Measuring gas concentration

I am a student at the "Opleiding Restauratoren", a restoration
college in Amsterdam, The Netherlands.  For a project I need to know
if there exist do-it-yourself tests to measure the concentration of
some specific gases (H2S, SO2, formic acid, etc.) in, for example,
show-cases. If these tests exist, does anybody know where I can get
them?

Joosje van Bennekom
Opleiding Restauratoren
Amsterdam, Nederland

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                  Conservation DistList Instance 10:44
                 Distributed: Friday, November 1, 1996
                       Message Id: cdl-10-44-008
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