This method of test is intended for the determination of the amount of constituents in petroleum products that will saponify under the conditions of the test. Since compounds of sulfur, phosphorus, the halogens, and certain other elements which are sometimes added to petroleum products also consume alkali and acids, the results obtained indicate the effect of these extraneous materials in addition to the saponifiable material present. Results on products containing such materials, on used internal combustion engine crank case oils, and on used turbine oils must be interpreted in this respect.