Title: First observation of Ce volume collapse in CeN,
Abstract: On the occasion of the 80th anniversary of the first observation of Ce volume
collapse in CeN a remembrance of the implications of that transcendent event is
presented, along with a review of the knowledge of Ce physical properties
available at that time. Coincident anniversary corresponds to the first
proposal for Ce as a mix valence element, motivating to briefly review how the
valence instability of Ce was investigated since that time.