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September 4, 1926


JAMA. 1926;87(10):758-759. doi:10.1001/jama.1926.02680100042013

The picture of Sanctorius, suspended on a balance, in the process of securing measurements of his continuous losses of weight, has become to students of nutrition a familiar reminder of the earliest quantitative measurements of bodily changes related to metabolism. Although more than three centuries have elapsed since the historic weighings on the unique steelyard, the feature that they sought to establish has scarcely awakened much scientific interest. The losses that are not included in urine, in feces or in the form of sensible moisture or sweat have long been designated as "perspiratio insensibilis"; they represent the insensible, invisible, intangible but weighable gaseous and vapor productions arising from the lungs in the process of exhalation, and from the skin by due process of vaporization. Insensible perspiration, or "intangible loss," as it has also sometimes been termed, represents the excretion of moisture and carbon dioxide. The development of physical apparatus has