ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 541 



largely upon the microscopic examination of annealed and quenched 

 specimens. Six weeks annealing was found to be sufficient to establish 

 equilibrium. The ^ constituent only occurs above 430^ C. The soHd 

 solubility of antimony in copper is much higher than has previously been 

 suspected. The accompanying table describes the constituents of alloys 

 annealed to equilil)rium at 400° C. 



Granular Pearlite.* — H. Hanemann and F. Morawe find that 

 granular pearlite may be formed in steel by any one of four different 

 treatments : — («) by very slow cooling through Ar^ ; {h) by repeated 

 heating and cooling through A^\ {c) byre-heating quenched steel at 

 650' to 700* C. without exceeding Ac^ ; {d) by long anneahng of 

 lamellar pearhte at temperatures just below Acj. Small pieces of steel 

 containing 0*86 p.c. carbon were drawn at different speeds from the hot 

 to the cold end of a tube (one end of which was inserted in a Heraeus 

 furnace at 900° C), to obtain different rates of cooling, and were then 

 examined microscopically. When the speed of cooling through kx^ did 

 not exceed 0*5° C. per minute, the pearlite was wholly s^ranular ; some- 

 what faster cooling gave mixtures of granular and lamellar pearlite. In 

 steels in which the carbon-content is higher or lower than in the eutectoid, 

 granular pearlite is more readily formed owing to the separation above 

 Ar^ of excess cementite or ferrite. 



Tenacity, Deformation, and Fracture of Soft Steel at High 

 Temperatures, f — W. Rosenhain and J. C. W. Humfrey have studied 

 the tensile properties, at high temperatures, of a sheet steel containing 

 * 1 p.c. carbon, and record the microscopic observations made upon the 

 specimens. The test pieces were strips cut from thin sheet ; they were 

 polished on one face, heated in a vacuum to the required temperature, 

 broken rapidly or slowly, and cooled rapidly or slowly, as desired. As 

 the enlarged ends of the test piece underwent the same treatment as 

 the strained portion, unstrained specimens were in each case available 

 for examination and comparison. Owing to the heat-reliefs developed, 

 combined with the effects of strain and of the vacuum-etching incidental 

 to the method, it was unnecessary to etch the specimens. Substantial 

 confirmation of the amorphous cement theory of crystal boundaries was 

 obtained. 



At temperatures well above Ax^ the material behaved as an aggregate 

 of crystals, themselves relatively strong, embedded in a viscous fluid. 

 The allotropic change occurring at Arg coincided with a marked weaken- 

 ing of the crystals, the cement apparently being unaffected. Thus 

 below Arg the cement was stronger than the crystals, and strain occurred 

 chiefly within the crystals, slip bands being formed. The behaviour of 

 the specimens was much the same in the a range as in the ^ range. 

 Below Aro the strength of the material was found to be largely dependent 

 on crystal size, unless the rate of straining was extremely slow, when 

 the influence of crystal size practically disappeared. Measurements of 

 crystal size were made by tracing upon a screen the outhnes of the 



* Stahi und Eisen, xxxiii. (1913) pp. 1350-5 (9 figs.). 



t Journ. Iron and Steel Inst., Ixxxvii. (1913, 1) pp. 219-314 (50 figs.). 



