70 



COMPARISONS OF RESPIRATORY EXCHANGE. 



MUELLER VALVES. 



The Mueller 1 valves have long been used for studies of the respira- 

 tion and respiratory exchange, and while many newer forms of valves 

 have been developed and are in use, this form still finds application in 

 a number of laboratories. Their continued use 2 is doubtless due to the 

 fact that they can be easily and inexpensively constructed from 

 materials that are found in any well-equipped laboratory. The prin- 

 ciple of the valve is simple, being that of an ordinary wash-bottle, the 

 liquid in the bottle acting as a seal and preventing the air from going 

 in more than one direction. 



One of the valves constructed for this research 

 is illustrated in figure 31. It was made of a 

 1 -liter wide-mouth bottle, in the neck of which 

 was inserted a two-hole rubber stopper (C). 

 The inlet tube was an elbow of thin-walled 

 brass tubing (A), with an internal diameter of 

 25 mm., of which the longer arm was inserted in 

 one hole of the rubber stopper; the lower end of 

 the tubing extended nearly to the bottom of the 

 bottle. A shorter elbow (B) of the same ma- 

 terial was inserted in the other hole in the stop- 

 per and served as the exit tube. Two valves of 

 this type were connected with a brass tee made 

 of the same kind of tubing. Sufficient water 

 was used in the valves to barely seal the lower 

 end of the tube D. . In use a valve was properly 

 supported on each side of the subject, the intake 

 tube being connected with the subject by a 

 mouthpiece and the exit tube to the spirometer 

 by means of rubber tubing. 



Fig. 31. — Mueller valve. 



A, inlet tube; B, outlet 

 tube; C, 2-holed rubber 

 stopper; D, water seal. Air 

 enters at A, passes through 

 D, and leaves at B. 



HALDANE GAS-ANALYSIS APPARATUS. 



Several forms of apparatus for the analysis of various mixtures of 

 gases have been devised by Haldane. Two of the forms, the laboratory 

 and the portable gas-analysis apparatus, have found considerable 

 application in the analysis of atmospheric air, mine air, and expired 

 air. They differ mainly in their size and portability. The laboratory 

 form is adapted for laboratory work only, as it requires considerable 

 space and permanent installation. The portable form' is constructed 

 on the same principle, but is of a size suitable for carrying easily>from 

 room to room or into mines, ships, or any other*places where analyses 

 of air are possible. 



'Mueller, Sitzber. K. Acad. Wiss., Math. Natur w. Kl., Vienna, 1858, 33, p. 99. 

 2 Loeffler, Arch. f. d. ges. Physiol., 1912, 147, p. 201. 



