1) SUNK IN DUNG
OPINIONS: The Mishnah describes the process of the punishment of Sereifah. The sinner is placed up to his knees in dung, his throat is forced open by two people who pull a cloth, wrapped around his throat, in opposite directions, and a molten bar of lead is thrown into his mouth which burns up his innards and kills him.
It is clear how the last two parts of the punishment, forcing open his throat and throwing in a molten bar of lead, are part and parcel of the punishment of Sereifah. In what way, however, is sinking him into dung up to his knees related to Sereifah?
(a) RASHI (DH Meshak'in Oso) explains that he is sunk up to his knees in dung so that he not move around wildly and cause the lead to miss his throat and fall onto his body.
The YAD RAMAH asks a number of questions on Rashi's explanation. Sinking him into dung until his knees will not stop him from wildly thrashing his head and upper body. He may still cause the lead to miss his throat. Moreover, one who is punished with Chenek (strangulation) is also sunk up to his knees in dung. However, there is nothing thrown into the sinner's throat in that form of execution, and thus there should be no need to stabilize the person.
(b) The YAD RAMAH explains that the reason why the sinner is put in dung is that people who are being executed often excrete waste involuntarily. In order to prevent damage to the clothing of the agents of Beis Din who put the person to death, the person is placed in dung in order to hold him steady so that the direction of his excretion will be known.
Why is this precaution not taken for all of the four punishments of death? Since Sereifah and Chenek take longer than Hereg (death by the sword) and Sekilah (stoning, whereby the transgressor is thrust down from the height of two stories, and then, if he is still alive, a large rock is thrown down upon him), the fear of death which causes the person to move his bowels involuntarily is prolonged, and therefore it is more likely that he will do so. This is why these punishments include sinking the person up to his knees in dung.
How does Rashi answer the questions of the Yad Ramah?
1. The LECHEM MISHNEH (Hilchos Sanhedrin 15:3) answers the Yad Ramah's question from Chenek. He explains that the reason why the sinner is sunk in dung in the case of Chenek is that it is a form of death similar to Sereifah, where a form of strangulation is also utilized. The Chachamim therefore decided to make them similar in this way as well.
2. The TIFERES YISRAEL explains that the purpose of sinking the sinner in dung is twofold. Although the Mishnah says that he is sunken only up to his knees, this gives him the opportunity to sit down in the dung, which would cover most of his body. Why would he want to have the option of sitting down? Since his natural reaction is to have his throat avoid the molten lead, the lead might fall on his body and cause him more pain. If he would bury himself in the dung, the wick would not burn his body.
Why, though, is he placed specifically in dung? Placing him in dung is part of his punishment; it is intended to cause him embarrassment. Although the Tiferes Yisrael does not quote Rashi, this explanation is consistent with Rashi's words. (Y. Montrose)

52b----------------------------------------52b

2) WHY IS A VERSE NEEDED TO EXCLUDE A KATAN FROM THE DEATH PENALTY?
QUESTIONS: The Gemara infers from the verse of "Ish" -- "a man" (Vayikra 20:10; the verse actually reads "v'Ish"), that the Torah includes only a man (over the age of Bar Mitzvah) in the punishments of illicit relationships. A minor is not punished. The question is obvious. Why is a special verse needed to teach that a minor is not punished? A minor is almost never responsible for sins he commits before he reaches adulthood. Why would one think that he should be put to death for this sin when he is a minor?
ANSWERS:
(a) The SEMAG (Lo Ta'aseh 103) asserts that the Gemara is not exempting the minor from punishment; it is obvious that he is exempt. Rather, the Gemara is exempting the woman who has relations with him. The Gemara means that a woman who has relations with a minor with regard to Arayos (that is, he is under the age of nine) is exempt from punishment. The Gemara in Nidah (45a) states that a woman who has relations with a minor who has reached the age of nine is put to death.
(b) TOSFOS in Kidushin (19a, DH Ish) and Erchin (3a, DH li'Me'utei Katan) gives a different answer. Tosfos says that one might have thought that the Katan should be killed just as an animal is killed in the case of an animal with whom a man had relations. Although the animal did nothing, the Torah requires that the animal be put to death due to the embarrassment of the man who is put to death; the animal, if left to live, would be a constant reminder of the man's sin, and therefore the animal must be killed. Similarly, one might have thought that a minor (over the age of nine) should be put to death if he had prohibited relations with an older woman. Since his existence would be a constant reminder of her sin, one might have thought that the minor should also be put to death. The verse of "Ish" teaches that he is not put to death.
Tosfos' answer seems problematic. Why would one think that a minor should be put to death just like an animal? How can the two be compared? It is logical that the Torah commands that an animal be put to death so that it not serve as a reminder of a man's sin. After all, animals were created to be subservient to man. (See, for example, Rashi to Bamidbar 22:33, who mentions that Hash-m caused the donkey of Bil'am to die, right after it defeated Bil'am in an argument, due to the honor of Bil'am.) Why, though, would one think that a child should be killed because of this reason? How can the embarrassment caused to a sinner, who is put to death anyway, be reason to kill an innocent human being?
This question was posed to HA'GAON RAV YOSEF SHALOM ELYASHIV shlit'a, who answered based on the Gemara later (55b). (His first response to the question was, "Did you ever learn Sanhedrin?") The Gemara there discusses the reason for why an animal is killed when it had relations with a person. The Gemara asks is it because of "Kalon" (the embarrassment that the act causes to the sinner), or because of "Takalah" (the fact that it served as a stumbling block and caused a man to commit a sin)? To answer this question, the Gemara quotes a Beraisa which discusses a girl over the age of three who has relations with "any of the Arayos stated in the Torah." The Beraisa says that the adult who has relations with her is Chayav Misah, but the girl is not punished. What is the meaning of the phrase, "any of the Arayos stated in the Torah"? The Gemara explains that this phrase teaches that even if an animal has relations with her, it is killed. In this case there is only "Kalon," as the animal is a reminder of an embarrassing and disgusting act, but there is no "Takalah," as the girl is a minor and therefore her act is considered no worse than an accidental sin (see Rashi to 55b, DH Takalah Leika). The Gemara answers that because she committed this act with the animal willfully, there is "Takalah," but the Torah had mercy on her and exempted her from death. This is why there is no proof from there that the death of the animal is due to "Kalon" and not "Takalah."
Rav Elyashiv explained that it is clear from the Gemara there that a Katan should be killed for willful perpetration of such a sin (for the reasoning behind this, see Insights to 55b). Rav Elyashiv suggested that when Tosfos in Kidushin and Erchin says that the Katan should be killed like an animal, Tosfos is working with the logic of the Gemara later (55b) that the Katan indeed is guilty to some degree for committing this act. This guilt, combined with the fact that an animal is put to death, provides grounds to think that the Katan should be killed, if not for the verse of "Ish." (Y. Montrose, as heard personally from Rav Elyashiv shlit'a.)