212 



Mr. J. C. Graham. On tlic Measurement [June 25, 

 Force Observations, 1902 (C.M.G.). 



[These annual reports will in future be published, along with the 

 other British magnetic observations, in the Reports of the National 

 Physical Laboratory. The Falmouth magnetic observations are 

 published in the Annual Reports of the Royal Cornwall Polytechnic 

 Society, and will also be reprinted in the Reports of the National 

 Physical Laboratory. SEC.] 



" On the Measurement of the Diffusion of Salts in Solution." By 

 J. C. GRAHAM. Communicated by Professor W. E. AYRTON, 

 F.R.S. Received May 14, Read June 11, Received in 

 revised form June 25, 1903. 



In order to get the solution of the salt below the pure water which 

 is above it, without any intermixing at their common surface, the 

 apparatus was used which is shown in fig. 1. A is a cylindrical glass 

 vessel containing a solution of the salt to be investigated, in the lower 

 half, and containing pure water in the upper half. The internal 

 diameter of the vessel was about 125 mm., and the depth of the 

 cylindrical part about 300 mm. B is a tube which passes up through 

 the bottom of the vessel, and is continued outside in the manner 

 shown. C is a tube which opens into the lowest part of the vessel 

 and is connected with a funnel Ci. D is a small tube which passes up 

 the centre of the vessel to the point DI. 



The vessel is first completely filled with pure water through the 

 funnel C l5 until it has risen to the point marked DI ; the cocks X 3 and 

 X 4 being closed, and the cocks Xi and X 2 open. 



