Was it because of the artist, or the intended audience? Possibly because there were already two silver-colored characters already (Platinum and Tin), and a third might have been deemed too much. Also, maybe kiddies would wonder “Why is Mercury silver, but the mercury in my thermometer is red?” Possibly the artist didn’t know what real mercury is silver, and was basing it on the thermometer fluid.
Anyone ideas???
You’re right: contrast for the characters and the fact that kids would think of mercury as being red from thermometers. Since the comics were full of facts about the elements, they certainly did know that mercury was silver, and probably mentioned that it was also called quicksilver more than once.
Although it’s no longer available in the US, Mercurochrome, a mercury-based antiseptic, was common at the time, and well known for its bright red color.
Cinnabar (HgS) has historically been used as a red pigment in art. Possibly the artist considered red the next best thing to silver.
Mercury in a thermometer is silver. If the thermometer is red, it’s using alcohol and it’s not even called a mercury thermometer (which were used for measuring body temperature; alcohol thermometers are used for weather temperature).
In any case, the issue was the usual one: no one particularly cared if it was an accurate representation of mercury. If the question had come up (and it never did), it would have been explained by saying that the surface of the mercury had oxidized (if they wanted) or just "it’s part of the process and can’t be changed, much in the same way that Platinum was female.
The writer and artist being, just for the record, Robert Kanigher and Ross Andru. And yeah, I should think it was probably the thermometer thing.
I remember being ill in bed as a child, and my Mum bringing me back some old 1960s Metal Men comics from the second-hand bookshop in town. I lay there in bed feeling both cosy and sorry for myself, reading those comics and eating Dairylea cheese triangles. I still get a power-of-suggestion hint of Dairylea’s taste and smell every time I see a Metal Men comic of that vintage today.
[aside]
In a nearby pharmacy last month, on the shelf with the old-school topicals such as Witch Hazel and Dr. Whatzisface’s Castile Soap:
“MERCUROCROMO” (subtitle): “Mercury Free”
I stood and stared and walked away shaking my head and grumbling.
[/aside]
Cinnabar is also the ore from which mercury is obtained, IIRC.
I kind of figured for thermometers. Is Mercury the planet reddish? That could be a thing, I guess.
Mercury, the planet, isn’t reddish. Looks like a star. (Mars is visibly reddish.)
I’d always thought it was an allusion to Cinnabar.
And then there’s Copper… (Who?)
And here’s me thinking it came from HG Wells. 
I loved those comics. So geeky! And I recall reading in the comic itself an explanation that Mercury’s red color was based on the color of thermometer (despite the fact that it was the alcohol and not the mercury kind).
They also had an explanation of how Mercury held his shape even though the metal is liquid at room temperature. His body was actually a transparent shell (some kind of super plastic I guess) that held the liquid mercury inside it. How exactly the mechanics of that worked wasn’t explained.
ETA: Actually onthis page Mercury explains his appearance to Iron by saying, “It’s evident you’ve never seen a thermometer.”
He went to some meetings in the '30s.
I think I only ever read one Metal Men comic, although it was enough to develop a bit of a crush on Platinum
However, in the particular story, the Metal Men (minus Platinum) are forced into a big crucible and heated, to the point that they have to combine powers (by alloying) to escape. Mercury spends his entire time whinging that he cannot form an alloy, but should be integrated into an amalgam, instead. :smack:
The youthful chemist in me was already aware that Tin, Gold and Lead would more readily dissolve into Mercury to make an amalgam at room temperature, and that Iron would not no matter how much heat you added (or at least, until the Mercury evaporated into toxic vapours), and that Lead and Tin and Gold would have been a puddle of pewter-ish metal before Iron broke into a sweat.