A ‘Heated’ Discussion
‘The Place of Shechita Is Hot’
To understand our daf, we must examine many halachos pertaining to cooking and heat. It is forbidden to cook on Shabbos and any cooked food on Shabos is forbidden (Chulin 15a). It is also forbidden to cook meat with milk, and hot utensils exude and absorb tastes by means of heat. All these halachos depend on a temperature defined by Chazal as “yad soledes,” a temperature from which the hand involuntarily withdraws (Shabbos 40b; Chulin 105a, b; etc.). But what is this temperature in modern measurement?
A Dispute In Degrees
In one of his responsa (Igros Moshe, Orach Chayim, 4:74), Rabbi Moshe Feinstein, zt”l, writes that “yad soledes” is somewhere between 43 and 71 degrees Celsius (or 110 Fahrenheit to 159 Fahrenheit). In other words, it is clear that a hand does not involuntarily withdraw from less than 43 degrees Celsius and certainly instinctively withdraws from over 71 degrees Celsius. The halachic status of the temperatures between these two numbers is unclear..
Other poskim prove that yad soledes is much less than 71 degrees Celsius. The Gemara (Chullin 105) discusses washing one’s hands (netilas yadayim) with warm water to the degree of yad soledes; it is obvious, though, that one cannot wash one’s hands with water even approaching 71 degrees Celsius (Meor HaShabbos 1:2, remark 14).
Regarding the temperature from which a hand does not spontaneously withdraw: It has been passed down in the name of the Chazon Ish, zt”l (see Meor HaShabbos, ibid, se’if 6 and remarks) that there should be no concern for anything less than 40 degrees Celsius. Rabbi Shlomo Zalman Auerbach, zt”l (Responsa Minchas Shlomo 91: s.k. 8), confirms this ruling based on the Bahag’s statement that an animal’s milk is defined as cool at the time of milking. Since milk during milking may approach 40 degrees Celsius, this temperature is evidently considered cool.
Rav Auerbach adds that 45 degrees Celsius is not yad soledes and proves this fact from our sugya:
A Matter Of Absorption
Rav and Rabah bar Bar Chanah disagree in our Gemara regarding the neck area of an animal (beis hashechitah). Is it boiling or cool? Accordingly, they disagree whether the beis hashechitah can absorb a forbidden taste contained in the slaughtering knife. If the beis hashechitah is boiling, it absorbs the taste, but if it’s cool, it does not.
The Gemara cites an opinion that the disagreement concerns another issue and that both agree that the beis hashechitah is cool. Rashi and the Rosh rule likewise. Although we rule strictly according to Tosfos that the beis hashechitah is considered boiling (Shulchan Aruch, Yorah Deah 10:2), that is only lechatchilah (Shach, ibid, s.k. 14).
(Our Gemara also explains that the dispute only concerns the end of the shechitah. At the beginning, all agree that the beis hashechitah is cool; moreover, the Ritva explains [Shabbos 42a] that even those who maintain that the beis hashechitah is boiling, “it is not so boiling that a hand instinctively withdraws from it.” See Minchas Shlomo, ibid, in the name of the Rosh Yosef.)
From here, our path to part of the definition of yad soledes is short. All we have to do is to determine the temperature of the beis hashechitah and then we can definitively know what is not yad soledes.
A “Feverish” Duck During Shechita
Poskim, says Rabbi Auerbach, do not distinguish between the beis hashechitah of an animal and a fowl. While a person’s average temperature is 37 degrees Celsius (98.6 Fahrenheit) and the average temperature of cattle is 40 degrees Celsius, a duck’s temperature is close to 45 degrees Celsius. At the time of slaughtering, its blood temperature increases by at least one degree Celsius and, if it is sick, it may reach 48 degrees Celsius!
Even if we ignore sick ducks and the increased temperature at the time of slaughtering, we are still left with the clear knowledge that 45 degrees Celsius (113 Fahrenheit) is not yad soledes.