140 GOODYKAR ON GUM-ELASTIC. 



4th. insolubility. 



It is not strictly true, as has been sometimes said, that this 

 substance is absolutely insoluble, because it can be softened and 

 even dissolved by powerful solvents of the gum, when heated 

 and boiled, and it can be charred by being kept a long time in 

 pure sulphuric or nitric acid ; but its power of resistance of the 

 solvents, and all other destructive chemical agents, is truly great. 

 The most delicate of the fabrics made of this material may be 

 brought in contact, or immersed with impunity, in such chemical 

 liquids as sulphuric or nitric acid, sulphuric ether, oil of turpen- 

 tine, or any of the essential oils. Or they may be boiled in 

 potash, lime, chloride of lime, soap-suds, &c., by which ordeal, 

 so far from being injured, they are rather improved. In other 

 words, it is either improved, or remains uninjured, when ex- 

 posed to destructive agents, that destroy other fabrics, and 

 even wood, leather, and the metals, such as iron, copper, and 

 brass. 



5th. UNALTERABILITY 



by climate and artificial heat or cold. 



Its endurance of artificial heat is very great, when com- 

 pounded with particular reference to this quality, and with a 

 larger proportion of sulphur than is ordinarily used, it will bear 

 a heat of 300° Farenheit. If a higher degree of heat is applied, 

 it chars, but does not melt. It may, therefore, be considered 

 superfluous to say, that this substance will resist the heat of any 

 climate ; and as has been stated under the head of pliability, it 

 remains soft and pliable in any degree of cold. 



