Experiments on the metabolism of matter and energy in the human body / By W.O. Atwater, PH.D., and F.G. Benedict, PH.D., with the cooperation of A.W. Smith, M.S., and A.P. Bryant, M.S.

Atwater, W. O. (Wilbur Olin), 1844-1907.

Date:: 1899

Credit: Experiments on the metabolism of matter and energy in the human body / By W.O. Atwater, PH.D., and F.G. Benedict, PH.D., with the cooperation of A.W. Smith, M.S., and A.P. Bryant, M.S. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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$TEMPKBATUBE OF MATEBIALS INTRODUCED INTO AND REMOVED FROM THE RESPIRATION CHAMBER. To insure the greatest accuracy in measurements of income and outgo of energy, the temperature of the food and drink as introduced into the chamber, as well as that of solid and liquid excreta as removed, sliould be known. The errors involved by introducing or removing such materials at temperatures varying but little from that of the chamber, which is usually about 20° C, are but slight, and would, perha])s, in the course of an experiment nearly counterbalance each other. The follow- ing precautions, however, were taken. The temperatures of the coffee, milk, and water were measured by inserting a thermometer in the liquid immediately before its introduction into the respiration chamber. Temperatures were read to tenths of degrees centigrade. Beef canned in glass jars was warmed in an ordinary water bath for one hour before use, and the temperature of the air in the water bath taken immediately before the beef was to be used. The bread, butter, cereal products, etc., were i)laced in a water oven at a temperature of about 20° C, the exact temperature being noted immediately before use. In later experiments the use of the water bath at the ordinary temperature was discarded, the materials being placed on a shelf against the wall of the room and the temperature of the air observed. The variations above or below 20° multiplied by the si)ecific heat of the substance gives a measure of the heat introduced in hot materials or the heat taken up by cool materials. The urine and feces were usually allowed to remain in the chamber until they attained the temperature of the latter. In some cases where the urine was removed shortly after it was voided its temperature was taken and the proper correction applied. ANALYSES OF FOOD. The methods of analysis were mainly those adopted by the Associa- tion of Oflficial Agricultural Chemists, but such modifications and changes have been made as experience has shown to be necessary or desirable.' OUTGO OF MATTER AND ENERGY—EXCRETORY AND RESPIRA- TORY PRODUCTS AND RADIATED HEAT. INTESTINAL EXCRETA. Tlir outgo ot matter in the feces includes both undigested material and metabolic i)roducts. In the experiments no attempt has been made to distinguish between these, and the feces are taken as representing matter and energy unavailable for use in the body.^ ' Sea diHcnwioD of tliiH aiibject and description of inetboilH of samyiling and of anal- JHIH in IJ. 8. \)i:]tt. Agr., f )fflf<i of Kxpf^rinnmt Stations JJul. 44. • For fnrther diHCtiHHion of thi« Hubject see ytorrs (Couu.) Sta. RptB. 189G, p. 153, and 18117, p. 163, *$