BY MOLECULAR COALESCENCE. 33 
force exerted between the molecules of the pure carbonate, 
so as to render the molecules compounded of both sub- 
stances neither attractive nor repulsive, and therefore 
susceptible to the effective operation of gravity; and 
certainly the fact of the ready and intimate union of these 
compound molecules, as abundantly manifested im the 
operation of coalescence, shows that this supposition has 
a weight of evidence in its favour which amounts to proof 
or demonstration that the point first supposed is in reality 
a fact; and hence, considering all the circumstances of 
the case, the attraction of tenacity inherent in the gum, 
the repulsion or some such influence existing between the 
nascent particles of the pure carbonate of lime in the act 
of crystallization, and the universal operation of gravity, 
it is difficult to see how the effect could have been other- 
wise than experiment has shown it to be, at least in kind. 
But in its amount or degree it may vary, producing all 
the results intermediate between the production of im- 
perfect crystals and perfect globules, according to the 
relative amount of the forces in operation. 
Of the three forces mentioned in the preceding explana- 
tion of the manner in which the rectilinear arrangement of 
the molecules of the carbonate of lime is changed into a cur- 
vilinear arrangement by the action of viscid substances, the 
existence of two is universally admitted by philosophers, 
namely, gravity and tenacity, though the latter, if not con- 
sidered a distinct force, is at least regarded as a form of 
cohesive attraction ; consequently, there remains only one 
force, which, having been so far only vaguely indicated as 
repulsive, or capable of causing the nascent molecules of 
pure carbonate of lime to assume the rectilinear or crystal- 
line arrangement, demands further consideration. As the 
demonstration of the nature and operation of this force, as 
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