In order to study the chemical effects of heavy charged particles, a number of organic compounds—gases, liquids, and solids—have been bombarded with deuterons from the M.I.T.cyclotron. This work, carried out under American Petroleum Institute Project 43c, included paraffins, organic acids, salts, and some complex mixtures. Gas bombardments were made at approximately atmospheric pressure in a water‐cooled gas chamber (volume: 2.54 liters) provided with a 2‐mil copper window for the entry of the external deuteron beam. A thermocouple and a Bourdon gauge connected to a Microtorque potentiometer allowed the gas temperature and pressure to be recorded electrically at the control bench during the bombardment of liquids and solids. Water‐cooled target‐holders provided with 2‐mil copper windows were mounted inside the gas chamber which served to collect the product gases. To prevent chemical reactions of the compounds with the metal parts, chamber and target‐holders were gold‐plated.