18 ©. M. Wetherill on the Crystalline Nature of Glass. 
When melted glass cools, its least fusible compounds separate 
at first, and when the refrigeration is gradual a distinct crystal- 
lization takes place. By a rapid cooling the crystals must be 
more numerous and much smaller. If they cannot be detected 
in such glass by the eye or by aid of the microscope, the reason 
may be in their extreme tenuity, so that the light behaves to 
them as to the natural roughness of the polished surface. The 
author observes that silica is often separated in so fine a condi- 
tion that it passes through the small pores of the filter. He 
finds no reason in the phenomena of this class of bodies for an 
actual amorphism; but assumes that they are composed of oe 
tals, which, although really small, are large in relation to the 
atomic molecules of the bodies. 
He concludes (op. cit., p. 476) that ‘ amorphous bodies, in the 
ordinary sense of the expression, are unknown among solids, for 
solidity depends upon crystallization.” 
wadin, in his brochure (Reforme de la Chemie Minerale et Or- 
ganrque, Paris, 1863), endeavors to show what crystalline forms 
are probable for all bodies, deducing his results from the num- 
ber of atoms in their chemical formule and the simplest man- 
ner in which they may be arranged. Chemists are divided as to 
the reliance to be placed upon Gaudin’s views; but if they are 
tenable, or if in any degree founded upon reasonable grounds, 
the crystalline condition of all solid bodies would seem to be a 
necessary consequence. piste oi 
Pelouze (Comptes Rendus, xl, 1321), in an investigation of the 
devitrefication of glass, as in the so-called porcelain of Réaumur, 
exposed a tablet of plate glass to incipient fusion upon the sole 
of a glass furnace for a period of 24-48 hours, and then suffered 
it to cool slowly. The result was a porcelain-like substance con- 
sisting of numerous opaque acicular crystals which were ar- 
ranged in parallel series, the individuals being perpendicular to 
the surface of the plate. It was found that the crystallization 
proceeded from the surface to the interior of the tablet, and that 
when the process was arrested there was a distinct line of de- 
marcation between the crystalline and vitreous portions. In 
rare instances the fibrous structure was wanting, and the erystal- 
lization was of such nature that the fractured glass presented the 
appearance of fine white marble. Occasionally the crystals were 
replaced by an enamel-like material. In repeated experiments 
of this character Pelouze found that the glass experienced no 
change of weight during the devitrefication, and the altered glass 
was restored to its transparency by a simple fusion. The pro- 
several times without any alteration of _ 
