The temperature of the oil is reduced by passing in air to 110deg. F. and 40 pounds of fine common salt per ton added through a sieve. About one-half of the acid (40 pounds of concentrated commercial hydrochloric acid) is now poured in and this is followed by the sodium bichromate in concentrated solution, previously prepared in a small lead vat or earthen vessel by dissolving 17 pounds of bichromate in 45 pounds commercial hydrochloric acid. This solution should be added slowly and should occupy three hours, the whole mass being thoroughly agitated with air during the addition and for one hour after the last of the bleaching mixture has been introduced. The whole mixture is now allowed to settle for one hour and the exhausted chrome liquors are then run off from the lower pipe to a waste tank. About 40 gallons of water are now run into the bleached oil and the temperature raised by open steam to 150deg. to 160deg. F. The mass is then allowed to settle over night. One such wash is sufficient to remove the spent chrome liquor completely, provided ample time is allowed for settling. A number of washings given successively with short periods of settling do not remove the chrome liquors effectually. The success of the operation depends entirely upon the completeness of settling. The wash water is drawn off as before and the clear oil run to storage tanks or to the soap kettle through the upper oil cock. The waste liquors are boiled with wet steam and the oil skimmed from the surface, after which the liquors are run out through an oil trap. By following the above instructions carefully it is possible to bleach one ton of palm oil with 17 pounds of bichromate of soda and 85 pounds hydrochloric acid. The spent liquors should be a bright green color. Should they be of a yellow or brownish shade insufficient acid has been allowed and more must be added to render the whole of the oxygen available. If low grade oils are being treated more chrome will be necessary, the amount being best judged by conducting the operation as usual and after the addition of the bichromate, removing a sample of the oil, washing the sample and noting the color of a rapidly cooled sample. A little practice will enable the operator to judge the correspondence between the color to be removed and the amount of bleaching mixture to be added. To obtain success with this process the method of working given must be adhered to even in the _smallest detail_. This applies to the temperature at which each operation is carried out particularly. AIR BLEACHING OF PALM OIL. The method of conducting this process is identical with the chrome process to the point where the hydrochloric acid is to be added to the oil. In this method no acid or chrome is necessary, as the active bleaching agent is the oxygen of the air.