THE URCEOLA ELASTIC*. 3 75 



and in butter in the fame degree of heat, but ftilJ 

 thefe folutions were without clafticity, or any appear- 

 ance of being ufeful. 



I fhall now conclude what I have to offer on the 

 caout-chouc, or Urceola c/ajfica, with obferving that 

 fome philosophers of eminence have entertained doubts 

 of the American caout-chouc being a finrple vegetable 

 fubitanee, and fufpeel: it to be an artificial produc- 

 tion, an idea which I hope the above detailed experi- 

 ments will help to eradicate, and confequently to re- 

 ftore the hiftories of that fubftance by M. De la Con- 

 damme and others, to that degree of credit to which 

 they leem juitly entitled, in lupport of which it may 

 be further obferved, that belides Urceola elajiica there 

 are many other trees, natives of the Torrid Zone, that 

 yield a milky juice, polleHing qualities nearly of the 

 fame nature, as artorarpus integrifolia (common jack 

 tree) Jicus reiigiojus et Lndica, Hijpomane biglanduhj'a , 

 Cecropia pelt at a, &V. 



The caout-chouc or jicus rehgiofa, the Hindus con- 

 fider the moll tenacious vegetable juice they are ac- 

 quainted with ; from it their beft bird lime is pre- 

 pared. I have examined its qualities as well as thole 

 of jicus Indie a and art a carpus integrifolia, by experi- 

 ments, iimilar to thoie above related, and found them 

 triilingly elaftic when compared with the American 

 and Urceola caout-choucs, but infinitely more vifcid 

 than either ; they are alfo inflammable, though in a 

 lefs degree, and mew nearly the fame phenomena 

 when immerfed in the mineral acids, folution of cauftic 

 alkali, alkohol, fat, and eflential oils; but the folution 

 in Cajeput oil could not be feparated by fpirits of 

 wine and collected again like the folutions of the 

 Urceola and American caout-chouc s. 



L4 XV. SOME 



