I don't use alchemy in Morrowind and Oblivion... I just find it to boring and flawed... I mean wouldn't it make much more sense if a master of alchemy didn't somehow know all usage of an ingredient without ever having used it? I'm hoping for a system somewhat like this:

Every single alchemy ingredient had a few effects, fx. a bearclaw had damage health 25 points, a 90% chance of giving weakness to disease 75 points for 25-200 sec, and a 50% chance of contracting Brainrot (or another disease), and a bear tongue had restore fatigue 10 points for 10 sec, a 25% chance of giving weakness to disease 45 points for 50-100 sec, restore health 5 points for 2 sec, and a 65% chance of contracting Brainrot (or another disease).
Now would it make sense that someone knew the usage of every single ingredient without ever using 'em... the only 3 ways of finding out what an ingredient does would be 1. drinking/eating it. 2. bringing it to an alchemist and paying him for info, this should however not always be just as successful, some alchemists might only know two effects on a 3 effect ingredient, other might know no of that exact ingredients effects (giving you your money back), and some may know all its effects. 3. finding/buying a note witch says something like: I've spend years researching diseases, so far I've gained much knowledge on brainrot, it is commonly gain from contact with bears, most notably their claws and mouth... the tongue in particuler have a large chance of giving you brainrot and lowering your defences a against other diseases, but the claws often course infection and even though the chance for brainrot is smaller, they mostlikely will leave you in a much worse condition and therefor making other diseases more common. While making potions you have a choice of adding a pinch of *random ingredient* (10%) half a *random ingredient* (50%) a *random ingredient* (100%) a dozen of *random ingredient* (1200%) finally you should have a choice of witch potion your making, fx. standard potion of healing. shopskeepers may give you a bounty if you sell a potion as something its not, and whoever bought it survives the encounter... journayman (and above) alchemists should be able to only use certain parts of the ingredient, fx. the tips of bearclaws being the part that damages your health, the middle should be the part that weakens you against disease, and the bottom should be the part witch can give you brainrot.
Therefor leaving a "potion of cure disease" witch is really a potion of 100 points posion for 10 sec might be quite usefull while assassinating.
There should also be notes saying fx: How to make a potion of extreme holyness (witch makes damage to holy places appeal in area): 5 entire canis roots, 3 cups of holy water, and a single pinch of the grayest part of a vampires dust.

What do you think of this system?

I didn't read everything because I just woke up and that's a little much, but I think I got the gist of what you're talkig about. Instead of automatically knowing the effects of unfamiliar ingrediets because you're a master, you suggest that using certain ingrediets more will unlock it's other effects. Or by learning about it through various sources in the gameworld.

I have no objection to this. It makes sense, and it would make alchemy a lot more engaging.

More engaging? Perhaps.

More complicated too.

The effects should never ever be strait forward visable one you scroll onto an ingredient (Morrowind, Oblivon) instead you must pay alchemists for knowledge or get your hands on notes... perhaps if writing on parchment is available you could take notes...

I liked just putting random things together and see what will happen

I never really had that much problem with the system.
The only thing that I would change would be to add the ability to select the desired effect that you want (like restore health) and the ingrediants that give that effect are automaticly selected for the posion

I never used Alchemy in Morrowind or Oblivion.

I didn't see the point of all the equipment, didn't understand the primary and secondary effects and couldn't be bothered writing down recipes for a health potion when I have restoration.

With Alchemy being moved to Stealth, I can see alot more potential for useful items that may not otherwise be available for purchase such as smoke bombs, flash grenades, poison gases and poisons.

I would like to change ingredients using a mortar and pestle : grind bones into bonemeal, grind flowers into paste and make useful powders like gunpowder.
For potions I would like to use 1 more tool and that's it.

Yeah smoke bombs would be nice... and that grind bones into bonemeal ain't a bad idea...

logically that would make sense. but it would make alchemy hard as hell, since you would not be able to know what affects ingrediants do without having already made something with them before. at least it would be hard until you memorized them, but I prefer that games don't use up the precous space in my brain that i use to memorize with because I have serious irl stuff that I need to remember, specificly numbers that I cant afford to forget.

It sounds much better than in Ob atleast (can't remember in morrowind) and much more rewarding.
Use this, and you learn about it. Learn about it (from alchies/notes etc) and you can use it to greater effect.
Great idea. Very engaging and hope they can put it in.

As far as choosing an effect ie. restore health, a new interface could make that really easy (a drop down menu with a list of known effects and what causes it)
and I would love to see something similar ingame.

Well... as said by the thread creator there were tons of small parchments like: mix boar meat with mushrooms to get restore health potion... all those would suddenly have use with a system like this, and it would also add for vendors to identify ingrediant uses for a prize... this would add even more difficulty to it but 'til now alchemy have been mix A with B with no thought whatsoever and sell it to get profit.

If you could space that out a bit... I didn't bother too read it. Too cluttered.
One thing we need in alchemy is an effect filter. Block out effects that we don't desire. And the option to choose how we use a creation (selecting if its a potion or a poison (if its 3/4 bad effects, it should not be a potion))
Alternative ways to use poisons, like a sort of make-shift bomb to hit multiple people. Using it on someone that is asleep without having to stab them, that general idea.

A while back Pete said on twitter that he spent "many a lunch" discussing Alchemy with one of the designers and that it was "well looked after." Sounds pretty reassuring to me.