/. TYPES OF HIGH-SPEED CENTRIFUGES 



While the ordinary centrifuge and the Sharpies instrument suffice 

 for many separations of cellular constituents, the ultra- or high-speed 

 centrifuge offers particular advantages in other instances. It would 

 carry the present discussion too far afield to give many of the 

 details of the various types of high-speed centrifuges that have been 

 employed for cytological work, but the instruments will be mentioned 

 and the most significant references will be included. 



The elaborate Svedberg oil-driven ultracentrifuge, adapted for 

 measurements of physical characteristics of large molecules and 

 various particles, has been the subject of a book by Svedberg and 

 Pedersen (1940) that gives complete details. It has been sufficient 

 for many cytological separations to employ much simpler apparatus 

 such as the gas-driven and electrically powered instruments. 



The construction of a centrifuge driven by a high-speed electric 

 motor than can yield a centrifugal force of about 34,800 times 

 gravity at 18,000 R.P.M. was described by Pickels (1942). 



A multispeed attachment may be used with the type SB, size 1, 

 centrifuge of International Equipment Co. This attachment with 

 head No. 295 may be used for centrifugal forces up to 18,000 times 

 gravity. The full capacity of this head is 84 ml. and the celluloid 

 tubes used with it each has a capacity of 14 ml. (may be obtained 

 from Lusteroid Container Co., Inc.). The centrifuge without the 

 multispeed attachment may be used at 1500 times gravity with the 

 horizontal yoke No. 242, which accommodates bottles of 250 ml. 

 capacity, or at up to about 2400 times gravity with the conical head 

 No. 823, which carries 50 ml. tubes. 



Gas-Driven "Spinning Top" Centrifuge. This instrument 

 was developed since 1925 when Henriot and Huguenard first spun 

 a small rotor (11.7 mm.) at a speed of 660,000 R.P.M. by means of 

 an air stream that also served as a low-friction cushion to support 

 the spinning rotor. Many improvements have been made in this 

 centrifuge (Beams, 1938, 1940, 1941; McBain, 1939). The instrument 



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