I've been messing with the alchemist a bunch, trying to find a change that makes it feel better than it currently does. Most of the fixes are related to action economy and quantity of reagents in early levels. I also wanted a way to add additives to your existing items because I don't like having additives trapped behind quick alchemy. Let me know what you think.
Hmm. Let's see...
Fields:
1) the fractional reagent ability from Field Discovery is gone entirely. This is crucial to class versatility, and especially to mutagenist who relies on long term duration buffs. While extending triple products early is a good move, this can backfire.
2) extending chirurgeon's specialty to all non-mutagens is extremely powerful. So is giving them essentially Medic archetype. Looks like a huge buff (which don't get me wrong is kinda warranted), but perhaps too far. Also, if you do intend to keep "all non-mutagens", keep in mind that there is almost no difference between having 4 Bravo's and 6 Bravo's in a party of 4. See point 1.
3) bomber still has very little damage pre-3. Combined with low reagents (despite the 3x aid), this maintains the current issues. The lv5 ability is nifty, but invalidates the lv1 version. I'd rather give it two different abilities.
4) mutagenist looks like a massive nerf tbh. Not only you removed flashback, you added an ability you will never (or close to never) use, because nobody drinks a mutagen during a fight (due to how long they last). Having a buff for one round is... just not worth the action cost here. Having two mutagens at lv5 is good, but having three mutagens starts getting too harsh as the penalties will start eroding into the benefits. Diminishing returns here.
5) lv5 toxicologist dealing energy damage is interesting. I like that it's morning prep only, but at the same time I'm worried there might be little value in keeping them poison.
Features:
1) lv1 powerful alchemy is nice, extending it to all items is nice. We're definitely raising the power level here but hey, it can be good.
2) I like volatile alchemy. I might recommend the DC and damage be based on the item's level (after adding the additive) but other than that it looks fun. Needs the action icon.
3) let's do perpetual all at once. I like the streamlining, I've done it the same way, but keep an eye on the levels. Some specialties have more selection than others. I used 2/6/12 rather than 1/5/11 in order to include sinew-shock and a few others. The 1/hr limitation is interesting and certainly discourages elixir of life spam, but the Common limit feels like it's just sitting there.
4) master in weapons. lol, should've known it was coming. Yeah, this doesn't help for the slew of reasons already highlighted over the years, not last the fact that alchemical bombs do not benefit from this as much as weapons. If you want to bury bomber as an option in favour of melee builds, this is the way - if you want bomber to work out, look elsewhere.
Feats:
1) Quick hands definitely looks like the strongest feat in the alchemist's list. I don't see this being an option - it's either built into the chassis or removed. Note that I realise it only works for the short term elixirs like Cat's Eye (and not 90% of the elixirs, which last forever and are used out of combat), but is still clutch when those are needed. Would take it over most lv6 feats no doubt.
2) fizzy feats! love the idea, and it helps ranged builds a lot, but again we are pretty high on the power level. If you want to set it as a new standard, you'll need to remake a lot of the current feats in order to keep them relevant.
Overall:
It's a general buff with strong emphasis on the mid-high levels which oddly manages to make the class a little stiffer. Chirurgeon is likely the favourite in this version, bomber falls, and additives get a ton of usability which I like, but the early levels still seem to suffer from flexibility issues.
There's a lot of good concepts here but the fact that most of the new introductions are "higher standards" means you're wading into a large-scale remake. Not sure if this is where you want to go.