544 MONOECIA MONANDRIA. FicUS. 



\y in the chasms of the rocks, on the declivities otthe moiin- 

 tainsjthat time has filled with the decomposed rocks,and ve- 

 getables ; I also find the young trees grow with the greatest 

 luxuriance in the common soil of the Botanic garden. 



Old trees are said to yield a richer juice than the young 

 ones, at least, they say the juice of the latter remains much 

 longer in its fluid undecomposed state, than that of the former. 

 It is extracted by incisions across the bark down to the wood, 

 at a distance of about a foot from one other, all round the 

 trunk or branch, up to the top of the tree ; and the higher the 

 more abundant is the fluid said to be. After one operation, 

 the same tree requires about a fortnight's rest, when it may 

 be again repeated. During the cool season, from October un- 

 til March, the juice is more scanty than in the warm weather, 

 from March to October, but richer. 



When this juice is exposed to the air, like milk when 

 rennet is added to it, it separates spontaneously into the firm 

 elastic substance itself, and a foetid whey-coloured liquid. 

 Fifty ounces of the pure milky juice taken from the trees in 

 August yielded exactly fifteen ounces and a half of the clean 

 washed Caoutchouc. 



With this milk, while in its rescent undecomposed state, the 

 natives of the mountains, a most barbarous race as can be 

 found in any part of the world, pay the inside of their rude 

 utensils that are intended to hold fluids. The Caoutchouc 

 itself being very inflamable, furnishes them with candles, 

 and flambeaux. They say they do not know of any mode by 

 which it can be dissolved after it has acquired its firm state. 



On reading Mr. Gough's description of a property of Caow^- 

 chouc in the 13th volume of J\richolso7i's Journal, p. 305, I 

 was induced to try if this sort acquired heat by sudden ex- 

 tension and again lost it by contraction. His method was fol- 

 lowed by suddenly extending a slip, and when it was applied 

 to the lips 1 was sensible of an increase of heat, but could not 

 perceive any diminution of that heat when the slip was suf- 

 fered to return to its original state of contraction. I also ap- 



