TECHNIQUE FOR METABOLISM DURING REST. 105 



As will be seen from figure 8, each of the copper cans, Ci and C^, is 

 provided with a flexible top consisting of a light weight, pure rubber, 

 lady's bathing cap, which allows considerable flexibility in the volume 

 of the can. Near the bottom of the can Ci is a f-inch pipe (13 mm. 

 inside diameter, see £', figure 8), which connects with the intake side of 

 a Crowell blower, Fi. The blower is connected by a belt with an elec- 

 tric motor, G. The air discharged by the Crowell blower passes 

 through the pipe, H, and is conducted through two Williams bottles, 

 Ji and J2, containing sulphuric acid, in which the air is thoroughly 

 dried. It then passes through a short length of hose, K, to a header on 

 top of the table provided with a 3-way valve, Fi, by means of which the 

 air may be deflected through a soda-lime can, L, and its accompanying 

 Williams bottle, M. The soda-lime in L removes the carbon dioxide 

 from the previously dried air-current and the sulphuric acid in M 

 removes the water vapor imparted to the dry air-current by the some- 

 what moist soda-lime. The air, now freed from carbon dioxide and 

 water vapor, enters another 3-way valve, F2, and passes through a can, 



a, brass disk with 10 mm. orifice; 6, 

 threaded collar; c, brass tube sol- 

 dered to top of wind chest; d, rub- 

 ber gasket; e, rubber gasket; /, 

 threaded collar. 



Fig. 10. — Detail of opening between wind chest (fig. 9) and can Ci or C2. 



N, containing sodium bicarbonate which removes slight traces of acid 

 fumes. Thence it passes through a pipe under the table to another 

 header, is delivered directly into an ordinary form of dry gas meter, 0, 

 and is finally discharged into the room. 



It is thus seen that by this system air coming from the respiration 

 chamber is delivered by a rotary air-impeller into a wind chest and 

 escapes through three openings, the largest being open to the air in 

 the room and regulated in size by disks, and the other two leading 

 into sampling cans with flexible rubber covers. The air delivered to 

 the sampling cans is immediately drawn out through pipes to a Crowell 

 positive blower which forces the air through a series of purifying vessels, 

 i. e., two sulphuric acid bottles for the complete removal of water- vapor, 

 a soda-lime bottle for the removal of carbon dioxide, and finally a sul- 

 phuric-acid bottle for the absorption of the water vapor taken up in the 

 passage of the air through the moist soda-lime. After being freed from 

 any trace of acid fumes by passing through a chamber containing 

 sodium bicarbonate, it is delivered into a dry gas meter which gives an 

 accurate reading of the total volume of the sample. 



Although the rotary air impeller, a, does not produce positive pres- 

 sure in the sense that the positive blower, Fi, does, it obviously causes 



