Tetrathionate In Gelatin?

Unsuccessful attempts have been made to detect tetrathionate added to enzymic hydrolysates of gelatin at pH 7. In the presence of sulphite an equivalent amount of thiosulphate is detected following the equationSO3"+S4O6"+S3O6".In the absence of sulphite or at low pH values, tetrathionate decomposes in some other way. Tetrathionate cannot therefore exist in commercial gelatin. Under the normal conditions of emulsion preparation tetrathionate will be converted into thiosulphate and cannot therefore be regarded as a sulphur sensitizer in its own right.