None of us ever went to school and learned the chemistry of it from books.

We learned the trick by doing it, standing with our faces in the scorching heat while our hands puddled the metal in its glaring bath.
And that is the way the farmer's son has learned hog scalding from the time when our ancient fathers got tired of eating bristles and decided to take their pork clean shaven.

To-day there are books telling just how many degrees of heat make the water right for scalding hogs, and the metallurgists have written down the chemical formula for puddling iron.

But the man who learns it from a book can not do it.

The mental knowledge is not enough; it requires great muscular skill like that of the heavyweight wrestler, besides great physical endurance to withstand the terrific heat.