Broad-range direct-reading polarograph

Claim 1

IN A POLAROGRAPHIC APPARATUS FOR DETERMINING THE AMOUNT OF A KNOWN METAL ION IN A SOLUTION CONTAINING SAID ION AND A KNOWN AMOUNT OF A SELECTED PILOT METAL ION, SAID POLAROGRAPHIC APPARATUS INCLUDING A TEST CELL CONFINING SAID SOLUTION AND HAVING A SMALL POLARIZABLE ELECTRODE AND A LARGE NON-POLARIZABLE ELECTRODE EACH IN CONTACT WITH SAID SOLUTION, A SOURCE OF POTENTIAL IN CIRCUIT WITH SAID ELECTRODES, A SET OF DIVIDERS OF THE POTENTIAL FROM SAID SOURCE, A PLURALITY OF VOLTAGE BALANCING MEANS INDIVIDUALLY CONNECTIBLE IN CIRCUIT WITH SAID DIVIDERS AND SAID ELECTRODES, FOR BALANCING EACH CIRCUIT AND THEREBY MEASURING THE DIFFUSION CURRENT PASSING THROUGH SAID ELECTRODES, AND SWITCH MEANS FOR SELECTIVELY IMPRESSING A PLURALITY OF POTENTIALS FROM SAID POTENTIAL DIVIDERS ACROSS SAID ELECTRODES TO OBTAIN A FIRST BALANCED POTENTIAL CANCELLING THE EFFECT OF RESIDUAL DIFFUSION CURRENTS, A SECOND BALANCED POTENTIAL CANCELLING THE EFFECT OF THE PILOT METAL ION, AND A THIRD BALANCING POTENTIAL PROVIDING DIRECT READING OF THE CONCENTRATION OF SAID KNOWN METAL ION, THE IMPROVEMENT WHEREBY A SINGLE POLAROGRAPHIC APPARATUS MAY BE EMPLOYED WITH ANY OF SEVERAL KNOWN METAL IONS HAVING A HALF-WAVE POTENTIAL (SCE) IN ACID OR NEUTRAL SOLUTION IN THE RANGE OF ABOUT +0.4 VOLT TO ABOUT -1.4 VOLTS AND HAVING A SINGLE WELL-DEFINED REDUCTION WAVE, AND WITH ANY OF SEVERAL PILOT METAL IONS HAVING SIMILAR HALF-WAVE PO-