4.7. M(CHO2)2-M1(CHO2)3-H2O systems Each system included in this section is composed of the following: (1) a bi-positive metal formate; (2) a tri-positive metal formate; (3) water. Solubility data have been reported for seven systems of this type. The values published for each of these systems are presented on the following pages. However, because there is only one report for each system, the data are presented without being evaluated.