Craft and Knowledge questions... (Alchemy specifically)

[Akennedy]

Okay, so I've been working on a class called the Tinkerer for quite a while, and posted to twice in homebrew design. But, I've a discrepancy that I can't quite solve. This tinkerer knows an early form on chemistry, which would be alchemy, but would alchemy be more craft or knowledge? I, on a personal level, go to a university lab on a regular basis and it seems more to me like knowing how to do it than just making it. Craft, to me, seems more like "Making this blade sharp makes more sense, as it would hurt more." Knowledge would be "the properties of X chemical are yadda yadda yadda, and if i combine it with chemical Y it will produce.."
So, to the ultimate question... should alchemy be a Knowledge skill or a Craft? does it represent the ability to make a chemical or know how. (I've often seen a blur between those two skills, because knowing how to do something and doing something are different things, but kinda the same). I hope there are people who can help me here. Thanks for your time!

[Riffington]

All three exist. If your goal is to create things, take Craft. If your goal is to deduce the properties of the Philosopher's Stone, take Knowledge. If your goal is to fleece passers-by, take Profession.

[Balkash]

Actually I think it could be both. I'd figure for Knowledge, if he knows an early form of chemistry. This could be if he needs to understand the chemical mix of something he finds, or if he needs to know the correct mixture of something. I'd figure Craft would be something else. If he builds something, it'll be Craft(something), not Craft(alchemy). He isn't making alchemy. In short I think it'd make sense to me to make a Knowledge (Alchemy) check to see if he understands what is needed in proper ratios and such, than a Craft (whatever he wants to build) check to see if he can actually build it.

[kamikasei]

There exists a Craft (Alchemy) skill which is used to create a variety of useful things. Gnomes get a bonus to it. You can find the details in the SRD.

If this fits your concept at all, then I would recommend sticking with it for simplicity.

edit: A thought... since the Craft skill is already in the rules, if your class is to know something of alchemy, it seems like it should have it. If you think a Knowledge skill is more appropriate or covers things Craft doesn't, you might try combining them in some way. Give the class a feature that lets them substitute Craft (alchemy) ranks for Knowledge (alchemy) ranks when making a check. Give them bonuses to both and the ability to use Knowledge untrained.

In short, don't oblige them to have ranks in two basically identical skills.