MICROLITER DIVER TECHXlQUE 



351 



relatively thick-walled divers having a total volume >10 ix\., al- 

 though this method involves a lack of economy of the carefully 

 selected and calibrated capillary glass tubing from which the divers 

 are made. Holter's method is more economical and it is far superior 

 for divers having a total volume <10 jjI. 



GO 



6 



B 



o 



V 







z\ 



D 



o 



5 mm. 



Fig. 116. Different types of divers. 

 From Halter' (1943) 



The following table has been given by Holter (1943, page 420) 

 to serve as a guide for the selection of glass capillaries suitable for 

 making divers : 



Inside diameter of capillary 

 (width of diver neck), mm. 



Wall thickness, 

 mm. 



0.65 to 0.75. 



0.75 to 0.85. 



0.85 to 1.0 . 



>1.0 . 



.0.08 to 0.09 

 .0.09 to 0.10 

 .0.10 to 0.12 

 .0.12 to 0.15 



The capillaries should be made from a stock of glass tubing hav- 

 ing a ratio of 1:10 between the inside diameter and the wall thick- 

 ness. The density of the glass should be measured, since this value 

 enters into the calibration of the divers. The waste glass left after 

 drawing the capillaries should be saved and used for making the 

 diver tails. Entrapped air bubbles, which may be visible only as 

 streaks, sometimes occur in the glass tubing. It is important that 

 the glass used for divers has no entrapped air, which would change 

 the density of the diver; accordingly, the glass should be tested by 

 fusing one end of the capillary into a ball and examining for air 

 bubbles. 



