PAPERS OX CHEMISTRY AND PHYSICS 



315 



A 3000-VOLT LEAD PLATE SHOP-MADE STOEAGE 



BATTEEY— ITS COXSTEUCTIOX AXD 



CHAEGING CHAEACTEEISTICS 



C. T. KxiPP AXD E. J. EuEDY^ UXIVERSITY OF TtJJXOIS 



111 the modern well equipped physics laboratory, 

 whether in secondary school or university, sources of 

 direct high electromotive forces are becoming increas- 

 ingly more important. It is not the object of this paper 

 to enumerate the uses of such potentials, but rather to 

 describe in some detail a battery of 3000 volts that was 

 built during the past winter by one of the writers and 

 which is now in commission and is giving excellent ser^"- 

 ice. This battery is a shop-made one, meaning thereby 

 that the complete installation, i. e., the lead plates, multi- 

 ple s^^i-tches for charging and discharging, binding posts, 

 and the cupboard in which the cells are assembled, was 

 made in our physics shop. The 1500 test tubes necessary 

 were especially blown by the Central Scientific Company, 

 Chicago. 



The cells are grouped in trays of 20 each, and thus 

 each tray has a potential, when fuUy charged, of 40 volts. 

 The trays are constructed of wood, and in appearance are 

 similar to a test tube rack as may be seen in Fig. 1. Each 

 tray was boiled in paraffine for 15 to 20 minutes. After 

 cooling it was dipped again in parafiBne so as to thor- 

 oughly protect the wood from the acid, and also to im- 

 prove the insulation. 



f/p. I. Trcry of ^O Tesr 7o6e Ce/h Connected /n 5er/e5 



