ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 469 



Alloys by Superposition.* — H. le Chatelier indicates his recent 

 progress with this method. In an alloy obtained by superposition the 

 crystals show in general a development along the longitudinal dimension, 

 to a greater degree than do crystals of the same constituent in an 

 alloy of uniform composition. The reason is, that owing to progressive 

 variation of composition in a particular direction, solidification proceeds 

 in the same direction, by the growth of crystals already formed rather 

 than by the formation of fresh centres of crystallization. The same 

 cause accounts for the absence of ordinary eutectic structures in many 

 examples of superposition alloys. Crystals of the two phases of which 

 the eutectic is constituted are well-formed throughout the region in 

 which eutectic would normally occur. It is suggested that the method 

 may be applied to the investigation of ternary systems. By bringing 

 together three small globules of the molten metals, a preparation should 

 be obtained containing the constituents of the three binary systems and 

 of the ternary system also. 



Metallographic Hyg^roscope.f — C. Benedicks and R. Arpi, when 

 attempting to etch a zinc-aiitimony alloy containing 9 p.c. zinc by hold- 

 ing the polished section over aqueous hydrochloric acid, observed that 

 instead of attacking the surface uniformly, the acid vapours condenspd 

 upon it in separate minute drops. When these drops evaporated, thin 

 layers displaying interference-colours remained, and the colours changed 

 with changes in the hygroscopic state of the surrounding air. Apparently 

 the thickness of the film of metallic chloride is a function of the sur- 

 rounding hygroscopic conditions. Various other alloys of the same 

 series, etched with alcoholic hydrochloric acid, were found to give similar 

 effects. 



Beilby, G. T. — The Hard and Soft States in Metals. 



Jotini. Inst. Metals, vi. (1911) pp. 5-43 (25 fig8.)_ 



Belaiew, N. T. — Damaskeening. 



Metallurgie, viii. (1911) pp. 449-56, 493-7, 699-704 (17 figs.). 



Fay, H. — Some Causes of Failures in Metals. 



Proc. Amcr. Soc. Testing Materials, xi. (1911) pp. 439-53 (20 figs.). 



Howe, H. j\L — Life-history of Network and Ferrite Grains in Carbon Steel. 



[The author's views, previously summarized (see this Journal (1912) p. 369), 

 are given with much detail.] 



Proc. A7ner. Soc. Testing Materials, xi. (1911) pp. 262-386 (74 figs.). 



Louis, H. — Failure of a Brazed Joint. 



Journ. Inst. Metals, vi. (1911) pp. 222-35 (9 figs.). 



MiJGGE, 0. — Microstructure of Magnetite. 



Jahrb. Min. Bcil., xxxii. (1911) pp. 491-534. 



RosEXHAiN, W., & S. L. Abchbutt — Constitution of the Alloys of Aluminium 

 and Zinc. 



[A more complete account of an investigation previously summarized (see 

 this Journal, 1911, p. 711) ]. 



Nat. Phys. Lab., Collected Researches, viii. (1912) pp. 41-72 (34 figs.). 



* Proc. Int. Assoc. Testing Materials, ii. (1912) No. 8, 8 pp. (7 figs.), 

 t Journ. Inst. Metals, vii. (1912) pp. 246-8 (2 figs.). 



