what does it mean ( but it was a chance stumbling upon a run-down ) ?
Perkin's innate curiosity prompted early interests in the arts, sciences, photography, and engineering. But it was a chance stumbling upon a run–down, yet functional, laboratory in his late grandfather's home that solidified the young man's ardor for chemistry

Question

what does it mean ( but it was a chance stumbling upon a run-down ) ?
Perkin's innate curiosity prompted early interests in the arts, sciences, photography, and engineering. But it was a chance stumbling upon a run–down, yet functional, laboratory in his late grandfather's home that solidified the young man's ardor for chemistry

Answer

I found the entire sentence: But it was a chance stumbling upon a run-down, yet functional, laboratory in his late grandfather’s home that solidified the young man’s enthusiasm for chemistry.

The young man stumbled upon his grandfather's run-down (dirty or possibly damaged) laboratory by chance(accidentally). The lab was still functional, meaning it could still be used and the equipment still worked. His enthusiam for chemistry was solidified by this accidental discovery of his grandfather's lab.

Answer

You really need to provide the entire sentence for context and possibly the sentences prior to and after this one.

Ne manquez pas cette occasion d'apprendre une langue depuis chez vous. Découvrez notre sélection de professeurs de langues expérimentés et inscrivez-vous dès maintenant à votre premier cours !