The Evaporation of Mercury
1) It is still stated unequivocally in textbooks today that within a Torricellian barometer an “absolute vacuum” occupies the space above the mercury, as in the image below.
2) If this experiment is carried out in the same way, but with a much longer tube, of say 1.5 metres, that is filled and erected to vertical the mercury in the tube will remain at a level determined by the atmospheric pressure acting on the surface of the exposed liquid.
3) It is observed that mercury freely evaporates and rises rapidly up through the atmosphere at STP, as seen in this video:-
http://www.youtube.com/watch?v=JABbofwD3MI
(Here it is important to point out that single mercury atoms could not by any means act to diffract ultraviolet light, therefore the gas that is illuminated is composed of a large number of atoms forming visible globules of mercury gas.)
4) Mercury liquid with an amu of 200 and a density of 13.5 gm/cc is said to have a “relative vapour density” of 6.9 gm/cc and, as the density of air is 1 gm/cc, it is obvious that this gas should not rise rapidly as observed in the video.
5) This experiment is therefore direct and unequivocal proof that gaseous mercury has a density lower than that of the atmosphere at 1 gm/cc.
6) In the conditions of low pressure generated by the action of gravity upon the mass of the liquid during the elevation of the ‘barometer’ tube to vertical (as described in 2 above), it will evaporate more rapidly than it does at atmospheric pressure, and so will fill the space above the liquid with mercury gas.
7) This is direct and unequivocal proof that an absolute vacuum is not present above the mercury liquid in a barometer.
8) Therefore a lower than atmospheric force of pressure is acting upon the surface of the liquid in the tube.
9) But if this space were filled with a kinetic atomic gas, that is volumetrically composed mostly of a vacuum then, as this vacuum component (as depicted in the diagram above) cannot resist its own expansion, there is no reason to assume that this process of the evaporation of mercury atoms into this void would cease at any level of pressure, and it should follow that evaporation would continue until the liquid in the tube subsides to the level of the mercury liquid that is exposed to atmospheric pressure.
As this does not occur, it is obvious that there are other forces acting on the liquid to maintain the levels that are observed to be directly dependent on the differentials between the internal pressures and the external, atmospheric, pressures.
Conclusion
It is obvious that a differential exists between the pressure acting on the surface of the liquid within the tube and that on the surface exposed to the atmosphere, and that the pressure within the tube is significantly lower than atmospheric.
It follows from 2 and 3 above that if any volume of vacua were present, either inter-atomically or sub-atomically, in the space above the liquid in the tube then, as a vacuum cannot resist its own expansion, it would do so and the column would subside to the exposed level.
As this patently does not occur then it follows that no vacuum (or indeed any aetherial, ‘vacuum filling’, non-interactive substitute) can ‘exist’ within the tube.
This is therefore a direct and complete contradiction of the general belief that Torricelli’s experiment proved the ‘existence’ of a vacuum and instead is unequivocal proof that it does not ‘exist’, it is not present here.
The evidence mentioned above is also an unequivocal proof that gaseous mercury cannot be, as is stated unequivocally in the literature – “Density of mercury vapour relative to air = 6.92”, i.e. 8.28 gm/cc.
There does not appear to be any data on the volumetric expansion of mercury to its gas state, however a comparison can be made with the expansion of water to steam/water vapour.
A drop of water of a volume of 1 cc on a table at STP will evaporate rapidly and completely within a few hours, and in doing so will have expanded to a gas occupying a volume 1700 times that of the liquid, and so produce 1.7 litres of water vapour.
This gives a density for such an enclosed volume of water vapour of 1/1.7 = <0.6 gm/cc, which of course as globules of steam are observed to rise rapidly.
If we have a pool of mercury of the same volume, it will also evaporate rapidly but, as is directly observed in experiment, it will take ten years to do so completely.
The mass of a water molecule is 18 amu and as this expands 1700 times to a gas, then it can be estimated that, in direct proportion mass to mass, mercury at 200 amu will expand 200/18 = 11.1 times that of water.
Therefore 1 cc Mercury would expand proportionately on this basis (11.1 x 1.7 = 18.9) and (in ten years) produce a volume of 18.9 Litres of mercury vapour.
Mercury in liquid form has a density of 13.6 gm/cc.
From this we get 13.6gm/18.9L = 0.72 gm/cc
Therefore 1 cc of Mercury liquid would over ten years evaporate and form a gas of total volume 18.9 Litres, and which, on this estimate, would have a density of 0.72 gm/cc and would accordingly, and as is observed, rise rapidly through an atmosphere at 1.0 gm/cc.
The video of mercury evaporation has similarities to that of the evaporation of water, in that globules of gas emerge from the surface of the liquid and progressively dissipate into single atoms, which do not diffract light and so become invisible.
Therefore it is evident that individual mercury atoms in the liquid state expand physically with a concurrent absorption of energy, there can be no other explanation.
Roger Munday