The cell is a borosilicate glass vessel with an inside diameter of 5.7 cm. This cell is surrounded with a coil of Cu tubing through which the cooling water flows for calorimetry. The cell and Cu tubing are further contained in an outer vessel which is filled with "coupling water" that serves to conduct heat from the cell to the Cu tubing. This assembly is then surrounded with thick Styrofoam insulation, which reduces heat losses to very low levels.

The cathode is a 1.6 mm diameter W rod, normally used for tungsten-inert-gas welding. These rods are available in two grades: (1) pure and (2) 2% thoriated. We conducted tests with both types of rods. The rod was covered with a thick tight-fitting Teflon sleeve (6 mm diameter) but 1.3 cm was exposed at the lower end. The exposed area of W was therefore 0.65 cm².

The anode is a piece of heavy Pt mesh (made with 0.2 mm wire) .76 cm x 1.4 cm. The nominal area of the mesh (both sides) is 2.1 cm². Thus the anode/cathode area ratio is about 3.2. A 0.5 mm diamter Pt lead wire is crimped to the anode mesh. This lead wire, sleeved with Teflon tubing, leads out of the cell through a rubber seal.

The top of the cell, the W rod, and the Pt lead wire are all sealed with rubber seals to make a gas-tight cell. There are two features not shown in the drawing above. 1. A glass-jacketed temperature probe sticks down into the electrolyte. This probe is also sealed to the cell top. 2. A gas port in the cell top permits the collection of the gases evolved during the experiment.