The Boy's Book of New Inventions

by Harry E. Maule

"Now," said the scientist, after he and his young friend had finished some experiments, and were ready to talk about autogenous welding, "imagine a little white flame no bigger than a pencil point at the end of a brass pipe about the size, and not entirely unlike in appearance the old-fashioned taper holder with which you used to light the gas, and you have before you in the rough, a picture of one of the oxy-acetylene torches that will in a few minutes weld two pieces of almost any metal, or in a few seconds cut a solid plate of the hardest steel of several inches thickness almost as fast and easy as a carpenter could saw a board, and yet without taking the temper out of the metal."

Picking up what seemed to be a little brass rod bent at the end, the man turned a valve, applied a match, and as the gas burned up with a beautiful little flame of dazzling whiteness, he continued:

"This tiny flame, so easily controlled, is hotter than any produced by man except that generated by the electrical furnace, for it reaches a temperature of about 6,300 degrees Fahrenheit. Previous to the invention of these wonderful torches the oxy-hydrogen was the hottest gas flame, but it only reached a temperature of 4,000 degrees Fahrenheit."

"How do you use it?" asked the boy.

"Well, for instance, Uncle Sam is enabled to weld and cut steel plate in building his battleships, steelworkers to carry on their gigantic tasks, and wreckers to clear away tangled masses of steel beams far more quickly and easily than with the older methods.

"If you had visited one of the navy yards, a shipyard or any place where big work in iron and steel was being carried on as short a time as three years ago, you would have seen a man sitting for hours sawing away on the end of a steel beam, for instance, trying to cut it down to the required length. He would dull many saws, use a great deal of energy, and an appalling amount of the most valuable thing in the world—time. Again, you would have seen them welding pieces of iron and steel by the old blacksmith method, or riveting other pieces that could not be joined by heating them and pressing them together.

"To-day you would see fewer of these processes because autogenous welding and cutting by the powerful little oxy-acetylene torches is revolutionizing certain methods of working with metals. Instead of squatting at the end of the beam and sawing away like an old-fashioned carpenter, the modern iron worker takes up his little torch, turns a valve in the handle and concentrates the flame on the steel beam that he wishes cut. Almost instantly a shower of sparks on the under side of the beam shows him that the flame has burned its way through. Then he slowly moves the flame along the line where he desires to cut and the trick is done."

Illustrating with his own little laboratory torch, the scientist continued his explanation, saying that cutting is only one of the many uses to which this modern invention in steel working is put. Not quite so spectacular but every bit as useful is the autogenous welding by means of these magic wands. Welding metals has ever been more or less unsatisfactory. The old process of heating the two ends and then beating them together is cumbersome and practically impossible in many cases. Consequently inventors have sought other welding processes with wider application and greater facility ever since the first metal workers of earliest times forged crude chains and weapons. With this modern device two pieces of steel or other metal are brought to within a small fraction of an inch of each other and by the use of the oxy-acetylene torch and a thin strip or rod of metal are melted and fused together.

Although the acetylene flame gives off a far greater proportion of light than heat, it is a very powerful gas and Le Chetalier, a French inventor, was sure that he could put it to other uses than furnishing lights for automobiles, etc. To this end he tried mixing acetylene gas with oxygen, for there can be no fire or combustion without oxygen. He very properly figured that by introducing pure oxygen into the acetylene, the burning, or combustion, would be greater, and the heat of the flame greatly intensified. His experiments were ultimately successful, and it was then only a short step to the time when three different oxy-acetylene torches were in use. In France there were developed low pressure, medium pressure, and high pressure torches; but the last named has not been found commercially practicable in the United States, where the "medium pressure" torch is sometimes called the high pressure. As we are dealing entirely with the American use of the invention we also will call the two kinds of torches used here the low pressure and the high pressure.

The general principle of the torch is, as we see, the mixture of oxygen with acetylene in order to obtain a hotter flame, but right here we come to the difference between the low-pressure and the high-pressure tools. Both are made of brass pipes, terminating in the burning tip and connected at the rear of the handle with rubber tubes which run to the separate tanks holding the acetylene gas and the oxygen, but the method by which these gases are combined in the torch constitutes the principle differences in the two systems, with the consequent greater or less efficiency claimed by the manufacturers. Without going into the technical details, which are a matter of controversy between scientists as well as the various commercial concerns interested in the torches, it will be sufficient to say that in the low-pressure torch the acetylene gas is only used under a pressure of a few ounces, with the oxygen under a much heavier pressure, while in the high-pressure torches, the acetylene and oxygen both are under an appreciable pressure of several pounds.