Fifty years ago electronic balances were the great new technological addition to analytical chemistry. The instructor for my quantitative analysis class did not inform his students that these were available until after we had been given the gratifying experience of using double pan balances requiring that we 'count the swings' for highly precise and accurate weighings. At the end of the second week we found out just how marvelous the new balances were but not until our notebooks had been filled with many pages of weighings. I still have that notebook and so will share a lab exercise.
The lessons learned from this exercise in 1962 remain with me as a way of conceptualizing the measurement process. All measurements can be represented numerically but also possess a physical reality. Counting the swings on a balance to estimate the last significant figure in the measurement gives a feel to the measurement process that a readout on a display cannot match.
The 3 minute video 'Classic Chemistry - The Way it Was' is based on the notebook entries for one afternoon in the Chemistry 131, Quantitative Analysis, laboratory in 1962. The sixteen pages of entries are mostly weighings with some calculations and notes. That was the way it was.
1 comment:
I found this article by searching: analytical chemistry "count the swings"
I knew somebody had a post on it. Thanks for the memories. FWIW, my analyt prof was doing the same technique 5 years later in '67. He made us love the electronic version
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