@sara posted a while ago referring to a technique proposed by Lionel J. Milberger for using copper pipe to detect hydrogen sulfide. The technique involves sanding a section of copper pipe, exposing it for a specific period of time to potential airborne H2S and inspecting it later for discoloration.

@gretchengehrke found the source article and was able to get permission for us to post it here, from the kind folks at TEST magazine.

(Reproduced with permission from TEST Engineering & Management magazine, April/May 2010, (c)2010, The Mattingley Publishing Company, Inc., Oakland, California.)

So, what I developed is to simply take a six-inch long piece of L grade 3/8-inch copper tubing, and prepare the center section. See Figure 3 for a drawing. The prepared center section is sanded to the raw copper for exposure, while mounted in a simple drill press. Then, it is hung in the air about one to three feet from the ground and exposed to any H2S than may be present. When exposure occurs, the center section of the rod turns to a characteristic blackish color. The visual color of copper that is exposed to H2S is well-documented in the literature as this technique is used widely in various applications including testing for H2S in propane, (12) in down-hole wellbores, (13) and others. (14) The prepared procedure, not included herein, prescribes that the prepared specimen not remain in the ambient air longer than three days so as to minimize oxidization by the oxygen in the air. Copper oxide has a reddish color, unlike the copper-sulfur compounds that can range from dark purple to dark bluish to black. Exposure is visible to the naked eye.

The PDF is here: TESTenmAM10_AsWeGoGreen_Milberger.pdf

The article had a few illustrations as well, reproduced here; you can also scroll down to view the whole PDF embedded:

Embedded PDF