Start of Chapter 7:

Emerald decides to go and try some alchemy ingredients himself. He wants to make a potion. How impressed would Joyride be if he had one made before she came back!

Taking his money, the potion book he borrowed, and the invisibility potion, Emerald steps out the door to Whitherwater.

Emerald supposes he could just try to find an apothecary, but it'd be more fun to find some ingredients himself, if he only had some idea where to go.