616 
OCEANOGRAPHY: J. F. McCLENDON 
nitrate solution. These observations, together with the mode ot 
preparation, leave little doubt that the crystals actually were calcite 
and aragonite. Under the microscope an occasional calcite crystal 
could be found among the aragonite crystals but the number was not 
sufficient to affect the cobalt nitrate test. These calcite crystals appar- 
ently grew slightly during the experiments but apparently no new ones 
were formed. To determine the equilibria, crystals were mechanically 
stirred or shaken with sea water in 'nonsol' flasks, six to fourteen hours 
at 30°, then the pH and alkaline reserve determined. 
FIG. 1 
The results are shown in figure 1. The alkahne reserve is measured 
on the ordinate and the pH on the abscissa. The results of agitating 100 
grams of calcite crystals with a liter of sea water until equilibrium was 
approximately reached are shown by black rhombs in figure 1. If we 
draw a straight line from the intersection of the ordinates of pH 7.3 
and alkahne reserve 0.0023 to pH 8.8 and alkaline reserve 0.0009, the 
determinations with calcite will fall very close to it; This shows that 
sea water of the surface of the oceans of the whole world is supersaturated 
in respect to calcite. We may therefore conclude that suitable nuclei 
for the precipitation of calcite are absent or deficient in number. The 
solubility of crystals varies inversely with their size, but after they have 
attained sufficient size to be readily examined with low powers of the 
microscope, further increase has an unappreciable effect on solubility. 
But such crystals if present, would be rapidly precipitated to the bot- 
