SUPERIORITIES OF LEAD-CALCIUM ALLOYS 701 



the lead-antimony alloys most generally used in storage battery con- 

 struction. It has been found, furthermore, that at ordinary tempera- 

 tures no decrease of tensile strength occurs with age. This main- 

 tenance of strength is probably related to the low rate of diffusion of 

 the hardening constituent PbaCa which, being a large and stable mole- 

 cule, does not diffuse readily in the matrix. The electrical conductivity 

 of this lead-calcium alloy is approximately 20 per cent greater than that 

 of lead-9 per cent antimony, a factor of importance in securing uniform 

 distribution of current when large currents are drawn from a battery. 

 Experimental cells of both Plante and Faure (pasted) types have 

 been constructed and are being subjected to a variety of tests. To 

 date, forty-two cells of the starting and lighting type have been pasted, 

 assembled, formed and cycled. This investigation has progressed 

 sufficiently to make it qliite evident that the behavior of a complete 

 cell can be predicted with a high degree of accuracy if the electrochem- 

 ical properties of the structural alloy are known. It has been definitely 

 established that when the negative electrodes of lead-calcium cells 

 of the starting and lighting type (previously subjected to 100 charge- 

 discharge cycles) are charged and allowed to stand one month, they 

 lose only 4 to 5 per cent of their charge as compared to 20 to 25 per cent 

 for lead-antimony cells similarly treated. The efficiencies of lead- 

 calcium cells have been found to be superior to those of lead-antimony 

 cells. No undue corrosion of lead-calcium grids has been observed. 



