342 Day — Residual Viscosity on Thermal Expansion, 



first reading is combined with the third, the second with the 

 fourth, in finding the values of P^ v^—P^ v^ and P^^-P^. 

 Reduced atmospheric pressure = Y4'T6°°^. 



P (cm.) 



V (c.c.) 



F(c.c.) 



Ib'11 



0-16 



239.0 



'74-63 



1-80 



241-1 



73-79 



4-47 





73-27 



6-20 





The method is equally serviceable when a long capillary of 

 irregular and appreciable volume joins the bulb with the ma- 

 nometer, a condition sometimes unavoidable in practice : the 

 volume of the capillary may then be separately found by 

 temporarily plugging up its detached end. 



Wilson Phys. Lab., Brown University, Providence, R. I. 



Aet. L. — The Effect of Residual Viscosity on Thermal 

 Expansion ; by Howard D. Day. 



In the course of certain laboratory experiments, I observed a 

 condition of molecular instability in vulcanized rubber, due to 

 residual viscosity, which seems to be of sufficient interest to 

 deserve publication. 



As the detection of this quality in rubber was made possible 

 by the excellent performance of the apparatus which I em- 

 ployed, a brief description of it will here be given, use being 

 made of the accompanying figure 1. 



The apparatus is essentially the well known German appara- 

 tus for noting the expansion of solids through ranges of tem- 

 perature, but it will be seen to embody several novel features. 



