704 SUMMARY OF CURRENT RESEARCHES RELATING TO 



qualitative analysis of metal-bearing substances. The lines characteristic 

 of each component, can usually be detected in the spark spectrum of an 

 alloy. 



National Physical Laboratory.* — An investigation of the alu- 

 minium-zinc alloys has revealed certain inaccuracies in Shepherd's 

 equilibrium diagram, the true diagram being more complex. The 

 eutectics research was continued in several directions. Autographic 

 cooling curves, taken with extremely sensitive apparatus, did not give 

 any indication of two separate stages in the solidification. Various 

 eutectic alloys were made to cool very slowly through their solidifying 

 points, and were submitted throughout this cooling to the action of a 

 centrifuge. Speeds of rotation up to 2500 per minute were used. The 

 lead-tin eutectic after this treatment did not show any signs of separa- 

 tion into the two metals, but in the lead-bismuth and tin-bismuth 

 eutectics a considerable amount of separation took place. Various 

 improvements have been introduced into the methods for determining 

 temperature-density curves. A more complete apparatus has been 

 designed for studying the effects of strain at high temperatures ; this 

 consists of an instrument for applying accurately measured stresses to 

 thin strips of metal heated in a small electric tube furnace in a high 

 vacuum. The plastic extension of the specimens may be measured 

 with some accuracy. A new Leitz arc lamp, having the carbons set at 

 right angles, has been installed for use with the photo-micrograph ic 

 apparatus. For the microscopical study of transverse sections of tin 

 plate, imbedding in electrolytic iron has been tried with success. 



Properties of Non-ferrous Metals.f — An extended study of the 

 elastic breakdown of copper, aluminium, Muntz metal and other brasses 

 has led C. A. M. Smith to conclude that any one of these materials has 

 either a very indefinite yield-point, or else varies considerably in its. 

 elastic properties. The effects of overstrain, and of heating overstrained 

 metals at 100° C. by placing in boiling water, were studied. Very deli- 

 cate measurements of strain were made by means of the sphingometer. 

 The mild steel tested appeared to be more homogeneous than any of the 

 other metals. 



Mixed Crystals or Solid Solutions ? $ — St. Ruzicka has made some 

 experiments on organic bodies to test van 't Hoff's theory that mixed 

 crystals (isomorphous mixtures), as well as amorphous mixtures (glasses,, 

 alloys), are to be regarded as solid solutions, and that accordingly diffu- 

 sion should take place in the crystals. The author found that no diffusion 

 occurred in the crystals examined. 



Metallographical Study of Slags. — With a view of identifying 

 the various substances which compose the inclusions of slag found in 

 iron and steel, Matweieff has prepared synthetically, and examined 

 microscopically, oxides, sulphides and silicates of iron and of manganese. 

 Each compound was melted, as a rule, in contact with iron. Of several 



* Nat. Pkys. Laboratory, Rep. for 1909, pp. 79-88. 

 t Journ. Inst. Metals, il. (1909) pp. 151-230 (44 figs.). 

 % Zeitschr. Phys. Chem., lxxii. (1910) pp. 381-2. 

 § Eev. Metallurgie, vii. (1910) pp. 447-55 (18 figs.). 



