X%- 
oer 
Mr. Silliman, Jr. on the Composi 
It now remains to give the constitution ot the precipitate of | 
fluorides and phosphates. The results ‘annexed are calculated 
for a hundred parts of the precipitate. 
a II Ill. IV. a. 
Silica, ~ 22-00 12-5 13-50 10-32 23-74 
Lime, 13-03 75 10-40 15-57 35:01 
agnesia, 7-66 42 1-63 38-49 1:35 
Fluoride of calcium, 7:83 26°34 34-85 7-50 8:88 
Fluoride of magnesium, 12:48 26°62 19-06 2-62 20°44 
Phosphate of magnesia, 270 800 5:87 0-25 3:46 
Alumina (and iron), 16:00 ~ 14-84 14:69 25-25 7-12 
Oxide of iron, 18-30 
VI Vil Vill IX 
Silica, f 5°35 11-0 =. 30-01 8-70 
Lime, 7:17 239 1745 16°74 
Magnesia, 0-49 08 2457 45-19 
Fluoride of calcium, 4:05 15-0 0-85 0-71 
Fluoride of magnesium, PRoyphate } gestion tes 4-31 234 
> of lime, mag. 
Phosphate of magnesia, | 16-30 4-7 0-32 0-34 
Alumina Pa iron), 35°00 19-4 22:49. 207 
Oxide of iron 27-39 
The faioing results show that, contrary to the expectation Z 
when the research was podigeineedi the fluorine is present in 
much larger proportion than phosphoric acid. The silica exists 
in the coral in its soluble modification, and probably is united to 
the lime. The free magnesia existed as carbonate, and was 
thrown down as caustic magnesia by the lime-water. Some 
small portion of lime was probably thrown down as carbonate, in 
spite of every precaution to the contrary. Only in two or three 
instances, however, was there any effervescence on the addition of 
chlorohydric acid to redissolve it. 
It need hardly be said that the existence in sea water of all 
the matters noted in these analyses, is a just inference; but this 
subject, as well as the important geological inferences which may 
be drawn from the results now presented, will be fully deca i 
on another occasion. . | 
My warmest acknowledgments are due to my fied ‘tid | 
pupils, Messrs. D. Olmsted, Jr. and T. S. Hunt, who have zeal- 
ously aided me in the laborious parts of these investigations. 
Yale College Laboratory, December 16th, 1345. 
