CARTESIAN DIVER MANOMETRY 



343 



reaction vessel, requires a corresponding charge in the pressure 

 necessary to hold the gas volume constant so that the diver will 

 remain submerged at a fixed level in the flotation medium surround- 

 ing it. Thus the pressure changes become measures of the changes in 

 the amount of gas in the diver. 



Divers having gas volumes of 1-10 pi. are referred to as "^uL- 

 divers" by Holter (1943), and he calls the methods which employ 

 them "/i,l. -methods." This nomenclature has obvious advantages over 

 the use of ambiguous terms such as "ultramicro," "submicro," etc. 



Fig. 111. Schematic drawing of 

 measuring apparatus and diver. 



Apparatus : 



A, rubber tubing 



B, coarse screw 



C, fine screw 



D, manometer 



E, flotation vessel 



F, circular mark 



G, connecting manifold 

 H, three-way tap 



J, rubber pressure tubing 

 K, ground-glass joint. 



Diver : 



a, bottom drop 



b, neck seal 



c, mouth seal 



d, gas phase. 

 From Holter (1943) 



^^=^ 



(a) Microliter Diver Technique'^ 



A diagram of the diver and apparatus is shown in Figure 111 

 (diver equipment may be obtained from E. Petersen, Carlsberg 

 Laboratory). The reaction mixture (a) is placed in the bottom of 

 the diver, and gas evolution or absorption changes the amount of gas 

 confined under the neck seal (b). Gas changes cause the diver to 

 rise or sink in the flotation medium in the vessels (E), and the water 

 manometer (D) is adjusted to vary the air pressure over the surface 

 of the flotation medium in order to bring the divers to the mark 

 (F) chosen as the equilibrium position. In this fashion the diver is 

 used as a constant-volume gasometer. 



* See Bibliography Appendix, Ref. 46. 



