The chemical decomposer is a machine used for breaking items up into the molecules they're made of, and for splitting these molecules into their individual atoms.
The chemical decomposer is used by putting the item to be decomposed in the middle slot, and providing empty test tubes in the 4 slots to the right of that. Resulting molecules/atoms will be put in the 9 bottom slots. Be careful, it decomposes very, very fast.
This machine requires Buildcraft power to use, which can be provided using either Buildcraft's own conductive pipe, or using Thermal Expansion energy conduits, or Galacticraft aluminum Wiring. It has an internal storage of 10,000 MJ, and a maximum usage of 20 MJ/t. Energy stored and used can be viewed using the "Energy" tab to the right of the GUI