[ CLARK] 



VISCOSITY OF ETHYL ETHER 



63 



CONCLUSIONS. 



The foregoing results lead to the following conclusions: — 

 I . The logarithmic decrement of an oscillating cylinder suspended 

 in the liquid side of the tube decreases with rising temperature, reaches 

 a minimum near the critical temperature and then rises rapidly as 

 the temperature is raised above this point. See Figure 11. For 

 very high temperatures the increase is approximately proportional 

 to the change in temperature. 



jp6 



,01- 



,oz 



lOO" 



Liquid 



200 



Fig. 11. 



II. The decrement for the cylinder in the vapour side of the 

 tube rises slowly as the temperature is raised above the room temper- 

 ature, more rapidly as the critical temperature is approached, and 

 still more rapidly above this point. (See Figure 11). The curves 

 for liquid and vapour probably coincide at some temperature well 

 above the critical temperature, which depends probably both on 

 the amount of substance in the tube and the rapidity of the rise of 

 temperature. This temperature has not been determined as it 

 was not wise to run the risk of breaking the tubes. 



III. Above the critical temperature the liquid side shows an increas- 

 ing decrement with rising temperature and a decreasing decrement 

 when the temperature is lowered again. The curve for falling tempera- 

 ture is always lower than that for rising temperature unless the meniscus 

 vanishes at the bottom of the tube. If the tube is heated a second 

 time from the critical temperature, the decrement is lowered again 

 slightly. This last curve is apparently about where the curve for 

 the vapour side of the tube would be. 



