66 A NATURALIST IN WESTERN CHINA 



fruit, after which the seeds are easily removed. The process 

 of extracting the oil is very simple. The seeds are first crushed 

 in a circular trough beneath a heavy stone wheel revolved by 

 horse or ox-power. The comminuted mass is then partially 

 roasted in shallow pans, after which it is placed in wooden 

 vats, fitted with wicker bottoms, and thoroughly steamed 

 over boiling water. Next, with the aid of an iron ring and 

 straw, it is made into circular cakes about i8 inches in diameter. 

 These cakes are arranged edgeways in a large press and, when 

 full, pressure is exerted by driving in one wedge after another, 

 thereby crushing out the brown, somewhat watery and heavy- 

 smelling oil, which falls into a vat below. This " T'ung oil " is 

 packed in tubs and bamboo baskets, and is ready for export. 

 The yield is about 40 per cent, by weight of the kernels. The 

 refuse cakes are used on the fields as fertilizers. 



" T'ung-yu " is the chief paint oil throughout the Chinese 

 Empire, being used for all outside woodwork ; as a " drier " 

 it excels linseed oil. The Chinese do not paint their boats, 

 they oil them, and the myriads of such craft which ply on the 

 Yangtsze and other rivers of China are all coated and the 

 upper works kept waterproof with this oil. The crude oil 

 boiled for an hour becomes a S5n:upy oil or " P'ei-yu," which 

 is used as a varnish for boats and furniture. Boiled for two 

 hours with the addition of certain mineral substances (" T'u- 

 tzu " and " T'o-shen "), a varnish called " Kuang-yu " is 

 produced which, when applied to silk gauze and pongees, 

 renders them waterproof. " T'ung-yu " is also used as an 

 illuminant and as an ingredient in concrete ; mixed with lime 

 and bamboo shavings it is used for caulking boats. Besides 

 these, and dozens of other legitimate uses, " wood oil " is 

 also employed as an adulterant in lacquer- varnish. Lamp- 

 black produced by burning this oil or the fruit-husks is a 

 most important ingredient in the manufacture of Chinese 

 ink. The trade in " T'ung oil " is very large. From Hankow 

 in 1900 the quantity exported was 330,238 piculs, valued at 

 Tls. 2,559,344. In 1910 the trade had risen to 756,958 piculs, 

 valued at Tls. 6,449,421. 



I have given rather full details of this subject on account 

 of its great importance, and because its value is only beginning 



