[Alt-photo] ferric oxalate properties-looking for information

[Peter Friedrichsen]

Having a hard time finding specific gravity and pH values for ferric 
oxalate that I made from ferric hydrate "mud" It is an olive green 
but more yellow when seen through an eye dropper and a 5% solution 
has a pH of 2.3. Anyone know of charts of S.G. vs concentration and 
expected pH values? Any way to determine if free oxalic acid is present?

Thanks,

Peter Friedrichsen