1. Experiment 2. Inversion of Sucrose
We use a polarimeter (shown to right) to monitor the time-dependent changes in the angle of rotation of polarized light from a sodium-D lamp.
The null point is obtained by turning the handle slowly until the two halves of the image grow equally faint, as illustrated crudely in the movie.
(Here the handle has been turned through the null point and then back again.)

2. 2
The scale on the polarimeter is equipped with a vernier, similar to that on the barometer (Expt. 1). Here the reading is –6.1°.
The polarimeter tubes have different-sized fittings on the two ends, requiring different windows. Take care to use the correct window in each case!

3. 3
Make sure that you understand clearly the concept of mutual dilution, as covered in Study Problems 5 and 6. You will start each run by mixing a measured volume of sugar solution with a measured volume of acid solution. The initial concentrations of both in the run will be determined by their prepared concentrations and their mutual dilution on mixing. Come to class with your plans for preparing these different solutions already worked out in detail. The volume of the polarimeter tubes is ~15 mL, so you will want each mix to contain at least ~20 mL.
Clean up all spillage at the end of the day: We don’t want the next day’s teams sticking to the table!