1889-90.] Dr J. Murray & Mr R. Irvine on Coral Reefs. 93 
organic matters at a high temperature, and its retardation in colder 
waters. The ammonia of the air and all the substances carried into 
the sea by the drainage from the land also effect changes in the 
internal constitution of the sea water ; indeed, the peculiar pelagic 
fauna and flora, which are met with in all regions of the ocean where 
the ocean is affected by river and coast waters, are as much in rela- 
tion with the internal constitution of the sea-water salts as with the 
lower salinity which prevails in these circumstances. It is well 
known that organic substances in the presence of alkaline and 
earthy sulphates become oxidised at the expense of the oxygen of 
these salts, with the production of carbonic acid and sulphuretted 
hydrogen,* which on oxidation produces sulphuric acid. The whole 
of the organic carbon, which it has been pointed out is of enormous 
amount, must apparently he oxidised into an equivalent amount of 
carbonic acid, and further of sulphuric acid. The effects of this 
reaction are likely to be more marked in the deeper parts of the 
ocean, where all motions of the sea water must be extremely slow, 
and where consequently the effete products tend to accumulate. 
In this way the larger amount of lime and carbonic acid and the 
less amount of oxygen in deeper waters are to be accounted for. 
Hot only so, but the very existence of such a relatively large 
quantity of sulphate of lime in sea water goes far to prove that 
this reaction is continually taking place, seeing that sulphuric 
acid cannot exist in a free state in the presence of carbonate of 
lime. Thus it is probable that the quantity of sulphate of lime in 
solution in the ocean is limited only by the amount of organic 
decomposition that takes place in ocean waters. On the other 
hand, if marine organisms procure the whole of their carbonate of 
lime from the sulphate of lime by the reaction of the ammoniacal 
salts, then the amount of lime that may be secreted from ocean 
waters is likewise limited by the amount of organic matter under- 
going this oxidation process in the ocean, f 
* MS0 4 + 2C = 2CO a + MS 
MS + C0 2 + H 2 0 = MC0 3 + H 2 S 
H 2 S + 20 2 = H 2 S0 4 . 
t Gmelin, Chemistry , vol. ii. p. 191, states : — “ In liot climates, as on the 
west coast of Africa, where the water of the* rivers highly charged with 
organic matter, mixes with the sea water which contains salts of sulphuric 
acid [sulphates], the same decomposition takes place, extending sometimes to a 
