402 



(iASOMETRIC-MANOMETRIC METHODS 



cavities will not How together, but may be mixed by means of a 

 magnetic "ilea." The "cups" are covered with glass "plates" con- 

 taining three holes, as shown in Figure 137. The large hole in the 

 "plate" is covered with a 12 mm. square mica membrane not over 

 18 fx thick. Two 1 mm. squares of cover slip glass are cemented to 

 the mica with Seccotine, and mirrors, 2X3 mm., are cemented to 

 the cover slij) squares. The mirrors are made by silvering or alumi- 

 nizing cover slips and then cutting to size. The "plates," "cups," 

 and mica membranes are sealed together with lubricant (No. 

 591822/39210— ^nYfs/i Drug Houses Ltd.). Another form of cham- 

 ber (Fig. 138) was used by Berenblum, Chain, and Heatley (1940) 

 for tiie determination of the respiratory quotient of tissue. 



Fig. 141. Schematic diagram of optical system. 

 The image of the spht (S) is thrown upon the 

 ground-glass screen (A'') by the mirror system {R', 

 W, R, Q. P).li the mirrors W are parallel, a single 

 image will result ; if the mica bulges, the mirrors W 

 will tilt in opposite directions and the image will 

 divide in two. Dial Z controls the position of one 

 half of the divided mirror Q. From Heatley (1940) 



The chamber is mounted in a metal case (Fig. 139) and the cases 

 are fitted into a revolving frame (Fig. 140). The chambers may be 

 opened or closed by rotating the "plate" over the "cup" through 

 60°. This is accomplished by turning disc C of the metal case (Fig. 

 139). A diagram of the optical system is shown in Figure 141, and 

 the principle of the pressure regulator is illustrated in Figure 142. 

 Finally, a view of the complete apparatus is given in Figure 143, 

 in which the following designations are used: 



.1. thciiuoharunieter; B. supporting bracket for revolving frame; C, safety 

 tube to legulate maximum gas pressure; D, thermoregulator ; E, manometer; 



