Methods of Chemical Analysis and Foundry Chemistry Volume 32 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 edition. Excerpt: ... ANALYSIS. Moisture. Until recently the sale of ore was based upon its analysis, when dried at 212F. Of late a careful estimation of moisture is required because the sale is now based, especially in wet ores, upon the percentage of iron in the natural state, figured from the analysis of the ore dried at 2120 F. and the percentage of moisture. Not less important is the moisture determination as an index of furnace yields and fuel consumption. A convenient method for making the determination is to weigh the ore into a counter poised pan, distribute evenly over the bottom of the pan, dry from 2 to 6 hours at 212 F., when cold, replace pan and counterpoise, and the weight necessary to add to the pan to make up the loss of moisture when divided by the weight taken will be the percentage of moisture in the sample. Iron. Since the percentage of this element regulates the selling price of ore more largely than any element save phosphorus, a correct estimation of it is indispensable. There are only two methods for the determination of iron which have won universal favor among chemists. One depends upon the titration of ferrous iron with a standard solution of potassium bichromate, the end reaction being ascertained by aid of a solution of potassium ferri-cyanide, used as an indicator. The other method, and the one which I prefer after cautious comparison with the foregoing, depends upon the titration of ferrous iron with a standard solution of potassium permanganate, which of itself acts as an indicator. In standardizing either of these solutions it has become the usual practice to do so by aid of standard ores assigned, a definite percentage of iron, which is the average of closely concordant results. Since the determination of iron involves the...