On the Crystallization of Carbonate of Lime. 343 
decomposing the lime-water,—or, if possessed of such power, 
added in so small a quantity as to leave lime.in excess, to 
yield a crust of carbonate of lime. 
1. Serum of sheep’s blood. Lime-water after admixture 
with a small quantity of this, put aside for a few hours, the 
jar covered with a glass plate, yielded, besides cubical cry- 
stals, some of a prismatic form and some pyramidal. In this 
instance and the following, the portion of pellicle examined 
was confined between two slips of glass, so as to prevent 
the formation of adventitious crystals by evaporation. 
2. Nitrate of barytes. Lime-water, to which a few drops 
of this salt in solution had been added, treated like the pre- 
ceding, yielded tabular crystals variously truncated, and 
some pyramidal. 
3. Muriate of lime. The crystals obtained in this instance, 
a few drops of the salt in solution having been mixed with 
the lime-water, were cubical and pyramidal,—with which 
granular globules were intermixed. 
4, Chlorate of potash. The crust formed on the lime-water, 
to which a very little of this salt had been added, consisted 
chiefly of little spindle-form masses, with plates of compa- 
ratively large size and great thinness, most of them imper- 
fectly formed, their outline being in part irregular. 
Do not these results admit of application? May they not 
serve to illustrate the extraordinary variety of form in which 
carbonate of lime, in its mineral state, is found in nature ? 
It occurred to me, as not improbable, that carbonate of 
lime, formed without previous solution of the lime, viz., from 
the combination of the lime of the hydrate with carbonic 
acid, might present itself in a crystalline form, the ten- 
dency to assume this form being so great. ButI have 
not, on trial, found it to be so. Recent carbonate of lime, 
obtained by exposing quenched lime to the atmosphere, has 
appeared, under the microscope, to be onlyminutely granular, 
as is the hydrate itself; and a mortar of nearly pure car- 
bonate of lime, attached to a stone, on which are hierogly- 
phies, from the walls of ancient Thebes, has exhibited the 
same minutely granular character. This fact, I may remark, 
is not in favour of the idea of homogeneous particles, ex- 
erting an attractive force on each other, independent of 
