184 



CHEMICAL TECHNIQUES 



for formol titrations in the manner shown in Figure 70. The cup is 

 made by blowing a bulb and then sucking in a depression. The 



\^ 



Fig. 69. 



Fig. 70. 



Fig. 69. Silver electrodes (A and A') arranged for chloride titration with 

 burette (B) and electromagnet on the left to enable stirring with the "flea" in 

 the vessel (see page 282). Tip of burette may be protected from contact with 

 A' by the glass sleeve shown on the right. From Linderstrdm-Lang , Palmer, 

 and Holler (1935) 



Fig. 70. Cross section of the glass electrode titration vessel. B represents an 

 inverted glass electrode, C a burette, D a reference calomel cell, E a glass 

 tube. A is a cup assembly, consisting of: a, a central block; b, a lower cup; 

 c, an upper inverted cup. From Sisco, Cunningham, and Kirk (1941) 



outside of the cup is coated with paraffin and the electrode is filled 

 with 0.1 A'" hydrochloric acid saturated with quinhydrone. The 

 chamber (A) is made of Lucite. Stirring is effected by blowing a 

 streari of nitrogen through the tube (E) in such a fashion as to 

 whirl the sample drop in the cup. 



Claff and Swenson Glass Capillary Electrode. Glass electrodes 

 employed for measurements of the hydrogen ion concentration of 

 small volumes of solutions have been numerous. One of the more 



