OF ZINC, CADMIUM, LEAD, COPPER, AND LITHIUM 



47 



LEAD AMALGAMS. 



In order to generalize concerning facts of any kind, it is desirable to 

 obtain as wide a variety of data as possible. Hence it was decided to 

 investigate lead amalgams in the same manner. Previous work on the 

 subject had been done by G. Meyer, 37 and by Spencer, 38 but no data of 

 sufficient accuracy had been published. The investigation was carried 

 out in a manner exactly similar to the above-described work, hence 

 details of manipulation will not be described again. 



Commercial " C. P." lead acetate was found to contain traces of iron, 

 but after one recrystallization with centrifugal filtration this impurity was 

 eliminated, and after two more such crystallizations the lead acetate was 

 considered sufficiently pure to be used as the source of the metal, as well 

 as for the electrolyte. 



The metallic lead used was prepared by the electrolysis of the acetate 

 solution. The crystals of the metal thus obtained were carefully washed, 

 and were then fused in porcelain boats in an atmosphere of hydrogen, and 

 the lead thus obtained was used to make the amalgams. The electrolyte 

 was prepared by taking a solution of the acetate, saturated at o, and 

 diluting with about one-tenth its volume of half normal " chemically pure " 

 acetic acid. In this way the formation of basic salts was prevented, and a 

 perfectly clear electrolyte was obtained. This solution was, as usual, 

 boiled in a partial vacuum in an atmosphere of hydrogen, and sealed in a 

 pipette, also in hydrogen. 



The amalgams were made by adding a weighed amount of lead to a 

 weighed amount of hydrogen-distilled mercury, a little very dilute acetic 

 acid being present to cover the metals and prevent oxidation ; for the 

 amalgam oxidizes very rapidly in air. The acetic acid was then analyzed, 

 and was found to contain neither lead, nor iron from the steel knife used 

 to cut the lead. The amalgams were then sealed in hydrogen in the 

 before-described apparatus. 



TABLE 10. 



' Zeit. phys. Chem., 7, 477. 



'Zeitschr. f. Electrochem., 11, 681. 



