OF ARTS AND SCIENCES : MARCH 28, 1865. 477 



the interior was transparent ; for, upon carefully removing the external 

 part of the bead, a clear, vitreous nucleus was disclosed ; but beads ex- 

 posed to longer heat, w^hen broken showed no trace of this vitreous 

 interior. 



But just beginning the study of Chemistry, I was wholly unac- 

 quainted with the phenomena of the devitrification of glass, and did 

 not feel well assured, therefore, that crystallization was the cause of 

 this opacity, though it occurred to me at the time that such was 

 probably the case. But if the change produced by flaming was a 

 result of crystallization, then a crystalline structure ought under some 

 circumstances to be discernible ; and the density of the crystallized 

 portion could be no obstacle, as I had already ascertained that to be 

 variable at the pleasure of the operator, my experiments yielding 

 results of every degree, from a translucent film to complete opacity. 

 Although density of aggregation did not seem to stand in the way, 

 minuteness of crystalline form might be an impediment to investigation. 

 A borax bead charged with lime exhibited a thin, filmy band stretch- 

 ing across the otherwise transparent surface, when slightly heated with 

 a fine-pointed flame ; but in this I could find no crystals with a hand 

 lens magnifying fourteen diameters. Magnesia, however, when simi- 

 larly treated, gave a very different result. The bead became studded 

 with beautiful, needle-Uke crystals, arranged in tufts, or fascicular 

 bunches, and visible even to the naked eye. Several trials with the 

 same base confirmed the fact of crystallization, and showed a surprising 

 uniformity of crystalline form. But was this form, seemingly constant, 

 a character whereby to recognize the earth, or would other members 

 of the group likewise exhibit it, if properly dealt with ? for the ex- 

 periments with magnesia had taught me that crystals were not always 

 obtained by flaming, an amorphous cloud being sometimes the only re- 

 sult. I reverted to lime ; but with no success. I could get no crystals. 

 Next, I tried baryta. The first trial of slight flaming yielded crystals, of 

 which the hexagonal and rectangular outline could be easily seen with- 

 out a glass. Sometimes a third shape was visible, looking something 

 like an hour-glass ; but these forms seemed to be constant, and there 

 was nothing in the beads in the least resembling the magnesia crystals. 

 Strontia, similarly treated, yielded transparent crystals of a plumose 

 character. 



Three members of the group, then, had yielded crystals with borax ; 

 and crystals possessing quite well-marked distinctive characters. Lime 

 VOL. VI. 53 



