Homebrew PCBs

At 2:21 pm ((PST)) Sat Jan 27, 2007, Randy Ledyard wrote:
>Stefan - Wikipedia also says [snip] For
>such small-scale laboratory use, H2S was made as needed in a Kipp generator
>by reaction of sulfuric acid (H2SO4) with ferrous sulfide FeS."

In producing analytical reagent H2S one would choose H2SO4 over
HCl because HCl is so volatile and would contaminate the product.

AFAIK, any serious laboratory uses H2S from a gas cylinder
(it liquefies easily under pressure) - hence the danger from a
leak, as there is a large amount available if it goes undetected.

>I can't see producing H2S from NaOH (lye), which might be another
>driveway cleaner product ingredient, and I can't see producing it from
>just a detergent-based product....

You gave the clue above: an acid + a sulphide, in this case
very likely an organic sulphide produced from rotting matter.
That's one of the reasons drains smell bad.

BTW, since it's been mentioned: Sodium Hydroxide (NaOH) is
shelf stock at Focus DIY (UK DIY chain), poly-bottles, 500g &
1Kg, rattle like a granular powder.

Perhaps we should build a directory of alternative chemical
suppliers - but let's leave the homeopathy clinic out, OK? ;-)


Regards, LenW