Strange Case of Dr. Jekyll and Mr. Hyde
How we cite our quotes:
"Changed? Well, yes, I think so," said the butler. "Have I been twenty years in this man's house, to be deceived about his voice? No, sir; master's made away with; he was made away with eight days ago, when we heard him cry out upon the name of God; and who's in there instead of him, and why it stays there, is a thing that cries to Heaven, Mr. Utterson!" (8.31)
Presumably inside the laboratory, Dr. Jekyll is in such depths of despair that he believes only God can aid him.
Here I proceeded to examine its contents. The powders were neatly enough made up, but not with the nicety of the dispensing chemist; so that it was plain they were of Jekyll's private manufacture. (9.11)
We are given concrete evidence that Dr. Jekyll performs his own scientific experiments.
He thanked me with a smiling nod, measured out a few minims of the red tincture and added one of the powders. The mixture, which was at first of a reddish hue, began, in proportion as the crystals melted, to brighten in colour, to effervesce audibly, and to throw off small fumes of vapour. Suddenly and at the same moment, the ebullition ceased and the compound changed to a dark purple, which faded again more slowly to a watery green. My visitor, who had watched these metamorphoses with a keen eye, smiled, set down the glass upon the table, and then turned and looked upon me with an air of scrutiny. (9.27)
The potion goes through a transformative process just as Dr. Jekyll does.