124 SUMMARY OF CURRENT RESEARCHES. 



ing of the surface, caused by etching', calculated to be not more than 

 '2 molecules in depth. The unetched polished surface shows no trace of 

 disturbance, and the presence of a disturbed surface layer is revealed 

 only by etching. The disturbed layer seems to have a different mole- 

 cular structure, and is harder than the original crystal. The presence 

 of this protective skin does not interfere with the parallel growth of 

 •crystals of sodium nitrate on the polished surface. 



Testing of Galvanised Metals.* — W. H. Walker, in discussing 

 methods of determining the resistance to corrosion of zinc-coated metals, 

 describes their microscopic structure. Between the outer coating of 

 zinc and the iron base are a number of zinc-iron alloys. 



Magnetic Transformation of Nickel and Cobaltf — I- I- Shukoff 



finds that sudden changes occur in magnetic properties, electrical con- 

 ductivity and thermo-electric properties, at about 340° C. for nickel and 

 1000° C. for cobalt. A heat effect was observed with cobalt at 985° C. 

 by the differential method of taking cooling curves, but no such effect 

 was observed with nickel between 600° and 180° C. The author concludes 

 that the transformation observed in nickel depends on some change 

 occurrin": in the internal structure of the atom. 



.-> 



Testing by Alternating Stress.} — H. le Chatelier discusses the 

 relation between the behaviour of a metal under A. Quillet's vibiatory 

 test§ and its resistance to alternating stresses. Perfect elasticity is 

 unknown. However small the deformation, a piece of metal, when the 

 •stress is removed, does not return completely to its original form, but 

 remains deformed to a slight degree. A part of this slight remaining 

 distortion disappears slowly, but an exceedingly small permanent de- 

 formation remains. In the slow recovery towards its original form, the 

 metal exhibits viscosity, and this is the property which the Guillet 

 " damping " test appears to reveal. 



Gases Occluded in Steel. || — T. Baker has determined the com- 

 position and volume of the gases evolved by two crucible steels, contain- 

 ing respectively 0*81 and ,( .)0 p.c. carbon, when heated in vacuo. A 

 little aluminium had been added to the second steel before casting, none 

 to the other. More than !)7 p.c. (by volume) of the total gas evolved 

 was hydrogen and carbon monoxide, and the sound steel, to which alu- 

 minium had been added, evolved twice as much gas as the steel contain- 

 ing blow-holes. 



Sang, A. — Cementation. 



[Theories of various cementation processes are discussed, and methods 

 described.] Electrochem. and Met. hid., vii. (1909) pp. 485-7, 532. 



Vanstone, E. — Miscibility of Solids. 



[The theory of the formation of solid solutions is discussed; and the results 

 of experimental work on various organic bodies are given.] 



Journ. Chem. Soc, xcv. (1909) pp. 590-604 (3 figs). 



* Electrochem. and Met. Ind., vii. (1909) pp. 440-2. 



t Journ. Russ. Phys. Chem. Soc, xl. (1908) pp. 1748-52, through Journ, Chem. 

 Soc, xcvi. (1909) pp. 209-10. 



t Rev. Metallurgie, vi. (1909) pp. 1156-GO (2 figs.). 



§ See this Journal, 1909, p. 675-6. 



|| Iron and Steel Inst., Carnegie Scholarship Memoirs, i. (1909) pp. 219-29 

 <3 figs.). 



