Kelim, Chapter Two, Mishnah Six
1) A damaged jar found in a furnace:
a) Before its manufacture was complete it is not susceptible to impurity,
b) But if after its manufacture was complete it is susceptible.
2) A sprinkler:
a) Rabbi Eliezer bar Zadok holds it is not susceptible to impurity;
b) But Rabbi Yose holds it to be susceptible because it lets the liquid out in drops only.
Section one: A damaged jar is one that is not complete, and is considered damaged even if only its handles have been removed. Mishnah 4:3 will discuss the damaged jar.
If it is found in the furnace before its manufacturing process was complete, then it cannot become impure. In other words, if it was broken before it ever became a complete vessel, then it is pure, even though it has a receptacle.
However, if it is first forged in the oven thereby completing its manufacturing, and then it breaks, since it does have a receptacle it is susceptible to impurity. In other words, once something is a finished vessel, it can receive impurity so long as it has a receptacle.
Section two: The “sprinkler” referred to here was a vessel with one hole above and many holes below. When one would cover the top hole with his finger, the water would not sprinkle out below. According to Rabbi Eliezer bar Zadok, such a vessel is not considered a receptacle and therefore is not susceptible to impurity.
Rabbi Yose holds that it is susceptible because it only lets out small drops. However, if it lets the liquid out faster, then it is not susceptible to impurity.