14 FORMATION OF SHELLS OF ANIMALS, ETC., 
of calculi of the same globular form and of the same 
structure as those of which they are made up. ‘ 
As every particle of matter, whatever may be its form 
or dimensions, is admitted by philosophers to be under 
the influence of gravity, to which law, if universal, the 
molecules of carbonate of lime, as produced in the manner 
already described, can form no exception, it must follow 
that, the instant they are brought into existence, they will 
commence arranging themselves in spherical figures, 
unless there should be some other force of an opposite 
kind acting upon them, adequate either entirely to over- 
come that of gravity, or sufficient only imperfectly to 
resist 1ts influence; im which case results of an interme- 
diate kind would be produced, depending upon the rela- 
tive powers and modes of operation of the opposing 
agencies. Now, as it is an undoubted fact, and one ad- 
mitting of ocular demonstration, that the particles of carbo- 
nate of lime formed by the double decomposition of a salt of 
lime and carbonate of potash previously dissolved m a solu- 
tion of vegetable gum, or of albumen of about the same 
density as the resulting carbonate, do assume, as their first 
appreciable form, that of minute spherules, and as this is 
exactly the figure which the molecules composing these 
particles would assume under the mechanical conditions 
in which they are placed, if they were simultaneously 
subjected to the effective influence of gravitation, that is, 
if they attracted one another with a force varymg in-. 
versely as the squares of the distances between them, and 
directly as the quantity of matter in each molecule, the 
sphericity of these particles may be inferred to be the 
effect of gravity. And, besides, as there is no other 
known agency which could produce the same results 
under the same circumstances, this fact ought not only to 
