ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 115 



Effect of Chromium in Steel.* — F. Osmond criticises Carpenter's 

 statement that chromium does not confer upon steel the property of 

 being self-hardening.f After re-stating his former results which led to 

 the opposite conclusion, the author points out that the temperature to 

 which his chromium steels were heated when the self-hardening effect 

 was obtained, was considerably higher than that employed by Carpenter. 

 Either this fact, or a difference in the rate of cooling, may account for 

 the discrepancy in the conclusions reached by Carpenter and the author. 



Mechanical Properties of Single Crystals of Iron.J — F. Osmond 

 and C. Fremont obtained some iron in abnormally large crystals, from 

 an old steel rail which had been in use as a guide for a damper in a 

 furnace-flue for 15 years, and had thus been subjected to thermal con- 

 ditions favourable to the development of crystallisation. The metal 

 contained 0*06 p.c. carbon. A tensile test-piece was obtained, the 

 effective portion of which was constituted almost entirely by two 

 crystals. Two compression test-pieces were cut from a single crystal. 

 Stress-strain diagrams are given. Brinell hardness-tests were made on 

 different faces of a crystal, giving somewhat different results. Statical 

 bending and shock tests showed that the angle made by the cleavage- 

 plane with the axis of the test-piece had great influence on the results, 

 and that brittleness only appeared under impact. 



Nickel-Manganese Steels.§ — Having completed a general investiga- 

 tion of the ternary steels (alloys of iron, carbon, and a third element), 

 L. Guillet has taken up the study of the quaternary alloys, starting with 

 nickel-manganese steels. Assuming the possibility of deducing their 

 properties from those of nickel steels and manganese steels, the author 

 gives equations from which the constitution (whether pearlitic, marten- 

 sitic, or containing y-iron) of a steel of given analysis, may be calculated. 

 Three series of alloys were prepared, the first containing - 15 p.c. 

 carbon, nickel 2 p.c, 12 p.c, or 30 p.c, manganese 5 p.c, 7 p.c, or 

 15 p.c. ; the second containing 0*75 p.c. carbon, nickel and manganese 

 both varying as in the first series. The members of the third series 

 have analyses which cause them to be placed on the limit of two groups. 

 Certain of the alloys could not be rolled. As in the author's former 

 researches, the alloys were examined micrographically and mechanically in 

 three states : (1) as forged (or normalised by slow cooling from 900° C.) ; 

 (2) quenched ; (3) annealed. Numerous tables of the results of 

 tensile, shock, and hardness-tests are given. As in nickel steels, etc., 

 alloys containing y-iron are transformed by cold working, the y-iron 

 changing to martensite in a greater or smaller degree. Similar effects 

 result from cooling in liquid air. The author considers that his deduc- 

 tions as to the constitution and properties of these alloys, taking the 

 properties of the nickel steels and the manganese steels as data, are fully 

 borne out by the results of his experimental work. Nickel-manganese 

 steels may for many purposes replace nickel steels. 



* Rev. Metallurgie, ii. (1905) pp. 798-9. 



t See this Journal, 1905, p. 776. 



t Rev. Metallurgie, ii. (1905) pp. 801-10 (12 figs.). 



§ Tom. cit., pp. 825-41 (1 diagram, 20 photomicrographs). 



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