268 TROPICAL AGRICULTURE 



the total oil content is recoverable by pressure. At this rate 

 100 pounds of nuts will yield 17.5 pounds of oil. These figures 

 were later verified in a commercial test on a rather large scale. 



The oil cake left as a residue from the press is a very valu- 

 able fertilizer. The material contains 53.75 per cent, protein, 

 2.77 per cent, potash, and 2.79 per cent, phosphoric acid. With- 

 out further treatment the press cake cannot be used as a 

 cattle feed for the reason that it exercises a poisonous effect. 



The kernel of the candlenut contains an active purgative 

 principle and is poisonous as human food. After roasting, 

 however, it is used by the Hawaiians as a delicacy in connection 

 with their native feasts. Even under such conditions, however, 

 it can be eaten only in small quantities. On account of the 

 fact that Chinawood oil and candlenut oil, as well as other 

 drying oils, are quite commonly mixed in order to get the best 

 properties for use in paints and varnishes, it has been thought 

 worth while to attempt a natural blend of the physical proper- 

 ties of Chinawood oil and candlenut oil through the production 

 of hybrids between these trees. In recent hybridization experi- 

 ments at the Hawaii Experiment Station, about 120 nuts were 

 obtained by cross-pollination between the Chinawood oil and 

 candlenut oil trees. These nuts will be planted in order to 

 determine whether the oil produced from the hybrid trees has 

 any advantage over either of the parent trees. 



Perilla oil, obtained from P. ocynwides, and native of East 

 Indies, China, and Japan, constitutes about 35 per cent, of the 

 seed of that plant. Seeds are sown in April and the plant 

 ripens another crop of seed in October. Perilla oil dries more 

 slowly than linseed oil. In Japan, the oil is commonly mixed 

 with cheap lacquer. Perilla oil has also been used in ex- 

 tracting Japan wax, and as an edible oil, particularly in Man- 

 churia. 



Stillingia oil is obtained from the seeds of a tree S. sebifera, 

 which occurs wild in Formosa and is quite largely cultivated in 

 China. The pulp surrounding the seeds yields Chinese vege- 



