The photosynthesis of naturally occurring compounds. IV .—The temperature coefficient of the photosynthesis of carbohydrates from carbonic acid

Abstract

The photosynthesis of carbohydrates from carbonic acid was described a short time ago in three communications, the method being the irradiation with visible light of carbonic acid adsorbed on finely divided nickel and cobalt carbonates suspended in water. It was pointed out that the carbonates must be free from every trace of adsorbed alkali, this result being difficult to secure when these salts are prepared by the method of precipitation. We have recently succeeded in developing a method whereby nickel carbonate can be prepared free from every trace of adsorbed salts. The method consists in the electrolysis of pure conductivity water, saturated with carbon dioxide, with nickel electrodes. A convenient form of apparatus may be made from a rectangular glass vessel with internal dimensions of 8 × 6 inches and 8 inches deep The cell is provided with a wooden cover to which are attached three nickel plates 8 × 5 inches and ⅛-inch thick. One electrode is fixed at each end of the cell and one in the centre, the two outside electrodes being connected together. Two cooling coils are also attached to the cover, one on each side of the central electrode, and a stream of water is maintained through them. The cell is filled with conductivity water to within 1 inch of the top of the cell and a stream of pure carbon dioxide is continuously passed into the water. The electrodes are connected with a 230-volt circuit and sufficient resistance is intercalated to reduce the current to from 2.2 to 2.0 amperes. Since the area of each electrode immersed is 35 square inches the current density is about 1 ampere per square decimetre.