Footenote in table appear only as alpha letters

Question

I'm trying to add footnotes to a table with arabic numerals, but it comes up as alpha letters instead:

begin{minipage}{500pt}   
\renewcommand{\thefootnote}{\arabic{footnote}}
\begin{tabular}{rcccc} \\ \hline
\noalign{\vskip 1mm}  
\multicolumn{5}{c}{\ce{Fe(NO)3\cdot9H2O}} \\ 
Trials & $m_o$\footnote{\scriptsize Mass of capillary} & $m$\footnote{\scriptsize Mass of capillary and sample} & $L$\footnote{\scriptsize Length} & $R$\footnote{\scriptsize Magnetic balance reading of sample} \\ \hline
1 & \SI{0.1873}{g} & \SI{0.2345}{g} & \SI{3.56}{cm} & 414 \\
2 & \SI{0.1914}{g} & \SI{0.2340}{g} & \SI{3.56}{cm} & 414 \\
3 & \SI{0.1827}{g} & \SI{0.2180}{g} & \SI{3.56}{cm} & 414 \\
4 & \SI{0.1881}{g} & \SI{0.2193}{g} & \SI{3.56}{cm} & 414 \\
\end{tabular}
\end{minipage}

Thanks for the help!