94 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



domestic animals/ it has in the immediate future the problem of study- 

 ing the metabolism of large wild animals, in connection with its inves- 

 tigations in progress at the New York Zoological Park. It also had the 

 immediate problem in the reduced ration research of studying the 

 metabolism of a group of individuals. Thus the need of a large cham- 

 ber was urgent. 



In the original architectural plan of the Nutrition Laboratory the 

 calorimeter room was tentatively subdivided to provide for several 

 respiration calorimeters, and space was left for the construction of a 

 large respiration calorimeter for studying the metabolism of groups of 

 individuals. Nearly a decade passed before it was practicable to 

 build an apparatus of any type in this space. During that time suffi- 

 cient experimental evidence had accumulated to show that direct 

 calorimetry on a large group of this kind would not only be very expen- 

 sive but also time-consuming. It was therefore considered that our 

 experience with indirect calorimetry fully justified the construction of a 

 respiration chamber without calorimetric features. 



The only chamber of this type which has been used for the study of 

 the metabolism of a number of individuals at one and the same time is 

 that formerly employed in Stockholm and constructed by Sonden and 

 Tigerstedt,^ but now demolished and subsequently duplicated in Hel- 

 singfors by Professor Tigerstedt.^ The Sonden-Tigerstedt chamber 

 had a capacity of 100 cubic meters and the carbon dioxide alone was 

 determined. According to their method of determination a rather 

 complicated meter, with blower system for ventilation, was required, 

 an elaborate aliquoting device for the storage of samples of air from 

 the chamber in 1 -liter mercury containers, and finally, a very delicate 

 and fragile and for Americans, at least, almost inaccessible form of 

 gas-analysis apparatus, namely, the Sonden-Pettersson^ gas-analysis 

 apparatus for carbon dioxide. 



The Nutrition Laboratory has already carried out an extensive 

 research with one of the ingenious gas-analysis apparatus of Sonden.^ 

 This apparatus, which is designed primarily for studying the composi- 

 tion of outdoor air, permits the determination of carbon dioxide to 

 three significant figures, that is, to 0.001 per cent. An accuracy of 

 0.001 per cent is possible in determining oxygen. The particular form 

 of Sonden-Pettersson apparatus used by Sonden and Tigerstedt was 

 designed especially for the determination of carbon dioxide only and an 



^ Since this was written, such a research has been begun by the Nutrition Laboratory, at the 



Agricultural Experiment-Station, Durham, New Hampshire. 

 '^ Sonden and Tigerstedt, Skand. Arch. f. Physiol., 1895, 6, p. 1. 

 3 Tigerstedt, Skand. Arch. f. Physiol., 1906, 18, p. 298. 

 *Pettersson, Zeitschr. f. anal. Chem., 1886, 25, pp. 467 and 469; Pettersson and Palmquist, 



Ber. d. deutsch. chem. Gesellsch., 1887, 20, p. 2129; Sonden, Zeitschr. f . Instrument- 



enkunde, 1889. 9, p. 472. 

 5 Benedict, Carnegie Inst. Wash. Pub. No. 166, 1912. 



