Tannate, Lead

Partial transformation of rust into ferric-tannates was found to occur with the addition of mangrove tannins leading to a low inhibitive behaviour. The mechanism of adsorption of catechin onto the iron surface has been established via theoretical... 

Copper ferrocyanide silicate Lead silicate Peptone tannate Barium sulphate Silver chloride... 

A similar titration curve (Fig. 50) is observed, when a suspension of lead tannate is titrated tvith dilute nitric acid in 20 per cent ethanol. By measuring the limiting current, lead can be determined in this complex. In a similar way insoluble precipitates can be analysed after the addition of complex-forming reagents, e.g. 

When solutions of lead or bismuth salts are treated with alkali hypo-bromite, lead peroxide and higher oxides of bismuth are formed. These products react with benzidine acetate to give benzidine blue (seepage 282). However, if bismuth salts are heated alone with alkali hydroxides, a yellow precipitate forms, [probably BiO(OH)] and, when once formed, is not converted into higher bismuth oxides on treatment with h3q)obromite. This resistance is applied in the detection of lead in bismuth salts. The following procedure is recommended in the examination of pharmaceutical bismuth preparations (e.g., bismuth sub-gallate, -tannate, -salicylate). 

Lead silicate is used mainly in water-based primers for wood, where it reacts with tannates to prevent them from bleeding and discoloring succeeding paint coats. Lead silicate may be eliminated from home use because of restrictions on the use of lead. 

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