Persulphuric acid

G’day; Further to my note on persulphuric acid, Marlin Cohrs
mailed me to say he disagreed with the formula I gave:

Never knew about persulfuric, so I looked it up.  I came up
with a different formula for it however.  H2S05 (see
http://turnerfenton.com/lessons/chem/lessons/l4.htm  ) 

Well, we are both right: For that posting I checked in my
edition of Mellors Inorganic Chemistry, and it gave the formula
that I thought, so I put that in. However, I checked up In the
‘Scientist’s Bible’, the ‘CRC Handbook of Chemistry and
Physics’: W East. - a tome about 3" thick - and it gave two
persulphates:- Per(di) sulphuric acid…H2S2O8 Per (mono)
sulphuric acid… H2SO5 So there you are, like I said, we’re both
right. Thanks, Marlin Cheers, John Burgess