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.
As a pharmaceutical grade inactive ingredient, castor oil is used to emulsify and solubilize oils and other water-insoluble substances. A brand name product that contains castor oil is Cremophor and it contains a range of non-ionic polyethoxylated detergents. It was originally developed for use as solubilizers and emulsifiers.