ELECTRIC WELDING DEVELOPMENT." 



Bv Emuu Thomson. 



The art of Avoldina" ii'on is i)r()l)al)ly as old as the earliest produc- 

 tion of that metal by man. In fact, the reduction of iron in the 

 primitive forces demanded the union by weldino; of the reduced par- 

 ticles, for no true fusion could have resulted, the percentage of car- 

 bon present being too low. Until the closing years of the last cen- 

 tury iron was the only weldal)Ie metal, if we except gold and plati- 

 num — too expensive for connnon a})plication. 



The fact that nearly pure iron, so difficult to melt, becomes quite 

 plastic at high temperatures, while the oxide, or black scale, melts 

 long before the metal itself becomes fluid, thus providing a liquid 

 flux which is squeezed out during the process of union, accounts for 

 the unique position Avhich iron held until recent years. AMien. how- 

 ever, the heating effects of electric current energy, so perfectly under 

 control, were applied to weld metals, a metal or alloy Avhich would 

 not weld became the exception instead of the rule, as before. ^luch 

 of the former work of the smithy fire is now accomplished by the 

 electric welding transformer, and although many metals are easily 

 manipulated l\y the electric process, iron, of course, still occupies, as 

 ever, the principal place. 



The electric weld is becoming a more and more important factor 

 in many industries. During recent years the extension of its appli- 

 cation has been steady, and each year has witnessed its entrance into 

 new fi(dds. Sometimes, indeed, new manufactures, or new ways of 

 obtaining results, have been based upon its use. The electric welds 

 under consideration are the results of that operation of uniting two 

 pieces of metal by what is known as the "" Thomson process,'' first 

 brought out by the writer and rendered available in connnercial 

 practice a considerable mnnber of years ago. The rai)idity, flexi- 

 bility, cleanliness, neatness, accuracy, and economy of the electric 

 process has won for it such an important standing in the arts that 

 many future extensions in its application are assured. 



The uniformity of the work, the control of the operation, the ex- 

 treme localization of the heat to the particular parts to be united, 

 and the fact that the process is not limited to iron and steel, but can 



" Reprinted, by i)enuission, from Cassier's Magazine, New Yorlc, June. 1004. 



281 



