(3) The White Lead Method.--In this case the white lead must be in the finest state of subdivision possible, and suspended in the water: White lead, 100 kilos.; nitric acid (36° B.), 12; bichromate, 13; and aluminium sulphate, 10: or nitric acid (40° B.), 44; bichromate, 24; sulphate, 20, the latter giving the more fiery shade. For the production of an orange: white lead, 100 kilos.; nitric acid (36° B.) 18; bichromate, 28; and caustic soda, 8, the latter being best added to the bichromate before precipitation, and the temperature kept between 150° and 165° F. (4) The Basic Chloride Method.--The same proportions and temperature are suitable here as in the case of the white lead. (5) The Sulphate Method.--Lead sulphate, 100 kilos.; bichromate, 24 to 25; Solvay’s soda, 8·75 to 16; ammonia (24 per cent.), 1 to 2; and acetic acid (30 per cent.), 5 to 10. The sulphate, in the form of a cream, is gradually added to the other ingredients after solution. A new and improved process for manufacturing from galena chemically pure chrome yellow having great colouring power, according to the _Paper Trade Journal_, consists in first dissolving pulverised galena with nitric acid to produce liquid nitrate of lead, and then precipitating the chromate of lead by subjecting the nitrate of lead to the action of bichromate of potash, neutral chromate of potash or chromate of potash-soda. The galena (sulphide of lead) is first pulverised by suitable means, and in case it contains foreign minerals or other impurities, it is washed or otherwise treated in a suitable manner to remove these substances. The pulverised galena is then placed in acid-proof vessels and is dissolved by adding nitric acid diluted with water, the entire mass being well stirred. A slow dissolving takes place at the ordinary temperature; but when the mass is heated artificially, either by heating the vessel, or by using hot water added to the nitric acid, or by the use of steam, more rapid solution is effected. The product obtained is nitrate of lead in a liquid state. The quantity of nitric acid necessary for dissolving a certain quantity of galena depends on the percentage of lead contained in the ore, and to a certain extent on the amount and nature of impurities present in it, and also on the length of time in which the dissolving takes place. In treating 100 lb. of galena having 80 per cent. of metallic lead, about 90 to 100 lb. of nitric acid of 36° to 38° B. are used, and the nitric acid is diluted with 100 to 200 lb. of water. This mixture is left for about 24 to 36 hours, and is stirred up occasionally, as above stated.