Today I am working on a Boston Cream Pie for my husband’s
birthday. It is his favorite. I made the filling from scratch. One of the steps is adding a mixture which
has been boiled for one minute into a slightly beaten egg yolk. Then putting that mixture back in the pan and
boiling it for another minute. If you
don’t understand the reasoning behind this, you might think “that’s silly!” I’ll just add the egg yolk right into the
boiling mixture….why be dumping things back and forth?” If you were to do that, you would not end up
with a nice rich sauce. You would end up
with a milky sauce with chunks of cooked egg floating around. Direction of addition matters.
It made me think about my days in college as a chemistry major. The second semester of organic chemistry most
students could take a regular lab session, but majors had to do something
called “Special Preps.” We would go to
the professor’s office and be given an index card with the name of the compound
we were supposed to create. This might
also include the reagents available to us.
We would then have to research in the chemistry library and determine
how this substance had been previously made, check out with the professor if we
were on the right track, and then hit the lab to create the compound.
On one of these occasions, I researched the substance I was
assigned, and discovered the only place in the literature where it was recorded
was in a Russian journal. I do not speak
Russian. I went to see my
professor. He knew that is what I would
discover, but he wanted me to go through the process. He then handed me another index card on which
he had written the translation from the Russian journal.
I assembled my equipment and followed the directions
carefully. This involved carrying out
the procedure in “the hood” where I was shielded, and any resulting gases would
be safely exhausted. The main flask in
which the reaction would occur was packed in ice, so obviously I was supposed
to expect an exothermic reaction. I was
not expecting an explosion, but that is what I got. The reaction was so violent that it blew the
glass stoppers out of the equipment.
What was left in the flask was a stringy mess of a polymer. I knew I was not supposed to get a
polymer. A liquid was expected, and I
knew at what approximate temperature it should come off and condense.
Thinking maybe I had inadvertently added too much, I ran the
reaction a second time. This time I was
careful to add only one drop of the reagent to the one in the main flask. The result was similar. I now suspected that the direction of
addition should be reversed. Instead of
adding Reagent B to Reagent A, I should be added A to B. But, the professor’s translation said B to
A. Did I really want to confront the
professor with the notion, he had translated incorrectly? I tried a third time with the same results.
I took a deep breath and went to the professor’s office. I told him I was getting polymer, and as
diplomatically as possible, I asked if perhaps the direction of addition was
reversed in the translation. He readily
agreed that was probably the case.
I returned to the lab and tried the fourth time. This time adding A to B. Much to my delight, I did not get a polymer,
but a liquid which boiled off and condensed at the predicted temperature. The professor was delighted with my results,
and I learned something important.
Transferred to the kitchen, it means do not add egg to a hot
liquid. Add small amounts of the hot
liquid to the egg, so that the egg doesn’t cook and is heated up
gradually. We haven’t eaten the Boston
Cream Pie yet, but I licked the spoon after making the filling, and it is
yummy! I definitely never licked anything in the chemistry lab!
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