The quantity of water required for the effective treatment of gold bearing rock in a stamper battery varies according to the composition of the material to be operated upon, but generally it is more than the inexperienced believe. For instance, “mullocky” lode stuff, containing much clayey matter or material carrying a large percentage of heavy metal, such as titanic iron or metallic sulphides, will need a larger quantity of water per stamp than clean quartz. A fair average quantity would be 750 to 1000 gallons per hour for each box of five stamps. In general practice I have seldom found 1000 gallons per hour more than sufficient. As to the most effective mesh for the screen or grating, that depends largely on the size of the gold particles contained in the gangue. The finer the particles the closer must be the mesh, so that nothing but careful experiment will enable the battery manager to decide this most important point. The American slotted screens are best; they wear better than the punched gratings and can be used of finer gauge. Woven steel wire gauze is employed with good effect in some mills where specially fine trituration is required. This class of screen requires special care as it is somewhat fragile, but with intelligent treatment does good work. The fall or inclination of the tables, both copper and blanket strakes, is also regulated by the class of ore. If it should be heavy then the fall must be steeper. A fair average drop is 3/4 inch to the foot. Be careful that your copper tables are thoroughly water-tight, for, remember, where water will percolate, mercury will penetrate. The blanket tables are simply a continuation of the mercury tables, but covered with strips of coarse blanket, green baize, or other flocculent material, intended to arrest the heavier metallic particles which have not been amalgamated. The blanket table is, however, a very unsatisfactory concentrator at best, and is giving place to mechanical concentrators of various descriptions. I have a device at present unpatented which will do away with the necessity for blanket tables or copper plates, as by the expenditure of from 1/2 to 1 h.-p. every particle of free gold after leaving the boxes must come within the embrace of a mercury amalgam. No cleaning of plates is required.