THE SEED OP OWALA OR OPOCHALA. 157 



mon with the oil of ben (Moringa aptera), and is valuable for diminish- 

 ing friction in clockwork. 



The oil which I obtained was rather acrid, but this might have been 

 the result of the age of the seeds, and the damage inflicted upon them 

 by the voyage, it has rather a marked odour, which, however, is by 

 no means disagreeable ; it resembles very much that obtained from 

 various pulses. The flavour, too, which it possesses is an agreeable one ; 

 indeed, I have but little doubt but that this oil will some day be a use- 

 ful addition to those already in use for comestible purposes ; in fact, 

 the Boulons or Bushmen, a tribe in Senegal, employ it in the preparation 

 of their food. 



If an attempt be made to dissolve this oil in alcohol without heat, 

 the improbability of success soon becomes apparent, the spirit, however, 

 carries off a peculiar matter as well as_a part of its aroma. 



One of the most remarkable properties of this oil is the colour which 

 it developes under the influence of sulphuric acid. If the farina, or the 

 oil obtained from the kernel be dissolved in concentrated sulphuric acid, 

 the mixture takes first an olive, then a violet, and finally a bright crim- 

 son red colour, which will, however, sometimes disappear on the addi- 

 tion of a certain quantity of water. I was induced by the appearance of 

 this phenomenon of colour to seek for the producing cause, and endea- 

 voured to find in what part of the seed this property displayed itself in 

 its maximum of intensity. To accomplish this I commenced by dis- 

 solving part of the kernel in water. Upon this solution, the moisture 

 being all drained off, I poured a quantity of concentrated sulphuric acid, 

 and it became slightly brown, but no trace of the red colouring matter 

 appeared. From this experiment I concluded that the part of the kernel 

 wherein lay the power (when aided by sulphuric acid) of producing a 

 red colour was insoluble in water. The same operation was performed 

 upon another portion of the kernel dissolved by the aid of heat in 

 alcohol. This experiment produced a magnificent red colour, and proved 

 that the colouring matter is soluble in alcohol. When ether was sub- 

 stituted for alcohol, the colour produced was no longer red, but violet, 

 which became less intense upon the admixture of ether or alcohol, and 

 this caused me to infer that the application of ether changed in a 

 great degree the nature of the colouring matter, or that to develope the 

 red colour some matter insoluble in ether was necessary. If so, this 

 would be found in the etherised residuum. That the last supposition 

 was correct will be seen from the following experiment. Having ex- 

 hausted with ether a certain quantity of kernels, and dried the insoluble 

 residuum, I recovered it again with alcohol boiling. I subjected the 

 alcoholic extract to evaporation, and there remained a viscous mass very 

 similar in appearance to molasses, which became brown when I added a 

 little sulphuric acid. I mingled a little sugar syrup with the oil ob- 

 tained by ether (which, as I have said, took only a light violet tinge), 

 and poured on the mixture some concentrated sulphuric acid. The mass 



