- Transmutation Master
- "Allows an Alchemist to sometimes to get greater results when transmuting materials."
- Instant cast
Alchemy specialization obtained by completing the quest 
[70] Master of Transmutation from Zarevhi at the The Stormspire
To change mastery: Talk to the quest giver of your current mastery and pay the 150g fee. Then talk to the quest giver of the mastery you want and acquire the new mastery instantly.
Transmute Mastery Issue- 12/21/07 | 2007-12-21 08:02 | 
Nethaera
As posted by Pavonum in the Customer Service Forum http://forums.worldofwarcraft.com/thread.html?topicId=3547795433&sid=1&pageNo=1#2 :
As of the 2.3 content patch, there's currently an issue with Transmutation Mastery by which the percentage chance to receive additional results from transmutations — aside from Transmute: Primal Might — is lower than the intended value. This is likely contributing to the dearth of procs you've observed, and I'd like to offer my apologies for any consternation that has arisen as a result of the discrepancy. I'm happy to report that this matter should be resolved in a future patch, but your continued patience in the interim is appreciated. :)