1888.] Mr Irvine and Dr Woodhead on Lime Secretion. 309 
Sea water is a complex mixture, or combination, of a variety of 
salts, how combined or how related to each other, it is impossible 
to define exactly. The proportion of salts, by combining the acids 
and bases in the most reasonable and approved manner, is, according 
to Dittmar — 
Chloride of sodium, . 
. 77-758 
77-758 
Chloride of magnesium, 
. 10-878 ) 
Sulphate of ,, 
. 4-737 > 
15-832 
Bromide of ,, 
-217 ; 
Sulphate of potash, 
. 2-465 
2-465 
Carbonate of lime, 
•3451 
3-945 
Sulphate of ,, 
. 3-600 J 
100-000 
100-000 
Average sea water contains about 3'5 of its weight of dissolved 
solids, the total lime salts therein contained amounting to *138, 
or more precisely — 
Sulphate of lime, . . . . '126 
Carbonate of lime (?), . . . ’012 
According to this method of arranging the acids and bases, the 
chlorine is represented as entirely combined with sodium and mag- 
nesium, and it will be seen that the carbonate of lime (?) here held in 
solution amounts to only one-tenth of the whole lime salts present. 
In coral, shells, and calcareous plants, the whole lime is prac- 
tically in the form of carbonate j and the question naturally pre- 
sents itself — Why is soluble carbonate of lime (?) present in sea 
water in such relatively minute quantities compared with the sul- 
phate of lime, whilst everywhere in the ocean we have evidence of 
the enormous amount of the former salt eliminated in an insoluble 
organised form by animal and vegetable life ? 
The relation between plant and animal life in the ocean is much 
the same as that between plant and animal life on land, so far as 
interchange of carbon is concerned, and considering the requirements 
of marine plant life in the form of carbon which it can only obtain 
from the sea in the condition of carbonic acid (which according to 
Dittmar is held in a loose state of combination with lime, or in the 
opinion of Tornoe, with soda) the question presses itself — Where do 
coral animals, shell-fish, and calcareous plants obtain their carbonate 
of lime ? 
