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Miscellaneous Intelligence. 238 
chilled and expanded, cemented to one another. e exterior 
layers, kept by the resistance of the interior ones, can only yield to » 
the force of elasticity which solicits them if, through any cause 
whatever, they are all at the same time set free to return to their 
normal state of expansion. 
It results, moreover, from the form of the drop, that all these 
layers, unequally stretched, meet together at the origin of the neck; 
so that on destroying this the common point of resistance vanishes, 
and these layers, the actions of elasticity of which are added to- 
gether, are displaced along the same directions and produce the 
disaggregation of the system. 
If this supposition is correct, one might make a drop burst by 
cutting it at the large end, in such a manner as to set free at one 
her consequence of this hypothesis is, that the vitreous mole- 
cules will be displaced in a direction different according to the 
manner in which rupture takes place. This displacement should be 
greater for the exterior than for the interior layers, which are less 
expanded ; and it is almost niZ for the central portions, which have 
not been chilled at all or but very little. Consequently, on consid- 
more displaced than those situated nearer to the center, which 
be less and less so as they are farther from the surface, so that 
after the rupture this plane section will have the appearance of a 
conic surface formed of little needles of glass, arising from the 
shrinkage on all sides; and the direction of the summits of these 
Sorts of cones will indicate that in which the displacement of the 
molecules has taken. : 
If the thin end be broken off, the shrinking will be toward the 
bulb, and all the summits of the cones will be directed toward a 
thin end, If the explosion be caused by sawing the big end ih 
pe ay the cones will have their summits directed toward the 
: big end, . 
_ That this is what in faci happens I have ascertained by operating 
In the following manner. I fit some Rupert’s drops in plaster, wh 
ering only a little more than half of their thickness. The thin end, 
Which is left protruding, I immerse in fluohydric acid. The mo- 
