OPTICAL, ELECTRIC, WEIGHING, MEASURING, SIGNALING AND CHECKING APPARATUS AND INSTRUMENTS, NAMELY BALANCES, MICROBALANCES, SURFACE AREA ANALYZERS, POROSITY ANALYZERS; APPARATUS FOR MEASURING MASS CHANGES OR MATERIAL TRANSFER, NAMELY, MAGNETIC SUSPENSION BALANCES, RECORDING MICROBALANCES, CALORIMETERS, MASS FLOW CONTROLLERS, MASS SPECTROMETERS; APPARATUS FOR THE EXECUTION OF SORPTION MEASURING, NAMELY GAS AND VAPOR DOSING SYSTEMS; SORPTION ANALYZERS, GRAVIMETRIC ADSORPTION AND ABSORPTION ANALYZ...