A Treatise on Chemistry and Chemical Analysis Volume 5; Quantitative Analysis (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 Excerpt: ...of nitric acid of 1.2 Sp. Gr., and boil until the solution becomes almost syrupy; then add 100 cubic centimeters of nitric acid of 1.42 Sp. Gr., boil for a few moments, and add from 5 to 10 grams of potassium chlorate to the boiling solution, a little at a time, to precipitate the manganese as dioxide. When precipitation is complete, the greenish-yellow gas above the liquid gives a puff and disappears. Now add 1 gram more of potassium chlorate, boil 1 or 2 minutes, and cool rapidly by standing the beaker in cold water. When the solution has become cold and the precipitate has settled, filter through asbestos, and from this point proceed as directed in Art. 25. 47. Volhard's Method.--Dissolve 1.5 grams of the drillings in a porcelain dish in 25 cubic centimeters of nitric acid of 1.2 Sp. Gr., and when the violent action ceases, add 12 cubic centimeters of half-strength sulphuric acid; evaporate to dryness, and ignite until dense white fumes of SO, are given off. Allow the residue to cool, add 100 cubic centimeters of water, and boil until solution is complete. When cool, wash the solution into a 300-cubic-centimeter graduated flask, nearly neutralize the acid with a concentrate solution of sodium carbonate, and add an emulsion of zinc oxide in water until the mixture assumes the color of coffee with cream. Dilute with water to exactly 300 cubic centimeters, mix thoroughly, and pour the solution through a large fluted filter placed in a dry funnel, receiving the filtrate in a clean dry beaker. By means of a pipette, transfer 200 cubic centimeters of this solution to a 500-cubic-centimeter flask, add 1 drop of concentrate nitric acid, heat to boiling, and titrate with potassium permanganate, bringing the solution just to boiling, and shaking it well after each...