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298 William James and Other Essays on the Philosophy of Life (1911); Brass Lectures on the Sources of Religious Insight (1912) ; The Problem of Christianity (2 vols., 1913, lectures before Manchester College, Oxford); War and Insurance (1914); The Hope of the Great Community (1916, war addresses) and the posthumously published Lectures on Modern Idealism (1919).

ROYDEN, AGNES MAUDE (1876- ), English social worker and preacher, was born at Mossley Hill, Liverpool, Nov. 23 1876, the daughter of Sir Thomas Royden, ist Bart., of Frankby Hall, Birkenhead. She was educated at Cheltenham Ladies' College and Lady Margaret Hall, Oxford, and afterwards for some years did settlement work in Liverpool. She also lectured on English literature for the university extension movement, and in 1909 was elected to the executive committee of the N.U.W.S.S. From 1912 to 1914 she edited the Common Cause, the organ of the union. Miss Royden became well known as a speaker on social and religious subjects, and in 1917 became assistant preacher at the City Temple, being thus the first woman to occupy this office.

 RUBBER (we 23.795*). Since 1910 the rubber industry has developed very largely and taken increased importance in the commercial world. The word rubber is applied to three different substances: (a) an elastic solid, the chief constituent of the coagulated latex or milk of a great variety of trees, shrubs, vines and plants, as Para rubber; (b) an elastic solid found in solution in the tissues of a few shrubs and vines, as Guayule rubber; (c) a chemical product from isoprene or homologous hydro- carbons, as synthetic rubber. In all commercial rubber caout- chouc exists in two forms, one fibrous or hard, the other viscous and soft. In the best trades the fibrous form preponderates. The soft form can be dissolved by benzol and many other substances of that class; the fibrous form swells but does not dissolve. Vulcanization (the chemical union of caoutchouc and sulphur) hardens the viscous portion. As the result of this process the rubber becomes less sensitive to heat and cold and to the effect of acids and alkalies and becomes more durable. A small amount of sulphur in rubber produces soft rubber. By using more sulphur and greater heat a very hard black substance called hard rubber is obtained. Moulding India rubber consists of softening by heat the stiff rubber dough until it is plastic, pressing it into a mould and vulcanizing it at a heat much less than that required to melt it; not in melting, pouring and casting according to popular misconception. Rubber once melted remains a sticky, worthless semi-fluid.

Wild Rubber. At first there were but three types of rubber to be found in the world's markets: India rubber, the product of the Ficus elastica from Assam, Burma and Java; gum elastic,

the product of the Hevea brasiliensis from S. America, and " virgin gum " from the Castilloa elastica of Central America. In 1921 all grades from whatever source were termed India rubber, and there were some 200 sorts. They were divided generally as follows: (i) S. American rubber, from the Hevea brasiliensis and kindred species which comprised Para rubber in 3 general grades and 20 sub-grades; Caera rubber (Manicoba) from the Manihot glaziovii and kindred species, 6 grades; Mangabeira from the Hancornia speciosa, 2 grades; and Caucho rubber from the Castilloa ulei, 3 grades. (2) Central American rubber, known as "centrals," the product of Castilloa elastica and kin- dred species, some 25 grades; virgin rubber, the product of the Sapium tolimense and kindred species, 3 grades; Guayule rubber, from the Parthenium argentatum, 12 grades. (3) African rubber, a lower grade of wild rubber, produced by a great variety of vines of the Landolphia genus and to a degree from trees, as the Ficus wgelii and the Funtumia elastica. The number of grades was 120. (4) E. Indian rubber, the product chiefly of the Ficus elastica from Rangoon, Penang and Java, 9 grades; together with Borneo rubber from the Willoughbia firma, 3 grades; Pontianak (Jelutong), from the Dyer a coslulata, 4 grades. (5) Plantation rubber. From 1860 attempts to cultivate rubber- bearing trees and vines have been undertaken in various parts of the tropical world. The most persistent and finally the most successful were carried on in the British experiment stations and Royal botanic gardens, especially in Ceylon and the Straits Settlements. A measure of success was attained in cultivating the Manihot glaziovii, the Castilloa elastica, the Ficus elastica and the Funtumia elastica. All of them proved to be good rubber- producers but could be tapped only at intervals of several months. The product found ready sale, and considerable plantations of Manihot in Ceylon, and Ficus and Castilloa in the Federated Malay States were installed. American interests also planted thousands of acres of Castilloa in Mexico, Nicaragua and Guate- mala. Experiments with another tree, however, the Hevea brasiliensis, developed the fact that through what was termed " wound response " it could be tapped daily without injury. This process in brief was the opening of the tapping cut by the removal daily of a thin shaving of the bark. The amount from each tapping was small, but the year's product far exceeded that of the planted trees of any other sort. The result was that most of the others were abandoned or destroyed and the Hevea brasiliensis put in wherever it could possibly thrive. Thus the Hevea plantation product, which in 1900 was four tons, increased to 8,400 tons in 1910, and from then on the increase was very large, as shown in the table below.

Herea Plantation Acreage and Production.

Plantation Acreage

Plantation Production (tons)

Total Wild Rubber Production (tons)

Total World's Production (tons)

1910

1,122,550

8,200

62,300

70,500

1911

1-505,350

H4I9

60,730

75.149

1912

1,817-350

28,518

70,410

98,928

1913

2,021,750

47,618

60,822

108,440

1914

2,181,050

71,000

49,000

120,380

1915

2.293.750

107,867

50,835

158,702

1916

2,458,950

152,650

48,948

201,598

1917

2,611,350

213,070

52,628

265,698

1918

2,759,950

255,950

40,629

296,579

1919

2,900,000

285,225

41,775

327,000

1920'

3,200,000

320,000

40,000

360,000

1 Estimated.

Distribution of the World's Rubber Production (Gross Tons).

Country

IQI2

1913

1914

1915

1916

1917

1918

1919

1920

. United States Great Britain ..... France Italy

45,928 14.500 IO.OOO I.OOO

9 ooo

46,400 18,640 6,500 2,000 9 ooo

61,240 18,000 5,000 4,000 1 1 610

96,792

15,072 10,770 6,500

IO OOO

116,495

26,760 14,000 9,000

7 <\OO

177,088

25,983 17,000 9,000

7 ^OO

142,772 30,104 18,000 9,800

2 OOO

236,977 42,520 22,000 14,000 i 500

235,000

56.572 14,500 7,000
 * oo

i 500

i 600

i 700

6 281

8 100

9 coo

1 1,000

Scandinavia Japan and Australia .... ! Germany and Austria .... Belgium

1,000

16,000

1,500 1,300 18,500 3,000

2,400 2,400 13,400 630

6,568

2,500 6,000

4,525 4,500

3,000

5,323 4,500

3,000

5,ooo 7,400 1,000

7,000 12,000 4,000 5,000

7,700

6,000

9,300 3,500

Total

98,928

108,440

120,380

158,702

189,780

255.675

224,376

354,497

350,872


 * These figures indicate the volume and page number of the previous article.