¢ 4 ) 
Though it appears that neither water nor alcohol, aided by all the 
heat capable of being produced in Papin’s digefter, could diffolve this 
fubftance, yet its folution was effected not only by the concentrated 
mineral acids, but in a confiderable degree even by moft of the 
unctuous, diftilled, and empyreumatic oils.. However, as it was found 
that the folutions of this infpiflated juice by thefe menftrua irrecover- 
ably loft their elafticity, and became ufelefs, the great defideratum of | 
re-forming the Caoutchouc was not attained till ether was employed 
as its folvent; which was firft done by Macquer, who for this purpofe 
found it neceflary to ufe the vitriolic ether in a highly rectified fate. 
The Caoutchouc, cut into finall pieces, and put into.a proper veflel 
with as much of the ether as was fufficient to cover it, was completely 
diffolved without the application of heat. This folution, which was 
tranfparent, and of an amber colour, on being thrown into water 
did not produce a milky liquor; but there arofe to the furface a folid 
membrane, poffeffing the elafticity and other properties of the Caout- 
chouc. This experiment was alfo executed with fuccefs by Theden;” 
therefore thofe with whom it failed muft have ufed ether in a lefs 
concentrated ftate.. According to Theden one dram of the Caoutchoue 
requires for its perfec folution at ounce of ether. Nitrous ether 
diflolves but a fmall proportion of the Caoutchouc, and at the fame 
time deftroys its elaftic power. Stand ed} on fi 
__ It has been afferted that the elaftic refin not only diffolves in oil of 
-guaiacum by digeftion, but-that on evaporating the oil, the refin in 
a little time recovers its elaftie property. By the induftry of Achard, 
who made this difcovery, we likewife learn that folutions of this 
fubftance, made by the etherial oils, may be decompofed by the 
addition of fpirit of wine, when the Caoutchouc feparates from the 
oil in the form of mucilage, and on being fufficiently expofed to the 
air, is reftored to its former firmnefs and elafticity. ‘a | 
However Juliaans, who attempted this. procefs, meas “anaie te 
re-produce a fubftance poffefling the charaéters of the elaftic refin: it 
is therefore to be feared that this method, which feemed to promife 
an eafy and cheap way of forming various inftruments of the Caout- 
chouc, has been prematurely recommended :. nor does the method of 
= N. Bemerk. a. d. Wundarzneyh. P.2. p. 152. 
i . =~ foftening 
