Kelim, Chapter Six, Mishnah Three
This mishnah continues the subject of stones lined up in a row to make multiple stoves.
1) If one made two stoves of three stones and one of the outer ones was defiled the half of the middle one that serves the unclean one is unclean but the half of it that serves the clean one remains clean.
2) If the clean one was removed, the middle one is regarded as completely transferred to the unclean one.
3) If the unclean one was removed, the middle one is regarded as completely transferred to the clean one.
4) Should the two outer ones become defiled, if the middle stone was large, each outer stone is allowed such a part of it as suffices for the support of a pot and the remainder is clean.
a) But if it was small all of it is unclean.
5) Should the middle stone be removed, if a big kettle can be set on the two outer stones they are unclean.
6) If the middle stone is returned they all become clean again.
a) If it was plastered with clay it becomes susceptible to impurity when it is heated to a degree that suffices for the cooking of an egg.
Section one: The structure described here consists of three stones, each attached either to the ground with clay or to each other. This will make two stoves, one between each stone. If one of the outer stones is defiled, then the half of the middle stone facing the impure stone is impure. But the side facing the pure stone remains pure.
Section two: If he removed the clean stone on the outside, then the middle stone is used entirely with the unclean stone. Therefore the middle one is now entirely unclean.
Section three: Similarly, if the unclean stone is removed, the middle stone is entirely pure because it is only used with the pure stone.
Section four: If both outer stones are defiled, then the parts of the middle stone that are used with the outer stones are also considered defiled, but if there remains unused space in between the used portions, the unused space is pure. If the middle stone was small and all of it was used to rest the pots whose other side was placed on the outer stones, then the entire stone is impure.
Section five: If the middle stone is removed, the outer stones remain impure if they can still be used to heat up a large vat.
Section six: If after removing the middle stone he returns it, the entire structure becomes pure again. We look at this stove as if it was first destroyed, which causes it to shed its impurity and then was rebuilt. In such cases the vessel does not return to its original impurity.
In order for this stove to again become susceptible to impurity, he must plaster it with clay to attach it to the ground and heat up all three stones such that they could be used to cook an egg. In other wordsthis is a new stove.