Re: How did Carl Wilhelm Scheele actually discover chlorine gas?

Scheele was an adherant of the phlogiston theory, and never realized that 
chlorine was a chemical element. He obtained it by treating manganese dioxide 
with hydrochloric acid (or "marine acid," since it was obtained by distilling 
sulfuric acid in the presence of sea salt), and regarded it as "marine acid 
minus phlogiston." He was almost right, since he thought hydrogen was 
phlogiston; "marine acid minus hydrogen" is pretty much what chlorine is.

My information is from pp. 185ff of J.R. Partington's "A Short History of 
Chemistry" (Dover). Check your local libraries for a copy; considerably more 
information on early work with chlorine is there. (I might add that part of 
your problem might stem from your reliance on web searching; there's a 
tremendous amount of information which is NOT available online!)

                                                    Dan Berger
                                                    MadSci Administrator