ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 125 



temperatures ; (3) influence of position from which the sample is taken, 

 on the amount of gas evolved. 



Extraction of Gases contained in Metals.* — 0. Boudouard has 

 shown, by successive heatings of samples of iron at 1100° C. in vacuo, 

 that gas is still evolved at the third heating. A much larger quantity of 

 gas (amounting to 0*22 p.c. by weight) was evolved from filings than 

 from the same metal in the form of wire or sheet, and a greater propor- 

 tion of the total gas evolved was given off at the first heating in 

 the case of filings. Volatilisation of the iron commenced at 1)00° C, 

 and was marked at 1100° C. 



Vibrations accompanying Shock.| — C. de Freminville has made an 

 extended study of the fractures of glass, sandstone, steel, and other 

 materials. It is to be regretted that his deductions as to the character 

 of the vibrations accompanying shock are so vaguely expressed as to 

 be of little practical value. A comprehensive classification of fractures 

 is given. 



Alloys of Cobalt and Copper.:}: — The equilibrium diagram of this 

 series, determined by N. Konstantinow, indicates that no compounds are 

 formed, and that there are two series of solid solutions with concentra- 

 tion limits, 6 • 5 p.c. cobalt and 15 p.c. copper. From :->0 to 70 p.c. cobalt 

 the melt splits up into two liquid layers on cooling. Confirmation of 

 the diagram was obtained by micro-examination : the separation into 

 two layers was not evident in the sections, probably on account of the 

 small difference in specific gravity of the two liquids. The etching re- 

 agents were hydrochloric acid for the copper-rich alloys, and ferric 

 chloride for the alloys of low copper content. 



Sorbitic Rails. §— By experiments carried out on 1*5 m. lengths 

 of steel rail, F. Limbourg has shown that the hardness, tensile strength, 

 and stiffness (indicated by deflection in a drop test) of rails may be 

 considerably raised by treatments of the kind suggested by Stead and 

 Richards. The treatment consisted in quenching the rails hot from the 

 rolls, in water, and reheating to temperatures ranging from 450-650° C. ; 

 or in immersing in water till no longer red, and cooling in air, the in- 

 ternal heat of the rail effecting a partial annealing. 



Iron-carbon System. || — A. Portevin considers that the multitudinous 

 investigations of this system have led to the final establishment of the 

 theory of equilibrium. He gives a clear account of the diagram ex- 

 pressing the labile equilibrium between iron and cementite and the 

 stable equilibrium between iron and graphite. The numerous references 

 in the course of the paper constitute a useful bibliography. 



* Comptes Rendus, cxlv (1907) pp. 1283-4. 



t Rev. de Metallurgie, iv. (1907) pp. 833-84 (38 figs.). 



I Tom. cit., pp. 983-8 (8 figs.). § Tom. cit., pp. 989-92. 



|| Tom. cit., pp. 993-1005 (3 figs.). 



