Recent studies of foods emphasize the importance of their various salts to nutrition, and especially to the nutrition of growing animals. In starting an investigation of this subject in its relation to the nutrition of infants, it seemed necessary, first, to study the concentration of the various salts that are found in milk. The sodium chlorid content of human milk obtained from mothers at various stages of lactation and living under various conditions was first investigated by us.1 It was shown that the concentration of this salt in human milk varied greatly, but that it was remarkably constant in the milk of mothers who gave relatively large amounts of milk and were able to nurse their babies satisfactorily. The present study concerns the sodium chlorid content of cows' milk, goats' milk, and formulas made from cows' milk that are commonly used in infant feeding.
The method employed for the