Practical Metallurgy; An Introductory Course for General Students (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. 1908 Excerpt: ...noted. For this and other reasons, sodium sulphite is frequently used as a reducing agent, care being taken to expel all the SO2 by boiling, before titration. As all commercial zinc contains at least a trace of iron, it is well to dissolve 3 to 5 grams of the zinc to be used in HC1, and estimate the iron in the solution. In all subsequent determinations the zinc used should be roughly weighed, and a correction introduced for any iron that is present. Estimation of Phosphorus.--The greater part of the phosphorus present in iron ores is in the oxidised condition (as lOs), and is generally combined with lime to form calcium phosphate. For the assay it is necessary that the whole of the phosphorus should be oxidised and dissolved in a moderate quantity of acid. In order to obtain good results, it is also necessary that the volume of the solution, temperature, excess of ammonium molybdate, and other conditions should be as nearly as possible constant. The Process.---Take 1 gram of the finely divided sample for ordinary ores, 2 to 5 grams with specially pure hematites or magnetites, or gram of tap cinder or basic slag. Place in a covered beaker, and for 1 gram add 5 c.c. of HNO3, then 15 c.c. of HC1; heat to boiling, and boil till all soluble matter is dissolved. Remove the cover, evaporate to complete dryness, and heat, when quite dry, for about half an hour on the hot plate. Take up with 10 c.c. of HC1, and boil witli the cover on. When dissolved, dilute with 2 to 3 parts of water, and filter hot through a dry filter-paper. The residue on the filter is washed, and if desired may be ignited and weighed to determine the insoluble matter. Dilute the solution, or concentrate it by evaporation if necessary, to about 100 c.c, heat to boiling, and add 50 c.c. of ammon...