PROPERTY OF INDIAN RUBBEft. 



ihen fwam again to fliore, announcing his viflory, and con- 

 gratulating the alTembly on the deliverance of the nation. 



" Thus (condiiued the old M'unfee) were the Indians of thofe 

 days Alanniltoes. Nothing could refift them. They knew 

 nothing of drowning. Oar firft Parents have fprung from the 

 bottom of a lake." 



305 



VII. 



A Defcription of a Property of Caoutchouc, or Indian Rubber ; 

 With fojue RcjkSiions on the Caufs of the ElajHdty of this 

 Subfiance. In a Letter to Dr, Holme.* 



SIR, Middlefhaiv, near Kendal, Nov. 26, 1802, 



A HE fubflance called Caoutchouc, or Indian Rubber, pof- 

 fefles a fingular property ; which, I believe, has never been 

 taken notice of in print, at leaft by any Englifli writer; the 

 prefent letter contains my experiments and reflections oh the 

 lubjedt; and (hould they appear to deferve the attention of 

 your philofophical friends, I ara certain you will take the 

 trouble of communicating the paper to the Literary and Phi- 

 lofophical Society of Manchefter. 



The property I am about to defcrlbe depends on the tempe- Caoutchouc 

 ralure of the Caoutchouc, which is ufed in the experiment ; '"^'^^ P'i^nt by 

 ibr heat increafes the pliancy of the fubftance, and cold, on * 

 tiie contrary, renders it more rigid : fo that when a flip of this 

 refin has b*^ tn lufticiently warmed, it may be extended to more 

 than twice its natural length, by a moderate force applied to 

 its extremities, after which it will recover its original dimen- 

 fions in a moment, provided one of the ends of it be let go 

 as foon as it has been flretched. This difpofition of the fub- 

 ilance may be produced by a degree of temperature lefs than 

 the heat of the blood ; it is therefore necelfary to prepare a 

 ilip of it, by fteeping it for a few minutes in warm water, 

 or by holding it fomewhat longer in the fift; either of thefe 

 precautions makes the refin pliant, and fits it for the ex- 

 rimentj which is performed in the following manner. 



* Manchester Mem. N.S. Vol.1, 



I made 



