_Soft White Lead._—The hard white lead prepared as just described consists of very heavy and very hard lumps of the purest white. When soft white lead is required, the admixed lead acetate must be removed by washing. This is accomplished by adding a larger quantity of water, either when grinding under the edge-runners or in the mills, so that a thin pulp is formed; this is run into a receiver, in which is a stirrer. The white lead is not completely prevented from sinking by the stirrer; a soft mud is deposited at the bottom of the vessel, which can only be stirred up with difficulty on account of its high density. When this vessel is full, the stirrer is stopped and the milky liquid allowed to settle, which happens in a short time on account of the high specific gravity of white lead. The clear liquid above the white lead is drawn off into a tank lined with cement. It is advisable to arrange the stirrer so that it may be placed at any height in the vessel; if this is the case, by gradually lowering the stirrer whilst in motion, the white lead lying at the bottom can be mixed up with fresh water. These operations are repeated until all the lead acetate is removed. Soda solution is added to the wash waters in order to recover the lead dissolved in them as lead acetate; lead carbonate is precipitated and settles at the bottom of the tank. This precipitation may also be effected by putting lumps of limestone in the tank. The paste remaining in the washing tubs, which now contains only pure white lead and water, is filled into bags of closely woven material and the water pressed out by a gradually increasing pressure, until a stiff pulp remains behind. This is then completely dried, either in the air or in drying stoves. Soft white lead forms either irregular lumps or a soft, heavy powder. The lower qualities of white lead contain a smaller or larger quantity of finely ground barytes; the higher the proportion of barytes the smaller is the covering power of the mixture. A very simple method for detecting barytes in white lead will be given later. (b) GERMAN PROCESS.