In a high-school physics textbook (Heath Physics, 1992, Lexington: D.C.
Heath and Company, pp. 281 - 282) I found some time ago a disturbing
statement about two opposite theories regarding the siphon working:
(1) atmospheric pressure theory and (2) molecular cohesion theory.
As everyone will notice, they differ, at least, in two points:
According to the (1), the maximum lenght of the short arm is the
barometric height of used liquid and a siphon would not work in vacuum.
According to the (2), for a very cohesive liquid, the maximum lenght can
be bigger than the barometric height and a siphon would work in vacuum.
A search through the literature at hand and the Internet confirmed that
statement about a controvers on siphon working is not an exaggeration.
As siphon working in vacuum is an experimentum crucius for this
controversial issue, I wonder if somebody on the list knows something
about any experiment which could corrobate the statement from the above
mentioned textbook:
"Experiments verify that pure liquid can be syphoned in a vacuum..."
(ibid, p. 281).
Best wishes
Josip Slisko
Professor of Physics Education
Faculty of Physical and Mathematical Sciences
Autonomous University of Puebla
Puebla, Mexico