The following is the introduction to a special e-publication called Determining the Age of the Earth (click the link to see a table of contents). Published earlier this year, the collection draws articles from the archives of Scientific American. In the collection, this introduction appears with the title, “Stumbling Toward an Understanding of Geologic Timescales.”
Water is produce bases and says
If you’re referring to he red stuff- the liquids can be ethanol, toluene, kerosene, or isoamyl acetate. They’re transparent so they’re made more visible with red dye. (So I’d guess the answer is ethanol)
I found this in the Wikipedia article ‘Alcohol thermometer’