I don't know how "Bromo Seltzer" got its name, but I doubt it had any bromides in it.If I remember correctly, it had
acetanilid in it that was very potent headache remedy, but caused methemoglobinemia which gave blue face to those dependent on it. (caused formation of an abnormal analogue of hemoglobin). I could spot chronic alcoholics on Washington Street's South End a block away.