Correspondence
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1
CENTIGRADE-FAHRENHEIT TEMPERATURE CONVERSION DEAREDITOR: EDUCATION, page In the December issue of the JOURNAL OF CHEMICAL 2946, I noticed a topic headed as above by JOSEPHG. BLANN,David Starr Jordan High School, h s Angels, California. What appears to the present writer to be a more simple means of conversion is the following: (1) To Centigrade add 40" multiply by 9/5 and subtract 40' or To Fahrenheit add 40' multiply by 5/9 and subtract 40". In either case add 40" at the beginning and subtract 40' at the end. If one is going from low to high (C. to F.), multiply by the improper fraction, 9/5. Or if one is going from high to low (F. to C.), multiply by the proper fraction, 5/9. There is really no formula to get wrong and this is the easiest method I have ever seen for converting one temperature into another. (2) Another easy conversion is to take as a basis 20°C. equals 6S°F. With that one can change C. to F. by solving how 20°C. equals 68°F. 20DC.multiplied by the improper fraction, 9/5, and 32' added to the result is the only way 20°C. can equal 6S°F. This being true then, one always has a ready means for conversion. By working this backward one can go from F. to C., thus 68'F.
- 32'
=
36' X 519 = 20%
Other numbers, for example, 100°C. and 21Z°F., could be used instead of 20°C. and 6S°F. ALFREDM. EWING* Tae Omo SmrB U m e n s m COLUXBUS, OWO
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* Graduate student, physical chemistry. DEAREDITOR: EDUCATION carried an TEe December issue of the JOURNAL OF CHEMICAL article on pages 2946-7 by JOSEPHG. BLANN,on the topic of conversion of Centigrade to Fahrenheit by referring to the boiling point of water, instead of the freezing point of water as the standard texts employ. This article created a great deal of interest for me, because I felt it was just as difficult to remember to use 212" and 100' as boiling points and substract the correct numbers at the right time, as in this illustration: 20°C. = ?OF. 20°C. is (100 - 20) 80°C. below the boiling point. Therefore, take 9/5 X 80 = 144'F. below the boiling point or 212' - 144' = 68°F. 370
