A Manual of Electro-Metallurgy; Including the Applications of the Art to Manufacturing Processes (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. 1860 Excerpt: ...this. However, when a fine surface is wanted, care ought always to be taken to have clean solutions filtered, and kept covered from dust; and when the single cell is used, the crystals of sulphate of copper should be suspended in a fine linen bag, or the shelf holding them be lined with linen. Effects of Difference In the Density of Solution--Although in principle this is the best method, we believe that very few practise it, because of the trouble attending the arrangement of the electrodes in this position. "When the medals are small the annoyances from unequal density are not so material, but if the surface of the article which is being deposited be large--say eight inches or upwards--the difference in the thickness of the lower and upper portion of the medal is very great. When suspended perpendicularly, they should be shifted several times, making the upper portion the lower, besides occasionally stirring the solution, or shaking the article. Indeed when convenient, the article receiving the deposit should be kept as much in motion as possible, as it regulates the deposit, making it smoother and less brittle. Crystals of Copper on Electrodes.--It will be found, when working with a battery, that the sulphate of copper solution will become stronger round the positive electrode, which is gradually dissolved by the transferred acid. A frequent effect is, that the electrode often gets coated over with crystals of sulphate of copper, which adhere with great tenacity, and stop the electric action. Under such circumstances, it is only necessary to clean the electrode from the crystals and to add a little water to the solution, which will prevent a recurrence of the crystals for a time. But the stirring of the solution occasionally will do much to prevent ...