534 Mr. J. Brown on the Difference of Potential 



In these well-known reactions the working hypothesis 

 stated above is contradicted by all except No. 7. In No. 8, 

 though chlorine is transferred from left to right, sulphur is 

 eliminated from the hydrogen sulphide and there is thus a 

 complicated reaction. 



3. A number of experiments were now made in the hope of 

 gaining some insight into the kind of results to be obtained 

 from the contact of two solutions between which double 

 decomposition occurred on mixing. After some trials of a 

 tentative kind with solutions of unknown proportions which 

 gave discordant and unsatisfactory results, the remainder 

 were made with solutions containing equivalent proportions. 

 At first the apparatus already described was used, and the 

 numbers obtained with it will be found in column A, Table II. 

 It did not, however, seem quite satifactory, and I constructed 

 another, which is represented diagrammatically in fig. 1 one 

 ninth actual size. Two glass cylinders A, B, about 11 centim. 

 long by 2 centim. diameter, were supported in holes in 

 a paraffin bridge C by means of tight rubber bands i, k. 

 The liquids to be tested were applied by means of pipettes 

 to the interior of these cylinders, or to paper rolls supported 



Fig. 1. 



on shorter glass cylinders which were occasionally used 

 instead of them. Contact was made between two little 

 pools of the liquids on the top of the glass stand D, each 

 connected to the liquid on its cylinder by a strip of filter 

 paper, or, in the case of corrosive liquids, by a tuft of asbestos. 



