308 Wisconsin Academy of Sciences, Arts, and Letters. 
tiiere is no experimental evidence upon which to base the as¬ 
sumption that in their aqueous solutions there is any free acid 
present. Moreover, an. alkaline reaction is imparted to the so¬ 
lutions of these salts by the magnesium soon after it has been 
immersed in them, and yet this alkalinity does not interfere 
with the evolution of hydrogen. 2 
There are no facts upon which to base the assumption that 
magnesium chloride in aqueous solution suffers greater hydro¬ 
lytic decomposition (of which free hydrochloric acid is one 
of the products) than do the chlorides of calcium, barium and 
strontium), for instance; and yet solutions of the last three 
salts are acted upon but feebly by magnesium, while from the 
magnesium chloride solution hydrogen is rapidly evolved. This 
point is illustrated still more strikingly by the fact that solu¬ 
tions of sodium and potassium chlorides are relatively strongly 
attacked by magnesium; what reasons are there to assume that 
these salts are decomposed more by water than those of the 
alkaline earth metals ? And again, would it be rational to sup¬ 
pose that because KOI solutions attack magnesium more read¬ 
ily than sodium chloride solutions that the former salt is de- 
composed more by water than the latter ? But the difficulty of 
this mode of explanation becomes even greater in the case of 
the non-saline solutions. So for instance the alcoholic solu¬ 
tion is acted upon more vigorously than pure water, clearly 
there is no chance for assuming free acid to be the active agent 
in the case of this solution. 1 
The idea that Mouraour advances in the case of solutions 
of ammonium salts, namely, that the solubility of magnesium 
hydroxide in them determines the liberation of hydrogen from 
them by action of magnesium, might possibly be applied to 
2 According to the dissociation theory, such an alkaline solution would 
contain less hydrogen ions than pure water, and yet hydrogen is evolved 
faster from them than from water. 
1,'Indeed from the standpoint of the dissociation theory one would 
have to hold that the alcohol solution contains fewer hydrogen ions 
than are present in pure water, and hence action ought to be less than 
in the latter. Moreover from the point of view of this theory, magne¬ 
sium ought to act rather less on solutions of magnesium! salts, for the 
presence of Mg ions would militate against the formation of more of 
them. And again the difference of potential between magnesium and 
an MgS0 4 solution ought to he less than between magnesium and a 
NaCl solution; the facts show that just the opposite is true. 
