1. chemistry of changing baser metals into gold.   Hint First letter clue   2. opening or gap.   First letter clue   3. channel for fluid flow or aqueduct.   First letter clue   4. division into two classes.   First letter clue   5. agent to speed up chemical reaction without it changing.   First letter clue   6. substance formed by decay of organic material.   First letter clue   7. lizard noted for changing color to surroundings.   First letter clue