A rapid volatility analyzer is described, as well as a method for rapidly determining weight changes in substances containing a volatile material. In particular, there is described an apparatus which rapidly determines the percentage of volatiles in a substance which contains unknown quantities of polar volatiles such as water or moisture, solvents, plasticizers and the like. The apparatus provides rapid determinations without operator assistance other than the placing of a sample of the substance being tested on the electronic balance. The particular improvement in the present invention relates to the ability of the apparatus to project final dry weight without completely drying the test sample utilizing a short heat induction period. This improvement greatly reduces the heating time required and avoids overdrying of the test sample.