2. Excess of subacetate of lead solution in clarification.
3. Incomplete mixing of solution after making up to mark.
4. Imperfect clarification or filtration.
5. Concentration of solution by evaporation during filtration.
6. Undue compression of the cover glass.
7. Alteration of the temperature of room, position of instrument, or intensity of light while the observation or control observation is being performed.
8. Performances of polarization with a cloudy, dim, or not completely round or sharply defined field.
In closing this report the members of this commission hereby signify their intention to promote uniformity and accuracy by adopting and using the standards and general plan of procedure recommended in this report in the polarimetric determinations over which, in their respective branches of government work, they have control.