The descriptions of commercial potash deposits indicate that most of these deposits have been formed by the evaporation of saline waters and are of a geological age younger than the Carboniferous.1 Glauconitic sands, alunite, wood ashes, and other materials have been used as a source of potash but these contain relatively small amounts compared with deposits formed by the evaporation of sea water and are not considered important to the subject of this paper.
The variation in the amount of salts dissolved in sea water or the gradual increment of some of these substances has been discussed at various times, but apparently no consideration has been given to the possibility of an appreciable increase or change in the relative amounts of potash in sea water throughout geological time. Daly has discussed the possibility of a limeless sea in the pre-Cambrian and the probable concomitant variation in the ratio of . . .