In the previous report, a Chemical Weathering Index（CWI） was proposed to quantitatively evaluate the chemical weathering degree and its trends of granitic residual soils distributed worldwide．This index enables an intuitive represatation of the overall feature of chemical weathering processes.

In this report, a simpler chemical testing method using the water component H₂O（±）（mass ％）is introduced as an alternative to CWI. It has been confirmed that the mass percentage of H₂O（±） is theoretically correspond to the Chemical Weathering Index（CWI）. Furthermore, this method has been found to be cost-effective and practical. By applying this testing method,various types of granitic residual products can be classified based on the following H₂O（±）（mass ％） vallues ： fresh granitic rock： 1–2％, weathered granite： 2–3％, decomposed granitic soil（Masado）： 3–8％, lateritic soil： 8–12％, and laterite（cemented）： over 12％.