Abstracts of Bell System Technical Papers Not Published 

 in This Journal 



Possible and Probable Future Developments in Communication* O. E. 

 Buckley^ Franklin Inst. JL, v. 251, pp. 58-64, Jan., 1951. 



Electrochemical Industry. R. M. Burns^ Bibliography. Ind. & Engg. 

 Chem., V. 43, pp. 301-304, Feb., 1951. 



Cracking of Stressed Polyethylene; Efect of Chemical Environment.* J. B. 

 De Coste\ F. S. Malm^, and V. T. Wallder^. Ind. & Engg. Chem., v. 43, 

 pp. 117-121, Jan., 1951. 



Abstract — In a number of applications for polyethylene, particularly 

 cable sheaths and cosmetic containers, it has been found that under certain 

 conditions failure of the polyethylene results in a cracking of the plastic. 

 Considerable information is available to show that in an unstressed condi- 

 tion polyethylene is highly resistant to a wide variety of chemical environ- 

 ments such as alcohols, soaps, and fatty oils. However, when polyethylene 

 is exposed to these environments under polyaxial stress it fails by cracking. 



The work described in this paper was undertaken to determine the factors 

 involved in polyethylene cracking. A qualitative laboratory test was de- 

 veloped to evaluate this property and the effect of a variety of organic and 

 nonorganic materials was studied. It was found that the higher the molec- 

 ular weight of a polyethylene the more resistant it becomes to cracking, 

 that the degree of crystallinity affects its readiness to crack, and that the 

 addition of polyisobutylene or Butyl rubber improves crack resistance. 



This paper shows that useful end products, which are resistant to crack- 

 ing, can be made from polyethylene. 



Atomic Relationships in the Cubic Twinned State.* W. C. Ellis^ and 

 R. G. Treuting^ References. Jl. Metals, v. 191, pp. 53-55, Jan., 1951. 



Abstract — The twinned state is characterized by a lattice of coincidence 

 sites. Imperfections are required at stable lateral twin interfaces. Twinned 

 regions can occur with relative ease in the diamond cubic structure. 



Transitions in Chromium.* M. E. Fine^, E. S. Greiner^ and W. C. 

 Ellis^ References. Jl. Metals, v. 191, pp. 56-58, Jan., 1951. 



ABSTR.A.CT — Discontinuous changes of Young's modulus, internal friction, 

 coefficient of expansion, electrical resistivity, and thermoelectric power 

 are evidence for a transition in chromium near 37° C. Although the X-ray 



* A reprint of this article may be obtained on request. 

 1 B. T. L. 



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