412 



Mr. T. Proctor Hall on New Methods of 



secure a more steady overflow. The flow was at the rate of 

 two or three litres per hour. The reservoir above was well 

 washed, filled with ordinary distilled water, covered, and left 

 till next day to acquire the temperature of the room. Then 

 the siphon was inserted, and after the flow had continued half 

 an hour the measurements were begun. The flow continued 

 and the temperature of the air in the closet remained constant 

 at 22°-2 C. throughout. 



W (grams). 



Temperature. 



T found. 



T at 18° C. 



2-5612 

 2-5613 

 2-5615 



22-20 

 22-20 

 22-15 



73-138 

 73-141 

 73-146 



73-726 

 73-729 

 73-727 



These measurements were made with a glass frame by the 

 maximum-weight method, and the corresponding values of T 

 found by the formula 



T=4-8926 + 14-027 la + 7-6891 w 2 -V07S6w% 



which was calculated from a series of measurements of the 

 surface-tension of mixtures of water and alcohol, by two 

 methods, as follows : — 



W found (grams). 



T by Method A or B 



(dynes). 



11033 

 1-9180 



2-1220 

 2-3261 



28-280 

 52-472 

 58-975 

 65-549 



A few days later tap-water was allowed to run more slowly 

 through the siphon for four hours, the surface-tension measured 

 in the same way ; then a fresh portion allowed to run more 

 rapidly for half an hour, then again for forty-five minutes. 

 The temperature of the air was in each case 22°'0 C. The 

 three measurements gave : — 



W (grams). 



Temperature. 



T (dynes). 



T at 18° C. 



2-5650 

 2-5631 

 2-5613 



20-6 

 20-5 

 20-5 



73-280 

 73-190 

 73-141 



73-644 

 73-540 

 73-491 



