OCEANOGRAPHY: J. F. McCLENDON 
617 
torn of the sea, hence the absence of nuclei for precipitation of calcite 
is what one might expect. 
Aragonite is said to be about 10% more soluble than calcite, but no 
difference in the point of equilibrium of the two substances with sea 
water was detected in these experiments. This may be explained by 
the facts that a few calcite crystals were mixed with the aragonite, 
equilibrium was only approximated and there were slight errors in the 
determinations. The results are shown by black rosettes in figure 1. 
During the rough weather, white calcareous mud is stirred with the 
sea water at Key West and to a lesser extent at Tortugas, and it was 
thought possible that the mud granules might form nuclei for precipi- 
tation and explain the low alkaHne reserve at Tortugas and lower alka- 
Kne reserve at Key West. On agitating white calcareous mud, dredged 
from the bottom, with sea water, no definite equilibrium was reached, 
even at the end of four days. If the alkahne reserve was first lowered 
by removal of some CaCOs, it remained lower than if shaken with cal- 
cite and if normal sea water was used the alkaline reserve remained 
higher than with calcite. It was thought possible that the grains were 
covered with an impenetrable film of organic matter; so some mud was 
dried and powdered in a mortar in order to break the pieces and form 
fresh surfaces, but similar results were obtained with this. The results 
are shown by black circles in figure 1. 
If mud was mixed with an equal weight of calcite, the results were 
the same as with pure calcite, as shown by the black dumb-bells in figure 
1 . This mud and calcite on standing in sea water for thirty days had not 
changed to calcite. All these facts tend to show that the particles in the 
mud are in some way retarded or prevented from getting into equihbrium 
with the water. 
In order to be sure of clean surfaces of natural calcareous substances, a 
specimen of coral, Maeandra clivosa, was ground and powdered in a 
mortar and agitated with sea water in the same manner as in previous 
experiments. The results were similar to those with mud, as shown by 
the white circles in figure 1. 
There seems to be a more soluble form of calcium carbonate (the ix 
CaCOs of Johnston), but since it cannot be obtained in a pure state, 
no attempt was made to prepare it. One experiment, however, was 
made with a precipitate of CaCOs that appeared as spherical grains 
under the microscope. It was agitated for twelve hours with sea water 
and the alkaline reserve was 0.0022 at pH 7.95. No further experiments 
were made to determine whether equilibrium had been approximated. 
