Liquid Potentiometer; Determining Electrolytic Resistances with Direct Current Instruments
Carl Hering · Transactions of the American Institute of Electrical Engineers · 1902
In a certain case which recently occurred in the writer's practice, the following problem presented itself.A number of elec- trolytic tanks were connected electrically in series.But for fill- ;ing, circulating and emptying, they had to be piped to a common tank.These pipes practically connected in multiple all the liquids in the tanks; hence the tanks, being connected simultaneously in both series and multiple, were all short-circuited.The con- ditions were such that the usuai methods of breaking the con- -tinuity of these columns of liquids in the pipes, by means of air bubbles, stop-cocks, successive filling, etc., were by their nature excluded, and the only thing left was to make the resistance of the columns of liquid in the connecting pipes so great that the loss by the leakage current through them, would be negligible.This is always possible, even for a given rate of flow of liquid in the pipes, and given mechanical pressure, because the mechanical resistance to the flow of liquids in pipes decreases more rapidly with an increase of diameter, than the electrical resistance; or in other words, for a given electrical resistance, the flow of liquid with the same head, increases with the diameter of the pipe.In this particular case, however, nothing but lead pipes could be used; and when the fall of potential in the liquid column was made relatively great, the current would naturally leave the high resistance liquid, pass into the low resistance pipe and back again 317 1902.