Vacuum possible from Gaede mercury pump from 1913.

[sum10fishy]

I am working on a computer simulation for an undergraduate capstone project. In the simulation I am trying to model an experiment done by Moseley and Harling in 1913 described in the paper The Attainment of High Potentials by the Use of Radium found in the Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character Vol. 88, No. 605, Jul. 1, 1913.

In the paper they draw a vacuum using a Gaede mercury pump while heating their apparatus as well as some other measures to try and achieve a very high vacuum, however, they never state what they consider a high vacuum.

Does anyone know what was considered the highest possible vacuum in 1913? I have done a good deal of searching but have had no luck in finding what vacuum was possible with this pump or at that time.

Thanks

 

[etudiant]

Scientific American did an excellent writeup on the various vacuum pump options and the issues arising at really low pressures, below .001 Tor. This was sometime in the 1960s, if memory serves, but it would answer your question.

 

[maimonides]

I used a mercury diffusion pump (quite) some time ago. With a bit of heating the vacuum got down below 10-5 torr.
Of course there was a cryotrap between the pump and the vacuum vessel (liquid nitrogen).

 

[sum10fishy]

Thank you both for the replies! I will see if I can get my hands on a copy of that article.