12 McDoUGALL AND HowLES, Nitric Acid from Air. 



air supply just to within the point of causing the flame 

 to become unsteady had no appreciable effect. The 

 temperature of the combustion-chamber was raised con- 

 siderably, so much so that it made the eyes smart badly 

 if brought and kept for any length of time within 6 inches 

 of the peep-hole for the purpose of observing the flame. 



By decreasing the high-tension current, so that only 

 0'I5 ampere was used to feed the flame, 55 grms. of nitric 

 acid were produced in an experiment extending over 9^ 

 hours. 



This is equivalent to 300 grms. per horse-power per 

 12 hours, showing an increase over the quantities produced 

 in all former experiments. A result which was anticipated. 



In the last three sets of experiments, whilst varying 

 the current, the voltage was kept as constant as possible. 

 The results are more easily compared in the following 

 table : 



Too great a decrease in the current caused the flame 

 to become unsteady, and liable to extinction. Of course 

 theoretically as the current is decreased, the discharge 

 should resemble more and more that obtained from a 

 Ruhmkorff's coil or electrical machine, onl)- less in 

 intensity, until finally only a streak or spark is obtained. 



The production of nitric acid in this apparatus, at the 

 rate of 300 grms. per horse-power per 12 hours, represents 



