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.
In addition to its internal use as a laxative, castor oil poultices and packs may alleviate joint pain. While using castor oil for pain relief is a popular practice in alternative medicine circles, scientific studies supporting the oilâs curative effects are lacking. Visit with your doctor to rule out a serious condition before using castor oil to relieve joint pain.