  This period as Lucasian Professor also marked the beginning of his more private researches in alchemy and theology. Newton purchased chemical apparatus and treatises in alchemy in 1669, with experiments in chemistry extending across this entire period. The issue of the vows Newton might have to take in conjunction with the Lucasian Professorship also appears to have precipitated his study of the doctrine of the Trinity, which opened the way to his questioning the validity of a good deal more doctrine central to the Roman and Anglican Churches.