236 



H. K. SCHACHMAN AND R. C, WILLIAMS 



fibrous materials, like nucleic acids or polysaccharides, and were largely 

 responsible for the observed viscosities of the solutions. As preparations 

 became more highly purified the observed intrinsic viscosity decreased. For 

 the two plant viruses, southern bean mosaic virus (Miller and Price, 1946) 

 and bushy stunt virus (Cheng and Schachman, unpublished), however, the 

 intrinsic viscosities were much lower, as would be expected for spherical 

 objects only moderately hydrated. 



° V refers to the viscosity increment and corresponds to the mtrinsic viscosity when 

 concentration is expressed as volume fraction [calculated from Simha (1940)]. 



^ Calculated from Perrm's equation (1936) and tabulated by Svedberg and Pedersen 

 (1940, p. 41). 



" p^[N/ (16200 77^) f/yo/fyl^ ; calculated and tabulated by Scheraga and Mandelkern 

 (1953). 



3. Rotational Diffusion 



a. General Considerations. As a result of thermal energy, large particles 

 in a viscous medium undergo continual zig-zag movements known as 



