NORMAL PROCESSES OF ENERGY METABOLISM 547 



to continue running for two or three minutes until the spirometer ceases 

 to fall and oxygen is then admitted until the spirometer comes back to the 

 original level. The blower continues running for a few seconds longer 

 to make certain that this 

 level will be maintained, the 

 oxygen now having been 

 stopped, whereupon the cur- 

 rent is turned off stopping 

 the blower. The oxygen 

 meter is now read. 



If a second observation 

 is to follow immediately the 

 valves are thrown connecting 

 with the second set of ab- 

 sorbers and the blower im- 

 mediately started. As soon 

 as it is certain that the sec- 

 ond train of absorbers is air 

 tight the second period can 

 be started. The absorbers 

 of the first train can be 

 weighed while the second 

 period is running. The ba- 

 rometer is read and the 

 temperature of the water 

 meter measuring the oxygen 

 is recorded. The volume of 

 oxygen is then reduced to 

 and 760 mm., and the 

 carbon dioxid obtained in 

 grams is likewise reduced to 

 the standard conditions. 

 The respiratory quotient is 

 obtained by division of the 

 volume of carbon dioxid by 

 the volume of oxygen. 



Recently several forms 

 of so-called portable instru- 

 ments constructed on the 

 general principle of the uni- 

 versal respiration machine of Benedict have made their appearance. The 

 best of these doubtless is the one described by Benedict and Collins. It 

 may be doubted, however, whether it is wise to attempt to make the deter- 

 mination of basal metabolism a bedside or office procedure. Special 



Fig. 22. Portable respiration apparatus of 

 Benedict and Collins. A, mouthpiece; B, tube 

 conducting expired air to bell C; D, hair dryer; 

 E, soda-lime container; F and G, tubes convey- 

 ing air current to mouthpiece A ; HH, tank in 

 which bell C floats; J and K, cord and pulley 

 supporting bell C; L, counterpoise; M, pointer on 

 counterpoise; A T , thermometer; O and P, supports 

 for pulley K. a, rubber gasket; 6, rubber gasket; 



c, c, tubes supporting spirometer; d, d, lower 

 part of frame supporting spirometer; e and /, 

 telescoping tubes supporting mouthpiece and 

 tubing ; g, g, supporting plates ; h, h, knobs fit- 

 ting into g, g; jk, part of support for mouthpiece 

 and tubing; mm, attachment to support c, c, to 

 tank HH; p, circular band connecting four tubes, 



d, d; r, r, leveling screws; t, sliding ring; u, 

 knobs for support of apparatus when collapsed; 

 iv, 'sliding ring. 



