Mr. Silliman, Jr. on the Composition of Corals, 193 
considerable yellowish precipitate of phosphate of silver, which 
is redissolved in ammonia and nitric aci 
Acetate of lead, added to a chigttliydtie solution, produces a 
copious precipitate of chloride of lead, which is not wholly re- 
dissolved by an excess of acetic acid, but is taken up by nitric 
acid. These facts are a sufficient proof of the presence of phos- 
phorie acid. 
Lime-water, added to a solution of coral, either neutral or 
slightly acid, will produce an immediate gelatinous precipitate of 
all the bases and acids which the coral can contain, except, of 
course, the lime and solvent acid. Great care is needed in this 
operation to prevent the formation of a carbonate of lime; the 
solution should have been recently boiled, and the test applied 
while it is yet hot, the air being excluded ; and the precipitate 
should be immediately collected on a filter ond washed. If the 
precipitate by lime-water be fused in a platinum capsule, with 
carbonate of soda, or carbonate of potassa in excess, the phos- 
phoric acid is all transferred to an equivalent portion of alkaline 
base, while the lime or magnesia, or the base with which it was 
before united, will remain as a carbonate. The usual tests, 
which have already been enumerated, will show the presence of 
the phosphoric acid. 
The lime-water test offers far the best means of. separating 
from the lime (which exists as a carbonate) all the other constit- 
uents of a coral, as these various substances are in very small 
quantity compared with the entire mass of the coral, Some 
easy means of completely separating them all, is an indispensable 
preliminary step in their examination and estimation. 
I am indebted to my friend Dr. J. L. Smith, of Charleston, 
South Carolina, for suggesting to me the use of this test in the 
analysis of the corals. 
As the several elements whose presence our researches have 
determined in corals, have been enumerated in the body of the 
work (p. 57), it is not necessary to repeat them here ; but we may 
state, in a summary manner, an outline of the gener] course of 
analysis pursued in determining the constitution of the lime- 
water precipitate, which it will be allowed contains several ele- 
ments whose association has always been considered as offering 
some of the most difficult problems in the whole range of inor- 
ganic analysis. The following plan of — has been con- 
Sxrconp a, Vol. I, No. 2.—March, 1846. 
