256 ) 



On the Decolor izat ion of Palm Oil* By William Davidson, 

 M.D., Glasgow. Communicated by the Society of Arts 

 of Scotland. 



Palm Oil has long been used in small proportions in the 

 formation of yellow soap ; but, owing to the great quantity of 

 colouring matter which it contains, it never can be used as a 

 substitute for tallow even for yellow soap, unless it be deprived 

 either partially or completely of its colouring matter. Nitric 

 acid is employed by soap-makers for this pui'pose, and it has 

 the effect of giving the oil a pale yellow colour ; but, as soon 

 as the acid which has been united with it is neutralised by the 

 alkali, in the process of soap-making, its deep red colour re- 

 turns. This method, therefore, is productive of no benefit. 

 It becomes, then, a desideratum to decolorize palm oil in such 

 a manner, as that its colour will not, in the least degree, re- 

 turn, on the addition of an alkali ; for it has been completely 

 established, by the experiments of soap-makers on the large 

 scale, that palm oil forms with soda as good a soap as this al- 

 kali does with tallow. Chloride of lime possesses the property 

 of completely depriving palm oil of its colour ; but, unless the 

 lime be separated from it, its properties are destroyed. This, 

 however, may be readily accomplished by the following pro- 

 cess ; and, as the price of palm oil is frequently 10s. or more 

 per cent, lower than tallow, the economy of using the former 

 ^^'ill be apparent. 



[ Take fi'om 7 lb. to 14 lb. of chloride of lime, and about twelve 

 times the quantity of water. Triturate the chloride of lime in a 

 mortar, or in an apparatus of a similar kind, gradually adding 

 a portion of the water, so as at first to form a smooth and soft 

 paste, and then the remainder, which will give the whole the 

 consistence of cream. The object of this careful trituration is to 

 break down every particle of the powder, so that it may be af- 

 terwards capable of intimate combination with the oil. Then 

 _ — ' - ' -''-W 



* Eead before the Society of Arts for Scotland, 20th Juiio 1838, The 

 Honorary Silver Me<l.il awarded 18th December 1839. 



