742 SUMMARY OF CURRENT RESEARCHES RELATING TO 



examined, and polished. In this section the boundary line between the 

 specimen and the copper constitutes a sectional view of the original 

 surface of the specimen. A thickness of £ in. of deposited copper is 

 sufficient. The author's results support the view, with some reservations, 

 that plastic deformation in metals takes place by slip and twinning alone. 

 A modified form of Beilby's theory, that by mechanical disturbance of 

 the molecular arrangement of a crystalline solid, a crystalline phase may 

 be converted into an amorphous phase, is supported. The well known 

 phenomenon of the transformation of y-iron when strained was studied 

 on a 20 p.c. nickel steel. The changed constituent was found to occur 

 only upon surfaces of slip. 



Hardness of the Constituents of Iron and Steel.* — H. C. Boyn- 

 ton has employed Jaggar's micro-sclerometer to measure this property. 

 The instrument was originally introduced for measuring the hardness of 

 minerals. It consists essentially of a diamond point of constant 

 dimensions, which is rotated at a uniform speed and under a given load 

 on the section to be examined. The number of rotations required to 

 bore to a given depth is determined : this quantity is a measure of the 

 hardness (resistance to abrasion). The instrument is adjusted to the 

 Microscope, and has suitable mechanical devices for recording depth of 

 hole, number of rotations, etc. The author uses a second Microscope, 

 with its axis horizontal, for measuring directly the downward movement 

 of a micrometer scale attached to the arm carrying the diamond point. 

 Considerable differences were found in the hardness of the same con- 

 stituent in different steels, and in the same steel differently treated. 

 The following hardness numbers are selected from a table given by the 

 author : ferrite 460-1643 ; pearlite 842-4711 ; sorbite 2400-24,650 ; 

 troostite 40,564; martensite 17,81)6-120,330; austenite 47,590; cemen- 

 tite 125,480. 



Adamson, E. — Influence of Silicon, Phosphorus, Manganese, and Aluminium on 

 Chill in Cast Iron. Journ. Iron and Steel Inst., lxix. (1906, 1) 



pp. 75-105 (5 figs.). 



Arnold, J. O., & F. K. Knowles— Preliminary Note on the Influence of Man- 

 ganese on Iron. Tom. cit., pp. 106-24 (1 fig.). 



Akrivaut, G. — Constitution of Manganese-Silver Alloys. 



Proc. de la Soc. des Sci. Phys. et Nat. de Bordeaux, 



1904-5, pp. 9-14. 

 ,, ,, Preparation and Properties of Manganese-Antimony Alloys. 



Tom. cit., pp. 85-9. 



„ „ Bismuth-Manganese Alloys. Tom. cit., pp. 89-93. 



„ ,, Manganese-Tin Alloys. Tom. cit., pp. 104-8 



„ ,, Manganese-Lead Alloys. Tom. cit., pp. 108-10. 



,, „ Manganese-Platinum Alloys. Tom. cit., pp. 147-8. 



,, „ Manganese-Copper Alloys. Tom. cit., pp. 148-51. 



A st, W. — International Researches in Macroscopic Examination (Etching Tests) of 

 Iron. Intemat. Assoc, for Testing Materials, B?-ussels Congress, 1906, 



42 pp., 27 figs. 



Journ. Iron and Steel Inst., lxx. (1906, 2) pp. 287-318 (8 figs.). 



