Twentieth century handbook for steam engineers and electricians, with questions and answers; a practical nontechnical treatise on the care and management of steam engines, boilers and electric machinery (1922)
Swingle, Calvin Franklin, 1846- [from old catalog] · Chicago, F. J. Drake & company · leaf 1474
^ is bestfor battery work. … Fig. 686using up old zincs The first signs of exhaustion in the cell will be a fadingof the deep blue color of the copper solution and a loweringof the line of separation between blue and white liquids. When this occurs drop in about an ounce of copper sul-phate in lumps. Be sure the lumps fall to…
