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BELL SYSTEM TECHNICAL JOURNAL 



the hydrogen electrode. The dotted curve shows different dilutions 

 for the same proportion of ammonia and boric acid. Since these 

 curves intersect it is evident that the acidity of an ammonium borate 

 solution decreases with dilution, and acid solutions may become 

 alkaline by the addition of sufficient water. 



Within the ranges of compositions and concentrations shown, it 

 will also be noted from the set of approximately horizontal full line 

 curves that the specific resistance of the electrolyte is practically 

 independent of the boric acid content. That is, within these limits, 

 the conductivity of the solution is substantially determined by the 

 ammonia content, the amount of boric acid in the electrolyte affecting 

 principally the degree of acidity or alkalinity of the solution. 



10 20 30 40 



TEMPERATURE-DEGREES CENTIGRADE 



50 



Fig. 1 1 — Effect of temperature on the resistivity of ammonium borate electrolyte 



The specific resistance of the solution is, of course, affected by 

 heat and decreases with increasing temperature, as shown graphically 

 in Fig. 11. In this figure the specific resistance in per cent of the 

 specific resistance at 21.1° C. is plotted against the temperature of 

 the electrolyte. 



In the selection of a suitable electrolyte for a condenser the choice 

 is influenced by the life of the solution, the effect of the specific re- 

 sistance of the electrolyte on the electrical characteristics of the cell, 

 and the susceptibility of the electrodes to corrosion in the solution. 



The life of the solution, as has been explained, is determined by 

 the rate at which it becomes saturated with aluminum hydroxide. 

 In general, the lower the specific resistance of the solution, the mpre 

 quickly does aluminum hydroxide form. On this basis the advantage 

 of a high-resistance electrolyte is obvious. 



