266 Prof. J. J. Thomson and Mr J. Monckman, On the [June 4, 
The experiments may be tabulated thus: 
Effect of placing the 
liquid in thin films 
between glass plates 
upon the chemical 
Changes in 
dies mixed. : 
Names of bodies mixed i et éo toReTOny 
action. 
1. Solutions of Sugar and of ; 3 
Permanganate of Potash decreased, quickened. 
2. Hyposulphite of Soda and é 
Bichromate of Potash increased, retarded. 
3. pe B eee and ines, ss 
4. Another specimen of Perox- 
ide of Hydrogen and three \ - 
other Aniline Colours (Red, HEELSGL quickened. 
Mauve and Dark Blue) 
5. Peroxide of Hydrogen and 
MeGue increased, retarded. 
6. Teen Hon Teunea © decreased, quickened. 
7. Indigo and Nitric Acid decreased, quickened. 
: diminished. See 
8. ais anid RE Ob aoh ere increased, | Liebreich, Phil. 
Mag. v. 33, p. 468. 
In experiment 7 there was at first an increase in the length of 
the capillary column, produced by evolved gas, but after standing 
twelve hours this disappeared and there was a decrease. 
Thus when the surface tension of the surface separating the 
solution from air increases as chemical action goes on, the action 
is retarded and vice versd. 
There is one point which requires explanation in the above 
results; it is evident from them that though the films are m 
contact with glass yet it is the surface tension of the surface 
in contact with air which determines the alteration in the rate 
of chemical action, for since the surface tension against glass 
diminishes when that of the surface in contact with air increases 
and vice versd, if the phenomena had been governed by the surface 
tension of the glass liquid surface they would have gone in the 
opposite way. We can we think see the reason for this if we 
consider how the energy which shows itself as surface tension 
arises. Let us consider a thin film near the surface, the difference 
between the energy in this film and that in one of the same 
thickness in the body of the fluid arises partly from the un- 
balanced attraction on it of the rest of the liquid and partly 
from that of the substances against which it is in contact. The 
