"Son of God, Eternal Savior"

Earlier this year, "Son of God, Eternal Savior" was one of the hymns I sang in church, and I noticed a small feature in the first line.  The hymn is sung to the tune "In Babilone."  Here's the first musical phrase:

The text here in the first verse (repeated as the first line in the fourth verse) is "Son of God, eternal Savior."  The "eternal" is sung with a melisma (G A G A).  Since the word is spread across more syllables than normal, there's something of a sense of the span of that "eternal."