USEFULPROJECTS. 



3,71 



tion of which we owe to Mr. Cavel- 

 lo, may perhaps explain the matter. 

 Ether, which before being washed 

 only makes the caoutchouc sweU, 

 dissolves it with ease after it has 

 been washed with a large quantity 

 of water. It necessarily loses, by 

 this operation, that acid, of which 

 indications are frequently found, 

 and saturates itself with water. 

 Be that as it may, it is easy at pre- 

 sent to obtain, by means of this 

 process, a solution whicli, after t!ie 

 evaporation of the solvent," is pure 

 elastic gum : yet this mode of ma- 

 king instruments, though possible, 

 is nearly impraccicable, as it is not 

 only too expensive, from theloss of 

 the ether which evaporates, and of 

 tiiat which is taken up by the wa- 

 ter ; but it is also very inconvenient 

 to manage the concentrated solution 

 (>£ caoutchouc, because it adheres 

 to every thing that it touches, and 

 bubbles of air are apt to be retained 

 in t!i* pelliclesof elastic gum, which 

 are formed by the evaporation of 

 the ether. 



Several essential oils, as those of 

 the turpentine and lavender, act 

 upon the caoutchouc, even when 

 cold : yet in making use of them, 

 in the manner already explained, 

 we shall succeed still less than with 

 ether, either in obtaining pure elas- 

 tic gum, or in forming instruments. 

 M. Fourcroy, in a memoir read in 

 December, IJQO, at the royal soci- 

 ety of agriculture, in which lie 

 mentions all the facts known in re- 

 gard to caoutchouc, and adds many 

 interesting experiments, has ex- 

 pressed his wishes, and given his 

 idea of the manner by which the 

 juice of the caoutchouc may be 

 brought to us without alteration. 

 The desireofa philosopherso worthy 

 of praise, and the luile probabiliiy 



there exists of seeing his wishes ful- 

 filled, made me recur to some ideas 

 I had formed upon the subject 3 and 

 I have succeeded in making, with 

 the bottles of clastic gum, the tubes 

 which are now presented to you. 

 My work is indeed very imperfect ; 

 yet, being certain that my ideas, by 

 being made- known, will sooner ac- 

 quire in the hands of artists the per- 

 fection of which they are suscepti- 

 ble, 1 shall not keep back, from 

 selfish motives, the knowledge of a 

 process which may be useful in 

 many arts. 



The following is the path I have 

 pursued, and the methods I have 

 employed ; it may be easy to substi- 

 tute better, but those of which I 

 am about to give an account may 

 certainly be of some advantage, in- 

 asmuch as they may prevent others 

 who may employ themselves in 

 such researches from making useless 

 trials. 



It appeared, even% my first ex- 

 periments, thst I was attempting 

 too much, and giving myself useless 

 trouble, in searching for a manner 

 of completely dissolving the elastic 

 gum, so that it might be again made 

 up in new forms. I then thought 

 that it would be easier to find out a 

 method, as it were, of soldering it, 

 and of not acting upon it more than 

 might be necessaiy to cause its 

 softened parts to reunite. Fxperi- 

 ence has shev^m me that a strong 

 pressure made upon two pieces of 

 caoutchouc (when brought to that 

 state of softness) and continued un- 

 til they areintirelydry, caused them 

 to contract so strong an adhesion, 

 Ibat the piece, being pulled out till 

 it broke, often broke, not at the 

 united part, but by the side of it. 



By means of ether I immediately 

 succeeded in making these tubes $ 



the 



