1911.] Disintegrating Bacterial and other Organic Cells. 



61 



near to the outside of the covering cylinder F, a pair of electromagnets are 

 mounted, with their poles in such a position that the iron bar on top of the 

 steel cone is attracted by them. In actual practice it is found convenient 

 and more efficient to let this electromagnet be a circular one, so that the 

 magnetic circuit is closed, with a pole on each side, in such a position that it 

 will attract the central iron armature. A suitable current of electricity 

 is then passed through the winding of the electromagnets, so that the iron 

 armature is kept in one position. It follows that, on rotating the containing 

 vessel, while the armature is held by the electromagnets, a drag is put on the 

 central steel cone, which in turn is communicated to the steel balls, and the 

 grinding action occurs in the manner indicated. 



To ensure that the bacteria are brought under the influence of the grinding 



I 



1 



1 



1 



1 .,, 



f """" 



1 f 



\ 





A B: C .E 



:D ;G 



\\ . w 



1 











K ; L -F 



J 















"Fig. 2. — Apparatus for disintegrating bacterial or other cells. Type with gravitational control. 



mechanism, the speed of rotation should be at least 1500 revolutions per 

 minute. The bacteria are placed in the pot in a semi-fluid condition or as 

 an emulsion. Centrifugal action then ensues, so that they are almost 

 immediately brought under the grinding action of the balls. As the 

 grinding action is one which takes place largely as the result of the rotation 

 of the balls in an exactly fitting race the amount of friction is almost 

 negligible ; and further as the pressure that is put on the balls consists of 

 a direct thrust by the steel cone, there is every opportunity for them to slip 

 should any additional friction be introduced, or if for any reason any added 

 load be put on the grinding mechanism. 



To ensure that the running is perfectly true, the whole appliance is 

 mounted between centres I, I, which are adjustable for wear. 



