OF ARTS AND SCIENCES : MARCH 28, 1865. 485 



litharge is followed by the appearance of an apparently insoluble sub- 

 stance, in the glass, which renders it opaque without devitrification 

 taking place ; but the reducing flame does not produce a precipitate in 

 a bead thus treated. When tex'oxide of antimony is added, in consid- 

 erable quantity, to a bead colored dark blue with oxide of copper, and 

 just removed from the oxidating flame, it is at once taken up by the 

 still fluid glass, in which an amorphous, red precipitate — apparently 

 sub-oxide of copper — is immediately formed. When the copper bead 

 is a very dark, nearly opaque, blue, addition of much teroxide of anti- 

 mony converts it, after fusion in the outer flame, into a parti-colored 

 enamel, in which red and yellow predominate ; and the bead, upon 

 cooling, loses its uniform convexity of outline, the surface becoming 

 very irregular. Treated in the reducing flame, a rather indistinct, dull- 

 gray looking precipitate is then obtained. When much less teroxide 

 of antimony is present, the precipitate is not unlike that of zinc, 

 though it is, in most cases, accompanied by a red border of sub-oxide 

 of copper, which I have not noticed in the zinc beads. 



With microcosmic salt, I have noticed an amorphous precipitate on 

 the surface of the glass, when treated in the reducing flame, which was, 

 in one case, accompanied by solitary, needle-like crystals, distinguish- 

 able by the lens. 



Arsenic. — With the intermittent flame, I have not obtained crys- 

 tals in either flux. 



Addition of arsenious acid to a hot borax bead, colored dark blue 

 with oxide of copper, is immediately succeeded by the formation of a 

 precipitate similar to that just described under the head of antimony ; 

 but in no case, however large be the quantity of arsenious acid added, 

 does the bead lose its form, or assume the colors of the antimony 

 enamel, after being reheated in the outer flame. The precipitate in 

 the reducing flame is principally sub-oxide of copper, accompanied 

 sometimes, however, by brassy-looking, metallic particles. With ses- 

 quioxide of iron, there is a rather scanty precipitate, in the reducing 

 flame, in color and lustre not unlike metallic arsenic. 



Tin. — In borax, binoxide of tin yields a very slight, filmy precipi- 

 tate, in the intermittent flame, made up of exceedingly transparent, 

 but very indefinitely shaped crystals, which, viewed under tlie micro- 

 scope, bring forcibly to mind a pellicle of recently formed ice floating 

 in clear water, the corrugations of whose surface alone serve to dis- 

 tinguish it from the fluid on which it rests. 

 VOL. VI. 54 



