142. Pro-mutuum.

Whenever a person, acting under misapprehension as to an existing fact or state of facts, delivers to another a chattel which cannot be restored in specie, there arises the quasi-contract of pro-mutuum, which imposes upon the recipient the obligation to restore its equivalent. Pro-mutuum differs from mutuum1 in that this obligation is imposed by law, whereas in mutuum it arises out of the voluntary agreement between the lender and the borrower; it resembles mutuum in that the subject matter to which it relates must always consist of money or fungibles, that is, chattels which, owing to their being consumed