310 THE AMERICAN MONTHLY [Nov 
versality of vaccination has rendered it impossible to see 
what would occur without it. , 
That rare and occasional accidents have accompanied 
vaccination may possibly betrue. But he who objects on 
this account is like the man whose store being on fire 
would not permit water to be thrown in lest some of the 
goods should get wet! 
CARBORUNDUM. —This is silicate of carbon manufactured 
at the Falls of Niagara by heat produced by a powerful 
electric current. A wall about 14ft. long, 7ft. broad and 
7ft. high, is built up of nuts of coke, faced outside with 
loose bricks. Along the centre of the wall runs a core 
composed of ground coke, mixed with sand, salt, and saw- 
dust. A current passed through the core soon heats it up, 
and burns the sawdust, which leaves the core porus. Next 
the salt is decomposed, the chlorine in it finding its way © 
to the outside, the sodium remaining behind and uniting 
with the sand. As the heat increases, the sodium comes 
_ off also in a state of vapor, leaving behind the silica of 
the sand in a state ready to unite with the carbon of the 
coke. The union produces carborundum in crystals. After 
long cooling, the wall is thrown down, and the carborun- 
dum is extracted. The name is hybrid between carbon 
and corundum, which has nothing to do with the sub- 
stance further than that it is half a grade higher than it 
is in hardness, being inferior only to diamond. It is 
largely used for polishing granite instead of emery. 
When pounded and mixed with clay, made into small 
bricks, and discs, and fired in a kiln, it makes hones of 
great abrasive power, and wheels which grind down axles 
or cut through rods of iron. | 
For Sale.— A Beck stand with three lenses, very little 
used. Price $10. Address: G.W. Wilcox, care this office. 
