Mr Davidson on the Decolorization of Palm Oil. '2h1 



liquefy 112 lb. of palm oil, and, when the whole is melted, re- 

 move the fuel from the furnace, and pour in the solution of 

 chloride of lime, and stir it carefully with a piece of wood, so 

 that the whole may be intimately combined. Allow it to cool 

 and harden ; then break it into as small fragments as possible, 

 and expose it to the air and- light for two or three weeks. After 

 it has been thus exposed, put it into the vessel which shall be 

 presently described ; add the same weight of sulphuric acid 

 (previously diluted with about 20 parts of water), as of chlo- 

 ride of lime used, and boil with a moderate heat, until the oil 

 drops cleai" from the wooden stirrer. When the boiling first 

 commences, the liquid is liable to froth up, which must be mo- 

 derated by constant stirring, and by the occasional addition of 

 cold water. After the boiling has been continued for a silfii- 

 cient length of time (which varies in proportion to the quantity 

 operated upon), it may be allowed to cool, when the palm oil 

 will remain on the top, and the acid liquor, with the insoluble 

 sulphate of lime, at the bottom. In this process, more acid 

 is directed than what is necessai'y to decompose completely 

 the chloride of lime ; but an excess of acid facilitates the clear- 

 ing of the oi!, and it ought always to be preserved for a future 

 operation ; for, by adopting this plan, no loss will be sus- 

 tained. 



The vessel best adapted for the process is a cast-iron boiler 

 lined with lead, placed over a common furnace ; for this metal 

 is less liable to be acted on by the chlorine which is given off, 

 and by the acid, than iron or copper. For the same reason, mor- 

 tars made of these two latter metals should not be employed 

 for the trituration of the chloride of lime with the water. 



There is a considerable advantage gained by allowing the 

 palm oil to remain in union with the chloride of lime for some 

 time, before boiling them with the sulphuric acid ; for even a 

 week makes a considerable change in the increase of decolori- 

 zation. This may be easily explained. The chlorine of the 

 chloride of lime gradually acts, in the one case, upon the oil, 

 so as to deprive it of colour, and is at last wholly expended 

 upon it ; but, if boiling be immediately employed after the two 

 have been united,a considerable (|uaniityof thechiorine cii-capes 



