I have been following along with interest. I don't know if I have anything conclusive to add here, except that the 'pine tree' smell is usually an indication of the presence of pinene and/or turpene's (from my Organic Chemistry classes, as I recall).
As a point of interest- It has been proposed that the 'Smokey Mountains' haze consists of tupene's (among other volatile tree oils) and water vapor. These oils being released by pine trees in particular.
However, back to the topic of coral dip there has long been interest in this hobby from extracts of the Melaleuca tree. These products include Melafix. I am pasting a post from an on-line discussion for consideration. Cajeput oil is extracted from Tea trees, also known as Punk tree or Melaluca.
Also as a point of interest, this tree species was imported to the US and planted in the Everglades in a blind attempt many years ago to drain the area of water. It is now considered a major pest/threat and the US Government is spending millions in attempts to eliminate it.
I'm betting this 'oil extract' represents one or more of the 'proprietary ingredients' liste on the MSD sheet kindly provided by Jenn (thanks).
"Cajeput oil contains: 1,8-cineol (14-65%), terpineol, terpinyl acetate, pinene, nerolidol, both free and as an ester of acetic acid, and small amounts of terpenes, such as laevo-pinene. Other compounds include: 20(29)-ene-3beta,17beta-diol, (2E,6E)-farnesol, phytol, squalene, alloaromadendrene, ledene, palustrol, viridiflorol, ledol, betulinaldehyde, betulinic acid, 3beta-acetyl-lup-20(29)-en-28-oic acid, 3-oxolup-20(29)-en-28-oic acid, and platanic acid."
Post is near the bottom of page below...
http://www.reef-geeks.com/forums/reef-geeks/2710-what-dipping-procedures-do-you-use-2.html">http://www.reef-geeks.com/forums/reef-geeks/2710-what-dipping-procedures-do-you-use-2.html</a>
There is a lot more about turpene's being produced by corals that I found, but that's another thread. Hope this helps -Bill