In 1854 the government introduced the culture of cinchona with free labour, and it had considerable success under F. Junghuhn and his successors, though the varieties grown were of inferior quality. Later seed of the best cinchona was obtained, and under skilful management Java has become the chief producer of quinine in the world. Cacao is produced in the Preanger regencies, Pekalongan, Semarang, Pasuruan, Besuki, Kediri and Surakarta. In 1903, a record year, 1,101,835 piculs (about 6540 tons) were produced. _Broussonetia papyrifera_ is grown for the sake of its bark, so well known in Japan (Jap. _kodsu_) as a paper material. The ground-nut (the widely spread _Arachis hypogaea_ from South America), locally known as kachang china or tanah, is somewhat extensively grown. The oil is exported to Holland, where it is sold as Delft salad oil. Tapioca has long been cultivated, especially in the Preanger. The industry is mainly in the hands of the Chinese, and the principal foreign purchasers are English biscuit manufacturers. The kapok is a tree from tropical America which, growing freely in any soil, is extensively used throughout Java along the highways as a support for telegraph and telephone wires, and planted as a prop in pepper and cubeb plantations. The silky fibre contained in its long capsuloid fruits is known as cotton wool; and among other uses it serves almost as well as cork for filling life-belts; and the oil from its seed is employed to adulterate ground-nut oil. The quantity of wool exported nearly trebled between 1890 and 1896, in the latter year the total sent to Holland, Australia, Singapore, &c., amounting to 38,586 bales. The rapid exhaustion of the natural supply of india-rubber and gutta-percha began to attract the attention of government in the latter decades of the 19th century. Extensive experiments have been made in the cultivation of _Ficus elastica_ (the karet of the natives), _Castilloa elastica_, and _Hevea brasiliensis_. The planting of gutta-percha trees was begun about 1886, and a regular system introduced in the Preanger in 1901. The _Palaquium oblongifolium_ plantations at Blavan, Kemutuk and Sewang in Banyumas have also been brought under official control. Java tobacco, amounting to about 35,200,000 lb. a year, is cultivated almost exclusively in eastern Java. Among other products which are of some importance as articles of export may be mentioned nutmegs, mace, pepper, hides, arrack and copra.