"Soon, however, fire became a necessity of life to mankind, for it was discovered that meat tasted better when exposed to a flame--that, is, when it was cooked--than when it was raw. That was a big step toward civilization, but it was a bigger one when some wild mountain tribe found that they could make much more deadly weapons than the rude ones they chipped from flint, by melting down a certain kind of rock and fashioning it into spear heads, arrow heads, and hatchets. From that time on the development of the art of metal working took only a few thousand years, until to-day man's great knowledge of metalurgy has enabled him to make such tremendous fighting machines that war is becoming entirely too destructive, and too expensive a thing to rush into lightly. Thus, heat and metal working are helping to force the world forward to another step in civilization--universal peace. "After learning how to make these hardest of metals, man has now solved the problem of making them boil like water with the thermit process and of cutting them like paper with the oxy-acetylene gas torch, all in less than a minute. "You see this bag of coarse black powder that looks like iron filings? Well, it is the thermit. Put it into a crucible, set off a pinch of ignition powder on the top, and the whole thing will ignite in half a minute, throwing off a blinding white light and thousands of sparks like beautiful fire works. That is the thermit reaction. "You know more about the oxy-acetylene gas torch, for in your metal working at school you used the gas blowpipe to make a very hot flame. The oxy-acetylene gas torch is just a high development of this, for instead of ordinary gas, acetylene is used and instead of air we use pure oxygen." The caller sat down and asked his friend to tell something more about these two marvelous inventions. The story was several days in the telling, for there were visits to foundries and experiments in the laboratory, besides many long talks. "First we will see about thermit," said the man, and began to talk as he worked over a crucible. THERMIT HEAT PROCESS As a result of his discovery that by starting a terrific battle for oxygen between two metals he could reduce one of them to almost absolute purity, Dr. Hans Goldschmidt has converted to the use of man a process of welding so simple and yet so forceful that it is making world-wide changes in the working of metals. This battle itself is the most interesting feature of the Goldschmidt process because of the terrific heat it generates. Imagine sticking your finger into boiling water. By so doing you would be exposing your flesh to a temperature of 212 degrees Fahrenheit. Imagine sticking your finger into a pot of molten lead if even for the fraction of a second. You know very well what the effect would be. The temperature is 618 degrees Fahrenheit. Still again, think of a redhot iron. This is about 1,652 degrees Fahrenheit. Steel boils at 3,500 degrees.