BY MOLECULAR COALESCENCE. 31 
is formed in pure or common water, its first form is crys- 
talline ; but when formed in the same manner in water 
containing a viscid substance in solution, its form is globu- 
lar. In the former case the molecules of carbonate of lime 
are uncombined, and therefore, in its crystalline state, it 
may be regarded as pure; in the latter, the carbonate of 
lime is combined with the viscid substance, as can be 
shown by chemical analysis, and therefore in its globular 
form it is obviously an impure carbonate—a compound of 
this substance and gum, or albumen. The facts requiring 
explanation are these: that, when the molecules of pure 
carbonate of lime, that is, carbonate uncombined with a 
viscid substance, come into existence, they immediately 
commence arranging themselves in straight limes, and 
thus, when collected together, form rectilinear figures or 
erystals; but when the impure carbonate, that is, carbon- 
ate combined with a viscid substance, comes into existence 
under similar circumstances, its molecules assume a curvi- 
linear disposition, and hence become collected mto glo- 
bules. Now, as these forms of arrangement are exactly 
the reverse of one another, and as the curviliear form 
has been shown to be the effect of attraction, the recti- 
linear arrangement might have been inferred to be the 
effect of repulsion, or at least of some force causing the 
separation of the elementary molecules of the pure car- 
bonate. Hence it appears, that when the gum or albu- 
men is intimately combined with the ultimate particles or 
molecules of carbonate of lime, it confers upon them a 
property capable of neutralizing this inferred repulsion ; 
and thus, making the molecules of this compound indif- 
ferent in respect to any inherent attraction or repulsion 
existing among themselves, they become amenable to the 
effective operation of gravity, a force which is ever in 
