OF ZINC, CADMIUM, LEAD, COPPER, AND LITHIUM 55 



LITHIUM AMALGAMS. 



Up to the beginning- of last year but little accurate work had been done 

 on the amalgams of the alkali-metals from the standpoint of potential 

 measurements. The very recent discovery by Lewis and Kraus of a 

 satisfactory method of measuring these metals against an aqueous solution 

 of their hydroxides was not known to us at the time of our work, hence 

 its assistance was not available. 44 The first step in the present quest was 

 obviously a repetition of the earlier work in the hope of discovering its 

 validity. If this promised well, more accurate determinations were to be 

 attempted. 



Meyer and Cady, in their publications already cited, have furnished the 

 chief figures concerning the electrochemistry of the amalgams of the 

 alkali-metals. Meyer recorded the results on sodium amalgam, but, as 

 he spoke of using an aqueous electrolyte apparently without suitable pre- 

 cautions, his data have little significance. Cady, working under Bancroft's 

 direction, made measurements upon amalgams of the three most plentiful 

 alkali-metals, using pyridine as the solvent for the electrolyte. This work 

 shows the effects of great haste ; the figures in his tables are not wholly 

 consistent with themselves and are evidently vitiated by serious errors, 

 both of experiment and of proof-reading. Therefore it was thought 

 advisable to repeat his work. We employed at first as the electrolyte a 

 solution of lithium chloride in pyridine. The specimen of salt employed 

 was a very pure sample which was being used for work on atomic weights 

 in this laboratory. We are greatly indebted to Mr. H. H. Willard for his 

 kindness in providing it. As a solvent the best pyridine, supplied by Kahl- 

 baum, was redistilled with a fractionating column, giving as boiling-point 

 115.2 0.1 at 760 mm. It was always protected from moisture during 

 distillation, and was subsequently kept in a potash desiccator. The con- 

 ductivity of lithium chloride 45 in pyridine is very small, hence the electro- 

 lyte was made very nearly saturated. 



The amalgams were made by placing mercury and lithium in the lower 

 of the two bulbs in the usual apparatus shown in fig. i, page 9, sealing 

 everything into its place, and finally melting the lithium after the whole 

 apparatus had been filled with hydrogen. After cooling, the amalgam was 

 driven by the pressure of hydrogen into the upper pipette, from which a 

 sample was taken for alkalimetric analysis by means of digestion with a 

 standard acid solution. Two amalgams made in this way, which were 

 expected to give concentrations of about o.i and 0.5 per cent, were found 

 to contain 0.037 P er cent an d 0.036 per cent respectively ; and in both 



"This method has not yet been published. In the near future it will be applied 

 either by Lewis and Kraus or at the Harvard Laboratory to a series of measure- 

 ments like those discussed in the present paper. 



45 Lasezynski and Gorski, Zeitschr. f. Electrochem., 4, 290. 



