Dry and Wet Reagents

Dry Reagents
The following paragraphs give a brief description of the more important dry reagents used in testing minerals:

Sodium Carbonate, Na₂CO₃, is a white salt that is used chiefly as a flux to decompose minerals by fusion on charcoal and more rarely as a flux in a bead test.

Borax, Na₂B₄O₇. 10H₂O, is a white salt that is used chiefly in making bead test and more rarely as a flux on charcoal.

Acid Potassium Sulphate, HKSO4, is a white salt that is used in making a test for fluorine (see p age 109).

Acid Potassium Sulphate and Fluorite Mixture is a mixture of three part of the former and one part of the latter. It is used in making a test for boron (see page 107).

Potassium Iodide and Sulfur Mixture. A mixture of equal parts of these two materials is used in making a test for bismuth.

Tin and Zinc are used in granulated form to make certain reduction tests in hydrochloric acid solutions.

Test Papers. Blue litmus paper is a test paper which changes in color from blue to red when exposed to the action o f an acid. It is most commonly used in the open tube test for sulfur. Yellow turmeric paper is a test paper that turns brown when exposed to the action of an alkali. It is most commonly used in making a test for the presence of an alkali. It is most commonly used in making a test for the presence of an alkali or alkaline earth in a mineral.. Red litmus paper can be substituted for the yellow turmeric. It turns blue when exposed to the action of an alkali.

Wet Reagents
The following paragraphs give a brief description o f the more important wet reagents used in testing minerals:

Hydrochloric Acid, Muriatic Acid, HCI, is an acid which is commonly used for the solution of minerals, etc. it is a non-oxidizing acid. The ordinary laboratory acid is diluted with three parts of water.

Nitric Acid, HNO₃, is a strong solvent and oxidizing agent. It is commonly used in its concentrated form.

Sulfuric Acid, H₂SO₄, is less commonly used than the others as a solvent. It may be used in its concentrated form, but usually is diluted with four parts of water. When water is added to the acid a large amount of heat is generated. Water should never be added to the hot acid. The acid boils at 337º C.

Ammonium Hydroxide. NH₄OH, is a strong alkali used chiefly to neutralize acid solutions and as a precipitant for aluminum and ferric hydroxides. For laboratory use it is commonly diluted with three parts of water.

Ammonium Carbonate, (NH₄)₂CO₃, and Ammonium Oxalate, (NH₄)₂C₂O₄, are chiefly used in the form of aqueous solutions to precipitate the alkaline earths, calcium, strontium and barium, from their solutions.

Hydrogen Sodium Phosphate, HNa₂PO₄, is used in the from of an aqueous solution to test for the presence of magnesium; Barium Hydroxide, Ba (OH)₂, in testing for carbon dioxide (see page 108); Barium Chloride, BaCI₂, for sulfuric acid; Ammonium Molybdate, (NH₄)₂M0O₄, for phosphoric acid; Silver Nitrate, AgNO₃, for chlorine.

Postassium Ferrocyanide, K4Fe(CN)6.3H2O, and Potassium Ferricyanide, K₆Fe₂ (CN)₁₂, are used in dilute solutions to test for ferric and ferrous iron respectively (see page 111). Ammonium Sulphocyanate, NH4CNS, is also used to test for ferric iron. Cobalt Nitrate, Co (NO₃)₂, is used in the form of a dilute solution in blowpipe tests for aluminum and zinc.