936. 
937- 
938. 
939. 
940. 
941. 
942. 
943- 
944. 
945. 
946. 
947. 
948. 
949. 
(42) 
Red Upper Congo rubber.—Made from an undetermined species, on the 
Upper Congo, Africa. 
French Congo ball rubber.—Another variety from the same region. 
Prime Lopori rubber—From an undetermined plant of the River Lopori, 
Congo Free State, Africa. 
Kamerun rubber.—Made from an undetermined species, at the German 
Colony of Kamerun, West Africa. 
Alima ball rubber.—From the Alima River, French Congo. 
Milk white rubber.—Rubber made from Forsteronia floribunda G. F.W. Meyer. 
Pink Madagascar rubber.—Made from a species of Landolphia. Native of 
Madagascar. 
Penang Rubber.—Made from Willughbeia firma Blume. Native of the 
Malay Peninsula. From Penang, East Indies. 
Leafy branch of Carpodinia lanceolata K. Schum. 
Stems of the same plant. 
Lower Congo red thimbles.—From a species of Carpodinia. Native of 
Africa. From the Congo Free State. 
Root rubber.—Made from a species of Carpodinia, native of eastern Rhodesia. 
Native Java rubber of unknown botanical origin. Presented by F. E. Lloyd. 
A rubber-yielding vine, imported from Mexico for the extraction of its rubber. 
Presented by H. H. Rusby. 
950-961.% The guayule rubber plant and its products. This is Parthenium 
argenteum A. Gray (Carduaceae—Thistle Family), a shrub native of the 
southwestern United States and Mexico. To obtain this rubber, the shrub 
is torn up by the roots and ground fine. It is then thoroughly boiled and 
stirred, by which the rubber is freed from its cellular tissues, and after- 
wards skimmed off and pressed into cakes. 
. The dried guayule rubber plant. Presented by F. Austin. 
. Leafy branch of same. Presented by I’. J. H. Merrill. 
. Dried plants of same. 
. The ground plant. Ground by passing through a 2-roll crusher. From 
Marathon, Texas. 
. The same, after passing through the pebble mill. 
. The rubber and floating bagasse. Taken from the surface of the skimming 
tank. 
. Sinking bagasse. Taken from the bottom of the skimming tank. 
. Rubber and bagasse after one hour’s boiling and one or two days in the 
settling tank, to prepare it for the compressor. 
. Rubber skim. The preceding after high pressure in the compressor for 40 
minutes. 
. Water-logged bagasse, after 40 minutes in the compressor. 
. The rubber, washed and sheeted and ready for the market. 
. Samples of commercial guayule rubber. Presented by the India Rubber 
World. 
. Colorado rubber.—Made from Picradenia floribunda Cockerell (Carduaceae— 
Thistle Family). Native of Colorado. From Buena Vista, Colorado. 
Presented by T. D. A. Cockerell, in 1904. 
® Unless otherwise specified, these samples were presented by Francis E. Lloyd. 
