296 Mi. Gr. A. Hemsalech and the Comte de Gramont on 



that practically in every case the spark lines were brought 

 out strongest during the early stages of the arc when the 

 distance between the electrodes was still very small. Both 

 hydrogen and coal gas gave them more prominently than the 



Fw. 3. 



electrode 



Fixed 

 electrode 



Rubber 

 membrane 



Cork 

 stopper 



Method of obtaining' arc in gases. 



other gases. The red and blue lines of hydrogen (H a and 

 Hjs) were brought out along with the spark lines when the 

 arc flash was taken in the first named two gases, and a 

 significant feature of all these lines is their remarkable 

 broadening, especially during the very early stages of the 

 discharge. In this respect they resemble their appearance in 

 condenser discharges. Although the spark lines are like- 

 wise brought out in oxygen, they are not so prominent 

 relatively to the arc lines as in hydrogen. In nitrogen the 

 spark lines of lead are fairly marked at the initial stage, 

 but those of magnesium show only feebly. With the last 



