means of a long iron bar called a paddle, and finally separates the whole mass of iron into large lumps, each weighing from 60 pounds upward. After this, the opening in the door of the furnace is closed, and the hot oxidizing flame allowed to impinge upon the halls until they are completely converted into bar-iron. The balls are then placed under a hammer; and, the melted slag being forced out, they are rolled into bars between the puddling-rolls.
The ancient mode of refining iron needed no rolls, a hammer was sufficient; nowadays, the huge quantities of refined iron turned out by the puddling-furnace require more than a hammer. The invention of the puddling-rolls was the natural sequence of the puddling-furnace. This furnace yields more than a hundred times the quantity of bar-iron produced by the bloomery of former times; and the blooms—or balls—can be made of a size sufficient to be turned into iron rails of from 16 to 24 feet in length.
At this point let us cast a glance upon the past. We are contemporaries of the great discovery which shortens the distances upon the globe. About forty years have passed since the first locomotive dashed over the track, and already our social and political conditions are mainly dependent on this invention. Not many years ago, a whole army was conveyed from the southern part of Germany to the north within a few days, and this without a straggler—an operation formerly requiring months. In 1866 we saw how an army, equal in size to the one that perished in Russia in 1812, started from the farthermost limits of Germany, was moved in a very short period to another field, and arrived there at the appointed time. Within a day or so, Germany or France can be passed over in its longest extent. The rapid supply of local wants by the importation of grain and cattle acts most powerfully upon the stability of prices. A famine, in the proper sense of the word, can scarcely be thought of at the present time, unless it be a universal famine. Fresh sea-produce, which formerly gladdened only the coast-land, penetrates now into the interior. Districts far remote from the commerce of the earth, but crossed by the iron track, can now take their produce to the great markets of the world. Hence it cannot be denied that the form of modern society depends upon the railroads. But where would our railroads be if we could not roll rails? Where the rails, if we had no puddling-furnace? Where the puddling-furnace, without a knowledge of the flame? And this knowledge is simply the result of the study of chemical science, which, in turn, may be traced back to the discovery of oxygen. This whole series of wonderful effects and causes dates from that glass of water in which Priestley first collected oxygen. Not a member of that series could have been passed by, not a link of that chain been wanting, without rendering impossible the remaining links. It can be asserted fearlessly, that the favorable condition of modern society has its rise in the discovery of oxygen.
