94 
Proceedings of Royal Society of Edinburgh. [sess. 
From the foregoing discussion it appears evident that in the various 
reactions taking place continually in ocean waters there are special 
conditions which are favourable to the secretion of carbonate of lime 
by organisms, chief among these being a high and uniform tempera- 
ture of the water at all seasons of the year. 
If now we turn our attention to the solution of the dead carbonate 
of lime shells and skeletons by the action of sea water it will, in like 
manner, be found that the rate of this solution varies greatly accord- 
ing to the conditions in which these dead remains are exposed to the 
solvent power of the water. 
The tables at the end of this paper give some of the results of a 
large number of experiments that have been conducted on the solu- 
bility of carbonate of lime in different states and in different samples 
of sea water. It may be pointed out that the normal amount of 
carbonate of lime dissolved in sea water is very small, especially 
when compared with the large amount of this substance that is 
continually being secreted from the sea by organisms. The amount 
in ordinary sea water (sp. gr. 1*026) is 0*12 grrns. per litre. Sea 
water may, however, take up 0*649 grms. per litre of carbonate of 
lime in the amorphous or hydrated condition. This solution is then 
supersaturated, and on being allowed to stand, the carbonate of lime 
is thrown out of solution in the crystalline form, and after a time 
the solution may contain less than is normally present in sea water. 
It has been found that sea water can hold in solution (at 80° F.) 
for at least a week 0*16 grms. per litre more than is normally pre- 
sent in it, and artificially prepared sea water can also hold in solu- 
tion 0*28 grms. per litre for at least a week, and 0*12 grms. (the 
normal amount in ordinary sea water) for six weeks. 
It thus seems that although sea water under certain conditions 
may take up a considerable quantity of carbonate of lime in solution, 
yet it is unable permanently to retain in solution more than is 
usually found to be present in sea water, and it is owing to this that 
distance of 27 miles from the months of the rivers, the water containing 
hydrosulphuric acid, sometimes as much as six cubic inches to a gallon.” 
This is confirmed from samples of water, which we have examined, taken 
from the roadstead at Monte Video by the telegraph ship “ Seine.” It consists 
of a mixture of fresh and salt water, with a considerable amount of organic 
matter which has decomposed the sulphate, giving rise to a large amount of 
hydrosulphuric acid. 
