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 " is a 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 

 sohds of milk during the summer months is shown in the table 

 quoted below from Dr. Van Slyke of Geneva, New York: 



^°"'"- of Water. Total Solids. 



May 87.44 12.. 56 



June 87.31 12.69 



July 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 sohds 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 1.3.47% 

 during the next two months, then gradually increasing with the 

 advance of the lactation period. In the tenth month the a^'erage 

 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 liigh 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 Konig's results. 



* Journ. Am. Chem. Soc. 



