1888.] Effect of Surface Tension on Chemical Action. 267 
influence of the latter will probably extend to a greater depth 
than that of the former, so that though a very thin layer imme- 
diately in contact with the glass is influenced by its attraction 
there will be a layer beyond this which is governed by the attrac- 
tion of the liquid and whose energy changes in the same way 
as the surface tension of the surface separating it from air, 
the fluid in this layer can move about more freely than that 
next the glass, and thus new portions of fluid are continually 
coming under the same influence, so that its effect on the rate 
of change gets multiplied and thus gains the upper hand over the 
effect produced by the glass. 
In Applications of Dynamics to Physics and Chemistry, 
p- 191, it is shown that when a solution of a salt flows through a 
tube, the solution will get stronger as it flows if the surface tension 
of the surface separating the solution from air diminishes as the 
strength of the solution increases and wice versd. The following 
experiments were made to illustrate this point. 
The apparatus consisted of a two-necked 
globe A, a glass tube B, and a receiver C. Ai B 
In Ba small piece of cotton-wool was first 
introduced and afterwards enough fine silica 
to fill half-an-inch of the tube. These were 
well compressed and another equal quantity of silica introduced, 
and so on until nearly full, when a little cotton-wool was pressed 
into the tube to prevent the powder being carried away by the 
liquid. So closely was the silica pressed together that although 
B was not more than 8 inches in length only 1 cc. of water passed 
through in 3 days. 
Three solutions whose surface tension were greater than water 
were first tried. These were sulphate of copper, chloride of 
iron and permanganate of potash, and in all cases the salt was 
retained behind the water. 
To test the matter more fully two liquids were mixed with 
the water whose surface tension is less than that of water. A 
little paraffin was shaken up with hot water, by which means a 
very small quantity was dissolved. After being in the apparatus 
about a week the liquid in A and that portion which had passed 
through into C were examined, and it was found that the surface 
tension in (’ was less; at the end of the second week the same 
appeared. 
The hydrochloric was diluted with an equal volume of water 
and placed in a similar bottle. This gave the same result as the 
others. 
Now, the surface tension of solutions of salts is, in almost all 
VO Vi Pi Lv, 19 
