J^S A Botanical Drfcripiiofi of 



It contains much combuftiblc matter, burning entirely 

 a\vay, with a clear flame, emitting a confiderable deal of 

 dark-coloured fmoke, which readily condenfes into a large 

 proportion of exceeding fine foot, or lamp-black ; at the fame 

 time it gives but little fmell, and that not difagreeable : the 

 combuftion is often fo rapid as to caufe drops of a black li- 

 quid, very like tar, to fall from the burning mafs; this is 

 equally inflammable with the rclt, and continues when cold 

 in its femi-fluid ftate, but totally void ofelafticity: in Ame- 

 rica, the Caout-chouc is ufed for torches ; ours appears to be 

 equally fit for that purpofe. Expofcd in a filver fpoon to a 

 heat about equal to that which melts lead or tin, it is re- 

 duced into a thick, black, inflammable liquid, fuch as' drops 

 from it during combuftion, and is equally deprived of its 

 elafi:ic powers, confequcntly rendered unfit for thofe purpofes 

 for which its original elallicitv rendered it fo proper. 



It is infoluble in fpirits of wine, nor has \yater any more 

 effeft on it, excJ-ept vvhca afllflcd by heat, and then it is only 

 foftened by it. 



Sulphuric acid reduced it into a blacky brittle, charcoal- 

 like fubftance, beginning at the furface of the Caout-chouc, 

 and if the pieces are not very thin or fmall, it requires fome 

 davs to penetrate to their centre; during the procefs the acid 

 is rendered very dark-coloured, almofl black. If the fulphuric 

 acid is previoufly diluted with only an equal quantity of wa- 

 ter, it docs not then appear to have any effecl on this fub- 

 itance, nor is the colour of the liquid changed thereby. 



Nitric acid reduced it in twelve hours to a foft, yellow, 

 unelaflic mafs, while the acid is rendered yellow; at the end 

 of two davs, the Cuout-cbouc had acquired fome degree of 

 friabiliiy and hardneis. The fame experiment made on 

 American Cauui-chouc was attended with fimllar effedls. 

 Muriatic acid had no efTcft on it. 



Sulphuric jetheronly foftened it, and rendered the diflxirent 

 minute portions it was cut into eafily united, and without 

 any fceming diminution ofelafiiclty. 



Nitric irther I did not find a better menftruum than the 

 vitriolic ; confequently, if the aether I employed was pure, 

 of which I have fome doubt, this fubftance mufl differ ef- 



fentially 



