its Relations to Temperature. 17 



Behavior of other metals. — Kohlrausch,* Streintz, f Schmidt,;]: 

 and Pisati § have discussed the effect of temperature on vis- 

 cosity. More minute investigations on the relation between 

 viscosity and temperature have recently been made with silver, 

 platinum, iron and german silver, and for temperatures within 

 100°, by Schroecler.j It is in place to advert in passing to cer- 

 tain important accordances between Schroeder's results and the 

 present results. In the data above, one or more alternations 

 of the sign of twist are applied to the steel wires (Tables 1 to 

 13, particularly Table 3), and the amount of deformation de- 

 creases (cast, par.) with the number of torsions applied gradu- 

 ally toward a limit. This fact has been studied by Wiede- 

 mann^" and by Streintz under the term "accommodation." 

 Schroecler has apparently enlarged the importance of these ob- 

 servations by showing that repeated alternations of temperature 

 from low to high values have the same effect.** It remains to 

 be seen, however, whether this is not an immediate result of 

 the fact that Schroeder's hard-drawn wires are annealed by ex- 

 posure to 100°. A second result of Schroeder's, ff viz: that the 

 amount of " after-action," as well as the amount of change of 

 after-action due to stated increments of temperature is greatest 

 in silver, of intermediate value in iron, and smallest in german 

 silver, has an important bearing on the present experiments. 

 The present results taken together with the earlier paper of 

 Barus and Strouhal^ show conclusively that the viscosity of 

 steel and the variation of viscosity due to temperature increase 

 in like order, and in ways which throughout the course of the 

 phenomena are thoroughly analogous. A final result of 

 Schroeder's bearing on the present paper, viz : that the viscous 

 detorsion occurring at 100° is arrested by suddenly lowering 

 the temperature as far as 20° is again fully corroborated by the 

 behavior of steel ; but the character of the viscous motion while 

 the temperature either rises or falls does not so fully appear, 

 because a large part of the retrograde movement observed dur- 

 ing cooling is here to be ascribed to concomitant changes of the 

 modulus of elasticity produced by temperature. In other 



* Kohlrausch : Pogg. Ann., cxxviii, p. 216, 1866; clviii, p. 371, 1876. 



f Streintz: Wien. Berichte, lxix, p. 337, 1874. 



t Schmidt: Wien. Ann., ii, p. 264, 1877. 



§ Pisati: "Wien, Berichte, lxxx, p. 427, 1879. 



|| Schroeder: Wied. Ann., xxviii, p. 369, 1886. 



1 Wiedemann: Wied. Ann., vi, p. 512, 1879. 



** !; Ebenso wie das log. Decrement bei Torsionschwingungen zeigt auch die 

 Nachwirkung unter deni Einflusse wiederholter Temperaturanderungen eine Ac- 

 commodation." 



f f " Sowohl die Nachwirkung wie die Anderung derselben mit der Temperatur 

 ist am grossten beim Silberdraht, geringer beim Eisen, am kleinsten beim Neu- 

 silberdraht." 



XX This Journal, xxxiii, p. 25, 26, 1887. 



Am. Jour. Sci.— Third Series, Vol. XXXIV, No. 199.— July, 1887. 

 2 



