450 



MECHANICAL SEPARATION OF CELLULAR COMPONENTS 



microscope are employed. The instrument is to be made com- 

 mercially available by Fisher Scientific Co. 



Vacuum-Type Air-Driven Centrifuge. In this instrument the 

 rotor spins in a vacuum on a flexible vertical shaft. Originally 

 designed by Beams and Pickels (1935), it has since been improved 

 in various ways as described by Beams ( 1941, 1942) . The advantage 



Fig. 158. Air turbine ultracentrifuge with plastic rotor. 

 From Stem (1942) 



Also shown in the figure are: B, analytical fluid cell inserted in cyhndrical 

 cell hole; C, brass disc connected with similar disc on other side of rotor by 

 brass bushing and screws; D, fastened to C and turned down and surface- 

 hardened at ends to fit E mounted in casing, //, and carefully aligned with 

 bearing on opposite side; F, Fi, brass contacts, inserted in rotor surface; G, 

 contact brush, made from spring bronze, insulated from casing H, adjustable in 

 position; H, centrifuge casing, made from sheet brass; /, semicircular opening 

 in casing H to permit free escape of expanded driving air; J, air jet, '/32 in. 

 lumen, trumpet-shaped at inlet end and conforming with rotor shape at outlet 

 end; K, angle for mounting on wooden base. Insert B, analytical fluid cell, 

 made by cementing, with Lucite cement, two outer discs of colorless Plexiglas 

 resin to central disc of red Plexiglas into which a sector-shaped opening of 

 12 mm. height and 3 mm. depth has been cut, connected with periphery by 

 narrow drill hole, through which the solution under study is introduced with a 

 hypodermic syringe. When in use the cell is inserted into cell hole in rotor 

 center and the broad base of the sector pointing toward the periphery. 

 During operation, the centrifuge is covered by a steel guard, made from 0.5 in. 

 thick boiler plate by welding, equipped with openings opposite the cell holes 

 and slots near the base to permit escape of air stream. 



