388 ORGANIC CHEMISTRY. 



rubber, and constitutes the material out - of which 

 most India-rubber goods are now made. The hard 

 rubber which is extensively employed for the manu- 

 facture of cornbs, knife-handles, pencil-cases, &c., is 

 composed of pitch, India-rubber, sulphur, and mag- 

 nesia. The mixture is softened at about 270, then 

 pressed into moulds to give it the required shape. It 

 is afterward wrought like ivory. 



Whatisgutta 973 ' G UTTA PERCHA. Gutta percha is 

 percha? identical in composition with gum elastic, 



Mention some , , _. 



of its proper- but possessed of quite different properties. 

 ties and uses, ^mong them is its extreme toughness, and 

 comparatively slight elasticity. It is rendered soft and 

 plastic by immersion in boiling water, and in this pasty 

 condition may be moulded into any required shape. It 

 can be vulcanized, like caoutchouc, and is then proof 

 against elevation of temperature. It is employed as a 

 substitute for caoutchouc where great elasticity is not 

 required. Both of the above substances approach more 

 nearly in their composition to the essential oils, than to 

 any other class of compounds. 



PROTEIN BODIES PUTREFACTION". 

 Stated com- 974 ' VEGETABLE FIBRIN. The glutin- 



position and ous mass which remains when dough is 



properties of . . 



vegetable kneaded in water until all the starch is 



fibnn. removed, is called gluten or vegetable 



fibrin. It diners from all the organic matter hitherto 

 described, in containing nitrogen, with small quantities 



