in not given byproducts: HCOOH; boiling dild. Ba(HCO2)2 soln. added to boiling Tl2SO4 soln. with stirring; pptn. and further boiling;; filtration, ppt. washed with strongly dild. HCOOH; filtrate repeatedly evapd. to dryness and redissolved in H2O until odour of HCOOH is gone;;
