Origin of the exact phrase "cold iron"?

Question

Loosely inspired by this closed rpg.stackexchange question titled "What is Cold Iron actually? — Forget what it is; let's talk about the origin of the set phrase "cold iron" in English!

Rudyard Kipling's poem "Cold Iron" (c. 1910) may well have popularized the exact phrase in today's pop culture, but it (1) is extremely recent and (2) isn't directly related to the fair folk.

This great rpg.net thread points to Robert Kirk's The Secret Commonwealth (written c. 1691 but published only(?) in 1893), chapter 1, which uses the exact phrase:

The Tramontains to this Day put Bread, the Bible, or a piece of Iron, in Womens Beds when travelling, to ſave them from being thus ſtollen; and they commonly report, that all uncouth, unknown Wights are terrifyed by nothing earthly ſo much as by cold Iron.

So, did Robert Kirk actually coin this poetic turn of phrase? Or can it be traced back farther?

The defining characteristic here is that we're not just talking about how supernatural beings dislike iron; we're talking specifically about textual sources that describe the elf-repellent iron as cold (regardless of what you think the source means by that).

Answer 1

Likely not a full answer, but expanding on @FumbleFingers' comments:

This 2017 blog post gives a good summary of the question "Why don't fairies like cold iron?", including the Robert Kirk citation above, and tracing the general "goblins' dislike of iron" meme back as far as Pliny the Elder. None of which is quite on-topic, until this citation from Current Literature (1:3, November 1891), in a section titled "The Superstitions of Fishermen":

The saying [aloud] of "cold iron" originates from the belief that if warm blood be drawn from a witch, her power to hurt you is past; as cold steel in all probability, in times when people were less amenable to the law, was the weapon most commonly used for this purpose, the name of the weapon in these days has come to be considered a sufficient and only protection. In reference to this form of superstition, I quote from Brewer: "By drawing the blood of a witch, you deprive her of her power of sorcery."

Current Literature was a sort of Readers' Digest of its day, and attributes this section to something called "The English Ladies' Treasury" — presumably Mrs Warren's, in which case this is just one aggregator quoting another aggregator. I haven't found the original source.

The quotation comes from Brewer's Dictionary of Phrase and Fable (1870), which also gives a very tenuous link to a line from Shakespeare's Henry VI Part 1:

Devil or devil's dam, I'll conjure thee.
Blood will I draw on thee— thou art a witch—
And straightway give thy soul to him thou serv'st.

So here we have a source circa 1890 claiming that the spoken watchword "Cold iron!" derives from the idiomatic use of "cold iron" to denote a bladed weapon, and that the witch-scaring property was not the metal itself but rather the fear of being bloodied. That is:

• witches dislike iron objects (says Pliny)
• but also witches dislike being stabbed (says Brewer), thus witches dislike swords
• swords are referred to as "cold iron"
• therefore (says Ladies) witches dislike the phrase "cold iron"
• therefore (presumably) the phrase "cold iron" got transferred onto iron in general, in the context of scaring witches

I'm not totally sold on the Ladies' Treasury answer, but I have to admit, it has more of its puzzle pieces in place than anything else I've got to offer.

Answer 2

Iron has long been associated with magic and the Wikipedia article "Iron in folklore" is worth a read.

"Cold iron" is historically believed to repel, contain, or harm ghosts, fairies, witches, and other malevolent supernatural creatures. This belief continued into later superstitions in a number of forms:

Nailing an iron horseshoe to a door was said to repel evil spirits or, later, to bring good luck.

Surrounding a cemetery with an iron fence was thought to contain the souls of the dead.

Burying an iron knife under the entrance to one's home was alleged to keep witches from entering.

placing a knife under a bed to "cut" pain.

"Cold Iron" is a substitute name used for various animals and incidences considered unlucky by Irish fishermen. A similar phenomenon has been found with Scottish Fishermen.

The folklore site "Folklore Thursday" is equally interesting:

Some fairy tales are older than any of the languages used to tell them… and the oldest ‘folk-tale’ of all seems to be that of a blacksmith forging a deal with the devil.

These findings were made known during 2016 in an article published in the Royal Society Open Science Journal,[...] The basic story is that of a blacksmith who outwits the devil, causing him to be fixed to a spot and only given leave when he had shared the dark magical arts of smelting and metalworking with the smith.

The association between iron and magic is widespread, and stems from long before the Iron Age. One of the oldest iron artefacts is a dagger found in the tomb of Tutankhamun, having been made circa 3,200 BCE, which is about 2,000 years before the Iron Age. [...] The metal in Tutankhamun’s dagger was worked from iron that had been ‘a gift from the gods’, ‘the solidified tears of the sun’ that had fallen to earth in the form of what we now call meteorites.

Edit to add. From the OED:

Cold adj. 2b. of material substances which in their natural state communicate this sensation by contact. Often as a descriptive epithet of iron or steel, as the material of a weapon.

c950 Lindisf. Gosp. John xviii. 18 Stodon..æt gloedum forðon cald wæs and wearmdon hia.

a1616 W. Shakespeare All's Well that ends Well (1623) i. i. 103 When Vertues steely bones Lookes bleake i'th cold wind.

1771 T. Smollett Humphry Clinker II. 204 To hazard a thrust of cold iron with his antagonist.

1816 W. Scott Old Mortality iii, in Tales of my Landlord 1st Ser. III. 69 Try him with the cold steel.

Answer 3

"Cold iron" in the U.S. Navy is when your moored ship has secured its steam boilers from operation and is now receiving all electric and steam service from connections to the pier.