1. IN LIME CONTROL APPARATUS OF THE TYPE HEREIN DISCRIBED INCLUDING A SIPHON FILTER DRAWING CLEAR FILTRATE FOR SAMPLING FROM GROUND ORE PULP, A LIME SLURRY SUPPLY, A LIME SLURRY SUPPLY PIPE LEADING FROM SAID SLURRY TO AN ORE PULP CHUTE CARRYING ORE PULP TO WHICH LIME IS TO BE ADDED WHEN NECESSARY TO MAINTAIN ALKALINITY, A LINE CONTROL VALVE IN SAID PIPE, AND A REVERSIBLE ELECTRIC MOTOR OPERATIANG SAID VALVE; APPARATUS FOR SAMPLING THE ALKALINITY OF SAID FILTRATE TAKEN FROM SAID ORE PULP AT DETERMINED INTERVALS AND FOR VARYING THE AMOUNT OF LIME SLURRY ADDED TO SAID ORE PULP IN SAID CHUTE THROUGH SAID LIME SUPPLY PIPE AT CORRESPONDING INTERVALS BY OPENING OR CLOSING MOVEMENT OF SAID LIME CONTROL VALVE INCLUDING A FILTRATE SUPPLY PIPE HAVING A NORMALLY OPEN ELECTICALLY OPERATED SAMPLE SUPPLY VALVE; A SAMPLE MEASURING VESSEL RECEIVING A FLOW OF FILTRATE FROM SAID SIPHON FILTERS THROUGH SAID LIME SUPPLY PIPE AT CORAN OVERFLOW PIPE NEAR ITS TOP TO DETERMINE A MEASURED SAMPLE OF FILTRATE IN SAID VESSEL, AND A NORMALLY CLOSED ELECTRICALLY OPERATED DISCHARGE VALVE; CHARGE TUBE IN ITS BOTTOM PROVIDED WITH A NORA MIXING AND DETERMINING VESSEL OF TRANSPARENT MATERIAL ARRANGED TO RECEIVE THE MEASURED CONTENTS OF SAID MEASURING VESSEL AT PREDETERMINED INTERVALS OF TIME THROUGH SAID DISCHARGE TUBE; AN EMPTYING TUBE IN THE BOTTOM OF SAID MIXING AND DETERMINING VESSEL PROVIDED WITH A NORMALLY CLOSED ELECTRICALLY OPERATED EMPTYING VALVE; AN ACID MEASURING VESSEL HOLDING A MEASURED AMOUNT OF STANDARIDIZED ACID MIXED WITH A DETERMINED AMOUNT OF COLOR RESPONSIVE ALKALI INDICATOR; AND HAVING A DISCARGE TUBE IN ITS BOTTOM DISPOSED TO DISCHARGE ITS CONTENTS INTO SAID MEASURING AND DETERMINING VESSEL PROVIDED WITH A NORMALLY CLOSED ELECTRICALLY OPERATED VALVE; A SAMPLE TAKING ELECTRIC TIMER SWITCH OPERATING SAID ELECTRICALLY OPERATED VALVES, AT PREDETERMINED INTERVALS OF TIME, ARRANGED TO SHUT OFF FILTRATE FLOW TO SAID MEASURING VESSEL BY CLOSING SAID VALVE IN SAID FILTRATE SUPPLY PIPE, TO EMPTY THE CONTENTS OF SAID MEASURING VESSEL INTO SAID MIXING AND DETERMINING VESSEL BY OPENING THE VALVE IN SAID MEASURING VESSEL DISCHARGE TUBE; TO EMPTY THE MEASURED AMOUNT OF ACID AND INDICATOR INTO SAID MIXING AND DETERMINING VESSEL BY OPENING THE VALVE IN THE DISCHARGE TUBE OF SAID VESSEL AND THEREAFTER, FOLLOWING A TIMED INTERVAL, EMPTYING SAID MIXING AND DETERMINING BY OPENING THE VALVE IN THE DISCHARGE TUBE IN THE BOTTOM OF SAID VESSEL, AND RESTORING SAID OTHER VALVES, ABOVE MENTIONED, TO NORMAL POSITION; AN ELECTRIC LAMP DIRECTING A BEAM OF LIGHT THROUGH SAID MIXING AND DETERMINING VESSEL; A PHOTO-ELECTRIC CELL DISPOSED TO RECEIVE SAID BEAM OF LIGHT PASSING THROUGH SAID MIXING AND DETERMINING VESSEL AND ARRANGED TO BE ELECTRICALLY RESPONSIVE THERETO; ELECTRICAL APPARATUS, INCLUDING A TIMER THERETO; ELECTRICAL APPARATUS SAMPLE TAKING TIMER SWITCH, COORDINATED WITH SAID PHOTOELECTRIC CELL TO BE CONNECTED TO SAID CONNECTED TO SAID REVERSIBLE LIME SLURRY VALVE MOTOR TO CONTROL THE OPERATION THEREOF, ARRANGED TO OPERATE SAID MOTOR TO PROVIDE OPENING MOVEMEMT OF SAID VALVE WHEN LIGHT PASSES THROUGH SAID MIXED SOLUTIONS IN SAID MIXING AND DETERMINING VESSEL AND ACTUATES SAID CELL, AND TO PROVIDE CLOSING MOVEMENT FOR SAID LIME SLURRY VALVE WHEN THE PASSAGE OF LIGHT TO SAID CELL IS IMPEDED BY OPAQUENESS OF SAID MIXED SOLUTIONS CAUSED BY THE ACTION OF SAID ALKALINITY INDICATOR.