ABSTRACTS OF TECHNICAL ARTICLES 247 



matter all bear charges and that the forces exhibited in Nature are 

 all electrical (exception being made for gravitation). A noted and 

 serious objection to this view was temporarily met by the adoption 

 of quantum mechanics. Since 1930 a reversal of trend has set in, 

 heralded by the discovery of the neutron as a subatomic chargeless 

 particle capable of independent existence; and at present there is a 

 strong tendency to develop the view that neutral as well as charged 

 particles of subatomic size, and non-electrical as well as electrical 

 forces, exist together in Nature. 



Electrical Networks for Sound Recording.^ F. L. Hopper. Electrical 

 networks are employed in sound recording for modifying and limiting 

 the frequency-response characteristic. The necessity for their use, 

 application, and design is described. Particular emphasis is placed 

 upon the constant-resistance type of structure. 



Sound Pictures in Auditory Perspective.^ Franklin L. Hunt. 

 Soon after sound reproduction in auditory perspective was demon- 

 strated over telephone circuits between Philadelphia and Washington 

 in 1933, experimental sound pictures in auditory perspective were 

 made at. the Bell Telephone Laboratories' sound picture laboratory. 

 Listening tests showed that they distinctly enhanced the illusion 

 that the sound originated at its apparent source on the screen and they 

 strikingly improved the feeling of spaciousness and reality. The 

 auditory perspective effect is not primarily dependent upon perfect 

 synchronism of the two sound-tracks required, nor on frequencies 

 above the present commercial range. Existing equipment can be 

 converted to project sound pictures in auditory perspective without 

 great difficulty. 



Composition and Colloidal Properties of Balata Latex} A. R. Kemp. 

 This paper reports the composition and colloidal properties of two types 

 of balata latex from Dutch Guiana. The white variety is shown to be 

 superior to the red, owing to its higher content of hydrocarbon. 



It is shown that balata latex is very stable owing to the presence 

 of a highly protective water-soluble substance in its serum. It cannot 

 be coagulated by acids or salts, but is readily coagulated by alcohol 

 or acetone. 



The balata latex particles are spherical and vary in diameter from 

 about 0.1 to 2.5 microns with an average diameter of about 0.5 micron. 



The balata latex particles are shown to enclose the resins, which 



» Jour. S. M. P. E., November 1938. 



« Jour. S. M. P. E., October 1938. 



^ India Rubber World, December 1, 1938. 



