1002 EXPERIMENT STATION RECORD. 



although the results which have been obtained are not yet published 

 in full. 



The measurement of the income and outgo of chlorin, phosphorus, 

 sulphur, and other mineral matters can be accomplished without great 

 difficulty, although it involves considerable labor. In order to estab- 

 lish a complete balance of income and outgo of material in addition to 

 the other factors enumerated the measurement of oxygen is necessary. 

 This was attempted by Regnault and Reiset. Their apparatus and 

 methods have been elaborated and improved by Rosenthal at Erlan- 

 gen. Investigations with this improved apparatus are about to be 

 undertaken in connection with the nutrition investigations of this 

 Department. 



The determination of oxygen would be of value in many ways aside 

 from its theoretical importance. For instance, at present it is not pos- 

 sible to judge absolutely of the gain or loss of protein and fat in the 

 body, although these factors may be approximately determined. If, 

 however, the income and outgo of oxygen was measured, in addition to 

 the determinations now made, the gain or loss of protein, fat, carbohy- 

 drates, and water could be accurately determined. These and other 

 deductions which would be possible would be of special interest in such 

 subjects as the following: Feeding for fat and lean; relation of food to 

 fattening of animals; feeding for milk; relation of food to muscular 

 work, and, in general, the foundation of the laws of nutrition, the clear- 

 ing up of numerous points now uncertain, and the establishment of 

 principles still in doubt. 



The determination of the income and outgo of energy is fully as im- 

 portant as the income and outgo of material. One of the important 

 factors in such determination is the heat of combustion of the food and 

 excreta. Brief reference is made to this subject on page 1016. Such 

 determination may be conveniently made with a bond) calorimeter. 

 The form devised by Berthelot has been modified by Ilempel and by 

 Atwater. For a number of years the Storrs Station, in cooperation 

 with this Department, has devoted considerable attention, with success- 

 ful results, to the perfection of the bomb calorimeter and the methods 

 of using it. A few Berthelot calorimeters as modified by Atwater are 

 now in use in this country. Several institutions in the United States 

 also possess Mahler calorimeters. The different forms of calorimeters 

 and the methods employed in calorimetric determinations have been 

 described at length in a previous publication of this Office. 1 



The use of the bomb calorimeter renders possible the measurement 

 of the income of energy and the outgo in the urine and feces. The 

 energy liberated in the form of heat has been successfully measured 

 with the respiration calorimeter devised by Atwater and Rosa, and 

 used in the nutrition investigations of this Department and the Storrs 

 Experiment Station. The results have not yet been published. 



U. S. Dept. A.gr., Office of Experiraeut Stations JJul. 21, p. 161. 



