COMPOSITION OF MILK. 3 
Variation of Total Solids—-As applied to milk, “Total 
Solids,” is a term that includes fat, casein, albumen, sugar, 
and ash; in other words, all the milk constituents except the 
water. ‘Solids Not Fat” is a term often used, and includes 
the casein, albumen, sugar, and ash, or all the milk constituents 
except water and fat. ‘‘Serum” isa term used to designate all the 
milk constituents except the fat. The fat is the most valuable 
constituent of the total solids. The variation in the total 
solids of milk during the summer months is shown in the table 
quoted below from Dr. Van Slyke of Geneva, New York: 
Month. Per Cent Per Cent of 
of Water. Total Solids. 
Mays esi aneicestoles 87.44 12.56 
JUNC te ona knees 87.31 12.69 
DU socio ttxveesia/ tease 87.52 12.48 
August........... 87.37 12.63 
September........ 87 13 
October, .......... 86.55 13.45 
Dr. Van Slyke also studied the effect of the lactation period 
upon the total solids in milk. A herd of fifty cows, calving 
in different months of the year, was used in the experiment. 
The per cent of total solids of this herd seems to average a 
little high all through the ten months. The total solids were 
found to be 14% during the first month, decreasing to 13.47% 
during the next two months, then gradually increasing with the 
advance of the lactation period. In the tenth month the average 
total solids was 14.83%. Pingree, of Pennsylvania, reports 
having found normal milk from a cow, which contained 17.01% 
total solids. Sherman * reports a very high average total of 
the milk solids. He treated the milk from thirteen cows, 
and found it to contain on an average 18.03% of total solids. 
Konig reports a minimum of total solids of 9.31%, a maximum 
of 19.68%, and an average of 12.83%. The average total 
solids quoted above from Richmond is 12.90%, which agrees 
closely with K6nig’s results. 
* Journ. Am. Chem. Soc, 
