BY MOLECULAR COALESCENCE. 35 
but if the density of the two solutions be properly adjusted 
(and it is upon this circumstance that the success of the 
experiment mainly depends), the principal part of the 
globular carbonate and triple phosphate will be produced 
at about the same altitudes; and thus, their particles 
beig borne up by the nearly equal density of the fluid me- 
dium in which they are contained and kept in motion by 
the diffusion of the unequally dense fluids, will be placed 
under mechanical conditions in all respects favorable to 
the mutual attraction of a great quantity of floating par- 
ticles, and to their final coalescence. If the density of 
the alkaline solution exceed much the degree mentioned 
in the formula, and if that of the simple solution of gum 
is not equal to the degree there specified, the alkali diffu- 
sing itself through the simple solution of gum more 
rapidly than the gum contained in the lower solution, a 
larger quantity of carbonate will be formed than there 
will be gum to combine with it in the proportion neces- 
sary to form the globular carbonate, and, consequently, 
the carbonate of lime formed in the upper part of the 
bottle will be deficient in gum, and therefore it will be 
erystalline and not globular. Now, as the forms of the 
deposit on one of the slides employed in this experiment 
will be the same as that in the fluid in contact with the 
lower side of it, the position of these slides being such 
that no particles in descending perpendicularly can fall 
upon their lower surface, the examination of the particles 
of carbonate attached to this surface will show the form 
of the deposit in the corresponding regions or altitudes of 
the fluid contained in the bottle, and consequently the re- 
sult of the conditions stated in this experiment will be 
best seen by examining the carbonate adherent to the 
lower side of one of these slides. Hence, in the case just 
