The Phosphorus and Arsenic Compounds of Sea-Water

1. Much of what was formerly considered to be phosphorus in organic combination, in sea-water, is in reality arsenic. 2. Certain analyses giving high values for phosphate in sea-water and a June minimum very far from complete exhaustion of phosphate are vitiated by the inclusion of arsenate, as arsenomolybdate, in the phosphomolybdate precipitate. 3. Arsenic in sea-water exists mainly in the form of arsenite. The arsenate present, if any, has hitherto been included in the results obtained for phosphate. 4. Since arsenic is found in algæ and has been recorded as increasing in quantity with increase of depth it seems that the arsenic present in sea-water must undergo seasonal changes.