… Instruments and apparatus for physical or chemical analysis (for example, polarimeters, refractometers, … instruments and apparatus for measuring or checking viscosity, porosity, expansion, surface tension or the like; …
Explanatory notes
… ‑ Instruments and apparatus for physical or chemical analysis (for example, polarimeters, refractometers, … or film ( spectrograms ); monochromators , instruments for isolating a particular line in a line spectrum or for … Mass spectrographs and similar apparatus for analysing the isotopic constitution, etc., of materials. But the heading …