A square piece of an index card with graphite (from a pencil lead) applied to one side is immersed in a beaker containing hexane and water (two layers). The graphite-coated side always faces the hexane layer.

More precisely, this barometer is made using an aqueous solution of potassium tetraiodomercurate(II)].

Water and diethyl ether are shaken in a separatory funnel with a small amount of red indophenol. The non-ionic indophenol remains in the ether layer, coloring it red. Addition of sodium hydroxide converts the indophenol to its blue ionic acid anion which is extracted into the water layer turning it blue.

Water and diethyl ether are shaken in a separatory funnel with a small amount of red indophenol. The non-ionic indophenol remains in the ether layer, coloring it red. Addition of sodium hydroxide converts the indophenol to its blue ionic acid anion which is extracted into the water layer turning it blue.

Water and diethyl ether are shaken in a separatory funnel with a small amount of red indophenol. The non-ionic indophenol remains in the ether layer, coloring it red. Addition of sodium hydroxide converts the indophenol to its blue ionic acid anion which is extracted into the water layer turning it blue.