
... High (above 1.032).... 
Low 
Xormal or nearly so. 
As the milk drawn from the breast during the first part of nursing 
is richer in proteids and much poorer in fats and the last portion 
rather poorer in proteids and rich in fats, the entire amoimt of milk 
present in the breast should be drawn off' for the purpose of this esti- 
mation. 
COW'S milk:. 
Cow's milk is the only food supply, apart from mother's’ milk, I 
aYailable in this country, from a practical standpoint, for the nourish- 
ment of infants under 1 year of age. It forms besides a large part of 
the dietary of older children and of many adults. It is consequently 
of the utmost importance, in Yiew of its perishability, that it should 
only be used as a food under conditions which will insure its whole- 
someness. 
IVe ha Ye already considered the enormous loss of life occurring 
among the artificially fed infants, of which the larger part is un- 
doubtedly due to bad milk and its unproper use as an article of diet. 
Stated as a general proposition, the following conditions should be 
fulfilled in milk that is to be used as a basis for the nourislnnent of 
young infants: First, it should be clean: second, it should be fresh; 
third, it should be whole (i. e.. not falsified by additions or subtrac- 
tions of its component parts or by the addition of preserYatfres) ; 
fourth, it should be free from pathogenic organisms and toxic prod- 
ucts : and fifth, it should be kept cold. 
Importance of dean milk . — By clean milk we understand a milk 
which has been collected under such hygienic conditions from healthy 
