B. THE BLUE COLOR.

(a.) The Chloride of Copper.—­Any of the chlorides produce a blue color in the blowpipe flame, or any salt which contains chlorine will show the blue tint, as the color in this case is referable to the chlorine itself.  There are, however, some chlorides which, in consequence of the peculiar reactions of their bases, will not produce the blue color, although in these cases the blue of the chlorine will be very likely to blend itself with the color produced by the base.  The chloride of copper communicates an intense blue to the flame, when fused on the platinum wire.  If the heat be continued until the chlorine is driven off, then the greenish hue of the oxide of copper will be discerned.

(b.) Lead.—­Metallic lead communicates to the flame a pale blue color.  The oxide reacts in the same manner.  The lead-salts, whose acids do not interfere with the color, impart also a fine blue to the flame, either in the platina forceps, or the crooked wire.

(c.) Bromide of Copper.—­This salt colors the flame of a bluish-green color, but when the bromine is driven off, then we have the green of the oxide of copper.

(d.) Antimony.—­This metal imparts a blue color to the blowpipe flame, but if the metal is in too small a quantity, then the color is a brilliant white.  If antimony is fused on charcoal, the fused metal gives a blue color.  The white sublimate which surrounds the fused metal, being subjected to the flame of oxidation, disappears from the charcoal with a bluish-green color.

(e.) Selenium.—­If fused in the flame of oxidation, it imparts to the flame a deep blue color.  The incrustation upon charcoal gives to the flame the same rich color.

(f.) Arsenic.—­The arseniates and metallic arsenic itself impart to the blowpipe flame a fine blue color, provided that there is no other body present which may have a tendency to color the flame with its characteristic hue.  The sublimate of arsenious acid which surrounds the assay, will give the same blue flame, when dissipated by the oxidation flame.  The platinum forceps will answer for the exhibition of the color of arsenic, even though the salts be arseniates, whose bases possess the property of imparting their peculiar color to the flame, such as the arseniate of lime.

C. THE GREEN COLOR.

(a.) Ammonia.—­The salts of ammonia, when heated before the blowpipe, and just upon the point of disappearing, impart to the flame a feeble though dark green color.  This color, however, can only be discerned in a dark room.