388 
AMERICAN AGRICULTURIST. 
[October, 
■was true, for when he looked into the spring, there was 
his green feather at the bottom, and the next time he 
found a locust, he discovered an opal in its head, which 
he was sure was one of those he had seen in the fairy- 
cave when he visited the Spring under the Willow. 
--— i-— 
The »octoi-’s TjjIIcs—A bout Irost 
and Steel. 
Little did the boy think, who asked the question as to 
the difference between iron and steel, that he would have 
to read so long a reply. But a brief dictionary answer 
would not tell much, and when I am obliged to describe 
everything about it, because boys and girls are not apt to 
know much about chemistry, it takes a great while. Let 
us see how far we have reached: The iron in the ore is 
usually mixed with oxygen, and we separate the iron by 
taking away the oxygen, which we do by giving the 
oxygen a plenty of carbon (coal). The iron runs from 
the furnace where it has been separated from the ore as 
cast-iron, and usually the first step is to run the melted 
iron into rough bars, called pigs,.as was described last 
month. Since that was printed, I have come across an 
engraving showing the interior of the casting shed to an 
iron-furnace, which I give here. Yon see on the left 
hand side the sand made into ridges with channels be¬ 
tween them ; these channels are the molds. Along one 
side of these there runs a long channel, which connects 
with these shorter ones, or molds, hut to have the molds 
furthest from the furnace filled first, these arc shut off 
from the long channel by gates, which are plates of iron 
with a handle, and look much like a spade. When the 
melted iron has filled the molds furthest from the furnace 
<a part of which you see at the rear), these gates are 
taken out, one at a time, to let the melted iron run into 
the other molds.' This cast-iron is not pure, hut contains, 
besides other matters that were in the ore, from two to 
five parts in the hundred of carbon, which it got from 
the coal. To change the cast-iron into wrought-iron, this 
carbon, or nearly all of it, and other impurities also, must 
be got rid of, which is done by burning it out; the melt¬ 
ed cast-iron is exposed to a great heat with a plenty of 
air, and the carbon nearly all disappears, leaving the iron 
nearly pure in the form in which it can only be worked 
by hammering and welding. Cast-iron is brittle, hard, 
and can be melted, but cannot be welded ; wrought-iron 
is tough, but soft, and cannot rehdily be melted,"but can 
be welded. _ For many purposes a metal is needed that 
has all these qualities; that is tough and hard, and may 
be melted or welded, and this is found in steel, which is 
iron containing a much smaller quantity of carbon than 
cast-iron, and more than wrought-iron. The original way 
of making steel was to first make wrought-iron from 
cast-iron, and then turn the wrought-iron into steel by 
adding more carbon. A very curious process it is. A 
case is built of fire-brick, and in this are placed bars of 
wrought-iron, which are packed in fine charcoal; the 
charcoal being all around and between the bars, the case 
is closed tight, heated bright red, and kept at this heat 
for a week or more. At the proper time the case is al¬ 
lowed to cool, and the bars taken out; instead of being 
soft and tough, as when they went in as wrought-iron, 
they are now hard and brittle, and are turned into steel. 
Being roasted so long with the carbon, or charcoal, the 
iron unites with enough of it to produce these changes. 
Bars of steel produced in this way are uneven in quality, 
the outside of the bar having more carbon than the in¬ 
terior; so the bars are broken up and put into a pot 
made of black-lead (such as pencils are made of) and 
clay, and exposed to a strong heat; the steel melts, and 
is then cast into molds, and the bars thus made are of 
even quality all through. Steel contains from about one 
part in four hundred to two parts in one hundred of car¬ 
bon. There are several other ways of making steel; or.e 
is by a mixture of certain different iron ores, which yield, 
by proper management, steel instead of cast-iron. There 
is what is called the Bessemer process, too difficult to 
describe to young people, but which makes steel so 
cheaply that it may be used for rails on rail-roads, in¬ 
stead of iron. However the steel may be made, the 
object is to get a mixture of iron with a small quan¬ 
tity of carbon. There are other substances besides car¬ 
bon that alter the quality of steel, but you must wait un¬ 
til you get older before you can learn about these. One 
of the valuable things about steel is that it may be soft 
and tough, or exceedingly hard and brittle, according to 
the use for which it is to serve. If a piece of steel is 
heated red hot, and then allowed to cool very slowly, it 
will he soft, but if, when red hot, it is plunged into wa¬ 
ter or oil, it cools suddenly, and will be very hard ancj, 
brittle. Another curious thing about steel is that it may 
be made of any desired hardness between these two 
points ; for razors and surgeons’ instruments much 
harder steel is needed than for saws and other carpenters’ 
tools; this giving the steel any desired hardness is called 
tempering. The steel is first made very hard by heating it 
red hot, and cooling it suddenly in water or other liquid; 
it is then tempered by heating it to a less strong 
heat. Polished steel, when heated to about 430°, turns a 
very pale yellow, as the heat is increased it turns 
yellow, then with more heat brown, then purple, 
and finally to various shades of blue. The skillful 
workman knows if he heats the steel yellow, and al¬ 
lows it to cool, it will still t>e very hard ; if he heats it 
until it is brown, and lets it cool, it will be softer, and so 
on ; he knows by watching the color what the temper of 
the steel will he. You have noticed that watch springs 
are of a bright blue color; this color shows the temper 
best suited for springs; in most articles the color (which 
is the thinnest possible film upon the surface, caused by 
the action ot the oxygen of the air) is rubbed off, but it 
is usually left upon the spring. Probably some boys, who 
have accidentally heated their pocket knives, and then 
found that they would not hold an edge, no matter how 
much they were sharpened, have learned something about 
tempering steel. There is very much that is interesting 
and useful to know about both iron and steel, that I have 
not been able to tell you; but what I have said will show 
you that the things that we have in such common use, as 
iron and steel, were only brought to their present perfec¬ 
tion by a vast deal of labor. The boy’s knife-blade, the 
girl’s scissors and needle, if we could only trace them 
back, what a story they would tell 1 and how many heat¬ 
ings and meltings, roastings and forgings, have there 
been to produce these familiar articles. No wonder then 
that the savage prizes a bit of iron so highly. The 
Creator gives us gold in pure grains, but iron can only be 
had by skilled labor. Gold is barbaric. Iron and steel 
are tokens of civilization. The Doctob. 
No. 457. A Transposition Puzzle Picture. —By transposing the letters of the objects in the above 
picture, you will find : 1. To hinder. 2. To burn. 3. A name sometimes given to an old inhabitant. 4. A French 
saloon. 5. A part of the neck. 6. A troublesome insect. 7. Troubles. 8. A toy. 9. Vehicles of thought. 10. Units. 
11. A step. 12. A sail-boat. 13. Perfume. 14. To rescue. 15. A part of a flower. 16. A horned animal. 17. To 
perform. 18. A hard knock. 19. To warble. 20. A planet, 21. A tree. 22. Passion. 23. Articles of apparel. 
24. The cry of an animal. 25. Instruments.—Now here is a chance for the puzzle readers to work. 
INTERIOR OF AN IRON FURNACE.—CASTING PIG-IRON. 
