METALLURGY. 



479 



the close of the last term, he was elected a 

 justice of the Supreme Court of Pennsylvania. 

 He resigned his seat in Congress in December, 



ULYSSES MERCUR. 



1872. Upon the expiration of the term of 

 Chief-Justice Sharswood, in January, 1883, 

 Judge Mercur was chosen his successor, and 

 he continued in that office till the day of his 

 death. 



METALLURGY. Iron and Steel. An important 

 contribution to the subject of measuring the 

 endurance of metals ha been made by Mr. Hen- 

 ry Adams in a paper on the strength of iron 

 and steel. He remarks, that at first sight the 

 material which would bear the greatest steady 

 stress before breaking would be considered the 

 safest and most reliable; this would be a mis- 

 leading conclusion ; for, in many cases this ap- 

 parent strength is due to a want of elasticity, 

 and a very slight jerk or sudden application 

 of a small stress would cause fracture. When 

 the failure occurs without much stretching the 

 pull acts through an extremely small distance, 

 and therefore the mechanical value or work 

 done is also small, although the pull itself may 

 be of considerable magnitude. The toughness, 

 which is after all the chief quality sought for 

 structural purposes, depends as much upon the 

 elasticity as upon the ultimate tensile stress. 

 Among the examples presented by the author 

 in illustration of modes of fracture was a piece 

 of wrought-iron known to have been in use as 

 a lever for fifty years, which was remarkable 

 for the very large and perfectly formed crystals 

 appearing over the whole section. 



The experiments of Carl Barus and V. 

 Stronhal upon the viscosity of steel and its re- 

 lations to temperature have led to some inter- 

 esting results. Abstracting for the moment 

 from the states of temper extreme hard and 

 extreme soft, it appears that the viscosity of 

 steel decreases in proportion as the hardness 

 of the metal increases. Experiments in com- 

 parison of the viscosity of glass and steel showed 

 that the torsional viscosity of annealed steel is 



greater than that of glass. The viscosity of 

 hard steel during the first ten hours of detorsion 

 was very much greater than that of glass; but 

 the curve thereon passed through a maximum 

 for which point the rates of viscous detorsion 

 of glass and of glass-hard steel coincide, after 

 which the viscosity of the steel is decidedly 

 less. The viscosity of iron during the first five 

 or ten hours of detorsion is in a strikingly pro- 

 nounced manner less than that of steel. As 

 detorsion continues the viscosity of soft iron 

 remains below that of steel, whereas the vis- 

 cosity of drawn iron grows temporarily greater 

 than that of steel, but finally reaches the same 

 value. These experiments justify the infer- 

 ences that the viscosity of glass is not uniformly 

 greater than that of glass-hard steel, and that 

 the viscosity of steel is not uniformly greater 

 than that of iron. Again, leaving the extreme 

 states of hardness out of view, it is found that 

 both the viscosity and the moment of linear 

 magnetization per unit of mass, of a perma- 

 nently saturated steel rod, increase in a marked 

 degree from hard to soft. Hence, permanently 

 saturated linear magnetic intensity and vis- 

 cosity on the one hand, magnetic stability or 

 coercive force or hardness on the other, seem 

 to belong together. The minimum of perma- 

 nent linear intensity of saturated steel rods has 

 no viscous equivalent ; but the viscosity of ex- 

 tremes of hard steel has not yet been studied 

 minutely by the authors, nor have they as yet 

 sufficiently precise data for determining the re- 

 lation of the magnetization of very long rods in 

 temper. In the extremely soft region, the oc- 

 currence of a unique maximum of magnetiza- 

 tion seems to be coincident with the occurrence 

 of maximum velocity, In general, as the ratio 

 of length to diameter increases, the minimum 

 of permanent magnetization shows a tenden- 

 cy to move from soft to hard. The general re- 

 lations between viscosity and maximum per- 

 manent linear intensity of magnetization ob- 

 served for steel are sustained in iron. Among 

 the chief results of their experiments the au- 

 thors place the light thrown on the crucial im- 

 portance of the physical changes which steel 

 undergoes when annealed at high temperatures, 

 that is, when subjected to the action of tem- 

 peratures between 500 and 1,000. 



In a subsequent paper on " The Effect of 

 Magnetization on the Viscosity and Rigidity of 

 Iron and Steel," Mr. Barus shows that the effect 

 of longitudinal magnetization on either mate- 

 rial within the elastic limits is marked detor- 

 sion, increasing in amount with the intensity 

 of the magnetic field, increasing also with the 

 rate of twist, at a retarded rate in both in- 

 stances, toward a maximum. If the sense of 

 the magnetization be reversed, the amount of 

 detorsion is in general unchanged. "With steel, 

 the effect of magnetization on rigidity during 

 the first phase of annealing is almost nil, but 

 becomes important during the second phase. 



Experiments have been made at the works 

 of the Bethlehem Iron Company in a new sys- 



