322 Proceedings of Royal Society of Edinburgh. [sess. 
as a vehicle for the carbonate of lime, as shown by the gradual 
crystallising out of the greater part that at first dissolved. After 
standing twenty hours, this solution only held 0*186 grammes CaC0 3 , 
and after four days 0*162 in place of 0*6 grammes above referred to. 
This soluble action of sea water on amorphous carbonate of lime 
has nothing to do with carbonic acid. An artificial sea water, free 
from carbonic acid and carbonates of any kind, will dissolve up 
quite as much. It is distinctly confined to the soluble action of 
the salts present. 
In regard to the solubility of the coral skeleton in the various 
salts of sea water, it will be seen from the Table that if all these salts 
be acting together on the substance in one solution, the soluble action 
of the mixture is about the same as that of sea water. That is to 
say, normal sea water, and that artificially prepared by adding in 
proper proportions the salts present in sea water to distilled water 
free from carbonic acid, will dissolve practically the same amount of 
carbonate of lime. But with solutions of the individual salts, the 
results are in some cases higher, as in sodium chloride and magnesium 
chloride, and lower, as in sulphate of potassium and sulphate of lime. 
This difference is most probably owing to the sulphate of lime, which, 
as before said, seems to have a deterring action on the solubility, 
although when the carbonate of lime is once dissolved, the 
subsequent addition of the sulphate has no precipitating effect. 
Curiously enough, if these results of the solubilities of the coral 
he added up as before mentioned, the resulting figure comes to very 
nearly the amount of carbonate, taken as lime, given by Professor 
Dittmar as being present in sea water : — 
NaCl . 
= 0*0525 
MgCl 2 . 
= 0*0746 
MgS0 4 . 
= 0*0712 
k 2 so 4 . 
= 0*0296 
CaS0 4 . 
= 0*0209 
0*2488 
Subtract amount dis- 
solved by 4 litres 
Sea water contains — 
0*1210 
extra water used, 
And will dissolve of 
= 0*0285 x 
4 = 0*1140 
same CaC0 3 
0*0237 
0*1348 
0*1447 
0*1348 
0*0099 
