PARAGUTTA, A NEW INSULATING MATERIAL 



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with tillers in vulcanized rubber ^ and hygroscopic salts on the surfaces 

 of textile fibers.^ 



On the other hand, the electrical properties of paragutta or gutta 

 percha are not impaired when several times their equilibrium water 

 content is incorporated with them. Gutta percha, however, does 

 show an increase in capacitance of about 10 per cent as a result of 

 water absorbed by a completely dried specimen, but as it is always 

 the practice to apply it to the conductor in a wet condition this 



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TIME-MONTHS 



Fig. 9— Changes in water content of 50 mil wet and dry paragutta and gutta perclia 

 sheets when immersed in 3.5 per cent NaCl at room temperature. 



change is not of practical significance. The electrical properties of 

 paragutta on the other hand show practically no changes as a result 

 of moisture absorption by a dry sample. These facts are taken to be 

 the best evidence of the electrical stability of paragutta in contact 

 with water. 



Hundreds of specimens of paragutta and gutta percha have been 

 studied as regards changes taking place in electrical characteristics 

 after long periods of continuous immersion in 3.5 per cent salt solution. 

 These tests, some of which have been for periods of three to five years, 

 show that paragutta is fully equal to gutta percha as regards its 

 ^ Williams and Murphy, Bell Sys. Tech. Jour., 8, 225 (1929;. 



