286 abstracts: technology 



With flour at $12.80 per barrel and potatoes at $1.75 per bushel, flour 

 is a cheaper food than potatoes, and will furnish considerably more dry 

 matter, protein, fat, and starch, and heat units for $1.00. On the other 

 hand potatoes will furnish four times as much mineral ingredients as 

 will the white flour for the same money. On the basis of average yields 

 of 100 bushels of potatoes and 14 bushels of wheat per acre, one acre 

 of land planted to potatoes will produce more food than in the form of 

 wheat to the following extent: 36 lbs. of mineral constituents or a 

 gain of 560 per cent; 28 lbs. of protein, a gain of 37 per cent; 437 lbs. 

 of starch, a gain of 87 per cent; 848,000 calories, a gain of 76 per cent. 



J. A. LeC. 



TECHNOLOGY. — The micro structural features of "flaky steel. Henry 

 S. Rawdon. Bull. Amer. Inst. Mining Eng. No. 146, p. 183. 19 19. 

 One of the most vital problems in the manufacture of steel is the 

 occurrence of defects designated as "flakes." These spots are usually 

 revealed, if present in steel, when the tension specimen is taken so that 

 it represents the mechanical properties of the material in a direction at 

 right angles to the direction of forging. Flakes constitute one of the 

 most serious problems met with in the manufacture of large caliber 

 guns. Their occurrence in chrome nickel steels of the type used for 

 air-plane crank-shafts is also a serious problem. To the unaided eye, 

 a "flake" appears in the fracture of a freshly broken test specimen as a 

 silvery white, very coarsely crystalline area surrounded by metal having 

 the normal appearance. Such areas vary in size from minute spots to 

 those I cm. or more in diameter. Microscopic examination of numerous 

 specimens showed that the coarsely crystalline appearance is a surface 

 configuration only. The "flake" has no depth; the metal in such areas 

 is refined to the same degree as throughout the body of the piece. 

 Within the mass of the steel, flakes exist as intercrystalline discontin- 

 uities. They may be located by means of X-ray examinations and when 

 the specimen is broken along the line of such discontinuities a typical 

 flake is revealed. The discontinuities in the metal often enclose in- 

 clusions of a nonmetallic nature in the form of very thin films. This 

 is not always the case, however, and while flakes appear to occur most 

 readily in "dirty" steel, it is not safe to assume that the presence of 

 inclusions necessitates the presence of flakes. H. S. R. 



