190 



C. Barus — Viscosity of Solids. 



Table. 3. 



Viscous detorsion of platinum 6=6' 





% + ^) 



rn 



S 



— 



— -xlO 3 



r 



i 

 i 



1 • 



CO 



M 

 r gg 



2(<P + f)\ S 



6 



a 



6— 6' 



— -xlO 3 



r 







X 



H- 









P3 



H 





Z=26-2 cm 



-•0867 



a 



2 



— 000 





-•0436 



d 



2 



- o-oo 



p = -0215 cm 







9 

 15 

 27 



—3-31 



-4-42 

 -565 









7 

 17 

 25 



-22-20 

 -41-40 

 -50-20 





-•0344 





33 



-5-89 









43 

 54 



-61-40 





-•0652 



b 



2 

 17 



-o-oo 



-3-59 



-•0773 



— 65-80 







-•0383 e 



3 



+ o-oo 





-0556 





44 



-4 90 



+ o-oo 







7 

 26 



5-56 





-•0443 



c 



1 



19-60 









4 



20-60 





■1 



47 



2780 









14 

 28 



46-80 

 61-90 





— •0826 



55 



30-00 





Z=26-5 cm 



-•0396 / 



3 



- o-oo 





— •0*766 





44 



71-90 



p=-0212 cm 





8 

 13 



-10-90 

















-17-50 



















29 



-29-20 



















37 



-33-00 















-•0813 





46 



-36-80 



The two wires of table 3 were originally identical, so that 

 the apparatus showed <p=<p'. Both wires were then twisted, 

 but the lower more than the upper. The results under a indi- 

 cate greater viscosity for the lower, a state of things which is 

 only partially wiped out by annealing at red heat, in air, as 

 indicated under t. I then commenced the experiments proper 

 of the table, by leaving the upper wire untouched and anneal- 

 ing the lower wire at red heat. The results under e indicate 

 an enormous difference, the un- annealed wire being of greater 

 viscosity. I then left the lower wire untouched and annealed 

 the upper wire at red heat. The results under d again show 

 an enormous difference, the un-annealed wire (now the lower) 

 being of greater viscosity. I then again annealed the lower 

 wire only, obtaining the results under e, corresponding to c, 

 and finally again annealed the upper wire only, obtaining the 

 results under f, corresponding to d. The operation of alter- 

 nate annealing might have been continued very much longer 

 with, practically the same results. In each case the freshly 

 annealed wire shows a pronounced loss of viscosity, as com- 

 pared with an otherwise identical wire, slightly twisted beyond 

 the elastic limits. 



As compared with the effects of alloying, I found this result 

 so large as to compel me to abandon my experiments on the 

 viscosity of series of platinum alloys, — at least until the me- 

 chanical error in question has been interpreted and brought 

 under control. 



