ABSTRACTS OF TECHNICAL ARTICLES 145 



capacitor paper, since, within the Umits observed in commercial material, 

 the chemical and physical tests usually made do not correlate with life. 

 Lack of correlation is ascribed to obscure physical factors which have not 

 yet been identified. 



Generally, several weeks are required to evaluate a paper by life tests of 

 the usual severity. Unfortunately, the duration of these tests is too long for 

 quaUty control of paper. 



The desire for a life test which requires no more than a day or two for 

 evaluation led to the development of a rapid d-c. test. The philosophy of 

 rapid life testing is based upon the experimental evidence that the process 

 of deterioration under selected temperature and voltage conditions is prin- 

 cipally of a chemical nature, and also upon the well-known fact that rates 

 of chemical reaction increase exponentially with temperature. 



Life tests on two-layer capacitors conducted at 130°C. provide an ac- 

 celeration in deterioration many fold more than that obtained in the lower- 

 temperature life tests, and correlate well with these tests. 



