[Alexey]

Cooling baths with dry ice
see uploaded file .pdf

cooling bath mixtures

[Alexey]

There is a nice mixture of o-xylene and m-xylene with dry ice which is decribed in the pdf in the post above. This mix can give a temperature in range -72 to -26 depending on proportions of o-xylene and m-xylene.
(m.p. of m-xylene is -48°C, m.p. of o-xylene is -26°C).

A few notes (from our experience):

1) The plot in the pdf above is not very precise. E.g. mix 66:34 indeed gives -40°C. On he other hand, mix 33:64 gave me not -60°C, but -70°C, so I had to add a little bit of o-xylene, but finally it worked fine.

2) Do not add too much dry ice, otherwise the whole mixture will freeze. It should be always a piece of dry ice covered with froozen xylenes AND the not frozen liquid phase. The desired temperature is the temperature of the liquid phase, but not of the solid.

[joetraff]

it would be better if you provide some pdf more specific.