“What about the opinion of the Shulchan Aruch?” asked Aharon.
“The Shulchan Aruch is even more stringent,” replied Rabbi Dayan. “He rules in a number of places that intention for the particular mode of acquisition is also critical. Thus, even the person who fell on the metziah does not acquire it.” (C.M. 198:12; 200:8; 268:1)
“Thus,” concluded Rabbi Dayan, “since Aharon had no intention whatsoever of acquiring the Chumash when he picked it up, he did not acquire it even according to the Rama, and it belongs to Yosef. I would recommend posting a notice, though, to see whether someone claims the Chumash and return it, beyond the letter of the law.” (See C.M. 259:5; Pischei Choshen, Kinyanim 1:13; Dvar Chok Umishpat, pp. 20-22)