A simple, compact apparatus has been designed for the estimation of carbon in organic materials by a wet combustion procedure employing the Van Slyke–Folch oxidation liquid. Oxidation of the sample and absorption of the resultant carbon dioxide take place under reduced pressure. The carbon dioxide is transferred from the oxidation Mask by diffusion and is absorbed in stirred sodium hydroxide, the excess alkali being determined by titration with hydrochloric acid after addition of barium chloride. Samples containing from 0.3 mgm. to 15 mgm. of carbon may be analyzed with a probable error of 0.35%. Volatile compounds in aqueous solution may also be analyzed. Sulphur, nitrogen, and halogens do not interfere. Determinations were made on the following compounds; sucrose, succinic acid, cysteine hydrochloride, cholesterol, stearic acid, and acetone. An analysis requires from 20 to 25 min.