Catalog number 726A is a solution of 2.5% w/v phosphotungstic acid and 2.5% phosphomolybdic acid in water. It is used in Masson’s trichrome stain is to demonstrate connective tissue in paraffin sections. The solutions required are: acetic aniline blue (catalog # 410A), Bouin’s fixative (catalog # 456A), Weigert’s hematoxylin A (catalog # 6201A, Weigert’s hematoxylin B (6206A), phosphomolybdic/phosphotungstic acid (catalog # 726A) and 1% acetic acid (catalog # 308A). The country of origin is the United States.