656 MILK 



by these authors: "The soluble compounds can be separated 

 from the suspended or colloidal compounds by filtration through 

 a Pasteur-Chamberland filter. The serum from fresh goat's milk 

 is nearly transparent and has a faint greenish-yellow tinge, with 

 slight opalescence. In true solution are sugar, the salts of potas- 

 sium, sodium, and chlorin. Partly in solution or in colloidal solu- 

 tion are albumin, inorganic phosphates, calcium and magnesium 

 compounds, and citrates. Entirely in suspension or in colloidal 

 solution are fat and casein. The insoluble portion of goat's milk 

 when freshly prepared and moist is grayish to greenish white, 

 glistening, and gelatinous. Shaken with water this insoluble 

 part is suspended and the mixtvire assumes the appearance of milk. 

 This suspension is neutral to phenolphthalein. The insoluble 

 portion consists of calcium caseinate, di- and tricalcium phosphate, 

 and magnesium phosphate." 



According to the same authors, goat's milk differs from cow's 

 milk "(1) in containing tricalcium phosphate, di- and trimagne- 

 sium phosphate, and monopotassium phosphate, and (2) in contain- 

 ing no monomagnesium or dipotassium phosphates. Human milk 

 differs from goat's (and cow's) milk in containing no insoluble 

 phosphates. Goat's and cow's milk contains more phosphates 

 than human milk. Chlorids are present in goat's milk in larger 

 quantity than in either human or cow's milk. In human and cow's 

 milk chlorin is present as calcixma chlorid, and in goat's milk 

 potassium and sodium chlorids are also present." 



The authors give the following table, showing the composi- 

 tion of cow's, goat's, and human milk: 



A COMPARISON OF THE COMPOSITION OF COWS, GOAT'S, AND HUMAN MILK 



Compounds. Cow's milk. Goat's milk. Human milk. 



Fat 3.90 3.80 3.30 



Milk-sugar 4.90 4.50 6.50 



Protein combined with calcium 3.20 3.10 150 



Salts 0.910 0.939 0.313 



Dicalcium phosphate 0.175 0.092 0.000 



Tricalcium phosphate 0.000 0.062 0.000 



Monomagnesium phosphate 0.103 0.000 0.027 



Dimagnesium phoaphate 0.000 0.068 0.000 



Trimagnesium phosphate 0.000 0.024 0.000 



Monopotassium phosphate . 000 073 . 069 



Dipotassium phosphate 0.230 0.000 0.000 



Potassium citrate 0.052 0.250 0.103 



Sodium citrate 0.222 0.000 0.055 



Potassium chlorid 0.000 160 000 



Sodium chlorid 0.000 0.095 0.000 



Calcium chlorid 0.119 0.115 0.059 



The molecular weight of goat casein was determined by Bos- 

 worth and Van Slyke to be 8888, and the valency of the protein 

 molecule in basic casein to be 8. The elementary composition of 

 moisture and ash-free casein from goat's and cow's milk was 

 determined as follows: 



