882 
wire or, to make the experiment more rigorous, on a hook of glass’). 
2. When we now apply our new views to what has been dis- 
cussed here, we immediately see that the disturbance of iron brought 
about by a solvent, will depend on two circumstances. 1 of the 
velocity of attack, and 2 of the velocity of the reaction 
Fes — Fe. +205. 
Hence it is clear that the disturbance will increase with the concen- 
tration of the Fe(NO,),-solution and that when the same Fe(NQ,),- 
solution is used, a slighter disturbance will be found when the 
influence of the temperature on the homogeneous reaction Fes 
Fes + 265 is greater, than on the velocity of attack, which is a 
heterogeneous reaction. À 
The continued investigation has now proved that this is really the case. 
The best way to realize this is by consulting the following tables, which 
show besides that the temperature at which the passivity occurs is 
the higher, the greater the concentration of the ferri-nitrate-solution is. 
Active iron-electrode put in a solution containing 0.14 grammolecules of 
Fe (NO3)3 per litre. 
Temp. of the solution Condition of the iron 
Aue passive 
30° passive 
35° active 
limit 31°—34° 
312 passive 
34° active 
30° passive 
Solution containing 0.11 grammol. Fe (NO3)3 per litre. 
Ee ee a ea EE ee 
Temp. of the solution : Condition of the iron 
10° * passive 
19° passive 
299 active 
limit 20.5°—22 
2059 passive 
Zee active 
20° passive 
1) When we take a platinum wire the experiment is not conclusive because 
then an element is formed, in which the iron forms the negative electrode, and 
this is continually polarized. 
