D. YELLOW.

The salts of soda all give a bright yellow color when heated in the platinum loop in the reduction flame.  This color is very persistent, and will destroy the color of almost any other substance.  Every mineral of which soda is a constituent, give this bright orange-yellow reaction.  Even the silicate of soda itself imparts to the flame of oxidation the characteristic yellow of soda.

E. RED.

(a.) Strontia.—­Moisten a small piece of the chloride of strontium, put it in the platinum forceps and submit it to the flame of reduction, when the outer flame will become colored of an intense red.  If the salt of strontia should be a soluble one, the reaction is of a deeper color than if an insoluble salt is used, while the color is of a deeper crimson if the salt is moistened.  If the salt be a soluble one, it should be moistened and dipped into the flame, while if it be an insoluble salt, it should be kept dry and exposed beyond the point of the flame.  The carbonate of strontia should be moistened with hydrochloric acid instead of water, by which its color similates that of the chloride of strontium when moistened with water.  In consequence of the decided red color which strontia communicates to flame, it is used by pyrotechnists for the purpose of making their “crimson fire.”

(b.) Lithia.—­The color of the flame of lithia is slightly inclined to purple.  The chloride, when placed in the platinum loop, gives to the outer flame a bright red color, sometimes with a slight tinge of purple.  Potash does not prevent this reaction, although it may modify it to violet; but the decided color of soda changes the red of lithia to an orange color.  If much soda be present, the color of the lithia is lost entirely.  The color of the chloride of lithium may be distinctly produced before the point of the blue flame, and its durability may be the means of determining it from that of lithium, as the latter, under the same conditions, is quite evanescent.  The minerals which contain lithia, frequently contain soda, and thus the latter destroys the color of the former.

(c.) Potash.—­The salts of potash, if the acid does not interfere, give a purplish-red color before the blowpipe; but as the color is more discernibly a purple, we have classed it under that color.

(d.) Lime.—­The color of the flame of lime does not greatly differ from that of strontia, with the exception that it is not so decided.  Arragonite and calcareous spar, moistened with hydrochloric acid, and tried as directed for strontia, produce a red light, not unlike that of strontia.  The chloride of calcium gives a red tinge, but not nearly so decided as the chloride of strontium.  The carbonate of lime will produce a yellowish flame for a while, until the carbonic acid is driven off, when the red color of the lime may be discerned.