The Elements of Blowpipe Analysis

by Frederick Hutton Getman

In flame on platinum wire____

With borax bead on platinum wire. In O. F. yellow while hot, limpid glass when cold.

With Co(NO₃)₂. Green mass.

Having now given the principal reactions for the most important metals, we will proceed to the examination of the alkali metals, the alkaline earths, and some of the acid elements.

The Alkali Metals

17. Ammonium, NH₄.—This hypothetical compound is commonly classed among the alkali metals from its close resemblance to the members of this group.

To detect the presence of this hypothetical metal, mix the assay with about four parts of Na₂CO₃, place in an ignition tube, and apply heat. The odor of the evolved gas will be recognized, and if a piece of red litmus paper be moistened and held at the mouth of the tube, it will be turned blue by the escaping ammonia gas.

We are not authorized to infer the pre-existence of ammonium, however, from the appearance of this reaction, for the presence of nitrogenous organic matter in the substance, which would be decomposed by this treatment, would give rise to such a reaction.

18. Potassium.—Potassium is recognized by the color which its salts impart to the Bunsen flame. If a portion of a salt of potassium be held on a platinum wire in the flame, it imparts a blue-violet tint which rapidly disappears.