122 PHILIPPINE RESINS, GUMS, AND OILS 



being placed in wooden vats fitted with wicker bottoms. The nuts are 

 next placed in steel frames with straw as an outside container. The 

 frames are arranged on edge in a press and pressure is applied. This is 

 usually accomplished by means of a system of wedges which are driven in 

 one after another by means of a huge battering-ram until the brown, 

 watery, and odoriferous oil is crushed out into the vat below. As a rule 

 the oil is then slightly heated and strained through a coarse grass cloth. 

 (If the heating process is carried too far the oil becomes dark brown 

 instead of retaining its desired light-yellow color.) The product is then 

 placed in wicker baskets lined with varnished paper and is ready for ship- 

 ment. As a rule the oil yield is about 40 per cent of the original weight 

 of the kernels. The refuse matter, which is in the form of cakes, is used 

 as a fertilizer. 



In the vicinity of Hankow the native dealers allow the oil to again 

 precipitate, drawing off the clear liquid and selling it to the foreign export- 

 ing firms. The residue is then sold to small dealers in Wuchang and 

 Hanyang, who once more skim the oil after a further precipitation process. 

 The oil is then sold to the native boatmen for use on their craft. 



About the only variation in the above method of oil extraction is that 

 in cold weather, when the oil congeals to a grease stage, it is necessary 

 to heat the mass slightly in order to allow precipitation to take place. 

 This is usually accomplished by steam coils being placed within the con- 

 taining tank. Under this treatment the product soon liquifies, the foreign 

 matter drops to the bottom, and the clear liquid is drained off through 

 stopcocks placed just high enough to avoid the thick, muddy sediment at 

 the bottom. 



VARIED USES OF THE OIL 



T'ung-yu is widely used throughout China as a paint oil for outside 

 purposes. It is held that as a drying oil it excels even linseed oil. One 

 of its greatest local markets is found among the native boatmen, who never 

 paint their boats but coat them with the cruder grades of wood oil, which 

 not only give the woodwork a bright, lustrous finish but also act as an 

 excellent preservative. When certain mineral substances known as t'utzu 

 and t'o-shen are added to the wood oil and the resulting mass heated for 

 about two hours a varnish called kuang-yu is produced which is valuable 

 as a water-proofing substance when placed on silks, pongees, and the like. 



T'ung-yu is also used as an adulterant in the manufacture of lacquer 

 varnish, as an illuminant, and as an ingredient in concrete, and when mixed 

 with lime and bamboo shavings it is used by the natives in calking their 

 boats. The so-called Chinese or Indian ink is made from the soot resulting 

 from the burning of the oil or the fruit husks. The product is also used 

 as a dressing for leather, in the manufacture of soap, and as a varnish 

 for fine furniture. It is chiefly used in foreign countries for the manu- 

 facture of varnish from cheap gums. Other oils require a higher and 

 more expensive quality of gum in order that the resulting varnish be of 

 equal grade. This feature, together with the rapidity with which wood- 

 oil varnish dries, has caused the demand for the product to steadily increase. 



According to Ennis: * 



China wood oil is rapidly becoming conspicuous as a linseed oil sub- 

 stitute in the varnish trade. * * * The consumption of the oil in the 



* Ennis, W. D. Linseed oil and other oils (1909), page 235. 



