The phenomenon of cathodic protection was investigated from the kinetic standpoint in an attempt to obtain an understanding of the factors controlling the process. The corrosion by acid of a zinc cathode at various current densities was investigated by time-rate, and temperature coefficient studies. In addition, a study was made of the corrosion of aluminum while cathodic in acid, in neutral, and in alkaline electrolytes, and the effect of agitation on the corrosion under these circumstances was determined. The results indicate that the nature and thickness of the film of solution immediately adjacent to the cathode determine the extent of corrosion of the metal while cathodic. Aluminum undergoes corrosion instead of protection when made cathodic in sodium sulfate solution. However, in sodium hydroxide solution its normal rate of corrosion is not altered as a result of making it cathodic. INTRODUCTION.
lowed to stand overnight (0' ) the crystdime %keto+galactonic acid was recovered, washed with aqueous diozane and recrystailiized from water: m..p. 170-171 ; [a]% -6.0' (c, 2 in water), and on titration with alkali Anal. Calcd. for GHtoG: C, 37.12; H, 5.19. Found: C, 37.02; H, 5.30. MstaJl2-K -The acid (5 g.) was d i m solved in 100 cc. methanol containing 0.15% hydrogen chloride. The mixture was refluxed for two hours, and evaporated by repeated concentration in uucuo with methanol. crystals of methyl !&keto-Dgalactonate were washed and recrystallized from alcoholchlorofm mixtures: m. p. 138-139O and [a]% -11.3' (c, 1.2 in water). n-Ascorbic acid m. p. 192' and [ a I m D -23' was made from this ester by the method of M m e r and Wedt,' and this served to establish further the constitution of 2-keto-xt-galactonic acid.solution of a-mgluco epto-r isctone' (416 g.) was neutralized with 106 g. sodium carbonate, cooled, diluted to 4.2 liters and 73 g. of sodium chlorate, 40 cc. of 86% phosphoric acid and 20 g. of vanadhm pentoxide were added. After stirring for two days, the reaction was complete; it was littered, treated with enough calcium ferrocyanide to precipitate the V+++, again, the PO,--precipitated with cakinm hydroxide. and the ex-Ca++ removed with oxalic add. The colorless solubon containing only d u m salts was concmtrated to 2 liters and an equal Volnme o f methanol added dropwise with stirring during
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