18 
HAROLD’S DISCUSSIONS. 
on a half-frozen river. Imagine the scene. A little 
water poured on a red-hot stove shoots up with a hiss¬ 
ing noise as a cloud of hot vapor. In tlie cold out¬ 
side boundarj of the world’s envelope the mist con¬ 
densed into rain, which, in falling, came in contact 
with the hot steam below, and was again quickly 
hurled out with hissing screams. These violent 
changes produced untold quantities of electricity, 
which must have shot hither and thither in forked 
lightnings, accompanied by deafening peals of rolling 
thunder. How weary it makes us to think of this as 
continuing for days and weeks, but it must have lasted 
through centuries. Finally the crust hardened, and 
so far cooled that most of the water was allowed to 
find a resting-place on this much-ridged globe. 
“ A shoreless ocean tumbling round the globe.” 
Mr. Mathew Williams has well told us what takes 
place in the open furnace of a pig-iron refinery. It 
is a very instructive experiment. A mixture of iron, 
sulfur, carbon, and silicon is melted in the open air. 
The carbon unites with oxygen and rises as carbon 
dioxid. The silicon takes on oxygen, and, being 
lighter, fioats on the iron, combines with the aluminum 
or calcium that is found to a greater or less extent in 
the pig-iron, and forms substances resembling the 
predominant material of the earth’s crust. When 
the melting process has been carried far enough, the 
mixture is poured out into a box usually ten feet 
long and three feet wide. Here it settles and cools. 
The silicates, the rock materials, separate from the 
