Platinum and Palladium Black Catalysts by Willstatter

who was also interested in precious metal catalysts, had earlier used platinum or palladium blacks to hydrogenate oleic acid at ambient temperature and much lower pressures than those used by Ipatieff. Platinum or palladium black catalysts, which were finely divided metals containing some oxygen, were then 

TABLE 3.4. Paal s Preparation of Colloidal Platinum Metals. 

1 Method depended on use of suitable protective colloid such as protein, gum arabic, or starch to stabilize particles. 

2 Paal prepared protalbic acid by dissolving egg albiunin in sodium hydroxide solution and precipitation using either sulfuric or acetic acids. Lysalbic acid remained in solution and could be recovered either by evaporation, or by precipitation with ethanol. 

3 Colloidal metal was obtained by adding sodium salts of llie protalbic acid to a dilute solu tion of platiniun chloride and reducing witli hy nzine hydrate. The colloidal solution was 

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