sipHONIA ELastTicA. ORD. XXXIX. Tricoece. 659 
the concentrated mineral acids, but in a considerable degree even 
by most of the unctuous, distilled, and empyreumatic oils. How- 
ever, as it was found that the solutions of this inspissated juice 
by these menstrua irrecoverably Jost their elasticity, and became 
useless, the great desideratum of re-forming the Caoutchoue was 
not attained till ether was employed as its solvent; which was first 
_ done by Macquer, who for this purpose found it necessary to use 
the vitriolic ether in a highly rectified state, 
The Caoutchouc, cut into small pieces, and put into a proper 
vessel with as much of the ether as was sufficient to cover it, was 
completely dissolved without the application of heat. This solu- 
tion, which was transparent, and of an amber colour, on being 
thrown into water, did not produce a milky liquor; but there 
arose to the surface a solid membrane, possessing the elasticity and 
other properties of the Caoutchouc. This experiment was also 
executed with success by Theden;” therefore those with whom it 
failed must have used ether in a less concentrated state. Accord- 
ing to Theden one dram of the Caoutchouc requires for its perfect 
solution an ounce of ether. Nitrous ether dissolves but a small 
proportion of the Caoutchouc, and at the same time ee its 
elastic power. 
‘It has been asserted that the elastic resin not ney dissolves 
oil of guaiacum by digestion, but that on eva > the 
resin in a little time recovers its elastic property. By the industry 
of Achard, who made this discovery, we likewise learn that solu- 
tions of this substance, made by the etherial oils, may be decom- 
posed by the addition of spirit of wine, when the Caoutchouc 
separates from the oil in the form of mucilage, and on being 
sufficiently exposed to the air, is restored to its former firmness 
and elasticity. 
However Juliaans, who attempted this 3 process, was unable to 
re-produce a substance possessing the characters of the elastic 
resin: it is thgrefore to be feared that this method, which seemed 
= N Bemerk. a. d. Wundarzneyk, P. 2. p. 152, 
