482 PROCEEDINGS OF THE AMERICAN ACADEMY 



crystal. Fui'ther flaming renders these crystals opaque white. They 

 are sometimes produced on cooling merely, without submitting the 

 bead to the flaming process. 



Strontia. — Strontia, with borax, yields plumose crystallizations, 

 more or less translucent, according to the state of saturation of the 

 glass, and the amount of flaming ; and which are made up of slender, 

 bladed crystals, sometimes arranged around a common centre in nearly 

 circular disks. 



With microcosmic salt, slight flaming gives to the surface of the 

 bead a peculiar speckled aspect, due to the formation of oblong, rectan- 

 gular crystals, varying in size, being often large enough to be made 

 out without using a lens (see Plate, Fig. 3) ; but never possessing 

 such well-defined angles as the crystallizations of baryta. (See Plate, 

 Fi"-. 3.") This is a better reaction than that with borax. 



Mixed with an equal quantity of baryta, in the same flux, a precipi- 

 tate is instantaneously produced by flaming, made up of microscopic 

 spiculoe, sometimes asteriated. The most superficial observation would 

 not, however, confound this reaction with that obtainable from the 

 earths separately. 



Lime. — Lime, with borax, yields on slight flaming a thin, filmy 

 precipitate, often in the form of a band stretching across the surface 

 of the bead ; but in which I have never been able to detect any crys- 

 tals, the element of opacity being a dense aggregation of colorless, 

 microscopic globules, or bubbles. 



Mixed witii an equal quantity of magnesia, I have been unable to 

 obtain any different reaction from that just described. 



With microcosmic salt, delicate flaming produces a slight precipitate, 

 which, when highly magnified, is seen to be made up of exceedingly 

 minute spiculge, closely aggregated. 



Magnesia. — With borax, magnesia yields quite readily elegant, 

 acicular crystals, almost invariably united in tufts, or sheaf-like 

 bunches. (See Plate, Fig. 4.) 



With microcosmic salt, microscopically small crystals are produced 

 by slight flaming, sometimes possessing a stellate form, and sometimes 

 being rectangles approaching the square. The reaction with borax, 

 I regard as by far the most decisive. 



Alumina. — With borax, alumina dissolves to a limpid glass, which 

 is not rendered opaque by saturation or flaming. When more of the 

 earth is present than can be dissolved by the flux, prolonged blowing 



