Add example for chemfig

book/book.tex

@@ -39,6 +39,7 @@ At around  \qty{60}{\degreeCelsius} (\qty{140}{\degF}) the microbes in your
 dough start to die.  There are rumors that until this happens the microbes
 produce a lot of \ch{CO2}.
 
+% Does not work
 \begin{figure}[!htb]
 \begin{center}
   \input{figures/fig-ethanol-oxidation.tex}
@@ -46,7 +47,15 @@ produce a lot of \ch{CO2}.
       acid~\cite{acetic+acid+production}.}%
   \label{fig:ethanol-oxidation}
 \end{center}
+\end{figure}
 
+% Works
+\begin{figure}[!htb]
+  \begin{center}
+    \includegraphics{figures/fig-ethanol-oxidation-external.tex}
+    \caption[Acetic acid creation]{Oxygen is required to create acetic
+        acid~\cite{acetic+acid+production}.}%
+  \end{center}
 \end{figure}
 
 \begin{figure}[!htb]

book/figures/fig-ethanol-oxidation-external.tex

@@ -0,0 +1,11 @@
+\documentclass[tikz]{standalone}
+\usepackage{chemfig}
+\begin{document}
+\footnotesize
+\schemestart
+\chemfig{H-C(-[2]H)(-[6]H)-C(-[2]H)(-[6]H)-O(-[7]H)} \+
+\chemfig{O_2} \arrow
+\chemfig{H-C(-[2]H)(-[6]H)-C(=[1]O)-[7]O-H} \+
+\chemfig{H_2O}
+\schemestop
+\end{document}