CAPILLARY U – TUBE

This apparatus is used for testing small quantities of gas produced by plants. It consist of a glass tube bent in U shape formed from 1 mm bore thick walled capillary tube with a brass screw and collar at the end of the longer limb with length 250 mm, shorter limb being 100 mm long. A bubble of gas is introduced into the shorter limb which is then lowered into the reagent solution. Change in the position of bubble indicates the amount of gas taken up by the reagent.
Potassium hydroxide to be used for Carbon dioxide and alkaline pyrogallol for Oxygen.