73 



Fig. 2. Analytical rotor for a commercially produced, electrically driven 

 ultracentrifuge (89) of the optical type. Also shown are assembled cell, counter- 

 balance, separate centerpiece for fluid column, and sector cups that hold two 

 quartz windows. (Courtesy Specialized Instruments Corporation.) 



Fig. 3. Analytical rotor of Figure 2 shown attached to flexible drive shaft in 

 operating position. Vacuum chamber and inner refrigerated cylinder shown in 

 lowered position. (Courtesy Specialized Instruments Corporation.) 



