Before making up a bottle charge on an unknown ore it is necessary to ascertain the probable alkali consumption. For this purpose weigh up 4 lots of pulp of about 200 grams each, and add water at a ratio of 3 : 1 , numbering the bottles 1, 2, 3, and 4. Then add slaked lime powder at the rate of 5 Ib. per ton of ore to No. 1, 10 Ib. to No. 2, 15 Ib. to No 3, and 20 Ib. to No 4, and agitate for from 6 to 12 hours. At the end of the period filter off some of the liquor from each and test for alkalinity.