140 PLANT PRODUCTS 



For the preparation of oil the primitive system consisted in 

 removing the husk, cutting up the kernel into small pieces, 

 exposing in piles to the heat of the sun, so that the oil ran 

 off and was collected. Another method was that of pulping 

 the kernels and placing them in a kind of sieve exposed to 

 the sun, when the oil ran off and was collected. Sometimes 

 artificial heat was used. In India the dried kernels were 

 ground in the primitive oil press, or were thrown into 

 boiling water and the oil skimmed off. The residues were often 

 used locally for cattle food. The dried husk, known as 

 copra, is liable to ferment, due to the presence of water, and 

 many of the difficulties of manufacture and the prejudice 

 against the materials resulted from this cause. Modern 

 systems eliminate much of this difficulty, by first removing 

 the fibrous matter (coir) and then striking the nut on a 

 sharp spike. The husk is removed by hand and the nut split, 

 drained and put in the sun to dry. Sun-dried copra gives 

 better quality oil than that which has been dried in kilns, 

 but improvements in the kiln system of drying are likely 

 to remove this difficulty. The coconut shells are used for 

 firing the kilns (see p. 131). In the modern system of 

 pressure, two pressings are carried out, the temperatures 

 adopted being higher than those used for linseed as described 

 above. About 65 per cent, of oil can be obtained from the 

 best qualities of copra. Owing to the fermentive changes 

 alluded to above it is not infrequent for considerable quantities 

 of free fatty acid to be present in the oil, but the great care 

 taken in modern manufacture tends to reduce this degree 

 of acidity. Owing to its high melting point, coconut 

 oil is not infrequently met with in the solid or semi-solid 

 condition. Although coconut oil requires a high strength 

 of alkali and high temperature for saponification, yet 

 with alkali of the right strength soap is formed at ordinary 

 temperatures. Soap made from coconut oil is soluble in 

 weak salt solutions and is used for washing in sea-water. 

 Although this confers an advantage in certain uses of the 

 soap, it compels the manufacturer to employ more salt 

 to throw soap out of solution in the boiling vat. 



