sIpHONIA ELASTI@A. ORD. XXXIX. Tricocce. 637 
The substance, known by the names India rubber, elastic gum, 
Cayenne resin, cautchuc, and by the French caoutchouc, is pre- 
pared from the juice of this tree: as subservient to several medical 
or chirurgical purposes, it comes within the scope of this work, and 
must therefore prove sufficiently interesting to the medical reader. 
This singular substance was little known in Europe till long after 
the commencement of the last century; and its origin and com- 
position was first learned from M. de la Condamine,* who by 
travelling into the interior parts of South America had an oppor- 
tunity of acquiring the necessary information: This active and 
enterprizing member of the French Academy found that the 
Caoutchouc was formed from the juice of a large tree, which has 
since been botanically examined and ascertained to be that here 
represented.° 
The manner of obtaining this juice is by making incisions 
through the bark of the lower part of the trunk of the tree, from 
which the fluid resin issues in great abundance, appearing of a 
milky whiteness as it flows into the vessel placed to receive it, and 
into which it is conducted by means of a tube or leaf fixed in the 
incision, and supported with clay. On exposure to the air this 
milky juice, according to Aublet, gradually inspissates into a soft 
reddish elastic resin; but M. de la Borde, and some others, ages 
that the dice undergoes a certain dbs erie before ‘its imspis 
tion, ¥ 4 ecu process, which the cae 
keep a ceatpiiic secret.* Tos suit “7% different purposes for which 
it is employed in South America, the Caoutchouc is shaped into 
various forms;* but it is commonly brought to Europe in that of 
~ 
» Relation @un voyage dans Vinterteur de b Amerique meridionale, in Mem: 
de U Acad. 1751. p. 322. 
¢ It was taken from a very complete specimen in the possession of Sir Joseph 
Banks. We must remark however, that some other vegetable juices admit of 
being formed into a species of caoutchouc, of which Fresnau has given an account. 
L.t. p. 324. 4 Vide Rozier. obs. et. mem. sur la physique. tom. 1. p. 464. 
© The curious diversity of figures in which this substance was sold in Portugal 
is noticed by Mr. Twiss. See Travels through Renineet and Spain. 323... 
No, 49.—vo1. 4. * ip 
