Na2S2O35H2O	99.0% min.
Water insoluble	0.01% max
Sulphide (as Na2S)	0.001% max.
Fe	0.002% max.
pH value (200g/L solution)	6.5 - 9.5

Used in photographic and electroplate applications
For purifying soft water and tanning hides
As a reducing agent, deo