Bava Metzia 40: Produce, Liquids and Barrels in the Care of Another Person

We are introduced to a new Mishna.  If one person leaves his produce with another, and that person holds that produce together with his own produce (which was agreed upon earlier), he may not be sure how much produce he has taken from the produce.  To account for this, when he returns the produce that he has stored, he deducts the amount that the produce decreased over the course of each year.  The Mishna provides specific figures: 

• wheat/rice: nine half-kav per kor (180 kav)
• barley/millet: nine kav per kor
• spelt/flaxseed: three se'a (18 kav) per for

The Mishna continues: Rav Yochanan ben Nuri  and Rabbi Yehuda argue about the amount that should be deducted.  Don't mice decrease the produce by the same amount whether there is a large or small amount of produce?  Or should the decrease only apply to the smaller amounts of produce, for the value of the larger amounts of produce actually increase because of other factors over time?

The Gemara considers why the amount of produce might decrease.  Mice might eat it, it might be scattered, it might be lost on the threshing floor.  Further, the Gemara speaks of why the produce might increase: over the rainy season, produce might hold the moisture in the air and increase in size.

A second Mishna is shared: If a person deposits a liquid with a bailee, that amount is decreased over time.  Due to evaporation, wine is decreased by one-fifth or one-sixth.  Three log of oil is decreased for every hundred log of oil.  A log and a half is decreased for sediment that falls to the bottom of the cask and a log and a half is decreased for the liquid that is absorbed into the cask.  Refined oil does not require deductions for sediment.  Old casks will not absorb liquid as they are saturated and so there is no deduction in those cases.  Rabbi Yochanan argues that a buyer will agree that the seller will deduct one and one-half log due to sediment, even regarding refined oil. 

How much can a person profit?  Is there not a limit of profits of one-sixth?  If it is permitted to mix sediment with clear oil and sell it together, why should there be any fixed deduction based on sediment?  How will the rabbis determine the best way to ensure that sales are fair and ethical to all parties?  The rabbis discuss how other sales that include residue or sediment might inform these questions.

A third Mishna ends today's daf: If a person deposits a barrel with a bailee and the barrel breaks, what is the halacha?  If the barrel breaks while the bailee is moving the barrel for his own purposes, and the bailee had asked for the barrel not to be moved, then the bailee is responsible.  But if the bailee was moving the barrel to ensure its safety, and the barrel broke whether while in the bailee's hand or at a later date, the bailee is exempt.  

The very beginning of the Gemara considers whether an owner needs to know that their property has been moved or stolen.  The rabbis disagree about this.