Cool little item , CC .
The liquid within your thermo is alcohol with dye in it , not mercury .
Mercury ore is generally red , but mercury is always silver-colored in it's liquid form .
Altho I'm unclear about the unit (is it sealed or open-bottomed?) , you should be able to gently heat it enough for the alcohol to reach the maximum temp on the scale (do this with a blow-drier , or warm water if the unit is sealed) . This should re-incorporate all of the liquid ; if not , just do the procedure in the following sentence .
While the unit is still warm , 'shake-down' the thermometer (with a sort of snap of the wrist) towards the bottom of the unit .
This should re-incorporate all of the liquid , sans the present air gap .