486 PROCEEDINGS OF THE AMERICAN ACADEMY 



With oxide of copper, and treated in the reducing flame, the pre- 

 cipitate closely resembles that of zinc under the same circumstances. 



With microcosmic salt, I have observed no crystallization. 



Silver. — Oxide of silver, fused with borax in the outer flame, to a 

 clear glass, and treated with the reducing flame, gives a yellowish 

 precipitate of very minute crystals, of which the form appears to be 

 octohedral ; and with microcosmic salt, the reaction is similar. 



Addition of considerable oxide of silver to a bead containing litharge 

 renders it opaque, and of an oil-yellow color. Treated in the reducing 

 flame, there is a precipitate of what appears to be metallic silver, in 

 minute globules and irregularly shaped masses. The part of the bead 

 acted upon likewise becomes straw-colored, and slightly iridescent. 

 When oxide of copper is substituted for litharge, the bead becomes 

 opaque, and of a light greenish-blue color. Touched with the re- 

 ducing flame, the part within its influence changes to a very beau- 

 tiful pale blue, bordered by bands of a somewhat cupreous shade, 

 and enriched by a fine play of colors. A precipitate resembling me- 

 tallic silver frequently accompanies this reaction. With oxide of 

 nickel, in the outer flame, a grayish-brown, streaked enamel is pro- 

 duced. The reaction with the reducing flame slightly resembles that 

 with copper ; but the bands around the part heated are very light, — 

 almost white, in fact, — and the delicate pale blue of the copper re- 

 action is entirely wanting. With teroxide of antimony, in the reducing 

 flame, there is a metallic precipitate. Addition of litharge to the 

 silver-copper and silver-nickel beads, and treatment with the reducing 

 flame, produces a metallic precipitate, in the form of globules distin- 

 guishable with the lens. 



Copper. — Oxide of copper, with borax, and treated as just described 

 under silver, yields a metallic precipitate, which is somewhat increased 

 by addition of litharge. 



With microcosmic salt, there is a similar precipitate, accompanied 

 sometimes by the formation of sub-oxide of copper. 



By means of the reaction with borax, I have detected copper — 

 obtaining a metallic cupreous precipitate, in an iron pyrites, said to 

 contain but two or three per cent of that metal ; and where the pro- 

 portion of copper was so small, that it did not affect the characteristic 

 iron-yellow of the glass when heated in the outer flame. 



Nickel. — With borax, oxide of nickel gives a gray, metallic precipi- 

 tate, when heated in the reducing flame. Addition of litharge renders 



