ABSTRACTS OF TECHNICAL ARTICLES 903 



Alkaline Earth Porcelains Possessing Low Dielectric Loss}^ M. D. Rigter- 

 INK and R. O. Grisdale. Alkaline earth porcelains have been prepared 

 from mixtures of clay, flint, and synthetic fluxes consisting of clay calcined 

 with at least three alkaline earth oxides. These porcelains possess excellent 

 dielectric properties, have low coefhcients of thermal expansion, are white, 

 and are especially valuable as bases for deposited carbon resistors for which 

 they were developed. Their characteristics make it probable that other uses 

 will be found for materials of this type. 



An illustrative composition is 50.0% Florida kaoHn, 15.0% flint (325 

 mesh), 35.0% calcine (200 mesh). The composition of the calcine is 40.0% 

 Florida kaolin, 15.0%, MgCOs, 15.0% CaCOa, 15.0%^ SrCOs, 15.0%o BaCOs, 

 calcined at 1200°C. The electrical properties of this body at 1 mc. are Q at 

 25°C., 2160; Q at 250°C., 280; Q at 350°C., 90; specific resistance at 150°C., 

 1013-5 ohm-cm. and at 300°C., lO^^-^ ohm-cm. 



Attenuation of Drainage Effects on a Long Uniform Structure with Distributed 

 Drainage}^ J. M. Standring, Jr. This paper discusses the general be- 

 havior of forced drainage currents on long uniform underground commu- 

 nication cables with particular regard to the case where drainage is applied at 

 regular intervals. Expressions are developed for the structure-to-earth po- 

 tential which is caused by uniformly spaced drainers when the power supply 

 is from variable e.m.f. sources, such as rectifiers, and also for the case where 

 fixed e.m.f.'s, such as galvanic anodes, are employed. 



"/owr. Amer. Ceramic Society, March 1, 1947. 

 12 Corrosion, June 1947. 



