MICROLITER DIVER TECHNIQUE 



365 



as rapidly as possible. When it is especially important to guard 

 against evaporation of the bottom drop, the operations should be 

 performed in a moist chamber. 



1 2 3 4 5 cm. 



Q 



D 







A B 



\ / 



3 mm. 



Fig. 126. Platinum loops for placing 

 wax rings. Above, general appearance; 

 below, detail. A, glass tube; B, 0.5 mm. 

 platinum wire; C, loop of 0.2 mm. plati- 

 num wire; d, diver. B and C are welded Fig. 127. Formation of neck seal; 

 together. Current needed is 2-6 amp. three successive stages. 



From Holler (1943) From Holier (1943) 



In general, the neck seals should not be less than 0.5 mm. in 

 length, i.e., the distance between the apexes of the opposing menisci, 

 and there should be at least 1 mm. of dry glass between the seals to 

 prevent their mixing. Oil seals should be about 0.5 mm. long and 

 other seals about 1 mm. The distance between the oil seal and the 

 mouth seal should always be as small as possible in order to keep 

 the volume of the air space between them as small a fraction of 

 the total gas volume as possible ( Linderstr0m-Lang, 1943). 



Aqueous Neck Seals. To insure proper wetting of the neck wall 

 by an aqueous seal, it should contain 0.1% sodium taurocholate 

 if the compound can be used in the experiment. The aqueous neck 

 seal should also be isotonic with the bottom drop to avoid distilla- 

 tion. In respiration work a seal of 0.1 A'' sodium hydroxide may be 

 used, since the difference in vapor tension between this solution 

 and water is small enough to be unimportant. 



Should liquid be drawn along the diver neck accidentally, when 

 placing the aqueous seal, and if it is not feasible to repeat the filling, 

 the moistened area may be dried with filter paper. It is particularly 

 important that no moisture be present on the neck above the oil 

 seal since the water would distill into the mouth seal during the 

 experiment. 



