Tension of Soap Solutions for Different Concentrations. 66' 



Table II. 



Surface Tension of Castyl Soap Solution used for Water 

 Analysis. 



(By the Bubble method.) 



Length of the Manometric column 9"40 cm. 



Saturated 



solution. 

 0-5 of 

 0-33 



No. of rotations j Diameter 

 of the micrometer j (to be multiplied 

 screw. by 5/5-70). 



Surface Tension. 

 (Dynes per cm.) 



13 121 

 13 185 

 13 00 



300 cm. 

 2-93 ., 

 3-09 „ 



23-66 

 23-61 

 23-52 





Length of the manometric column : 9'75 cm. 











Diameter 













(to be multiplied 













by 3/5-34). 







0-25 





12 189 



2-86 cm. 





23-70 



0-17 





12 69 



2-96 „ 





23 57 



0-090 



}) 



12 237 



2-80 „ 





23-57 



0062 



jy 



15 87 



2-38 ., 





23-69 



0-048 





14 71 



2-55 „ 





23-62 



0038 





14 236 



2-47 „ 





23-98 



0032 



„ 



15 46 



2-40 „ 





23-62 



0-028 





16 45 



2-31 „ 





24-23 



0024 



.. 



16 45 



2-31 „ 





24-23 





For f- 



irther dilutions no 



bubbles could be formed. 





To compare the values thus obtained with those by the 

 capillarity method, the surface tension for the same concen- 

 trations has been determined by the capillarity method. 

 Most of the tubes, to be ordinarily met with have been 

 discarded for want of a perfectly uniform and circular bore. 

 For this purpose, the stem of a broken thermometer is found 

 to answer excellently well, notwithstanding the elliptical 

 nature of the bore. If 2a and 2b are the major and minor 

 axes, the area of the section of the bore is evidently irab, 

 and the perimeter 



7T 



4 1 {a 2 sin 2 cf> — b 2 cos 2 (£)^?</> 



Jo 



= 4al (1 — e 2 cos 2 (f))id<fi, 



