19. Sodium.—Like potassium, this alkali metal is detected by the color which its salts give to the flame.
If a sodium salt be held on the platinum wire in the flame, it imparts an intense yellow color.
The extreme delicacy of this reaction has been mentioned elsewhere. The value of this test is really lessened by its great delicacy, for it is possible to detect minute quantities of sodium in almost all substances, although it may not be in chemical combination. As an example, draw the platinum wire between the fingers, and then place in flame, and note presence of sodium.
20. Lithium, Li2O.—In the Bunsen flame on the platinum wire it imparts a carmine-red tinge.
Hydrochloric acid on the sample augments the coloration.
The Alkaline Earths
21. Barium, BaO.—In the Bunsen flame on the platinum wire it imparts an apple-green coloration. This reaction is intensified by moistening the sample with hydrochloric acid.
22. Calcium, CaO.—In the Bunsen flame on the platinum wire it imparts an orange-red color, which appears gray when seen through blue glass.
Hydrochloric acid on the sample makes the color more intense.
23. Strontium, SrO.—In the Bunsen flame on the platinum wire it imparts an intensely red color, which is increased by converting the substance into the chloride.