[ WEIGHING SCALES; BAROMETERS; PRESSURE GAUGES; TITRATION APPARATUS; HYDROGENION-DETERMINATION APPARATUS; LIGHT-MEASURING APPARATUS; APPARATUS FOR DETERMINATION OF SURFACE TENSION OF LIQUIDS; LABORATORY DISTILLATION AND EXTRACTION APPARATUS; AIR LIQUEFYING APPARATUS FOR USE IN PHYSICAL CHEMICAL LABORATORIES; THERMAL MEASURING AND RECORDING APPARATUS; LABORATORY RACKS, CLAMPS AND SUPPORTS; ELECTRIC METERS; ELECTRIC-LIGHT-PROJECTION APPARATUS FOR SCIENTIFIC OPTICAL TESTS AND PICTURE PROJECTION; ELECTRIC FLASK HEATERS FOR LABORATORY USE; GRADUATED FLUID MEASURES FOR SPECIFIC-GRAVITY WORK; CONTAINERS AND APPARATUS FOR DEMONSTRATING HYDROSTATIC PRESSURE; BALANCES; BALANCE WEIGHTS AND ACCESSORIES; DESICCATORS FOR LABORATORY USE; WATER ASPIRATORS FOR LABORATORY USE; PNEUMATIC TROUGHS FOR LABORATORY USE IN FILLING CONTAINERS WITH GAS; LABORATORY WATER BATHS; GAS ANALYZERS; APPARATUS FOR MEASURING THE MELTING POINTS OF SUBSTANCES; ELECTROANALYZERS (METALLURGICAL); FLUOROMETERS; SOIL TESTERS; BACTERIOLOGICAL COUNTERS; MICROSCOPE SLIDE BOXES; EMBEDDING BATHS FOR PRESERVING LABORATORY SPECIMENS; HYDROPHYL BALANCES; ELECTROMETERS; ELECTROSCOPES; APPARATUS FOR MEASURING THE RATIO OF ELECTRONIC CHARGE TO ELECTRON MASS; MODELS FOR DEMONSTRATING ATOMIC STRUCTURE; OSCILLOSCOPES; CATHETOMETERS; MEASURING MICROSCOPES; MEASURING TIMERS; MEASURING IMPULSE COUNTERS; YOUNG'S MODULUS APPARATUS; TORSION MEASURING APPARATUS; WIRE TESTERS; OSMOMETERS; VISCOSIMETERS; ] PHYSICS APPARATUS FOR THE STUDY AND MEASUREMENT OF COMPOSITION OF FORCES, INERTIA, LAWS OF MOTION [ , CAPILLARITY VAPOR PRESSURE, IMPACT, MOMENTUM, AERODYNAMICS, GAS LAWS, HEAT RADIATION, CONVECTION, AND CONDUCTIVITY, MAGNETISM AND ELECTRICITY, ELECTRICAL RESONANCE, RADIO PHENOMENA, OHM'S LAW, AND ELECTRICAL SPARK DISCHARGE; STROBOSCOPES; GYROSCOPES; ACCELERATION APPARATUS; WAVE METERS; AUDIO OSCILLATORS; PHOTOELECTRIC DEMONSTRATION APPARATUS; THERMOELECTRIC MAGNETS; RESISTANCE TEST SETS; TUNING FORKS FOR LABORATORY USE IN DEMONSTRATING SOUND PHENOMENA; ACOUSTIC RADIATORS; WAVE APPARATUS ] ; SONOMETERS; [ APPARATUS FOR DETERMINING THE RELATIONSHIP BETWEEN THE FREQUENCY OF A STRETCHED WIRE AND ITS MASS, LENGTH AND TENSION, OR FOR DETERMINING THE FREQUENCY OF AN ALTERNATING CURRENT CIRCUIT; GLASS TUBE APPARATUS FOR THE STUDY OF RESONATING AIR COLUMNS; APPARATUS FOR THE STUDY OF THE REFLECTION AND REFRACTION OF LIGHT; OPTICAL BOXES; OPTICAL BENCHES; TRANSFORMERS FOR SPECTRUM TUBES; APPARATUS FOR THE STUDY OF COLOR PHENOMENA; ELECTRIC LAMP DEVICES FOR MICROSCOPE ILLUMINATION; LIGHT-DEMONSTRATION ILLUMINATORS; CLOCK-CONTROLLED ELECTRIC SWITCHES; LABORATORY DISTILLATION APPARATUS, INCLUDING CONDENSERS THEREFOR; THERMOSTATICALLY OPERATED THERMOREGULATORS; ABSORPTION CELLS FOR MEASURING LIGHT ABSORPTION; GRADUATED BOTTLES AND FLASKS OF SPECIAL CONSTRUCTION FOR LABORATORY USE; MICROSCOPE SLIDES; MEASURING VARIABLE CONDENSERS; ] PULLEY DEVICES FOR USE IN DEMONSTRATING THE MECHANICAL ADVANTAGE AND EFFICIENCY OF PULLEY SYSTEMS [ ; HYDRAULIC PRESS APPARATUS FOR LECTURE AND LABORATORY USE IN DEMONSTRATING TRANSMISSION OF PRESSURE IN AN ENCLOSED LIQUID; RUBBER DAMS FOR USE IN EXPERIMENTS IN PNEUMATICS AND FOR PROVIDING A FLEXIBLE WATERPROOF DIAPHRAGM IN LABORATORY APPARATUS; RUBBER HOLDERS FOR LABORATORY CRUCIBLES; FLASH POINT TESTERS, I.E., APPARATUS FOR DETERMINING THE FLASH POINT OF COMBUSTIBLE SUBSTANCES; THERMOMETERS; MOLECULAR WEIGHT DETERMINATION APPARATUS; HYDROMETERS; CALORIMETERS; MILK SEDIMENT TESTERS; MICROTOMES; COSMIC RAY COINCIDENCE COUNTERS; LABORATORY DEMONSTRATION MODEL HEAT ENGINES, DYNAMOS, ELECTRIC MOTORS AND GENERATORS; MAGNETIC COMPASSES; VACUUM TUBE TESTING APPARATUS; ELECTRIC BACTERIOLOGY INCUBATORS AND DRIERS FOR LABORATORY USE; AND ELECTRIC MACHINES FOR DEMONSTRATING ROTATIONAL FORCES AND FOR SPINNING COLORED DISCS TO SHOW THE RESULTS OF MIXING COLORS OF THE SPECTRUM ]