404 SUMMARY OF CURRENT RESEARCHES RELATING TO 



mixture, the other on the association of the dissolved metal. The 

 curves of the bismuth-tin and other series, thus corrected, approximate 

 very closely to the ideal curves. The presence of a solid solution or a 

 chemical compound renders the method inapplicable. 



Alloys of Iron and Carbon.* — G. Charpy reviews recent work on 

 the iron-carbon system, and discusses the application of the various 

 methods of investigation to the construction of the equilibrium diagram. 



Ultra-microscopic Observations.! — J. Reissig describes the ultra- 

 microscopic examination of colloidal solutions of brown tellurium, 

 selenium, and silver, and of red and blue gold. The stability of the 

 colloidal gold, indicated by the slowness with which flocculation takes 

 place on addition of hydrochloric acid, is greater in dilute than in con- 

 centrated solutions. 



Freezing-point of Iron.J — H. C. H. Carpenter states briefly the 

 present condition of high temperature pyrometry, and gives an account 

 of the determinations which have been made, of the freezing-point of 

 iron. This point is best defined either on the thermo-electric or the 

 optical scale. The mean value of several closely agreeing determinations 

 by different workers is 1505° C. on the thermo-electric scale, corre- 

 sponding to 1519° C. on the optical scale, which is probably more 

 nearly the true value. The freezing-point is independent of the 

 atmosphere in contact with the iron. 



Constitution of Carbon Steels.§ — E. I). Campbell gives an account 

 of the commonly accepted views as to the nature of the constituents of 

 steel, and describes some experimental work on the separation of car- 

 bides from a 1*17 p.c. carbon steel by electrolysis in a neutral solution 

 of ferrous sulphate. The carbide separated from the steel quenched in 

 water from 900° C. corresponded to the formula C 10 Fe 9 , while the steel 

 in the troostitic condition resulting from reheating to 350° C. after 

 quenching in water from 900° C. gave a carbide with the approximate 

 empirical formula CFe 2 . The author suggests the possibility of the 

 existence of a number of carbides of iron in addition to the well-known 

 Fe 3 C. 



Influence of Thermal Treatment on Linear Deformations of 



Steels. || — Demozay gives at some length the results of experiments on 

 the effect of heat treatments, such as quenching in oil and in water, 

 and annealing at a high temperature, upon the breadth and thick- 

 ness of bars (dimensions originally 100 x 10 x 5 mm.), of 7 steels of 

 carbon 0*19-1 '15 p.c. Each treatment was repeated a number of 

 times. Repetition of a treatment accentuates the deformation, which 

 increases in proportion to the number of treatments. 



* Joum. Chem. Soc, xciv. (1908) pp. 697-8. See also Bull. Soc. Chim., iii. 

 (1908) pp. 1-46. 



t Tom. cit., pp. 933-4. See also Ann. Physik, xxvii. (1908) pp. 186-212. 



J Joum. Iron and Steel Inst., lxxviii. (1908) pp. 290-9. 



§ Torn, cit., pp. 318-35. 



|| Rev. Metallurgie, vi. (1909) pp. 413-41 (44 figs.). 



