X-Message-Number: 17041
From: 
Date: Sat, 21 Jul 2001 00:29:45 EDT
Subject: Refrigerators are good for converting temperatures

Cryonet:

At first, I was a little dismayed by the following two sentences of text 
starting the ninth paragraph of Mike Darwin's post yesterday (Message 17031, 
titled "Liquefied Brains").

QUOTE:
"Finally, in early 1980's as I recall) Jerry Leaf, Hugh Hixon and I examined 
rates of postmortem deterioration in dogs kept at ~23C for up to 48 hours. 
Results were variable but we were surprised to see in even very mushy brains 
that could only be fixed by immersion, that the large microscopic anatomical 
areas of the brain were clearly identifiable even at 48 hours." UNQUOTE

Reading it again made it understandable; a trip to the refrigerator made it 
more so.  I will explain.

Yep, I know that the "squiggle" in ~23C means "about" or "approximately," but 
I had read it as a "minus" the first time through just the same.  Also, I 
still think in terms of Fahrenheit, not Celsius, and maybe always will.  This 
is the rest of the world's revenge on the USA for the emergent predominance 
of English as the "world language."  Under the circumstances, and 
particularly with the language as embarrassingly illogical as it is, I'm sure 
the States deserve it.  And I believe other English-speaking countries at 
least made this and other metric-type switches years or decades ago.  But, 
it's still an irritate.

Anyway, once I recognized we were talking a positive 23C, I was relieved 
(because of all the deterioration noted), but I still was not immediately 
sure what amount of thermal energy/temperature we were talking about.  But I 
sure did know the right way to figure it out fast!  I retrieved my Radio 
Shack digital thermometer from the refrigerator and monitored it for a minute 
or two until it warmed to precisely 23C per its liquid crystal display and 
then I flipped the switch on the back to the Fahrenheit scale to read 73.5F 
on the display.  Now it all makes sense!  Room temperature!

I like fossils.  My father's worn slide rule (retired industrial engineer) 
will be mounted on the wall along with the megladon (sp?) tooth I unearthed 
while inspecting a large tract on the NC coast several years back, but I did 
not really grow up as part of the "calculator generation."  I did not buy my 
first Texas Instruments hand held until my first quarter (of two) at Georgia 
Tech in 1976. So, perhaps more cognitively lethargic than mathematically 
challenged, I normally opt for the refrigerator, however, I am aware of an 
alternative means of going about all of this, and absent a refrigerator, it 
can be rather handy.  And since Cryonet is somewhat "temperature related," it 
may be that an observation and some quick "reminder math" in temperature 
scale conversions are reasonably topical. And since I decided to work it 
through, I took the extra step of committing it to print.  Now wait a minute. 
 Don't laugh, yet. Think quick. Answer on impulse. You have 1/2 second to 
respond to the following question:  You find yourself a victim of heat 
stroke.  Which would be worse, a sudden rise in ambient temperature of 5 
degrees Celsius or 5 degrees Fahrenheit?  Or, how about this: If Mike had 
actually meant to say -23C rather than ~23C, what would this translate to in 
F degrees (i.e., real temperature in standard, propert Americanese)?  My 
answers follow in this post.

So here goes with the conversion mathematics:

Water goes from its freezing/melting point of 32 degrees Fahrenheit to its 
boiling point of 212 degrees, for an indicated temperature difference of 180 
degrees; while a Celsius thermometer would register zero at the freezing 
point and 100 degrees at the boiling point.  For this reason Celsius readings 
are multiplied by 1.8 to equal Fahrenheit readings (180/100).

For example, nitrogen exists at its liquid state at just over -196 degrees C 
(~ -195.7C, I believe).  So, -195.7 X 1.8 = -352.26.  However, there is not 
only a difference in relative scale of "degrees," there is also a difference 
in the "arbitrary" starting points originally selected for the two 
temperature-measuring systems/scales.  Thirty-two degrees must added to this 
mathematical product.  So, -352.26 + 32 = -320.26F.  The temperature of LN2 
in Fahrenheit degrees is about -320F (i.e., ~-320F).

Converting from F to C requires that the 32 degree issue be handled prior to 
the rate conversion and the 32 degrees is subtracted this time around.  And 
the conversion multiple is the reciprocal of the previous rate (1/180/100 or 
100/180 or 0.5556).  To check the indicated conversion result for the ambient 
temperatures for the dog brain experiments cited:

73.5  - 32 = 41.5 and 41.5 X .5556 = ~23C.

So what is the answers from the two questions posed from above?  The first 
answer is that a Fahrenheit degree is not quite as substantial as a Celsius 
degree by a factor of 1.8 (and therefore, while begrudgingly, the USA should 
probably make the switch).  And what about the conversion of -23C to its 
equivalent in degrees F?  Well, I will post the correct answer tomorrow if I 
can figure out how to get the freezer section to go a few degrees colder, and 
if I can figure out where I put that digital thermometer!

Regards,

David C. Johnson, Raleigh, NC

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