I believe the correct answer is: It suggests the principles have the illusion of truth.
The effect of using the word chimerical to describe the powers of the principles of Agrippa in the line of Mary Shelly’s novel “Frankenstein”:
“If... my father had taken the pains to explain to me that the principles of Agrippa had been entirely exploded and that... the powers of Agrippa were chimerical... I should certainly have thrown Agrippa aside...”
Victor suggests that the principles have the illusion of truth, as chimera represents the deception or illusion of the mind. He wasn’t satisfied with the knowledge and scientific training he had and he wanted to apply himself to the more “rational theory of chemistry which has resulted from modern discoveries”.