We report hereafter some results on experiments on mobility of charge
carriers in a point-plane electrode geometry in a wide density range f
or Argon gas to liquid. For point anode mobilities of positive ions ar
e recovered and agree with the values found in planar geometry. For po
int cathode, due to the phenomenon of electron attachment two populati
ons of charge carriers (electrons and ions) are coexistent and we stre
ssed out a large impurity dependence of mobility. Finally we discuss a
bout some optical observations for gas in negative polarity.