1. A stable aqueous composition comprising stannous ions and a liquid containing an aqueous phase comprising: dissolved tin in the formal oxidation state + II, dissolved nitrates irastvorennuyu carboxylic acid which is not a chelating agent to the dissolved tin in the formal oxidation state + II, where the liquid the aqueous phase has a pH of 2 to 4.2. Composition according to Claim. 1 in which the carboxylic acid is a monocarboxylic acid, unsubstituted gidroksigruppami.3. Composition according to Claim. 1 or 2, wherein the monocarboxylic acid is selected from the group consisting of C1-C4 linear or branched alkanoic acid, C3-C5 linear, optionally alkyl-substituted alkenoic acids and C6-C14 aryl carboxylic kislot.4. Composition according to Claim. 1 or 2, wherein the carboxylic acid is a C1-C4 linear or branched alkane kislotu.5. Composition according to Claim. 1 or 2, wherein the carboxylic acid is acetic kislotu.6. A method of increasing stannous stability in the formal oxidation state + II, dissolved in the liquid aqueous phase against oxidation by molecular oxygen, comprising dissolving vzhidkoy phase salt nitrate and a carboxylic acid which is not a chelating agent for tin in the formal oxidation state + II, and adjusting the pH of the liquid the aqueous phase to a value of 2 to 4.7. The method of claim. 6, wherein the carboxylic acid is a monocarboxylic acid, unsubstituted gidroksigruppami.8. The method of claim. 6 or 7, wherein the carboxylic acid is selected from the group consisting of C1-C4 linear or branched alkanoic acid, C3-C5 linear, optionally alkyl-substituted alkenoic acids, C6-C14 arylcarboxylic1. Стабильная водная композиция, содержащая ионы двухвалентного олова и содержащая жидкую водную фазу, включающую:растворенное олово в формальной степени окисления +II,растворенные нитраты ирастворенную карбоновую кислоту, которая не является хелатирующим веществом для растворенного олова в формальной степени окисления +II,где жидкая водная фаза имеет pH от
