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+{\overfullrule0pt\def\cite#1{[#1]}
+% Warning: This is an input file for AMSTeX, rather than for LaTeX.
+% This is just so that I can use the commands for arrows
+% mentioned on pages 140-141 of "The Joy of TeX".
+% It may not be "good AmSTeX", since it's the first time
+% I've used AmSTeX seriously!
+\title{Could \LaTeXbf\ do more for chemists?}
+From time to time I have seen queries in {\TeXhax} and
+elsewhere from people who wish to use \LaTeX\ for documents
+that involve chemical formulae, etc. Since there are now plans for
+\LaTeX\ 3.0 \cite{1},
+I thought this might be a good time to consider
+what facilities one could reasonably ask the people implementing the new
+\LaTeX\ to provide for chemists.
+
+I'm not a chemist myself, but have been involved in helping chemists
+use \LaTeX\ 2.09 \cite{2} for producing theses, etc.
+
+\section{Typesetting and artwork}
+ It may help to consider the division of labour within a traditional
+publishing house. A `copy-editor' \cite{3, p236} might divide the work on
+chemical formulae up between `the printer' and `the draughtsman'. Thus,
+some formulae can be typeset, but others are treated as `artwork' and are
+drawn.
+
+Although there have been valiant attempts \cite{4-5} to define \TeX\ macros
+for drawing chemical structure diagrams, I think it is inevitable that,
+whatever \TeX\ macros are defined, there will be chemists who come along with
+requirements that are beyond the abilities of the macro packages. Therefore,
+it seems sensible to retain the traditional division between typesetting and
+artwork: to typeset those formulae that can be typeset easily and to get the
+other formulae drawn in some way.
+
+In \TeX\ terms, artwork can be treated as `graphics' to be
+`pasted' into a typeset document via |\special|.
+For example, {\sans Chemdraw}
+\cite{6} can produce `encapsulated {\PS}',
+so a \LaTeX-ed document with {\sans Chemdraw} diagrams can be printed on
+a {\PS} printer.
+
+\section{Desirable facilities for chemists}
+\LaTeX\ is never going to be a system for producing `artwork',
+so it seems to me that it would be unwise to attempt to provide
+comprehensive facilities for `chemical artwork' in \LaTeX. However, it does
+seem worth providing a limited number of facilities to make it
+easier to produce the chemical formulae that should be
+treated as `typesetting'.
+
+\subsection{Environments}
+Chemists' problems start when they use \LaTeX's `mathematics'
+environments for `chemistry'. Chemistry is not mathematics, and
+the conventions for typesetting chemistry are different from those for
+typesetting mathematics. In terms of the \LaTeX\ philosophy \cite{2, p6},
+`mathematics' and `chemistry' represent `logically distinct structural
+elements'.
+
+It would seem natural to:
+\bi define environments for chemists that are
+ analogous to the environments that are available for mathematicians
+\bi within these `chemistry' environments, aim to keep to
+ whatever typesetting conventions are usual in chemistry.
+
+\noindent
+How about defining {\tt chem}, {\tt displaychem} and {\tt chem\-equation}
+ environments,
+by analogy with {\tt math}, {\tt displaymath} and {\tt equation}?
+
+If such environments were defined, the style-file writer would then
+have control over `mathematics' and `chemistry' separately.
+In particular:
+\bi The default would be {|\rm|} for chemistry (although
+ a designer could change the default in a {\tt .sty} file).
+ Individual
+ authors would no longer have to search through
+ ``double bend'' sections of the \TB\ themselves
+ \cite{7, pp163 \& 179}.
+\bi A designer could implement a house-style in which
+ mathematical and chemical equations are numbered in separate
+ sequences \cite{3, p224} or a house-style in which there is only one
+ sequence of numbers \cite{8, p32}.
+\bi It might be possible to arrange that subscripts will normally be
+ at the same level \cite{7, p179} inside the environments
+ for chemistry.
+
+
+\subsection{Commands}
+At first sight, the \LaTeX\ manual \cite{2, ch.\ 3} gives the impression that
+\LaTeX\ 2.09 provides the `building blocks' to give all the arrows,
+harpoons and annotation that a chemist could want. However, it is often
+difficult to get these building blocks arranged in the ways required.
+For example:
+
+\bi How does one obtain CH${_3}$(C=O)OCl \cite{3, p235} in `math mode'?
+ We can't
+ use `='
+ to mean ``double bond'', since \TeX\ puts space
+ around it.
+\bi To represent a reversible reaction with rate constants above\slash below
+ a pair of harpoons, I ended up with
+\begintt
+\renewcommand{\arraystretch}{0.5}
+A \begin\{array}{c}
+ \scriptstyle k_1\\[1mm]
+ \rightleftharpoons\\
+ \scriptstyle k\_2
+ \end{array} B
+\endtt
+ before it looked right. Surely individual \LaTeX\ users shouldn't have
+ to re-do the `tuning' needed to get these things right?
+\bi As in the above example, arrows and harpoons are often labelled to show
+reaction conditions. It is not clear how to get
+arrows\slash harpoons that expand to the width of the labels.
+
+\noindent Many of these difficulties are another consequence of trying to
+use, for chemistry, the structural elements that were designed for
+mathematics.
+
+So what commands might usefully be made available inside some future
+`chemistry' environments?
+
+It seems desirable \cite{3, p237} to have documented facilities for
+single and double bonds. Triple bonds might also be needed \cite{9}.
+A documented facility for representing single
+bonds by raised dots would also be useful \cite{10, p59}.
+Might commands such as |\bond|, |\doublebond| and
+|\triplebond|
+be appropriate?
+
+It seems desirable to have specific commands for typesetting
+arrows\slash harpoons with labels above\slash below (to indicate conditions or
+rate constants). An indication of the combinations
+of arrows\slash harpoons that have been typeset traditionally is given
+in \cite{11,~p371}. Thus, as well as providing simple arrows for one-way
+reactions, it might be worth aiming to provide commands for: equilibrium
+reactions (beginning at left and right); reversible reactions (beginning at
+left and right); reactions beginning at left\slash right and completed to
+left\slash right. Might it be worth defining some commands such as
+
+\centerline{\vbox{\tt\halign{\char'134#\quad&\char'134#\cr
+oneway\cr
+equilibriumR &equilibriumL\cr
+reversibleR &reversibleL\cr
+rightright &rightleft\cr
+leftright &leftleft\cr
+}}}
+\noindent that each accept two parameters: one to give a label
+above the symbol, the other to give a label below the symbol?
+For example,
+\begintt
+\begin{chem}
+2H_2 + O_2
+\oneway{catalyst}{300 K; 4 bar} 2 H_2O
+\end{chem}
+\endtt
+might be a natural way to specify
+% This is the line that contains the command that made me use AMSTeX.
+% I couldn't find anything else ready-made in plain TeX or LaTeX.
+\newdimen\bigaw
+\def\oneway>#1>#2>{%
+\setbox0\hbox{$\scriptstyle#1$}
+\setbox1\hbox{$\scriptstyle#2$}
+\bigaw\wd0\ifdim\wd1>\bigaw\bigaw\wd1\fi
+\mathrel{\mathop{\hbox
+to\bigaw{\rightarrowfill}}\limits^{#1}_{#2}}}
+$${\rm2H}_2 + {\rm O}_2
+ \oneway >{\rm catalyst} > {\rm 300 K; 4 bar} >
+ {\rm 2H}_2{\rm O}
+$$
+
+\section{Work involved}
+I'd guess that my suggestions about environments could be implemented
+by slight modications of the code that implements the corresponding
+environments for mathematics.
+
+Some new work would be required for commands such as |\oneway|,
+\dots\ , |\leftleft|. The only similar facility that I've found
+in an existing macro package is that for arrows in \AmSTeX\ \cite{12, p140},
+but (from a chemist's point-of-view) this doesn't provide sufficient
+choice of symbols.
+
+It might be worth seeking advice about objectives
+from people who typeset chemistry professionally.
+% Perhaps the UK's Royal Society of Chemistry would be prepared to advise
+% about details. I've been in e-mail correspondence with their Publications
+% Manager about authors submitting mansuscripts electronically to them,
+% although they seem to be going the wordprocessor + chemdraw + SGML route.
+
+\section{Documentation}
+If the facilities that I've outlined above were provided, I would
+be inclined to give them less prominence in the documentation than
+the analogous facilities for mathematicians. This would help
+give the impression that, whereas mathematicians can expect \LaTeX\
+to do everything they want, chemists can only expect \LaTeX\ to do a certain
+proportion of what they want.
+For example, in the successor to \cite{2}, the description of facilities for
+chemists might be relegated to an appendix, which could start with a
+paragraph explaining that the facilities are intended to support
+`typesetting' but not `artwork'.
+
+\section{Bibliography}{\parindent0pt\frenchspacing\raggedright
+\everypar{\hangafter1\hangindent20pt}
+\par
+[1] Frank Mittelbach and Rainer Sch\"opf, 1989,
+With \LaTeX\ into the Nineties
+TUGboat 10,
+681--690.
+
+
+
+[2]
+Leslie Lamport, 1986,
+\LaTeX: A Document Preparation System,
+Addison-Wesley.
+
+
+
+[3]
+Judith Butcher, 1981,
+Copy-editing
+Cambridge University Press,
+
+
+
+[4]
+Roswitha T. Haas and Kevin C. O'Kane, 1987,
+Typesetting chemical structure formulae with the text formatter
+ \TeX\slash \LaTeX,
+Computers and Chemistry 11,
+251-271.
+
+[5]
+Michael Ramek, 1990,
+Chemical structure formulae and $x/y$ diagrams with \TeX\ {\it in:}
+ \TeX: applications, uses, methods, Malcolm Clark (editor),
+Ellis Horwood.
+
+[6]
+{\sans Chemdraw} (A program for the Macintosh),
+Cambridge Scientific Computing,
+Cambridge, Massachusetts.
+
+%
+[7]
+Donald E. Knuth, 1986,
+The \TeX book,
+Addison-Wesley.
+
+[8]
+Janet S. Dodd, 1986,
+The ACS Style Guide
+American Chemical Society
+
+[9]
+Handbook for Chemical Society Authors, 1961,
+The Chemical Society
+
+[10]
+Hart's Rules, 1983,
+Oxford University Press
+1983
+
+
+[11]
+Chicago Manual of Style, 1982,
+Chicago University Press
+% \publaddr Chicago
+
+[12]
+Michael Spivak, 1986,
+The Joy of \TeX,
+American Mathematical Society
+
+}}
+%
+
+\author{David Rhead}