The Collaborative International Dictionary of English v.0.48:

Electro-metric \E*lec`tro-met"ric\, Electro-metrical
\E*lec`tro-met"ric*al\, a. [Cf. F. ['e]lectrom['e]trique.]
   Pertaining to electrometry; made by means of an electrometer;
   as, an electrometrical experiment.
   [1913 Webster]