Making the Acid

[Romulator]

Assuming that this Vessel is the Container/Jar (Can't remember exactly), and you have gotten 4 Chemicals (which have the same image in the inventory, but different names), select the Container/Jar from the inventory. Double click it and hover it over the valve machine. If you see that the Jar becomes more white or glows slightly in the middle of the screen, click That should place it, then you can turn the valves which will fill the jar.