Better Control for Dropwise Addition The adjustment of standard stopcocks to obtain dropwise addition of reagents is a tricky process. Flow regulation at these low flow rates can be improved by a simple modification of the stopcock. Using a triangular file, cut a V-shaped ridge 1-2 mm deep at each end of the bore. Clean the stoncock of filines before reinsertine it into the ioint. The modified stopcock will open earlier and close later than the unmokfied unit,ind offer better regulation of dropwise reagent addition. This modification is applicable to both glass and Teflon stopcocks.
SUNY a t Syracuse
Robert F.Cassidy, Jr.
Syracuse. New York 13210
Volume 53, Number 5, May 1976 / 303
