The importance of water to the human organism is greater than that of any other substance. It normally comprises 65 per cent of the total body weight and is fundamentally concerned with every physiologic process. For centuries the intake and output of fluids have been investigated by man, the observations of Sanctorius,1 published in 1614, on the perspiratio insensibilis of water from the skin and lungs being classics of early scientific endeavor.
Rowntree2 and, more recently, Underhill3 have presented reviews of the literature on water metabolism. Basic studies on an accurate measurement of the water balance of human beings have been carried out by Newburgh and his associates4 and we acknowledge the inspiration and counsel given by this investigator.
From the surgical aspect, water balance becomes most important in dealing with the patient who, because of his disease or treatment, cannot take in sufficient fluids by