(a) This is a systematic scheme for the examination of industrial water and industrial waste water. The order of application of methods for chemical and physical measurements permits the determination of existing constituents and properties in logical sequence. (b) This scheme is intended to aid the water analyst in choosing an analytical course that he can follow to determine one or all of the constituents or properties of industrial water. The outline indicates by general groupings of water constituents and properties the general procedures that must be followed in obtaining the sample, depending upon the information desired. By further subgrouping it also indicates what general precautions must be observed in preserving the character of the sample with respect to the desired analysis. (c) There are four schematic outlines. The first (Fig. 1) shows the general schematic relationship of the principal groups of samples. The remaining three (Tables I to III) list the constituents and properties that can be determined on each group of samples. (d) The constituents or properties in each group appear in alphabetical order, where possible. Where a simple, acceptable test for a given constituent or property is desirable in providing information useful in subsequent analyses to be performed on a sample, it is indicated by an asterisk. For example, a colorimetric silica determination would indicate the volume of sample that would contain silicon compounds equivalent to at least 10 mg of SiO2, as specified in the referee method for SiO2 in the Methods of Test for Silica in Industrial Water and Industrial Waste Water (ASTM Designation: D 859). Completion of such a simple preliminary test would save considerable time. (e) Each constituent or property of a sample group that is listed without indentation from the margin (see Table I to III) indicates that a separate portion is required for the analysis for that particular constituent. Where an analytical scheme is possible or desirable, and one or more constituents may be determined on a single sample by a scheme of successive analyses of filtrates or aliquots, the constituents determined in the scheme are indented in reference to the appropriate preceding constituent.