Re: Symbols for chemical bonds

From: Curtis Clark (
Date: Thu Mar 31 2005 - 14:31:40 CST

  • Next message: Kenneth Whistler: "Re: Version 4.1 of the Unicode Standard Released"

    I am not arguing against encoding chemical bonds, and I think Jukka
    raises some good points, but it's not all that simple.

    on 2005-03-31 09:29 Jukka K. Korpela wrote:
    > 1. It is illogical to use characters with fairly definite semantics
    > for something completely different.

    Of course it is. It also happens all the time, as we all recently
    noticed with the visual ambiguation of apostrophe and right quote in
    English, say, but not in French. I think the semantic argument is the
    strongest for encoding these bonds, but it certainly doesn't end the

    > 2. The glyphs are not of the same width except by accident, but the
    > meaning of bond symbols would rather naturally call for glyphs
    > of the same width.

    The bonds themselves are not of the same length. They vary based on the
    atoms bonded, the type of bond, the number of bonds, and the nature of
    atoms adjacent to the atoms bonded. I point this out simply to
    empphasize that making the glyphs the same width is *purely* a
    typographic decision, and has nothing to do with the underlying semantics.

    > 3. The glyphs for the four characters are not very suitable for
    > use as bond symbols. They should be wider. Or, to put it
    > milder, the bond symbols should be coded separately to _allow_
    > font design that makes them wider, or otherwise different
    > from em dash etc.

    This is IMO the second-strongest argument for separate encoding. The
    other side of the coin, though, is that virtually all fonts already
    contain glyphs that can be used for single and double bonds, and many
    fonts already include the triple. If the bonds are disambiguated from
    the existing signs, it will take a while for them to appear in fonts,
    which will mean even more documents that use the old methods.

    Another argument *for* encoding the bonds is that they can be given the
    same properties, and be treated the same wrt word breaks and such (I
    could make an argument that they should be non-breaking, since the
    semantics of a chemical formula strongly support keeping it in one piece).

    Curtis Clark        
    Web Coordinator, Cal Poly Pomona                 +1 909 979 6371
    Professor, Biological Sciences                   +1 909 869 4062

    This archive was generated by hypermail 2.1.5 : Thu Mar 31 2005 - 14:32:50 CST