602 
PHYSIOLOGY: T. M. CARPENTER 
born infant, with the usual periods of activity, asleep, and awake, is 
estimated to be approximately 62 calories per kilogram of body-weight 
per 24 hours. This takes no account of the requirement for growth, 
which may be neglected in considering the energy requirement for the 
first week of hfe. The results of the research give opportunity for 
suggestions as to supplemental feeding and methods of conserving energy. 
A detailed report of the investigation, together with a complete trans- 
lation of the interesting article on the respiratory exchange of infants, 
pubhshed by Hasselbalch in 1904, is given in Pubhcation No. 233 of the 
Carnegie Institution of Washington. 
A COMPARISON OF METHODS FOR DETERMINING THE 
RESPIRATORY EXCHANGE OF MAN 
By Thome M. Carpenter 
NUTRITION LABORATORY. CARNEGIE INSTITUTION OF WASHINGTON 
Presented to the Academy, November 2, 1915 
The principal methods of determining the respiratory exchange of 
man in short periods require the use either of a chamber in which the 
subject is confined or breathing appliances which are attached to the 
nose or the mouth or, as in the case of a mask, to the face. Apparatus 
with breathing appliances are of two classes. In one the subject breathes 
into and out of a closed current of air driven by a positive blower, the 
products of respiration being absorbed and oxygen being admitted. In 
the other type of apparatus valves are used to separate the currents of 
inspired and expired air and the latter is either measured by a meter or 
collected in a bag or a spirometer, a sample being taken and analyzed 
by means of a suitable gas-analysis apparatus. 
Thus far no adequate comparison of these different types of apparatus 
has been made, the only attempt at such comparison being the compila- 
tion of results obtained with various respiration apparatus to show that 
these apparatus measured accurately the respiratory exchange. It 
therefore seemed desirable to compare the several types of apparatus for 
determining the respiratory exchange, with men as subjects and with as 
nearly identical conditions as possible. 
The apparatus employed in this investigation were the following: Bed 
respiration calorimeter (chamber type with closed circuit) ; two forms of 
the Benedict universal respiration apparatus, i.e., tension-equalizer unit 
and spirometer unit (apparatus with breathing appliance, closed circuit 
type); Zuntz-Geppert apparatus (valves with meter and gas-analysis 
apparatus); Tissot apparatus (valves with an automatically counter- 
poised spirometer) ; Douglas apparatus (valves with rubber-lined cloth 
