holy water and the devil, a bit from Palgave on "Superstition and Knowledge"

In the December 1851 installment of "Scenes Beyond the Western Border," the narrating "Captain of U. S. Dragoons" has devils, witchcraft, and magic on his mind.  A riff on the howling of wolves invokes

"the 'witching' midnight hour."

Then, after an exchange between the Captain and his Imaginary Friend (I. F.) in which each one would send something "to the D—," the Captain refers humorously and familiarly to the power of holy water over devils as a kind of "magical" spell: 

 I. F. "A forfeit! Mathematics are infernal.'"

"— I assure you (it is a secret of mine) that nothing else known among men can cope with feminine logic; but that is magical; the d—l can as well resist holy water."

("Scenes Beyond the Western Border")

Demonology was much on Herman Melville's mind around the same time, as we know from notes Melville made from Francis Palgrave's unsigned essay on "Superstition and Knowledge."  Just two pages after one key source-page for Melville's verbatim notes, Palgrave explicitly cites the same power of holy water over devils, in the larger context of ritual magic and medieval "spells":

The rites of Christianity were secretly and silently blended with the magical ceremonies of the Eastern tribes, and the spells of the middle ages exhibit a strange confusion of the practices of the church and the Platonic cabala.  The sign of the cross alternates with the pentalpha, and the names of the Evangelists are added to the angels of the stars.  Holy water which chased away the demon, also assisted in consecrating the hallowed Lamen and the Periapt.
("Superstition and Knowledge")

As Geoffrey Sanborn discovered, Palgrave was Melville's source for what he called, in a letter to Nathaniel Hawthorne the "secret" motto of Moby-Dick.  That letter was written June 29, 1851.  In November 1851 Melville was probably still

"thinking of 'Superstition and Knowledge'"

(Hershel Parker, Herman Melville: A Biography, Vol. 2.15)

 when he described Moby-Dick as "a wicked book."