On the supposed extracellular photosynthesis of carbon dioxide by chlorophyll

In two recent papers, Usher and Priestley have brought forward evidence to show that chlorophyll is able to assimilate carbon dioxide and produce formaldehyde outside the plant, and that hydroxyl is the other product and is decomposed into water and free oxygen in the presence of a particular ferment. It is, unfortunately, necessary to point out that their work is to some extent vitiated by certain oversights and by one serious inaccuracy. In their first paper they confirm Bach’s statement that formaldehyde is produced when light acts on a solution of uranium in the presence of carbon dioxide and water, although formic acid is much more abundant. In a later paper they contradict this result, stating that formic acid alone is present and no formaldehyde, thus confirming Euler’s criticism of Bach’s Results.