24 BULLETIN 1475, U. S. DEPARTMENT OF AGRICULTURE 
(Aleurites montana). is much more widely distributed and grows in 
central and western China. A. montana is found in southeastern 
China from Fukien southward to Tonkin. In China A. fordii is 
known as the tung-oil tree, and A. montana as the wood-oil tree. The 
trade makes no distinction between the oils from these species, how- 
ever, and the oil exported is frequently a mixture of the two. As 
the two oils are practically identical in composition and properties, 
nothing would be gained by keeping each by itself. 
The use of tung oil is constantly increasing both here and in 
Europe. To meet the demand for the highest-grade oil in the United 
States large tracts of land in the vicinity of Gainesville, Fla., have 
been cleared and thousands of young trees {A. fordii) have been 
planted. Many of these trees were raised from seeds produced at the 
Florida experiment station. In 1905 the Department of Agriculture 
imported and distributed seeds from which small plantings were 
made in Florida. Georgia, and California. Some of these trees are 
still living. 
The fruits from which China-wood oil is obtained somewhat re- 
semble large hickory nuts (entire with husks). Each fruit contains 
three or more seeds. The oil content of the decorticated seeds ranges 
from 33 to 50 per cent. In China it is customary to gather this 
fruit just before it is fully mature. 
Preparation 
The fruits are either heated in large iron pans over a fire until the 
husks open, or they are collected in heaps and allowed to ferment 
cinder a covering of straw or grass until the seeds can be readily 
separated from the husks. 
At the small oil mills the shelled seeds are crushed in a circular 
trough with a heavy stone roller. The pulverized mass is then par- 
tially roasted in shallow pans, after which it is subjected to a steam- 
ing process in wooden vats fitted with wicker bottoms. The heated 
meal is mixed with straw and made into cakes, which are placed in 
a crude wooden press consisting *of a hollow log of strong wood. 
Pressure is exerted on the cakes by means of wooden wedges, usually 
driven in by a huge battering ram. The oil runs from the press into 
a vat below. Xext, the oil is heated slightly and filtered through 
coarse grass cloth to remove particles of meal and dirt. After being 
strained, it is placed in covered bamboo baskets lined with layers ji 
paper waterproofed with tung oil and transported to warehouses at 
the seaports. Here it is crudely separated into different grades, the 
highest being the lightest in color, and tested for purity. When 
prices are high tung oil is subject to adulteration with other oils, 
such as tea-seed, sesame, and peanut oils. 
In recent years modern expeller mills have been established in 
China. In America it has been found that by coarsely crushing 
the seeds and drying them so that the moisture content is reduced to 
7 or 8 per cent, it is possible to express the oil with expellers, thus 
producing a press cake which does not contain more than 5 per cent 
of oil. When sound nuts or seeds are expressed cold in the expeller. 
a very pale oil is obtained. Hot pressing yields a somewhat darker 
product. 
