Findings generated from past classroom observation and individual interviews indicate that certain framework conceptions can be identified by which students explain special transformations of substances and which are activated in view of new experiences made in the course of chemistry instruction. This study investigated these framework conceptions by conducting approximately 30 interviews with 8-13 year-old students. The interviews dealt with burning of alcohol, occurrences during the heating of copper vitriol (aqua copper sulfate) and its recovery, and the extraction of lead from lead ore (lead (IV)-oxide). Several general conceptions of changes of substances were found during the interviews. These include the conception: (1) of an irreversible destruction of substances; (2) of an irreversible changing of properties of lasting substances; (3) of a reversible changing of properties of lasting substances; and (4) that substances with all their properties continue to exist, that they are merely distributed or mixed or separated. (Author/JN)