(b.) Boracic Acid.—­If any one of the borates is mixed with two parts of a flux composed of one part of pulverized fluorspar, and four and a half parts of bisulphate of potash, and after being melted, is put upon the coil of a platinum wire, and held at the point of the blue flame, soon after fusion takes place a dark green color is discerned, but it is not of long duration.  The above process is that recommended by Dr. Turner.  The green color of the borates may be readily seen by dipping them, previously moistened with sulphuric acid, into the upper part of the blue flame, when the color can be readily discerned.  If soda be present, then the rich green of the boracic acid is marred by the yellow of the soda.  Borax, or the biborate of soda (NaO, 2BO_{3}) may be used for this latter reaction, but if it be moistened with sulphuric acid, the green of the boracic acid can then be seen.  If the borates, or minerals which contain boracic acid, are fused on charcoal with carbonate of potash, then moistened with sulphuric acid and alcohol, then the bright green of the boracic acid is produced, even if the mineral contains but a minute portion of the boracic acid.

(c.) Copper.  Nearly all the ores of copper and its salts, give a bright green color to the blowpipe flame.  Metallic copper likewise colors the flame green, being first oxidized.  If iodine, chlorine, and bromine are present, the flame is considerably modified, but the former at least intensifies the color.  Many ores containing copper also color the flame green, but the internal portion is of a bright blue color if the compound contains lead, the latter color being due to the lead.  The native sulphide and carbonate of copper should be moistened with sulphuric acid, while the former should be previously roasted.  If hydrochloric acid is used for moistening the salts, then the rich green given by that moistened with the sulphuric acid is changed to a blue, being thus modified by the chlorine of the acid.  Silicates containing copper, if heated in the flame in the platinum forceps, impart a rich green color to the outer flame.  In fact, if any substance containing copper be submitted to the blowpipe flame, it will tinge it green, provided there be no other substance present to impart its own color to the flame, and thus modify or mar that of the copper.

(d.) Tellurium.—­If the flame of reduction is directed upon the oxide of tellurium placed upon charcoal, a green color is imparted to it.  If the telluric acid be placed upon platinum wire in the reduction flame, the oxidation flame is colored green.  Or if the sublimate be dissipated by the flame of oxidation, it gives a green color.  If selenium be present, the green color is changed to a blue.

(e.) Zinc.—­The oxide of zinc, when strongly heated, gives a blue flame.  This is especially the case in the reducing flame.  The flame is a small one, however, and not very characteristic, as with certain preparations of zinc the blue color is changed to a bright white.  The soluble salts of zinc give no blue color.