In answer to the editorial, did you know that ultrasonics use
different frequencies? Some of the better ultrasonics have dual
transducers that operate on different frequency ranges
simultaneously. Did you know that sound waves can kill? Older
ultrasonics (35+yrs. ago) used a frequency that was very
efficient for cleaning, but was deleterious to flesh and bone.
The newer machines use more benign frequencies but are still not
totally safe. The sound waves travel through the liquid. The
resonance of the waves changes with different liquids. The
better the 'sonic cleans with a particular cleaning solution, the
more efficiently the transducer is working, the faster the liquid
gets hot, and the greater probability that danger is present for
fingers, toes, or what have you. The sonic burns from inside
out and that is the reason for the arthritis enhancement
problem, besides, I have a problem sticking my hand into any
liquid with electrical conductivity while the machine is running!
Just my $0.02 worth.