Methyl alcohol vapour in air is estimated by Nicloux by passing the air through a series of six or

1 Compt. rend. Soc. Biol, 1910, 73, 59, seven wash-bottles containing water at the ordinary temperature. The solution thus obtained is distilled and oxidised with dichromate in the same way as before.

In order to differentiate between methyl alcohol and other substances oxidisable by dichromate, the ratio of the carbon dioxide produced to the oxygen used up in the reaction is determined. The volume of dichromate reduced gives the quantity of oxygen in question by a simple calculation. To obtain the amount of carbon dioxide, a specially-designed sealed tube is employed in which the distillate is oxidised; the resulting carbon dioxide is then withdrawn by a mercury pump and its volume ascertained by absorption in potassium hydroxide solution, as in ordinary gas analysis.

(Note

It would be simpler to estimate the methyl alcohol in any of the foregoing distillates by the author's modification of Deniges's process already described; or, for the air, by Elvove's adaptation of the same method.)