SENSING AND CONTROL APPARATUS FOR INDUSTRIAL PROCESSES; NAMELY MICROPROCESSOR-BASED APPARATUS FOR SENSING AND CONTROLLING INDUSTRIAL PROCESS VARIABLES; CONSISTENCY TRANSMITTERS; CHLORINATION CONTROL SENSORS; TEMPERATURE SENSORS; BRIGHTNESS CONTROL SENSORS; AUTOMATIC TITRATORS; IN-LINE MIXERS; OXIDATION REDUCTION POTENTIAL PROBES AND MOUNTING APPARATUS THEREFOR; APPARATUS FOR PROVIDING DENSITY-CONTROLLED DILUTION OF FLUID MIXTURES; HYPOCHLORITE REACTORS; CHLORINE GAS WATER DISPERSERS FOR RELEASING MEASURED AMOUNTS OF CHLORINE AND CHLORINE INJECTOR PORT SPOOL SECTIONS THEREFOR; AND WINDOW BLOCK KITS, FIBER OPTIC PORTS AND NIPPLES THEREFOR, TRANSMISSION CELLS AND STOCK LINE VIEW PORT SECTIONS FOR COUPLING SENSORS TO FLUID LINES