OF ARTS AND SCIENCES : MARCH 28, 1865. 483 



produces a white, vitreous-looking exudation at the margin of the bead, 

 which is hard enough to scratch glass, and is not easily soluble in borax. 

 Keeping the bead a long time at a high temperature produces the same 

 effect, even when the glass is not saturated ; and the same thing 

 occurs when this earth is treated with microcosmic salt. 



With microcosmic salt, patient flaming is rewarded by a very slight 

 precipitate, consisting of an immense number of exceedingly minute, 

 asteriated crystals, partaking of the snow-flake character, but not 

 nearly so well defined and symmetrical as the crystallizations of baryta 

 with the same flux. 



In borax, mixed with an equal quantity of lime, I have obtained 

 crystals ; but of a very irregular form, and unfinished appearance. It 

 should be borne in mind, however, that I have not been able to crys- 

 tallize either of these earths alone in borax. 



Glucina. — AYith borax, an exudation, similar to that noticed with 

 alumina, takes place upon long heating. Flaming produces a precipi- 

 tate composed of colorless globules or bubbles. Mixed with an equal 

 quantity of lime, a similar precipitate is obtained. 



"With microcosmic salt, upon flaming, the surface of the bead becomes 

 studded with crystals, but so minute as to require a high. magnifying 

 power to discern their form. They are generally rather slender, soli- 

 tary, oblong figures ; but quite often cruciform, and sometimes irregu- 

 larly assembled.- 



Zirconia. — In borax, the intermittent flame causes a crystalline pre- 

 cipitate ; but the individual forms are too minute to be distinguished, 

 when magnified four hundred diameters. Long blowing produces the 

 exudation observed with the two preceding earths. Addition of lime, 

 in very considerable quantity, causes a very decided precipitate upon 

 flaming, consisting of bubbles. The zircon, from which the earth used 

 was prepared, gave a similar precipitate to that last named, but much 

 less dense. 



With microcosmic salt, flaming is followed by the formation of an 

 indistinct, crystalline film. 



Zinc. — Oxide of zinc, with borax, yields, in the intermittent flame, 

 acicular crystals, arranged in tufts, asteriated, and sometimes arbores- 

 cent. These crystals resemble those of magnesia in the same flux, 

 except that I have not observed either the stellate or arborescent 

 arrangement with the latter. In the reducing flame a bright metallic 

 precipitate, flesh-colored to brassy, is easily obtained, after adding oxide 



