% de naeste seks makroer anvendes internt
% de kan uden problemer fjernes i hele filen
\let\START\relax
\let\STOP\relax
\let\SPECEXTSTART\relax
\let\SPECEXTSTOP\relax
\let\DCBEGIN\relax
\let\DCEND\relax
 \DCBEGIN
\documentclass[a4paper]{article}
 \DCEND

 \usepackage [latin1]{inputenc}
 \usepackage [T1]{fontenc}
 \usepackage [danish]{babel}
 \usepackage {felineekssupp}
 \usepackage {kpfonts}
 \usepackage [scaled=0.8]{beramono}
 \usepackage [scaled=0.85]{berasans}

% al anvendelse af geometry i eksemplerne boer man slette,
% dette anvendes mht. at stoerrelsen skal passe til brug i bogen
\usepackage{geometry}
\geometry{textwidth=183.29863pt}
% vil ikke have sidetal med, fjern selv
\pagestyle{empty}
% forfatteren snyder maaske, fjern kode fra HER -->
\parindent =0pt
% <-- til HER.
 \START
\usepackage[version=3]{mhchem}
\usepackage{amsmath}
 \STOP

\begin{document}
\begin{gather*}
\ce{C6H5#ClZ}\\
\ce{\cmath{x\,} Na(NH4)HPO4 ->[\Delta]
(NaPO3)_{\cmath{x}} + \cmath{x\,} NH3 ^
+ \cmath{\dots}}\\
\ce{H+ + OH- <=>> H2O}\\
\ce{\cmath{A} ->[\cmath{+H2O}] \cmath{B}}
\end{gather*}
\end{document}