ASTM D565 Standard Test Method for Carbonizable Substances in White Mineral Oil
7. Procedure
7.1 Clean a test tube with a chromic acid (H2CrO4) cleaning solution (Warning - Causes severe burns. A recognized carcinogen. Strong oxidizer.), or use a nonchromium containing, strongly oxidizing cleaning solution.
7.2 Fill the test tube to the 5 mL mark with H2SO4 (94.7 +/- 0.2 %). Then add the oil to be tested to the 10-mL mark, insert the stopper loosely, and place the test tube in position in the water bath at 100 +/- 0.5°C.
7.3 After the test tube has been in the water bath for 30 s, loosen the stopper sufficiently to release any pressure and reinsert, remove the test tube from the bath quickly, hold with a finger over the stopper, and give three vigorous, vertical shakes over an amplitude of about 5 in. (127 mm), shaking the test tube quickly and at a rate corresponding to 5 shakes/s. (A shaking machine may be employed provided the results that can be obtained agree with those obtained by the prescribed manual agitation.) Repeat every 30 s. Do not keep the test tube out of the bath longer than 3 s for each shaking period.
7.4 At the end of 10 min from the time the test tube was first placed in the bath, remove the test tube and allow to stand in the room for not less than 10 min nor more than 30 min. Observe and record any discoloration of the oil layer. Place the test tube in the color comparator, and compare the acid layer with 5 mL of the standard colorimetric solution and 5 mL of white mineral oil in a test tube that has been shaken vigorously for 10 s and allowed to stand just long enough for the contents to separate into two layers.
