INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (separating components of materials in general B01D, B01J, B03, B07; apparatus fully provided for in a single other subclass, see the relevant subclass, e.g. B01L; measuring or testing processes other than immunoassay, involving enzymes or micro-organisms C12M, C12Q; investigation of foundation soil in situ E02D 1/00; monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N 11/00; sensing humidity changes for compensating measurements of other variables or for compensating readings of instruments for variations in humidity, see G01D or the relevant subclass for the variable measured; testing or determining the properties of structures G01M; measuring or investigating electric or magnetic properties of materials G01R; systems in general for determining distance, velocity or presence by use of propagation effects, e.g. Doppler effect, propagation time, of reflected or reradiated radio waves, analogous arrangements using other waves G01S; determining sensitivity, graininess, or density of photographic materials G03C 5/02; testing component parts of nuclear reactors G21C 17/00)