310 Wisconsin, Academy of Sciences, Arts, and Letters. 
ous solutions with, sodium amalgam ; in those cases where no 
precipitate forms., similar large differences in the rate of evo* 
lution of hydrogen occur. 1 Again it is well to bear in mind 
in this connection that during the time of duration of the 
above experiments hut small quantities of magnesium hydrox¬ 
ide or basic magnesium salts were formed; in. fact, in many 
cases a precipitate was not at all discernible. I assured my¬ 
self that from a bar of magnesium that had remained in, a nor¬ 
mal solution of NaCl long enough to be visibly covered with 
a white coating, hydrogen was nevertheless much more rapidly 
evolved than from a fresh bar of magnesium just placed in 
water. 
One might further be inclined to ascribe the action of mag: 
nesium on these aqueous solutions to mere contact action, i. e., 
to so-called catalytic action of the solute or some of its ingre¬ 
dients. Tomassi 2 states that in the case of the KC1 solution 
we apparently have the best instance of such contact action; 
for here the KOI remains unchanged and the magnesium hy¬ 
droxide only is formed. Nevertheless, even here it is not an 
easy matter to free the latter from “adhering chlorides” by 
washing. It would scarcely be helpful to dismiss the matter 
by saying that in these diverse solutions the rate of evolution 
of hydrogen is increased by the catalytic action of the solute 
when the hydrogen is liberated more rapidlv than from water, 
and that the rate is diminished by the negative catalytic action 
of the solute, when the formation of hydrogen takes, place less 
rapidly than from water. 
All the facts above presented are very readily explained on 
the basis of the view of solutions which suggested this research; 
namely, that solutions are chemical combinations, of solvent and 
solute according to variable proportions. 3 It is clear that if 
iThis most interesting problem of the action of alkali metals and 
their amalgams upon aqueous solutions is being studied in this labora¬ 
tory by Mr. Gustav Fernekes at present. His work is already well 
advanced. 
2 1. c. 
3 The view that solutions are chemical combinations according to 
variable proportions, does not detract one particle from the law of 
definite proportions which is well established in the case of so very 
many compounds. Horstman (1. c.) presents the whole matter so well 
that it is unnecessary to dwell further upon it here. 
