Publisher's Synopsis
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. 1909 edition. Excerpt: ... in 20 grammes (0.7 oz.) of water and gradually add this solution, whilst constantly stirring with a glass rod, to 10o grammes (3.52 ozs.) of the silver bath in a beaker, as long as the precipitate of silver cyanide formed dissolves by itself. If, after adding the entire quantity of silver solution, the precipitate dissolves rapidly, too large an excess of potassium cyanide is present in the bath; and vice versa, if the precipitate does not completely dissolve, after stirring, potassium cyanide is wanting. The quantitative determination of the content of potassium cyanide and of silver will be described later on under " Examination of Silver Baths" Agitation of silver baths. In heavy silver-plating constant agitation of the strata of fluid is of decided advantage, grooves and blooms being otherwise readily formed upon the plated objects, especially when the baths are over-concentrated or thickened. The depressed grooves can only be explained by the fact that the strata of fluid on the cathodes having become specifically lighter by yielding metal are subject to a current towards the surface; the lower strata richer in silver give rise to heavier deposits on the lower cathode portions, so that agitation of the bath becomes an actual necessity. With a bath in constant agitation a greater current-density may be used, the deposits, notwithstanding the greater currentdensity forming with finer structure and in a correspondingly shorter time, which is especially noteworthy for heavy silvering. To keep the articles in gentle motion while in the bath, one method is to connect the suspending rods to a frame of iron having four wheels, about 3 inches in diameter, connected to it, which slowly travel to and fro to the extent of 3 or 4...
