1888. ] Mr Monckman, Note on some Experiments. Ziel 
March 12, 1888. 
Mr J. W. CLARK, PRESIDENT, IN THE CHAIR. 
W. H. Macautay, M.A., Fellow of King’s College, was elected 
a Fellow of the Society. 
The following communications were made: 
(1) Note on some Experiments on the Creeping of Solutions. By 
JAMES MoncKMAN (D.Sc., Lond.), Downing College. 
The curious property of certain salts in solution, of covering 
the sides of the vessels in which they are placed with crystals is 
well known. It is often slow at first, as though it varied with the 
state of the vessel, or required something to set it off, after which 
it progresses rapidly. When one side of a crystal of sulphate of 
copper is rubbed flat and polished it is found that a solution of the 
same salt does not rise so high on the smooth surface as on the 
rough one, but that in both cases it extends further than on glass. 
This is shewn by placing a crystal, one of whose sides 1s polished, in 
contact with the solution in such a manner that the side may be 
vertical. Strips of glass are also fixed in the same liquid, and 
after remaining for an hour they are removed, and the portion over 
which the liquid has spread is measured. 
An experiment gave the following numbers :— 
Height to which the liquid rose on the . 
rough side of the crystal... 10 mm. 
ee 56 
»” »” ” smooth %) > ” 
“5 i, rough glass a on Os 
3 5) - smooth glass... Ein es 
These numbers shew that when crystals are once deposited the 
solution will rise more rapidly, but they afford no indication of the 
cause of deposition of the first line of solid. Thinking that this 
was probably due to the combined action of shaking and evapora- 
tion, I placed a number of watch-glasses of various sizes and cur- 
vatures upon a stone table, which was free from the vibrations of 
the floor. When perfectly still, sulphate of copper solution was 
allowed to flow into them from a burette, care being taken to pre- 
vent dropping by which waves would be produced and the watch- 
glass wet above the line of the liquid. 
The glasses were then covered with a bell jar. After remaining 
thus for three days there was no trace of creeping, but when the 
jar was removed and evaporation allowed to commence the crystals 
began to appear, and, in the case of those glasses which contained 
sufficient liquid, the crystals spread over the edge of the vessel. 
