A question about liquid sound /r/ and /l/ (xinhui zhou )

Subject: A question about liquid sound /r/ and /l/
From:    xinhui zhou  <zxinhui2001@xxxxxxxx>
Date:    Mon, 30 Jan 2006 13:20:19 -0500

Hi, everyone,

why /r/ and /l/ are called liquid and how this term liquid  originated ?
 I happened to read an online book  called '' A Little Encyclopaedia
of Phonetics'' (www.personal.rdg.ac.uk/~llsroach/encyc.pdf), which
reminds me of this question I had  before.

 That book mentioned (pp.47) liquid is an old-fashioned word but
somehow the term suvives. Can someone have more details about the
origin of this term ?  Thanks a lot,

Xinhui Zhou