diff --git a/004/codex-004.tex b/004/codex-004.tex
index 3b9b9be..cde6e04 100644
--- a/004/codex-004.tex
+++ b/004/codex-004.tex
@@ -581,18 +581,37 @@ will give us this reaction:
 \noindent{}\ch{$2n$ Na + $n$ Cl2 -> $2n$ NaCl}
 \vspace{\baselineskip}
 
+We can also write the names of substances underneath them by using a ! and two pairs of parentheses. This code:
+
+\begin{Verbatim}[]
+\ch{!( sodium )( $2n$ Na ) + !( chlorine )( $n$ Cl2 ) -> !( s
+odium\ chloride )( $2n$ NaCl )}
+\end{Verbatim}
+
+gives us this example:
+
+\vspace{\baselineskip}
+\noindent{}\ch{!( sodium )( $2n$ Na ) + !( chlorine )( $n$ Cl2 ) -> !( sodium\ chloride )( $2n$ NaCl )}
+\vspace{\baselineskip}
+
+Notice that we had to use spaces inside the parentheses so that the package will know how to format these separate types of input. Also, because a space delineates different inputs, in order to get that space in ``sodium chloride'' we had to escape the space with a backward slash.
+
 Again, there are lots of options to customize the output. Here's one with fractions:
 
 \begin{Verbatim}[]
-\ch{3/2}
-\ch[frac-style=xfrac]{3/2} 
+\ch{3/2} (vertical fraction) \quad
+\ch[frac-style=xfrac]{3/2} (diagonal fraction)
 \end{Verbatim}
 
+which gives us:
+
 \vspace{\baselineskip}
-\noindent{}\ch{3/2}  \par
-\noindent{}\ch[frac-style=xfrac]{3/2} 
+\noindent{}\ch{3/2} (vertical fraction)  \quad
+\noindent{}\ch[frac-style=xfrac]{3/2} (diagonal fraction)
 \vspace{\baselineskip}
 
+Like I said, this one operates a lot like \texttt{mhchem}. If \texttt{mhchem} works for you, there's no need to look further. But if you need more control over the appearance of your formulas and equations, \texttt{chemformula} will give you a lot of that control.
+
 
 \section{Package \texttt{chemfig}}
 
@@ -604,6 +623,10 @@ Glucose:
 -[:-10](-[6,0.7]OH)-[:130]O-[:190]?(-[:150,0.7]-[2,0.7]OH)}
 
 
+\chemfig{*6(-=(-OH)-=(-OH)-=)}
+\chemfig{**6(---(-OH)---)}
+\chemfig{HO-*6(-=-=-=)}
+
 \chapter{A \texttt{git} Workflow}