296 THE POPULAR SCIENCE MONTHLY 



Thus chemists and chemical engineers have answered the demand 

 of the hour. With the boundless atmospheric nitrogen and with water 

 power, the development of which has scarcely begun, man need never 

 fear an insufficient nitrogenous food supply. 



We are inclined to lament because of the extent to which some of our 

 limited natural resources, such as iron, are being drawn upon. But if 

 we compare the condition of the people of the United States now with 

 that at the time when these resources were comparatively untouched we 

 must admit that their use has added immensely to human comfort and 

 progress, and that this increased comfort could have been gained in no 

 other manner. In addition we must consider that, although much ma- 

 terial is being used, the processes of putting it upon the market are gain- 

 ing immensely in economy of operation through the studies of scientific 

 men, and that much that we were in the habit of discarding is now 

 used repeatedly. So that the total amounts taken from their terrestrial 

 storehouses does not fairly represent the loss to humanity. 



For instance, since the time of Tubal Cain until about the end of 

 the fifteenth century iron ores were reduced in a crude forge where the 

 yield ran from 100 to 300 pounds per charge — far less than a ton per 

 day. Compare the continuous process of the modern blast-furnace pro- 

 ducing 75,000 or more tons annually and think how many conveniences 

 we should be deprived of if we were still limited to the primitive meth- 

 ods. Compare also the price per ton of pig iron from the old and the 

 present processes and no doubt will remain that wastefulness is rela- 

 tively immensely less in the iron industry now than then. Nor is iron 

 once used discarded, but it is worked over into new forms and employed 

 for other purposes. 



Previous to 1856 the only means of producing steel was to labori- 

 ously remove the carbon from the pig iron in the puddling furnace, roll 

 the iron into bars, slowly add the requisite carbon again by heating the 

 two together for days, and melting or hammering to get a homogeneous 

 product. But in 1856 Henry Bessemer announced his process for ma- 

 king steel from pig iron in one operation, a process so simple that we 

 please ourselves by thinking that we might have invented it if it had 

 not previously been done. Bessemer found it necessary only to burn 

 out from the molten crude iron the impurities, carbon and silicon, by a 

 blast of air forced into the bottom of his crucible, just as we stimulate 

 the burning of fuel in our fireplaces by the use of a bellows. No fuel 

 was added as the heat from the burning impurities was adequate to 

 keep the mass melted until the change was complete. To the purified 

 iron thus obtained he added the requisite amount of carbon and, in 

 half an hour, had a dozen tons of steel. The price of steel rails before 

 and after the Bessemer process came into vogue is a testimony not only 

 to the knowledge of the metallurgist, but to the saving in time, labor 



