You try to talk to Tarzan but only grunts escape your throat. You're an ape, a gorilla, now, so of course your vocal cords are of no more use for human speech.
"Ook?" asks the ape-man.
You do not know what to say so you ansewer the same.
"Ook," you utter timidly.
"Ook? Narh go ook takalo ook! Jargle! Ook!" exclaims Tarzan with a big smile.
"Ook," you repeat to this sentence you cannot possibly decipher.
"Ook?" says Tarzan again.
And once again you say the same word.
"Roog bo ba gha."
"Ook," you say again.
The ape-man then sneers down at you.
"You human transformed. I knew. Tarzan smart!" he claims loudly while thrusting a thumb at himself.
Uh-oh... Now you're in a worse situation.
"I knew from start, then I talk and you cannot talk ape. You no ape! You bad man sent here to be punished! But you no real gorilla. You no real Tarzan friend!"
You look at him in pure fright. Tarzan knows! But what was the liquid? Tarzan must have guessed what you were thinking because he grins evilly.
"Potion to make sure you not enemy anymore. Potion to stop you pretending you friend of Tarzan and of other apes."