BY MOLECULAR COALESCENCE. 4) 
to a temperature of 212°, either by simply heating it, or 
immersing it im boiling distilled water, or in oil, turpentine, 
or Canada balsam raised to that heat, when the calculi 
containing the triple phosphate, as well as the crystals of 
the same substance, will instantly become changed into 
masses of rhomboidal crystals of various sizes, whilst the 
calculi composed only of globular carbonate of lime will 
not be sensibly altered. Now, it must be observed, that 
though the attraction of tenacity may, in the above in- 
stance, have assisted in preserving the integrity of the 
calculi containing the largest proportion of the tenacious 
matter, yet if this attractive force exceed a certain limit, 
it will prevent the act of coalescence by effectually 
opposing the action of gravity in the preliminary 
stage of disintegration. Hence all the phenomena of 
coalescence must take place between this limit and the 
total extinction of the attraction of tenacity, and it is 
the result of experiment which alone can prove whether 
the conditions proper for coalescence are included or not 
within these two limits. The production of crystals, as 
observed in this experiment, is different to that under 
which crystallization ordinarily takes place. There is no 
indication of a prior state of solution, or igneus fusion, 
but the molecules of triple phosphate appear to pass 
directly and instantaneously from one form of arrange- 
ment to a different one, and, in the spherical particles, 
from a curvilinear to a rectilimear arrangement. As this 
takes place about the boiling point of water, it might 
have been thought, especially in the case of the crystals, 
to be produced by the solution of the triple phosphate in 
some combined or interstitial water raised to 212°, on the 
cooling of which it had again crystallized, though in a 
different form. If this effect had followed only the im- 
