A kaliapparat is a laboratory device invented in 1831 by Justus von Liebig (1803–1873) for the analysis of carbon in organic compounds.^[1] The device, made of glass, consists of a series of five bulbs connected and arranged in a triangular shape.

To determine the carbon in an organic compound with a kaliapparat, the substance is first burned, converting any carbon present into carbon dioxide (CO₂). The gaseous products along with the water vapor produced by combustion are passed through the kaliapparat, which is filled with a potassium hydroxide (KOH) solution. The potassium hydroxide reacts with the CO₂ to trap it as potassium carbonate. The global reaction, ignoring intermediate steps and the corresponding ionic dissociation, can be written as follows:

2 KOH + CO₂ → K₂CO₃ + H₂O.

Subtracting the mass of the kaliapparat before the combustion from that measured after the combustion gives the amount of CO₂ absorbed. From the mass of CO₂ thus determined, standard stoichiometric calculations then give the mass of carbon in the original sample.

A stylized symbol of a kaliapparat is used in the American Chemical Society logo since 1909,^[2] originally designed in the early 20th century by Tiffany's Jewelers.^[3]