E 
5 
W. Thompson on the size of Atoms. 41 
a chemical combination, if ee such thin plates could be 
made without splitting atom 
The theory of capillary aiirockielk shows that when a bubble 
—a soap-bubble for instance—is blown larger and larger, work is 
done by the stretching of a film which resists extension as if it 
were an elastic membrane with a constant contractile force. 
This contractile force is to be reckoned as a certain number of 
contractile force. In an a ai mm. the Thermal effect of 
g 
energy, in the shape of heat, must be esp to the film to pre- 
vent 1t from sinking in temperature while it is being drawn out. 
Hence the intrinsic energy of a mass of water in the shape of 
a film kept at constant temperature increases by twenty- “fore 
ee for every square millimeter added to its 
gop then a film to be given with a thickness of a milli- 
— and suppose its area to be augmented ten thousand and 
one fold: the work done per square millimeter of the orig- 
seed film, that is to say per milligram of the mass, would be 
240,000 millimeter-milligrams. The heat equivalent of this 
is more than half a degree centigrade of elevation of nap sic 
ture of the substance. The thickness to which the film is 
reduced on this supposition is veky approximately a ten-thou- 
sandth of a millimeter. The commonest observation on 
whieh gives ‘the ak ci Eon ot se the lack 
pas seen where the oncom is thinnest, is only about an eight- 
Sama: of a millimete 
very moderate smasher of work shown in the preceding 
parc is quite consistent with this deduction. But su 
now the film to be further stretched, until its ee is 
reduced to a twenty-millionth of a millimeter. ork 
spent in doing this is two thousand times more than that which 
we have just calculated. The heat equivalent is 1,180 times 
