Talk:Stalagmometric method
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correction
[edit]The first formula says that
\ mg=2\pi r \sigma
The drop is falling when the weight (mg) is equal to the circumference (2πrσ) multiply by the surface tension (σ). The surface tension can be calculated when we know the radius of the tube (r) and the mass of the fluid (m)
--mg should be changed to simply m. g implies another variable. also, it says "(mg) is equal to the circumference (2πrσ) multiply by the surface tension (σ)." The text is wrong in that it sounds like the formula should be σSuperscript text. The σ should be removed from "...equal to the circumference (2πrσ)" —Preceding unsigned comment added by 71.197.129.22 (talk) 19:51, 12 January 2009 (UTC)
Tate's law
[edit]Tate's Law [T. Tate, Phil Mag, 27, 176 (1864)] is very generalized. Harkins and Brown published a landmark paper on surface tension by drop size [W.D.HARKINS & F.E.BROWN, J. Am Chem Soc, 41,499-524 (1919)] in which the imperfections of Tate's Law were addressed. These result because the entire drop, which weight is suspended by the orifice circumference, does not fall - there is a residual drop remaining at the dropping tip, reducing the size of the fallen drop. Also the walls of the hanging drop are not vertical so the downward component of drop weight is reduced. A third problem is that the drops are in a dynamic condition where fluid is flowing into the drop during the detachment process. Harkins and Brown corrects for the first two problems. The surface tension calculated by the use of a ratio of a standard fluid drop size is probably the best approximation you can get, but it is an approximation.
Ccronan (talk) 19:44, 27 February 2010 (UTC) Cronan