A few googles pertaining to chemicals in wood finishes, IMO before 1950.

lacquer ~ http://www.wikipedia.org/wiki/Lacquer ~ look for solvents such as naptha, toluene (and I think benzene) and ketones (acetone)

varnish ~ http://www.wikipedia.org/wiki/Lacquer ~ look for solvents such as alcohols (methanol, ethanol) in general, the smaller molecules were outlawed first.*****My dad used some spar varnish (marine varnish) when he refinished an upright piano in the 1950s.******

shellac ~ http://www.wikipedia.org/wiki/Shellac