The vials look like laboratory test tubes, corked and sealed with wax. You also remember that they were not magic. As for determining their contents, it will require unstopping one.
Heather will carefully unstopper one the vials and using my knowledge of herbs and medicine I will tr to identify the contents. Perhaps by smell, viscosity, colour ect.
The game does not go into detail about the content of the vials other than what it can do... so I guess you smell a certain herb or other ingredient which is reknown for often being used in the treatment of deadly diseases.
Darren considers for a moment before nodding, "I agree with Heather. If we are to give you this medicine, I would rather it be under the care of a skilled healer."
Ireena looks obviously dissatisfied with this decision, but will not speak against it.
The Vistani is surprised at your decision, but looks like it accomodates him.
"Ah, good, then ve can all head back to camp. It's not too far from here, but you already know that as you visited already... Vell, most of you that is..."
You turn around and make your way toward the vistani camp instead of the ruined monastery. The sky turning orange as you approach the camp. Looks like you'll have to visit the ruined monastery tomorrow and that you'll probably have to camp at the Vistani's camp tonight.
The disease is unlike anything you've ever seen or heard. The states of the diseased reminds you of the female werewolves you encountered in the sub-levels of the abandoned tower in how they are shivering. As far as you can see, unless you do something, the victims will simply be slowly wasting away...