56 FORMATION OF SHELLS OF ANIMALS, ETC., 
imoperative but for the previous action of gravity. So 
that in this way the attraction of tenacity maintains a 
position intermediate between an universal influence 
strictly physical, and a condition of matter which seems 
to connect inorganic with organic forms of existence. 
The condition which I mean is that of sphericity or rotun- 
dity of contour, a character which has generally been 
regarded as one of the characteristic distinctions between 
inorganic and organic bodies. It is also observed in the 
same page, that the relative intensity of these two forces 
is In proportion to the quantities of the triple phosphate 
and the globular carbonate present. And, for reasons 
there given, it is further stated, that the more there is of 
triple phosphate combined with the globular carbonate in 
these calculi, the less will be the attraction of tenacity ; 
so that such proportions of these substances may be asso- 
ciated in these bodies as to neutralize the force of tenacity, 
in which case their molecules would be held together only 
by the attraction of gravitation. It is in calculi of this 
description that the disintegration in question can be best 
displayed. And the experiments by which this is effected 
will furnish additional evidence in proof of the principles 
which have been adverted to in explaining the facts of 
molecular coalescence, and of their perfect applicability to 
the explanation which has been given of this process. 
The following is one of the experiments which, for the 
convenience of those who may wish to repeat it, I will give 
in detail. Three bottles are to be charged with the two so- 
lutions mentioned at page 6, and provided each with two 
glass slides exactly according to the directions there given. 
Then one of these bottles is to be tied over with oiled silk, 
to prevent evaporation of its contents, care being taken 
not to disturb the solutions. The other two are to remain 
