396 



ELECTRICAL MACHINERY 



Capacity of Mercury Tubes. For charging storage 

 batteries the tubes are made in various sizes with capacities 

 of from three amperes to fifty amperes. For greater cur- 

 rent capacities, the glass tubes are likely to overheat and so 

 attempts have been made to utilize metal tubes immersed 

 in oil to get proper cooling. However, the metal used must 



Fia. 262. View of a Mercury Rectifier Outfit, 

 trie and Mfg. Co. 



Westinghouse Elec- 



be one which does not amalgamate with mercury and iron 

 seems the only suitable substance. But an iron tube will 

 not hold a proper vacuum, so that tubes suitable for heavy 

 currents are, as yet, in the experimental stage. If this 

 problem is solved, it may be possible to substitute mercury 

 tubes for synchronous converters for railway operation. 



