Nitric for silver etching

it worked amazingly well. till shortly after I found out that the
Yellow vapor that was coming off the mixture and falling down to
the ground, (vapor heavier then air?) was apparently Mustard Gas…

Not from Nitric Acid - Mustard gas was Chlorine...... however, the
brown gas from Nitric acid is just as toxic and is very

Minor clarifications:

The brown gas that may be emitted by concentrated or fuming nitric
acid is nitrogen dioxide, which forms nitric acid when it reacts
with water. Nitric oxide, which is colorless, is another product of
metals reacting with nitric acid. It reacts with oxygen in the air
to form nitrogen dioxide.

Mustard gas is 1,5-dichloro-3-thiapentane, infamous for its use in
WWI. Note that it contains chlorine and sulfur in its composition.

Chlorine gas was also used in WWI gas warfare.

Dick D.
Fairfax, VA

Where do you live? I have a large bottle in my garage. If you
lived near me you could have it. Maybe someone lives near you and
they give you some or sell you some. That way you save on shipping
and do not have a ton to store. 

For anyone looking to dispose of chemicals, think about donating
them to local High School or University chemistry department. As long
as the chemical is in its original container, I’ve been successful
with this approach (including a bottle of mercury that a family
member had “hanging around.”