1. The lamp VV, TT, AA, or the wheel burner:
2. The lens B for condensing the rays and rendering them parallel:
3. The tube I, blackened inside to carry the lens:
4. A thin lamina E, cut from a crystal of potassium bichromate, serving to render the sodium light more monochromatic: When the saccharine liquids under examination are colored the crystal of bichromate is removed before the observation is made.
5. The polarizer R, which is rotatable through a small angle by the lever K:
6. The lever JK for rotating the tube containing the polarizer: This is operated by the rod X extending to the left.
7. Diaphragm D, half covered with a lamina of quartz.
8. Trough L for holding the observation tube: In the large instrument shown in the [figure], it is more than half a meter in length and arranged to hold an observation tube 500 millimeters long.
9. Disk C, carrying divided circle and arbitrary sugar scale:
10. Mirror M, to throw the light of the lamp on the vernier of the scale: