[Avodah] Just How hot is Yad Soledes Bo anyway?

[Chana Luntz]

RRW writes:

> My chavrusa is a chemist and I entreated him to share some of his
> experimental data....
> 
> Years ago he played with cooking at the lower extremes of YSB and he
> was able to actually complete some cooking, albeit it did take a long
time.

...

> Now for some details of his hands on experiments.
> 
> Beef:
> > Depends on what you are cooking: I was cooking beef at 131F/55C, but
> > you can go down to 51C safely if the meat is fresh.

Etc.

With all due respect to you chemist colleague's expertise, it seems to me
that all this is, in terms of the halachic debate, not that relevant.  Yad
Soledet Bo is defined in the gemora as being the point at which a baby's
tummy scalds (or however you want to define that phrase).  Given that
experimenting in babies is not an option, we have various halachic arguments
as to what that temperature may be, but determining when something cooks
chemically is not one of them.

Proof of this would seem to come in the form of kli sheni and kli shlishi.
Your chemist friend could no doubt obtain much swifter cooking effects from
a kli sheni and kli shlishi, but again that does not matter -even though in
many cases these have higher temperatures that something deemed a kli
rishon.

The one in common use is to point out that the knife used for shchita is
deemed cold (ie does not need to be treated as though it was cooked by the
blood of the animal it schechted), even though it is in contact with the
body temperature of an animal (43 degrees or so, although others have
pointed out that if you had a sick animal, their temperature can be higher,
just as a human's can, and we still deem the knife cold.  I have seen
figures of 45 degrees at least on that basis).  Not everybody  accepts that
argument.  The Yalkut Yosef that I referred to previously brings an argument
that the fact that a knife is deemed cold when involved in shechting is a
halacha like kli sheni not cooking is a halacha, despite the fact that the
contents of a kli sheni can be well above anybody's definition of yad
soledet bo.  Just as you cannot derive what yad soledet bo is from the
temperature capable of being achieved in a kli sheni, so you cannot derive
yad soledet bo from the temperature that a shechita knife is in contact
with.

I personally am not totally convinced by the argument in the Yalkut Yosef.
It seems to me that the default position should be that we ought to be able
to learn yad soledet bo out, unless we are specifically made aware that this
is not a situation we can learn it from.  Kli sheni is such a situation, it
is always made very clear that it is an independent test of cooking (or non
cooking) that works in parallel to the definitions vis a vis a kli rishon.
As far as I am aware, the case of a schechita knife is not specified as
having its own rules - and hence why, if contact with a heat sources at yad
soledet bo cooks, then why is the blood of an animal not considered a heat
source?  On the other hand, I suppose, given that understanding vis a vis
the sun, which after all is clearly, physically a heat source, maybe you
just say the same thing for the blood of an animal.

On the other hand, where the Ben Ish Chai got his test seems a bit of a
mystery.  The Yalkut  Yosef quotes the Ktzot Hachoshen and making this very
point, that this is not mentioned in the poskim prior to the Ben Ish Chai
(who is after all, very late).  The Yalkut Yosef does say that he has found
some friends for the Ben Ish Chaim, quoting for example the Minchas Shai.
Still, I checked the Ben Ish Chai over Shabbas, and he gives absolutely no
detail as to where he gets his test from.  He quote the bit about the baby's
tummy, then quotes the Drisha (well I only know it is the Drisha because the
Yalkut Yosef told me) that you cannot therefore use a finger to work it out,
and then just states that the general rule is in our hand, if it is too hot
to drink or eat it is yad soledes, otherwise it is not.  Is this some sort
of minhag?

On the other hand, if one was considered able to use modern technological
methods, it seems IMHO that what we could genuinely use modern technological
methods for is to determine when a baby's tummy scalds.  After all, we now
do indeed have a body of medical literature built up about the temperatures
that are dangerous for small children (mostly due to coffee and tea
accidents, I believe).  While you no doubt could have an argument about what
the state is that Chazal were referring to regarding a baby's tummy, surely
what we classify as a burn must fit within that, and so anything that is
deemed to cause a first degree burn surely that would fit within the
definition?

After all, it seems to me, that the gemora could very well have said, if
that is what it meant, that the temperature of yad soledet bo was the
temperature that was too hot to eat or drink.  It did not, it gave the test
as being in terms of a baby's tummy.  I note there appears to be an
independent test in the Yerushalmi, but I am not sure it adds anything (and
if it disagrees with the Bavli, then surely we would pasken like the Bavli).

On the other hand, when I put this to my husband, he said that he could not
believe that the Ben Ish Chai did not know that a baby would suffer severe
burns if subject to heat well below the threshold that he set, and it is
clear from the Yalkut Yosef that Rav Ovadiah is certainly aware of this, so
obviously he does not deem it important, preferring to rely on the Ben Ish
Chai (which really means that this is the psak for the vast vast majority of
Sephardim).  On the other hand, he really does not go into detail as to why
he does not deem it important, and just relies on the Ben Ish Chai, which
given the facts seems very odd.

I also note that when I went looking for the Rav Moshe that RMB quoted,
while he gives the range of temperature quoted, he does not give any reasons
for the temperature range he has given.

All of which is a little frustrating, because I really don't understand why
they get to where they are (except for the shchita test, which does make
sense to me - and which, it seems to me, is probably not that far from the
figure we would arrive at if we used a modern medical test).

> RRW

Regards

Chana