Happy takes all of the Scrolls and puts them in his backpack.
While he does he says to the others: "There is a name on one of these scrolls, Ulric Theobrand. I guess he also has to do something with all this."

You can taste a small amount to discover the effects. The glittering red potion you can assume with certainty is a health potion, but you'd have to taste to find out the strength of it.

(Didn't realize you could find out in this way until now. I always assumed one needed to either drink all of it or casting identify to find out what it was. So nice and easy. Here's what you find assuming you do so.)

You uncork the health potion and take a small sip. You taste a slightly stronger earthy flavor than your run of the mill basic health potion and you feel the familiar buzz of restoration (Greater Health Potion). Moving to the vial with the nail clipping, you uncork and sip it. It tastes as if you just licked a rock. Your muscles also begin to tense and feel as if they are going to swell (Potion of Hill Giant Strength [STR score is boosted to 21 for one hour]). You set that aside and move to the last one with some excitment. As you uncork it, you bring it to your lips and pause as an intense acrid smell takes your breath away. Instead you let a drop fall onto the table. The droplet hits and begins to sizzle as the wooden begins to eat away in the location (Vial of Acid).

Lucas, you jump to try and grab the arms of the stone entity, as if beginning to climb a tree. As you bodyweight is put onto the arm, it snaps. Your suddenly back on the ground with a heavy stone arm in your hands. The statue wobbles a few times before coming to a rest.

You all notice a slight haze starting to accumulate. Nothing serious yet, but Arlo's work is beginning to make an appearance.

“I think it’s time we left,” Arlo says a bit nonchalantly as the smoke makes its appearance 

Noticing the smoke, Sieghart nods in agreement with Arlo. The group seemed to have searched the place well enough. All that remained was the chest. Sieghart moved over to open it and look at its content.

Disappointed, Lucas makes his way toward the exit.

Happy gets ready to leave this place. “Let’s get out of here”

Sieghart, you find a purse of coins, various clothes for fiddling around in his workshop, and a leather bound book. Looking in the purse, you'll see 26 gold, 15 silver, and 4 copper.

Making your way out of the laboratory and back into the hall you find that it is indeed smoky, but the thickest and nastiest smoke is rolling across the ceiling, up the stairs, and into the temple.

Collectively holding your breaths and keeping low you all feel your way up the stairs until you find yourselves back in the temple, which has also been collecting smoke. However, the structure is large enpugh that the smoke is no major hindrance.

Is there anything else you all would like to do before making your way back down the waterfall?

I don’t think so. Does the smoke make any secret doors etc apparent?

I think we’ve done all we wanted. We should leave while we can still breath normal air

Arlo, make a perception check for your travel from the lab to the temple.

Quote from Dungeon_Maxter >>

Arlo, make a perception check for your travel from the lab to the temple.

 12 

As you begin exiting the lab, you scan the walls for any smoke disappearing through them, indicating a hidden passage. Entering the room between the lab and the ghoul's holding cell, a small bored hole catches your eye instead. It does so because, though this inner sanctum is ancient, the walls have remained in impecable condition with no cracks in the mortar to be found. Swinging over to give a quick inspection, you see that it is a key hole.

“Didn’t somebody pick up a key along the way domewhere? I’ve found a lock!” Arlo says staring right down the keyhole.

Sieghart remembers the key he found after their battle with Orbid. "I found one earlier. Can’t hurt to try it out..."

He goes over to try and unlock the door.

The key goes in and turns with ease, resulting in a series of clacks and knocks from within the wall. When the sounds cease a door sized section of the wall recesses the depth of the stone blocks, and gently lowers into the floor until it is flush. The torchlight bathes the room allowing you to see the contents, which are two medium sized chests, two ornately made clerical garbs, a ceremonial scepter, and a ceremonial longsword (blunted edges and rounded tip, but could easily be commissioned to a weapon smith to make it leathal).

The lack of activity in this secret room is apparent by the layer of dust coating everything and no foot prints to be found.

Can we carry the chests?

Given their size you think that either a pair could carry one with relative ease, or the two strongest could each heft one but might need a break every so often. This is assuming they are both full. 

Arlo will pick one up and start leaving. “We’ll check ‘em out once we’re clear of the smoke.”

Happy takes the ceremonial scepter as he wants to inspect it later. He puts it in his backpack. (assuming it is small enough to fit)

"I don't know if I can carry the second chest alone. Maybe someone can help?"

"Here. Let me give you a hand." Sieghart takes one of the handles of the second chest and helps Happy carry it out. Noticing the sword out of the corner of his eye, he also picks it up on their way out. He didn’t see much use for it, as it was blunt, but maybe one of the other could do something with it once it was restored.