134 



O. U. VONWILLER. 



of potential across the junction was greater than when 

 the direction of flow was reversed, and when observations 

 were made with very small currents it was found that 

 when the current flowed from brass to silicon the difference 

 of potential across the junction increased relatively more 

 rapidly than the current ; for larger currents, the reverse 

 was the case, and when the current flowed from silicon to 

 brass the difference of potential across the surface always 

 increased relatively at a less rate than the current. 



Iu figure 2 are given curves showing the relation between 

 currents (abscissae) and the differences of potential across 

 the surfaces of contact (ordinates); the unit of current is 

 0*001 ampere, and of potential difference, O'l volt. A + 

 represents the difference of potential at the apex when the 

 current flows into the silicon at that place, A - represent- 

 ing the case of a flow in the opposite direction. B-f and 

 B- represent the differences of potential at the base, B + 

 being the case when the current enters, and B — that when 

 it leaves at the base. 



Fig. 2. 



■ MM II 



O I 7 5 4 5 6 7 



In the case of both A+ and B+ the curves are at first 

 concave upwards; A— and B- are convex upwards 

 throughout. With higher values of current all the curves 

 are convex upwards ; in figure 3 are given observations for 

 A+ and A- , readings being taken for much higher values 



