contrast in the same tests the bis triazoles according to this invention produced inhibition values in excess of 90 even when used in a concentration of 10 g m 3 the bis triazoles according to this invention may be used in any corrosion inhibitive effective amount the quantity of bis triazole which is best added is between 0 1 and 50 g per m 3 of aqueous media and preferably between 1 and 10 g m 3 the corrosion inhibitors can be applied in the form of aqueous solutions dispersions or emulsions with or without non interactive adjuvants the bis triazoles are produced by methods known per se for example by reacting u03b1 u03c9 dicarboxylic acids with 2 moles of aminoguanidine or in the case of the bis mercaptotriazoles by reacting u03b1 u03c9 dicarboxylic acid esters with 2 moles of thiosemicarbazide however the production of the bis triazoles is not the subject of the invention three carefully pretreated and weighed test strips zinc 99 5 80 u00d7 15 u00d7 1 mm are suspended in a 1 liter test vessel containing 800 ml of test water 30 ml of buffer solution and a predetermined quantity of the corrosion inhibitor to be tested and left therein for 6 hours at room temperature 80 revolutions per minute the corrosion inhibition value s based on a blank test specimen was calculated from the weight loss ______________________________________s 100 1 a b a weight loss test specimen b weight loss blank value______________________________________ the test water used as the corrosive medium was prepared in accordance with deutsche industrienorm din 51 360.