… instruments and apparatus for measuring or checking viscosity, porosity, expansion, surface tension or the like; …
Explanatory notes
… instruments and apparatus for measuring or checking viscosity, porosity, expansion, surface tension or the like; … analysed is placed, an observation eyepiece and a measuring scale. In addition to the essential optical elements … for examining an enlarged spectrogram projected on to a screen ( heading 90.08 ); micrometric microscopes and …