= Langmuir mica adsorption experiment
{c}
In 1918, <Irving Langmuir> measured <adsorption> using freshly split <mica> strips, handled at their edges, separated by <iron> spacers and held with <brass> fasteners. A <glass> bulb contained the bundle; a similar blank contained matching <iron> and <brass> but no <mica>. Evacuated <glass> connections, <Mercury> seals, <liquid air> traps, and <McLeod gauges> provided controlled <gas> handling. Calibrated compartment <volumes> and <pressure> readings before and after expansion gave free-gas amounts; their deficit indicated uptake. Lowering <pressure> and measuring released <gas> tested <desorption>.<The Adsorption of Gases on Plane Surfaces of Glass, Mica and Platinum by Irving Langmuir>[Langmuir 1918, printed pp. 1376–1377: Experiments with Mica, preparation, blank, apparatus and Methods I–II]{ref}
<Hydrogen> blank runs calibrated cooling-related <pressure> differences. <Irving Langmuir> pre-cooled the bulbs to reduce thermal delay; he suggested slow <diffusion> between strips could control the remaining approach to equilibrium. Critically, blank uptake was not subtracted: he estimated the <mica>-bulb results were 10–30% too high. <Liquid air> <temperature> drift was unrecorded. These limits constrain inference of intrinsic binding from the uptake curve. The paper's <pressure> unit called “bar” was $1\,\mathrm{dyn\,cm^{-2}}=0.1\,\mathrm{Pa}$, unlike the modern bar used above.<The Adsorption of Gases on Plane Surfaces of Glass, Mica and Platinum by Irving Langmuir>[Langmuir 1918, printed p. 1365: pressure-unit definition; pp. 1377–1378: cooling calibration; p. 1381: equilibration; p. 1385: blank bias and bath drift]{ref}
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