ANALYTIC DATA 7 
averages being deduced by analysis of 10 samples. 
The following data are selected from this table. 
For explanation of the figures in the last column 
see page 42. 
Sotips REFRACTION 
aoe Fat Paka a AsH Not OF COPPER 
Fat SERUM 20° 
15.70 6.01 4.13 4.79 0.77. 9.69 38.1 
15.00 5.62 3.75 4.87 0.76 9.38 38.3 
14.50 5.30 3.61 4.82 0.77. 9.20 38.3 
14.00 4.78 3.51 4.98 0.73 9.22 38.5 
13.50 4.61 3.37 4.77 0.75 8.89 38.1 
I3.00 4.24 3.17 4.86 0.73 8.76 37.9 
12.50 3.99 2.84 4.94 0.73 8.51 38.0 
12.00 3-45 2.88 4.96 0.74 8.55 37-7 
II.50 3-33 2.67 4.80 0.70 8.17 37-3 
11.00 3.02 2.64 4.63 0.71% 7.98 37.0 
10.70 2.90 2.60 4.49 0.71 7.80 36.4 
From these figures Lythgoe derives the rule 
that differences in proportion of solids not fat in 
unadulterated milks are principally due to dif- 
ferences in the amount of proteins. Lactose and 
ash are fairly constant. On these facts depend 
recently introduced methods of detecting water- 
ing milk, as will be pointed out later. 
Colostrum.—This is the secretion in the early 
stages of lactation, and differs from ordinary 
milk. It contains characteristic structures, 
known as colostrum corpuscles, and usually 
contains much less fat than fully developed 
milk, but a larger proportion of proteins. Colo- 
strum coagulates on boiling. Lactose is in small 
amount. 
2 
