NORMAL PROCESSES OF ENERGY METABOLISM 519 



sisted of a chamber 2.15 x 1.22 x 1.92 meters or a cubic capacity of 5.03 

 cubic meters. It was ventilated by means of a so-called Blakeslee pump of 

 a reciprocating type. By means of a toothed wheel containing 100 teeth, 

 the first and fiftieth of which were longer than the others, samples of air 

 could be diverted from the main stream at each fiftieth stroke of the pump. 

 These samples were collected in pans for analysis. 



The apparatus was not long used in this form. Realization of the 

 necessity for accurate determination of the oxygen absorption led to its 

 modification to the closed-circuit type as will be described later. 



The apparatus was at once a respiration chamber and a calorimeter for 

 direct measurement of the heat. The method of heat measurement will 

 be described in a later section. 



d. Apparatus of Jaquet. This apparatus in its original form has a 

 cubic capacity of 1393 liters. The subject can either sit or lie down during 

 the observation. It is ventilated by means of a bellows driven by a water 

 motor, the air being withdrawn from one end through an exit tube and 

 being replaced by pure air from the outside which enters at the other end. 

 The air is passed through a gas meter after withdrawal from the apparatus. 

 Samples are aspirated from the exit tube by means of a mercury pipette, 

 the leveling bulb being lowered by means of a pulley connected with the 

 axle of the measuring meter so that the rate of sampling is proportional 

 to the rate of ventilation. 



The air analyses for CO 2 and O 2 are accomplished by means of the 

 Petterson apparatus. 



Precaution against change of composition of air in the apparatus is 

 taken by analysis of the air just before the beginning and just at the end 

 of an observation period. 



By burning alcohol in the apparatus an average error of 1.8 per cent 

 was attained. An experimental period could be prolonged with this ap- 

 paratus for some 12 to 13 hours. 



e. Apparatus of E. Grafe(b}. This is a modification of the Jaquet 

 type of apparatus so constructed as to accommodate a man in a standing, 

 sitting or lying position. The respiration chamber consists of a rectangu- 

 lar base bordered by a groove into which the superstructure of the chamber 

 is made to fit air-tight by means of a liquid seal. The whole upper part of 

 the chamber is suspended from the ceiling of the room by means of pulleys 

 and a counterpoised weight. Entrance to the apparatus is gained by rais- 

 ing one end of the superstructure. The rectangular section of the ap- 

 paratus measures 0.9 meter at the head and foot ends and 2 meters in 

 length. In the vertical section one end is higher than the other, measuring 

 1.7 meters at the head end and 0.75 meter at the foot end. The frame 

 is constructed of wood covered with sheet metal painted with an oil paint. 



Ventilation of this apparatus is accomplished in exactly the same man- 

 ner as in the original Jaquet construction, air being drawn through and 



