Apparatus, Reagents.—Apparatus as before. For the standard solution, pure HgCl2 is required. For analysis the student may take further portions of the materials used in the last estimation.
Method, Reactions.—If to an ammoniaeal solution of KCN a solution of HgCl2, be slowly added, Hg(CN)2, is formed and is soluble in water. When
Apparatus, Reagents, etc.—The same as in the last analysis, except that the chromate is not required. For analysis the student may take a solution prepared by the demonstrator, or a sample of ‘ gold ’ cyanide (KCN), which, if the potassium salt, will contain from 95% to 98% KCN. This salt now frequently contains NaCN, so that
Apparatus, Reagents.—The usual apparatus. For the standard solution, ammonium molybdate is required [(NH4)2MoO4], or by a simple calculation the heptamolybdate (NH4)6Mo7O24,4H2O which is non-deliquescent, or the trioxide MoO3 dissolved in NH4HO may be used. For an indicator a solution of 1 gm. tannin in 500 c.cs. water is used.
Apparatus, Reagents.—The usual apparatus. For the preparation of the standard solution pure K4FeC6N6 (free from K6Fe2C12N12) is used, and pure ZnO is employed for checking the standard. As an indicator a solution of uranium acetate is employed. In the preparation of the ore for analysis the following solutions are required
VOLUMETRIC ESTIMATION OF MANGANESE BY POTASSIUM PERMANGANATE. (Volhard’s Method)
Aparatus. Reagents.—The usual apparatus. For the standard solution K2Mn2O8 is required. Zinc oxide free from Mn is used for neutralisation. For analysis the student may take a ferro-manganese ore (containing Fe and Mn).
Method, Reactions.—If a dilute,
VOLUMETRIC ESTIMATION OF ARSENIC (Pearce’s Method)
Apparatus, Reagents —The usual apparatus. For precipitation E. AgNO3 may be used. For the standard solution NH4CNS is used, and as an indicator a saturated solution of iron alum. For the solution of the silver arseniate, pure HNO3 is required.
Method, Reactions.—The ore
THE ESTIMATION OF IRON BY STANDARD SOLUTION OF POTASSIUM PERMANGANATE (Marguerite’s Method).
Apparatus, Reagents.—The usual volumetric apparatus, For standardising the solution soft iron wire such as is used for binding flowers is best suited. This wire contains 99.6% of iron. Pure K2Mn2O8 is required for the standard solution.
THE ESTIMATION OF IRON BY STANDARD POTASSIUM BICHROMATE SOLUTION (Penny’s Method).
Apparatus, Reagents.—For the preparation of the standard solution pure K2Cr2O7 is required, also the iron wire as before, E. SnCl2, 2/5 E. HCl and E. K6Fe2C12N12, freshly prepared and containing no ferrocyanide. A white porcelain plate is
THE DETERMINATION OF CHLORINE IN BLEACHING POWDER BY IODINE AND STANDARD HYPOSULPHITE.
Apparatus, Reagents, etc.—As before. The student may take for analysis a sample of ordinary commercial bleaching powder.
Method Reactions.—If, to the milky liquid obtained by treating the powder with water, excess of KI be added, and then HC2H3O2