El Bar Americano en España by Pedro Chicote (1927, p.79)

10 dropsGrenadine syrup — Grenadine syrupbase
Seltzer water — Cold seltzer waterdilution
1 copitaAmer Picon modifier
  1. Build in a vermouth glass with grenadine and Amer Picon.
  2. Fill with very cold seltzer water and serve.

Chicote notes the same structure can be made with curaçao, cassis, pineapple, orange, or lemon.