120 SUMMARY OF CURRENT RESEARCHES RELATING TO 



275° and 350° C. the elongation greatly increases and tensile strength 

 falls off. The effect of annealing is in the same direction, but is more 

 gradual from 350°-750° C. Litfcle'change takes place from 750°-830° 0. ; 

 at higher temperatures the brass deteriorates. Corresponding changes 

 in microstructure are a rapid recrystallisation between 275° and 350° C, 

 followed by a growth of size of crystal at higher temperatures. Similar 

 investigations were carried out on brass containing 90 p.c. copper, and 

 on pure copper. The etching solutions used were :— 



For 67/33 Brass. For 90/10 Brass and 

 . pure Copper. 



Water 100 c.cm. 100 c.cm. 



Hydrochloric acid 6 50 



Ferric chloride 19 grin. 5 gi'm. 



Iron Alloys.*— C. F. Burgess and J. Aston tabulate the forging, 

 welding, and machining properties of alloys of iron with some seventeen 

 other elements. The alloys, which contained so little carbon that its 

 influence might be neglected, were prepared by melting together electro- 

 lytic iron containing about 0*03 p.c. of impurities, and the alloying 

 element, in weighed quantities. In the nickel, copper, cobalt, tungsten, 

 molybdenum, chromium, manganese and silicon series there was a 

 general agreement between the weights used and the percentage com- 

 position of the resulting alloy. Silver, selenium, aluminium and lead 

 do not alloy at all in the proportions added. Although arsenic and tin 

 vaporise at temperatures much below the melting point of iron, con- 

 siderable amounts of these elements remained in the alloy. 



Iron-manganese Alloys.f— C. F. Burgess and J. Aston give dia- 

 grams and tables showing the effect of increasing manganese content 

 upon the permeability and other magnetic properties of iron-manganese 

 alloys prepared from pure electrolytic iron. The tests were made on 

 the material (1) as forged ; (2) annealed at 675° C. ; (3) annealed at 

 1000° C. ; (4) quenched from 900° C. The permeability falls as the 

 manganese content increases. 



Iron-copper Alloys4— C. F. Burgess and J. Aston have determined 

 some mechanical properties of a series of alloys, prepared from electro- 

 lytic iron and electrolytic copper. An alloy containing 1 • 5 p.c. copper 

 appears to be a promising material. Segregation was not observed in 

 the alloys containing 0-8 p.c. copper. 



Steels for Gears.§— L. ReVillon gives, in addition to the results of 

 practical tests of gears, much information as to the thermal critical 

 points, heat-treatment and mechanical tests of 26 steels, most of which 

 contained nickel and chromium in varying proportions. 



Special Steels.||— W. Giesen deals with a variety of subjects related 

 to alloy steels. Great importance is attached to nitrogen content. The 

 critical nitrogen content lies between 0"037 and 0-041 p.c. for carbon 

 steel, that is the point at which no elongation is obtained in tensile 



* Electrochem. and Met. Ind., vii. (1909) pp. 436-8. 

 + Tom. cit., pp. 476-8 (4 figs.). J Tom. cit., pp. 527-9 (2 fi<rs ) 



§ Rev. Motallurgie, vi. (1909) pp. 1024-53. Iron and Steel Inst. Carnegie 

 Scholarship Memoirs, i. (1909) pp. 161-218 (12 figs.). 



|| Iron and Steel Inst., Carnegie Scholarship Memcirs, i. (1909) pp. 1-59 (2 figs.). 



