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 oil is extracted from the seeds of the castor bean plant. Since time immemorial the oil is used for a various hair and skin care problems. It is regarded as valuable oil due to its myriad uses. This liquid oil can be colorless or very pale yellow in color with mild or no odor or taste.