Morgenstein's trades starts with Morgenstein in Inside Geffen (141, 140). The steps below are read from the quest's script on this server, in the order the script's quest stage moves through them.
Walkthrough
1 Talk to Morgenstein in Inside Geffen (141, 140)
When Room in your inventory for what you get; Script check: MISC_QUEST & 4 Choose “Ask him to make a new solution.” then “Counteragent” then “Make” Have with you 1 × 
Alcohol, 1 × 
Detrimindexta, 1 × 
Empty Bottle, 3,000 zenyIt takes 1 × Alcohol, 1 × Detrimindexta, 1 × Empty Bottle, 3,000 zenyYou get 1 × 
CounteragentBwahahahah!
Oh, I just can't wait to make this! Are you ready to begin?
Ooooooooh...... heeheeheeheehee...... yes... like that...... yes... more... more........ heeheeheehee.
.... Aaah.... ahah... ha....ahahooooooooohoh!
Script:
npc/quests/counteragent_mixture.txt:4722 Talk to Morgenstein in Inside Geffen (141, 140)
When Room in your inventory for what you get; Script check: MISC_QUEST & 4 Choose “Ask him to make a new solution.” then “Mixture” then “Make” Have with you 1 × Alcohol, 1 × 
Karvodailnirol, 1 × Empty Bottle, 4,000 zenyIt takes 1 × Alcohol, 1 × Karvodailnirol, 1 × Empty Bottle, 4,000 zenyYou get 1 × 
MixtureBwahahahah!
Oh, I just can't wait to make this! Are you ready to begin?
Ooooooooh... heehee...... yes... like that...... yes... more... more........ heeheeheehee
.... Aaah.... ahah... ha....ahah...oooooooooooooooooh!!!...!!!!!!
Script:
npc/quests/counteragent_mixture.txt:516
Rewards over the whole quest
1 × Counteragent; 1 × Mixture
How this page is made: every step comes from the NPC scripts the server loads for Episode 13.2 (the file and line are under each step). "When" lists the checks the script makes before that branch runs; "Have with you" are the items it counts; experience from getexp is multiplied by the server's 50x quest rate. NPC lines are the script's own text.