It's back! MineChem version 2, Pre-Release 1 is now available for download.
Add chemistry to your minecraft world. Craft machines that decompose minecraft items into elements
and molecules. Use the microscope to discover new molecular structures. Operate the Chemical Synthesis Machine to turn elements back into items. Turn your coal, sugar or even spider eyes into diamonds!
Minechem 2 is designed to work alongside Buildcraft so you can build automated chemical factories. Minechem comes preconfigured to work with Forge's ore dictionary.
Of course, I give permission for this mod (v2+) to be on any FTB mod pack.
Please head to the thread on Minecraft Forums for more information:
http://www.minecraftforum.net/topic/1611745-minechem-2-pr1-brand-new-the-chemistry-mod/