The casein, which is the curd or coagulable part of milk, differs greatly in its physical property in the milk of the cow from that in human milk. Mother’s milk curds in _soft flaky coagula_ which are readily dissolved in the infant’s stomach, while cow’s milk curds in a semi-solid conglomerate coagulum which the cavity of the child’s stomach is often unable to tolerate nor the gastric juice to penetrate and dissolve. It is this heavy curd which forms the main objectionable feature of cow’s milk as a substitute for that of the mother. This can be greatly modified by first thoroughly beating or churning the cow’s milk with an egg beater, and afterwards scalding it as above described; the milk treated in this manner curds light and flaky. But it must not be presumed that the physical characteristic of casein is the only peculiarity of cow’s milk in comparison with mother’s milk, for this is not so; it also differs in quantity, that is, mother’s milk has less of casein, a fact which may be better understood by the following chemical analysis of both: Human milk. Cow’s milk. Water 87.09 87.00 Casein and albumen 2.48 3.72 Fat 3.90 3.66 Sugar of milk 6.04 4.92 Phosphatic salts 0.49 0.70 —————— —————— 100.00 100.00 There are some children who are unable to digest cow’s milk in any form, either from a peculiarity of constitution, or from a derangement of the digestive apparatus; the milk, no matter how prepared, passes through them curdled, in lumps and undigested; to continue feeding infants on milk, notwithstanding this symptom would in all probability sacrifice the life of the child. If curds persist in the stools milk is to be withheld for a time, and crushed wheat, barley gruel or other diluents should be given alone or in combination with the thoroughly beaten white of egg. This treatment must be continued for several days and in some cases for several weeks. Whey prepared from sweet and pure milk has often been borne by delicate and suffering infants, when nothing else could be retained. An examination into the chemical composition of whey reveals astonishing nutritive virtue, which it holds in solution; the following table shows the proportional constituents in one hundred parts: Water 93.31 Nitrogenous matter 0.82 Fat or butter 0.24 Sugar of milk 4.98 Fixed salt 0.65