A potometer measures how factors such as light, temperature, humidity, light intensity and wind will affect the rate of transpiration. The main type of potometer is the 'bubble' potometer shown in Figure Figure 6.
Physicians recommended against the practice because they did not want medicines associated with punishment. A heavy dose of castor oil could be used as a humiliating punishment for adults, especially political dissenters. Colonial officials used it in the British Raj (India) to deal with recalcitrant servants. Belgian military officials prescribed heavy doses of castor oil in Belgian Congo as a punishment for being too sick to work.
Castor works well as a toenail fungus treatment. For the same reason it helps fight acne, castor oil can get rid of persistent fungal infections, moles and cysts. Traditionally, the method used was to apply a small amount of castor oil with a pinch of baking soda to the infected area.