WARNING: I have been advised by someone who presumably is a better chemist than me(I) that in my clue to 57a "sodium" is not correct, but a derivative of it, if I understood his tip at all. Will confirm tomorrow more precisely --- just wanted to avoid too many unnecessary headaches (tho' I think even with the factual error the right answer is easily guessable --- hopefully not another excuse for a tirade from les's undiplomatic critic just over a week ago). Mea culpa!
Noticed that but wasn't going to quibble about it.
Technically the term refers to a compound such as a salt, eg, NaCl, but loosely also to the ions (elements) produced. http://en.wikipedia.org/wiki/Electrolyte
Thank you, Syzygy. OK, I'll leave it at that then: I had no idea of this business, googled, and was perhaps slightly misled. Thanks to "My Corrector" anonymously. There should be no reason now not to finish on account of that little problem, I hope.