Itllil] 



on Liquici Oxygen in Warfare 



617 



iillov, was placed in an enclosurL- maintained at - 2u" to -25° C, its 

 rate of loss was 23 grams per hour, as compared with 34 grains per 

 hour ill the room at 12° 0. 



RELATION OF VAf'UUM TO EFFICIENCY WITH DIFFERENT 

 VESSELS. 



The relation l)etweeii rate of loss and degree of exhaust was 

 studied with several vessels attached to the vacuum circuit (Fig. 14). 

 The rate of evaporation of the flask was measured at different steady 



Rate. of Evaporation related to Vacuum. Attained 

 Class and Metal Vessels Compared 



Litres plr Minute 



•001 002 003 -004 -005 006 -007 



m m'^ Hg 



Fig. 17. 



009 -010 



Stages of the exhaust, down to the highest vacuum. This was easily 

 controlled l)y the stop cock on the charcoal bull), and measured on 

 the McCleod gauge. Three of the resulting curves are shown in 

 Fig. 17. 



These curves serve to illustrate the rapid loss of efficiency of a 

 metal flask as compared with one of glass, when the vacuum becomes 

 deteriorated : they also show the relative values of the reflecting 

 surfaces on the outer and inner shells respectively of a spherical 

 silvered glass vessel. Curves (1) and (2) refer to a 2j-litre glass 

 -vessel, and (8) to a 3-litre nickel vessel. For curve (2) the silvering 



