364 J.D. Dana on the Consolidation of Coral Formations. 
higher temperature needed ? The common deposition of carbonate of 
lime from the waters dripping through the roofs of caverns is evidence 
to the contrary.’ 
ce | 
He goes on to illustrate by reference to soda water, etc. In 
another place, after mentioning the remark of the writer, he says, 
with point, ‘ The reply to this may be found in elementary works 
on chemistry.” 
I do not care to damage by my remarks any elementary work 
on chemistry. But how does the case stand? Prof. Horsford 
is right as to the pith of my criticism, and also as to my opin- 
ions being gratuitous. Now suppose we collect some of the 
water dripping from the roof of a cavern; and suppose we cool 
it down at once from 60° F. to 40° F., and allow such a wind 
as occurs often at the Mammoth Cave to blow over it, would 
it not evaporate, and the carbonate of lime be thereby deposited ? 
Suppose again the barometric pressure upon that water could be in- 
creased from one atmosphere to fwo, would not the winds still pro- 
duce evaporation and a deposition of the lime? There can be only 
an affirmative reply to these questions. All that is needed is evap- 
oration, and this may take place with a diminished temperature 
and increased pressure. If we should now take that water and 
attempt to deposit the carbonate of lime by means of heat, it 
would be necessary according to such elementary treatises of 
chemistry as we have seen, to raise the heat to the boiling point 
of water, before the carbonic acid would be entirely driven off, 
and the carbonate of lime which it contains, would be deposited.* 
the 
article first appeared; and in the copy of the , revised by him for this 
Where it was published at his request, the rg eas uncorrected. 
