From these experimental results, we can reach the conclusions:
(1) Phenyl-tetrazoles and their derivatives are effective as fog inhibitors on the boiling emulsions but no effective action is expected on the ammoniacal emulsions.
(2) The fog inhibiting effect which was observed on the boiling emulsion, is due to mercapto or imino groups contained in the molecules of their compounds; however it is difficult for us to conclude about the effect of hydroxy group without trying the emulsion test to which has been added the larger sample (more than 10
-3 mol).
(3) In the next table, some data about the silver salts of these phenyltetrazoles are shown which are obtained from the curves of the potentiometric titration of silver ion concentration.
According to these tables, 1-Pheny1-5-mercapto-tetrazole and 5-Phenyl-tetrazole require mole silver ion to combine in the medium of sodium carbonate than of sodium bicarbonate. Especially 5-Phenyl-tetrazole combines with 7.5 moles of silver ions in the solution of sodium carbonate. Perhaps 5-Phenyl-tetrazole decomposes easily in the basic medium under the catalitic action of silver and the decomposion products combine with more silver ions. The products which 1-Phenyl-5-mercapto-tetrazole combined with two moles of silver ions in the sodium carbonate solution, is also not considered to be a normal silver salt, and perhaps decomposes in the strong basic medium too. On these assumptions, we can explain the fact that these compounds had the unexpected influence upon the arrimoniacal emulsion in spite of the existence of active groups. 1-Phenyl-5-hydroxy-tetrazole, which forms the most stable silver salt among those three compounds mentioned above, also had no effect on the ammoniacal emulsion. It is presumably because the solubility of the silver salt of this compound is larger than that of the silver chloride, and so it may be unable to be a stabilizer when we aply the quantity usually used.
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