25 a 
CAim’s DOUBLE-ACTING DRUG-MILL. 
tempts liad been made to produce an apparatus that would enable the retail 
druggist to prepare his own powders in the same state as they were sup¬ 
plied in by wholesale houses, but hitherto it could hardly be said that the 
requirements of the trade in this respect had been fully met. To produce 
a perfectly smooth and soft powder from vegetable substances, it appeared 
to be necessary to have the conjoined action of contusion and trituration, 
or to effect the result by trituration under great pressure. This was done 
at the drug-mills by the use of the edge-runners employed for the purpose. 
Mere contusion with a pestle and mortar did not bring the particles to a state 
in which they were equal in every direction. Mr. Carr’s patent levigator 
professed to accomplish the object, but he (Dr. R.) had not had the means of fully 
testing its capabilities. In the description given by the patentee, it was stated 
that it comprises the advantages of two well-known mills, namely, the Edge- 
Runner Mill and the Horizontal Mill-Stone. The drawings represent the mill in 
two positions; Fig. 1 being that in which it is used, and Fig. 2, the position into 
which it is put for emptying out its contents. It consists of one or two edge- 
runners working in a pan which forms the bed-plate. Both the runners and the 
pan are made to rotate, but with unequal velocities, although in the same direc¬ 
tion, and the effect of this is the production of a very efficient triturating 
action. In the small mills, such as the one before the meeting, the runner and 
the pan were made of Wedgwood ware, but in the larger mills they were of 
t 2 
