If a person finds an object that somebody had lost, and the object has Simanim distinguishing features whereby it can be identified by the owner he must announce in the synagogue that he found the item. He must specify what the object is, and announce that the owner can retrieve it after naming the Simanim. It is not sufficient to announce that he found an object, without specifying what kind of object, and invite the owner to name the item. For example, if somebody found a wallet, he should not announce that he found something, and then give the wallet to somebody who comes forward and says that he lost a wallet. Rather, he should announce that he found a wallet, and then the one who lost his wallet should come and name the color, the size, and other distinguishing features, such as if it is torn in a certain place, or had specific contents, and so on. Similarly, if a bag containing several items was lost, the owner can specify how many items were in the bag, and this qualifies as a valid Siman.
If the lost item was found in a place where the majority of people are gentiles, the finder is not required to announce the find. In such a case, he may assume that the object was lost by a non-Jew, in which case the obligation to announce the find does not apply. Thus, for example, if a person found something in Penn Station in midtown Manhattan, he may assume it was lost by a gentile and keep the item, even if it has Simanim. If the owner comes along and identifies the object based on its Simanim, then, in certain circumstances, the finder will still be entitled to keep the item. Namely, if the item is something that a person notices immediately when it is lost such as money, since people regularly check their pockets when carrying money to make sure it is still there then the finder may keep the money. In such a case, we may reasonably assume that the owner despaired immediately after the money was lost, since it was dropped in a public place, and thus the finder legally acquired the money. It would then be too late for the owner to demand that the money be returned. Since he despaired as soon as the money was lost, the finder acquired ownership when he found it, and may therefore keep it for himself.
(Based on Ben Ish Hai, Parashat Ki-Tabo)
Summary: If a person finds a lost object with unique features, such that it could be identified by its owner, he must make an announcement in the synagogue. He must specify the kind of object that he found, and the owner should then identify its unique characteristics, such as size, weight, color, and other distinctive features. If a person finds a lost item in a place where most of the people are non-Jews, he may keep the item.
