It's tough to work with COL numbers - at least the way you seem to want to. And actually, if you're thinking of living in France, it's the French COL numbers you'd want to be looking at. Of course that also means that you'd be going onto the French cotisations, which probably vary from those in Switzerland.

When I was working in Freiburg (Germany), we had a few folks who were living in France. Evidently the social insurances were quite a bit cheaper (and that's back before the euro - so they had the whole currency conversion issue to deal with, too).

A friend of mine was living in Switzerland and working at the airport in Mulhouse (which is considered to be the airport for Mulhouse, Freiburg and for Basel.

It's very do-able and there is lots of precedent for "Grenzenspringers" (as the Germans call them. You pay your taxes and social insurances in the country in which you reside (which may be a factor for the employer, depending on what the employer's share is in the various countries).

Check the newsstands when you get over here - in France, at least, the consumer magazines often publish special surveys of salaries by profession for the new graduates - and this is about the right time of year. It should give you at least some idea of what your level of chemical engineer should be getting (in France). Switzerland may have something similar.
Cheers,
Bev