The publication of several relatively accurate and simple micro-methods for the determination of calcium in the blood has opened the way for many interesting lines of investigation in the field of calcium metabolism. About two years ago, inspired by the acquisition of a new weapon, we embarked on the study of an old and much investigated problem, viz., the calcium metabolism of children. The obvious connection between rickets, and probably infantile tetany, and some error of calcium metabolism, has naturally led us to lay special stress on the study of patients suffering from these disorders, but we also have attempted to collect data on the calcium content of the blood of children suffering from a variety of pathological conditions.
Our calcium determinations have been made by the method of Lyman,1 which we have modified in a few minor details. Lyman's method for the determination of calcium in blood consists