ABSTRACTS OF TIXIINRAL ARTICLES 507 



GoERTZ, M., see H. J. Williams. 



Gray, M. C.^ 



Legendre Functions of Fractional Order, Quart. Appl. Math., 11, 

 pp. 311-318, Oct., 1953. 



Grisdale, R. O.^ 



Formation of Black Carbon, J. Appl. Phys., 24, pp. 1082-1091, Sept., 

 1953. 



Electron microscopic evidence is presented in support of the hj^pothesis 

 that black carbon resulting from pyrolysis of gaseous hydrocarbons is 

 produced through the intermediate formation of droplets of complex hy- 

 drocarbons. Electron diffraction studies further confirm the hj-pothesis if, 

 as has been found for joarticles of carbon blacks, the droplets consist in 

 l)art of gra])hitic nuclei arranged with their basal ])lanes tangential to the 

 droplet surface. The carbonization of small sohd splierules of highly cross- 

 linked oi-ganic ])olymers is described, and it is sliown that the morpholog}' 

 of the carl)onization products is wholly analogous to those for pyrolytic 

 carbon and carbon blacks. It is suggested, therefore, that the formation of 

 carbon by the carbonization of solids and by deposition from the gas phase 

 occurs through similar mechanisms and that the two processes are simply 

 two extremes in an infinite series of ])rocesses which are all fundamentally 

 ahke. 



Grisdale, R. O.^ 



Properties of Carbon Contacts, J. Appl. Phys., 24, pp. 1288-1296, 

 Oct., 1953. 



Microphone carbon has been ])roduced l)y deijosition of ])yi()l\-tic cai'bon 

 films over the surfaces of small sphei'ules of silica. The ]iro])erties of con- 

 tacts between these spheiules are shown to be dependent on the structure 

 and geometr}' of the carbon surface as determined by election diffi'actif)n 

 and microscopic .studies. The gra])hite-like civstallites in ])yi(jlytic carbon 

 surfaces are more or less ])referentially oriented with their basal jilanes 

 parallel to the surface, and the contact piopcrties depend systematicalh' 

 on the degree of orientation. This is explained in terms of the anisotropy 

 in properties of these ciystallites which are closely approximated by those 

 of single crystal giaphite which were determined. The contact resistance 

 and its tem])erature coefficient and the "bui'uing voltage" for carbon con- 

 tacts are exijlicable on this basis. Howevei', the microphonic sensitivity of 

 carbon contacts is indei)en(I('iit of the suifacc sti-uctiiie and dc])ends only 

 on the surface geometr^^ 



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