256 



TITRIMETRIC METHODS 



advantage of this group of microburettes is that their accuracy is 

 independent of the lumen of the capillary. 



Linderstr^ni-Lang and Holler Burettes. These instruments 

 possess an approximately fivefold refinement of the original Brandt- 

 Rehberg ( 1925) instrument, and they have been constructed in two 

 main forms. The type 1 burette ( Linderstr0m-Lang and Holter, 

 1931), shown in Figure 82, has a cahbrated glass capillary tube 



Fig. 82. Burette, type 1. 



From Linderstr0m-Lang 



and Holter (1931) 



Fig. 83. Burette, type 2. 



From hinder At rOm-Lang 



and Holter (1933a) 



58 cm. long, having a total capacity of 100 ix\. and graduated in 

 divisions of 0.2 ix\. Estimations may be made to 0.02 /xl. When the 

 screw in the bottom is turned in, the mercury is forced up into the 

 capillary, which, in turn, forces the liquid out of the burette. The 

 tip of the burette is dipped into the liquid to be titrated in order that 

 quantities less than a drop may be added. Readings are taken from 

 the meniscus of the top of the mercury column. In filling the burette 

 the tip is dipped into the standard solution and the screw is reversed. 

 The top of the mercury column is in contact with the standard 

 solution. 



