Apparatus for producing direct readings of concentrations of constituents of liquids

Claim 1

APPARATUS FOR RECORDING THE CONCENTRATION OF A SUBSTANCE IN A SAMPLE LIQUID BY COMPARING THE LIGHT RECEIVED FROM THE SAMPLE LIQUID WITH THE LIGHT RECEIVED FROM A REFERENCE AND RECORDING THE CONCENTRATION ON A CHART PAPER WHICH IS ADVANCED WITH RESPECT TO TIME IN A FIRST DIRECTION BY A STYLUS WHICH IS TRAVERSED IN A SECOND DIRECTION PERPENDICULARL TO SAID FIRST DIRECTION, COMPRISING: A FIRST PHOTOELECTRIC DEVICE FOR PROVIDING A VOLTAGE WHICH VARIES IN RESPONSE TO THE LIGHT FROM SAID REFERNCE; A SECOND PHOTOELECTRIC DEVICE FOR PROVIDING A VOLTAGE WHICH VARIES IN RESPONSE TO THE LIGHT FROM THE SAMPLE LIQUID; A NULL TYPE CURRENT RATIO BALANCING SYSTEM OPERABLE IN RESPONSE TO SAID VOLTAGES FOR TRAVERSING SAID STYLUS; SAID CHART PAPER HAVING AT LEAST ONE SCALE OF SUBSTANCE CONCENTRATION VALUES REPRESENTED THEREON WITH AN AXIS PARALLEL TO SAID SECOND DIRECTION; A FIRST LOAD RESISTOR, HAVING A MOVABLE TAP MEANS, COUPLED ACROSS THE VOLTAGE OUTPUT TERMINALS OF SAID FIRST PHOTOELECTRIC DEVICE; SAID BALANCING SYSTEM INCLUDING A SLIDEWIRE PHOTENTIOMETER HAVING A FIRST SELECTABLE FIXED TAP MEANS AND A SECOND MOVABLE TAP MEANS, COUPLED IN PARALLEL WITH SAID FIRST LOAD RESISTOR, SAID FIRST TAP MEANS OF SAID SLIDWIRE POTENTIOMETER BEING CONNECTED TO SAID MOVABLE TAP MEANS OF SAID FIRST LOAD RESISTOR, SAID SECOND MOVABLE TAP MEANS OF SAID SLIDEWIRE POTENTIOMETER BEING ELECTRICALLY CONNECTED TO ONE OF THE INPUTS OF SAID NULL-TYPE CURRENT RATIO BALANCING SYSTEM AND MECHANICALLY COUPLED TO SAID STYLUS; WHEREBY SAID MOVABLE TAP MEANS OF SAID FIRST LOAD RESISTOR AND SAID FIRST TAP MEANS OF SAID SLIDEWIRE POTENTIOMETER ARE PRESETTABLE TO DETERMINE THE MAXIMUM CONCENTRATION VALUE TO BE RECORDED.