[texhax] \raisebox problem

[Simmie, John]

In order to have same size symbols aligned in a Figure caption I have
used the construct

\caption{Estimated rate constants for 1-hydroxybutyl decomposition
leading to the formation of {\footnotesize $\square$}~ethenol, {\small
$\triangle$}~butanal, \raisebox{-0.2ex}{\Large $\circ$} butenol.}

But LaTeX doesn't like it all ... altho'  \raisebox{-0.2ex}{\Large
$\circ$} works okay in normal paragraph mode.  
The Guide to LaTeX discourages me from using \protect, so what's my
problem?

Emeritus Professor John Simmie::Combustion Chemistry Centre::National
University of Ireland, Galway