J.D. Dana on the Consolidation of Coral Formations. 359 
he makes of the facts I have published, show that he intends for 
it this universal application. 
V. In the analyses of the “crust-rock” in Prof. Horsford’s for- 
mer paper, he claimed to have found in one case, 20 per cent. of 
animal matter. In the recent paper, another analysis is given in 
which there are but 1:47 per cent., (no more than was found by 
Prof. Silliman, Jr. in some of the bleached corals,) and the differ- 
than quantitative. The foundation for the theory proposed, is 
therefore based on ascanty supply of imperfectly ascertained data, 
VI. In discussing the chemical objections to his theory, he 
comes at last to the point on which the whole turns,—the forma- 
tion of hydrate of lime,—and thus observes : 
“Prof. Dana proceeds : But suppose the uncombined ammonia to be 
formed during the decomposition, will this ammonia precipitate the hy- 
drate of lime from the solution of the sulphate? It is perhaps sufficient 
to say in regard to this statement of Prof. Dana’s, that it was written in 
: g 
view, the learned author correctly states what I did say. He says in 
‘ i¥ 
The small capitals and italics are Prof. Horsford’s. 
The assertion, “I have never uttered anything of the kind,” is 
forcible and apparently decisive. 
e verbal difference between the statement alleged to be er- 
roneous, and that acknowledged to be correct, consists in sub- 
Stituting precipitate for separate, and in omitting the word soluble. 
Judging from the peculiar stress laid upon the word soluble by 
the use of capitals, it might be supposed that Prof. Horsford be- 
lieved in a souuste hydrate, as distinct from another which was 
insoluble. 
But chemists know of but one, and that takes 778 parts of 
water, at 60° F’. (according to Dalton) to dissolve one part, or it 1s 
about one half as soluble as sulphate of lime or gypsum :} 1n pro- 
_ * Prof. Horsford in his former paper, uses the words, “The nitrogen going over 
into the form of ammonia at a later period, decomposed the cw gi of lime, forming 
phate of ammonia and soluble hydrate of lime.” We therefore add, “of the sul- 
phate of lime,” to make the statement complete. 
According to Bucholz, gypsum dissolves in 460 parts of water, either hot or cold, 
according to Giese, in 380 parts of cold and 388 parts of boiling water—Gmel. Chem, 
iii, 202, 
