1919] 



on Liquid Oxygen in Warfare 



613 



vessels for ordinary purposes. The bad effect of poor charcoal was 

 demonstrated in one case of an old container that had a relatively 

 high rate of loss \Yithout showing any sign of leak. It was decided 

 therefore to determine the state of the exhaust and what improve- 

 ment, if any, could he made in the behaviour of the vessel. To 

 attain this object a special vacuum-jacketed drill was fixed on its 

 outer surface (shown diagrammatically in Fig. 15) for tlie purpose of 



TO 

 McCLEOO r 

 GAUGE I 



Fig. 15. — Testing Storage Vessels. 

 Piercing to Measure Exhaust. 



opening the annular space to an exhausted McCleod gauge, to 

 measure the pressure and determine how niuch the vacuum had 

 deteriorated without altering the container in any way. The fitting 

 employed consisted of a cylindrical flanged cap soldered to the outer 



