Abstract: A process for preparing metal salts of alkyl phosphate of either one of the formulae: ##STR1## WHICH COMPRISES REACTING AN ALKYL PHOSPHATE OF EITHER ONE OF THE FORMULAE: ##STR2## in the form of its alkali metal salt with a metal salt of the formula: M.sub.n X.sub.m in an aqueous medium at a temperature of from about 50.degree. to 80.degree. C. (wherein R is an alkyl group of not less than 12 carbon atoms, M is an alkaline earth metal, aluminum or zinc, X is halogen ion, sulfate ion or nitrate ion, l is an integer corresonding to the atomic valency of M, r is an integer of 0, 1 or 2, m is an integer of 1, 2 or 3 and n is an integer of 1 or 2).

Abstract: A polyazo dye represented by the formula ##SPC1##Wherein A is an optionally substituted aromatic ring; B is an aromatic ring having at least one substituent selected from the group consisting of amino, substituted amino and hydroxy; Y is hydrogen, alkali metal, --NH.sub.4 or amine salt residue; n is 1 or 2; and one of R.sup.1 and R.sup.2 is hydroxy and the other is amino.

Abstract: An aqueous barium sulfate contrast medium which comprises barium sulfate, carbon dioxide, a suspending agent and an additive selected from the group consisting of ascorbic acid, erythorbic acid and a water-soluble salt thereof, the barium sulfate concentration being at least 750 grams per liter of the medium, the carbon dioxide concentration being 0.2 to 4 gas volumes and the additive concentration being in the range of 1 mg% to 150 mg% is disclosed.