60 



Messrs. Barnard and Hewlett. Method of [Mar. 28, 



grinding action would take place, as the vessel and its contents would 

 rotate as a whole. To bring about a grinding or crushing action, a drag 

 must be placed on the central steel cone, which retardation is in turn 

 conveyed, at least in part, to the steel balls. It is therefore necessary 



Fig. 1. — Apparatus for disintegrating bacterial or other cells. Type with, 

 electromagnetic control. 



either to let the central steel cone remain at rest, or for it to rotate at 

 a speed less than that of the steel balls. This has been effected in the 

 type of machine now described (fig. 1), by mounting on the top end of 

 the steel cone a bar of soft iron L, which is slightly less in length than 

 the diameter of the covering cylinder. On each side of the machine, but 



