correction: PCE

[ttweed@wildrockies.org (Tony Tweedale)]

I was kindly corrected--the '-per' prefix is greek and means fully
saturated in organic chemistry (ie all the available  H's are substituted,
in this case w/ Cl).  Generally it means "fully", totally", etc..  I had
said it is latin for '4', as I was once told when asking why percloethene &
tetrachlorethene are synomyms.  In fact, it is another example of the
useful finesse of organic chemistry nomenclature!

Tony Tweedale

Causality is a concept not subject to empirical demonstration. -David Hume
(1711-'76)

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